ogr_core.h and ogr_api.h: Vector C API

Core portability services for cross-platform OGR code.

Defines

OGRERR_NONE

Success.

OGRERR_NOT_ENOUGH_DATA

Not enough data to deserialize.

OGRERR_NOT_ENOUGH_MEMORY

Not enough memory.

OGRERR_UNSUPPORTED_GEOMETRY_TYPE

Unsupported geometry type.

OGRERR_UNSUPPORTED_OPERATION

Unsupported operation.

OGRERR_CORRUPT_DATA

Corrupt data.

OGRERR_FAILURE

Failure.

OGRERR_UNSUPPORTED_SRS

Unsupported SRS.

OGRERR_INVALID_HANDLE

Invalid handle.

OGRERR_NON_EXISTING_FEATURE

Non existing feature.

Added in GDAL 2.0

wkb25DBit

Deprecated:

in GDAL 2.0. Use wkbHasZ() or wkbSetZ() instead

wkbFlatten(x)

Return the 2D geometry type corresponding to the specified geometry type.

wkbHasZ(x)

Return if the geometry type is a 3D geometry type.

Since

GDAL 2.0

wkbSetZ(x)

Return the 3D geometry type corresponding to the specified geometry type.

Since

GDAL 2.0

wkbHasM(x)

Return if the geometry type is a measured geometry type.

Since

GDAL 2.1

wkbSetM(x)

Return the measured geometry type corresponding to the specified geometry type.

Since

GDAL 2.1

ALTER_NAME_FLAG

Alter field name.

Used by OGR_L_AlterFieldDefn().

ALTER_TYPE_FLAG

Alter field type.

Used by OGR_L_AlterFieldDefn().

ALTER_WIDTH_PRECISION_FLAG

Alter field width and precision.

Used by OGR_L_AlterFieldDefn().

ALTER_NULLABLE_FLAG

Alter field NOT NULL constraint.

Used by OGR_L_AlterFieldDefn().

Since

GDAL 2.0

ALTER_DEFAULT_FLAG

Alter field DEFAULT value.

Used by OGR_L_AlterFieldDefn().

Since

GDAL 2.0

ALTER_UNIQUE_FLAG

Alter field UNIQUE constraint.

Used by OGR_L_AlterFieldDefn().

Since

GDAL 3.2

ALTER_DOMAIN_FLAG

Alter field domain name.

Used by OGR_L_AlterFieldDefn().

Since

GDAL 3.3

ALTER_ALTERNATIVE_NAME_FLAG

Alter field alternative name.

Used by OGR_L_AlterFieldDefn().

Since

GDAL 3.7

ALTER_COMMENT_FLAG

Alter field comment.

Used by OGR_L_AlterFieldDefn().

Since

GDAL 3.7

ALTER_ALL_FLAG

Alter all parameters of field definition.

Used by OGR_L_AlterFieldDefn().

ALTER_GEOM_FIELD_DEFN_NAME_FLAG

Alter geometry field name.

Used by OGR_L_AlterGeomFieldDefn().

Since

GDAL 3.6

ALTER_GEOM_FIELD_DEFN_TYPE_FLAG

Alter geometry field type.

Used by OGR_L_AlterGeomFieldDefn().

Since

GDAL 3.6

ALTER_GEOM_FIELD_DEFN_NULLABLE_FLAG

Alter geometry field nullable state.

Used by OGR_L_AlterGeomFieldDefn().

Since

GDAL 3.6

ALTER_GEOM_FIELD_DEFN_SRS_FLAG

Alter geometry field spatial reference system (except its coordinate epoch) Used by OGR_L_AlterGeomFieldDefn().

Since

GDAL 3.6

ALTER_GEOM_FIELD_DEFN_SRS_COORD_EPOCH_FLAG

Alter geometry field coordinate epoch Used by OGR_L_AlterGeomFieldDefn().

Since

GDAL 3.6

ALTER_GEOM_FIELD_DEFN_ALL_FLAG

Alter all parameters of field definition.

Used by OGR_L_AlterGeomFieldDefn().

Since

GDAL 3.6

OGR_F_VAL_NULL

Validate that fields respect not-null constraints.

Used by OGR_F_Validate().

Since

GDAL 2.0

OGR_F_VAL_GEOM_TYPE

Validate that geometries respect geometry column type.

Used by OGR_F_Validate().

Since

GDAL 2.0

OGR_F_VAL_WIDTH

Validate that (string) fields respect field width.

Used by OGR_F_Validate().

Since

GDAL 2.0

OGR_F_VAL_ALLOW_NULL_WHEN_DEFAULT

Allow fields that are null when there's an associated default value.

This can be used for drivers where the low-level layers will automatically set the field value to the associated default value. This flag only makes sense if OGR_F_VAL_NULL is set too. Used by OGR_F_Validate().

Since

GDAL 2.0

OGR_F_VAL_ALLOW_DIFFERENT_GEOM_DIM

Allow geometry fields to have a different coordinate dimension that their geometry column type.

This flag only makes sense if OGR_F_VAL_GEOM_TYPE is set too. Used by OGR_F_Validate().

Since

GDAL 2.1

OGR_F_VAL_ALL

Enable all validation tests (except OGR_F_VAL_ALLOW_DIFFERENT_GEOM_DIM) Used by OGR_F_Validate().

Since

GDAL 2.0

OGRNullFID

Special value for a unset FID.

OGRUnsetMarker

Special value set in OGRField.Set.nMarker1, nMarker2 and nMarker3 for a unset field.

Direct use of this value is strongly discouraged. Use OGR_RawField_SetUnset() or OGR_RawField_IsUnset() instead.

OGRNullMarker

Special value set in OGRField.Set.nMarker1, nMarker2 and nMarker3 for a null field.

Direct use of this value is strongly discouraged. Use OGR_RawField_SetNull() or OGR_RawField_IsNull() instead.

Since

GDAL 2.2

OGR_TZFLAG_UNKNOWN

Time zone flag indicating unknown timezone.

For the OGRFieldDefn::GetTZFlag() property, this may also indicate a mix of unknown, localtime or known time zones in the same field.

OGR_TZFLAG_LOCALTIME

Time zone flag indicating local time.

OGR_TZFLAG_MIXED_TZ

Time zone flag only returned by OGRFieldDefn::GetTZFlag() to indicate that all values in the field have a known time zone (ie different from OGR_TZFLAG_UNKNOWN and OGR_TZFLAG_LOCALTIME), but it may be different among features.

OGR_TZFLAG_UTC

Time zone flag indicating UTC.

Used to derived other time zone flags with the following logic:

  • values above 100 indicate a 15 minute increment per unit.

  • values under 100 indicate a 15 minute decrement per unit. For example: a value of 101 indicates UTC+00:15, a value of 102 UTC+00:30, a value of 99 UTC-00:15 ,etc.

OGRPARSEDATE_OPTION_LAX

Option for OGRParseDate() to ask for lax checks on the input format.

OLCRandomRead

Layer capability for random read.

OLCSequentialWrite

Layer capability for sequential write.

OLCRandomWrite

Layer capability for random write.

OLCFastSpatialFilter

Layer capability for fast spatial filter.

OLCFastFeatureCount

Layer capability for fast feature count retrieval .

OLCFastGetExtent

Layer capability for fast extent retrieval.

OLCFastGetExtent3D

Layer capability for fast 3D extent retrieval.

OLCCreateField

Layer capability for field creation .

OLCDeleteField

Layer capability for field deletion .

OLCReorderFields

Layer capability for field reordering.

OLCAlterFieldDefn

Layer capability for field alteration.

OLCAlterGeomFieldDefn

Layer capability for geometry field alteration .

OLCTransactions

Layer capability for transactions .

OLCDeleteFeature

Layer capability for feature deletion.

OLCUpsertFeature

Layer capability for feature upsert.

OLCUpdateFeature

Layer capability for specialized \ UpdateFeature() implementation.

OLCFastSetNextByIndex

Layer capability for setting next feature index .

OLCStringsAsUTF8

Layer capability for strings returned with UTF-8 \ encoding.

OLCIgnoreFields

Layer capability for field ignoring.

OLCCreateGeomField

Layer capability for geometry field creation.

OLCCurveGeometries

Layer capability for curve geometries support.

OLCMeasuredGeometries

Layer capability for measured geometries support .

OLCZGeometries

Layer capability for geometry with Z dimension support.

\ Since GDAL 3.6.

OLCRename

Layer capability for a layer that supports Rename()

OLCFastGetArrowStream

Layer capability for fast GetArrowStream() \ implementation.

OLCFastWriteArrowBatch

Layer capability for fast WriteArrowBatch() \ implementation.

ODsCCreateLayer

Dataset capability for layer creation.

ODsCDeleteLayer

Dataset capability for layer deletion.

ODsCCreateGeomFieldAfterCreateLayer

Dataset capability for geometry \ field creation support.

ODsCCurveGeometries

Dataset capability for curve geometries support.

ODsCTransactions

Dataset capability for dataset transcations.

ODsCEmulatedTransactions

Dataset capability for emulated dataset \ transactions.

ODsCMeasuredGeometries

Dataset capability for measured geometries \ support.

ODsCZGeometries

Dataset capability for geometry with Z dimension \ support.

Since GDAL 3.6.

ODsCRandomLayerRead

Dataset capability for GetNextFeature() returning \ features from random layers.

ODsCRandomLayerWrite

Dataset capability for supporting CreateFeature \ on layer in random order.

ODsCAddFieldDomain

Dataset capability for supporting AddFieldDomain() \ (at least partially)

ODsCDeleteFieldDomain

Dataset capability for supporting \ DeleteFieldDomain()

ODsCUpdateFieldDomain

Dataset capability for supporting \ UpdateFieldDomain()

ODrCCreateDataSource

Driver capability for datasource creation.

ODrCDeleteDataSource

Driver capability for datasource deletion.

OLMD_FID64

Capability set to YES as metadata on a layer that has features with 64 bit identifiers.

Since

GDAL 2.0

Typedefs

typedef int OGRErr

Type for a OGR error.

typedef int OGRBoolean

Type for a OGR boolean.

typedef enum ogr_style_tool_class_id OGRSTClassId

OGRStyleTool derived class types (returned by GetType()).

typedef enum ogr_style_tool_units_id OGRSTUnitId

List of units supported by OGRStyleTools.

typedef enum ogr_style_tool_param_pen_id OGRSTPenParam

List of parameters for use with OGRStylePen.

typedef enum ogr_style_tool_param_brush_id OGRSTBrushParam

List of parameters for use with OGRStyleBrush.

typedef enum ogr_style_tool_param_symbol_id OGRSTSymbolParam

List of parameters for use with OGRStyleSymbol.

typedef enum ogr_style_tool_param_label_id OGRSTLabelParam

List of parameters for use with OGRStyleLabel.

Enums

enum OGRwkbGeometryType

List of well known binary geometry types.

These are used within the BLOBs but are also returned from OGRGeometry::getGeometryType() to identify the type of a geometry object.

Values:

enumerator wkbUnknown

unknown type, non-standard

enumerator wkbPoint

0-dimensional geometric object, standard WKB

enumerator wkbLineString

1-dimensional geometric object with linear interpolation between Points, standard WKB

enumerator wkbPolygon

planar 2-dimensional geometric object defined by 1 exterior boundary and 0 or more interior boundaries, standard WKB

enumerator wkbMultiPoint

GeometryCollection of Points, standard WKB.

enumerator wkbMultiLineString

GeometryCollection of LineStrings, standard WKB.

enumerator wkbMultiPolygon

GeometryCollection of Polygons, standard WKB.

enumerator wkbGeometryCollection

geometric object that is a collection of 1 or more geometric objects, standard WKB

enumerator wkbCircularString

one or more circular arc segments connected end to end, ISO SQL/MM Part 3.

GDAL >= 2.0

enumerator wkbCompoundCurve

sequence of contiguous curves, ISO SQL/MM Part 3.

GDAL >= 2.0

enumerator wkbCurvePolygon

planar surface, defined by 1 exterior boundary and zero or more interior boundaries, that are curves.

ISO SQL/MM Part 3. GDAL >= 2.0

enumerator wkbMultiCurve

GeometryCollection of Curves, ISO SQL/MM Part 3.

GDAL >= 2.0

enumerator wkbMultiSurface

GeometryCollection of Surfaces, ISO SQL/MM Part 3.

GDAL >= 2.0

enumerator wkbCurve

Curve (abstract type).

ISO SQL/MM Part 3. GDAL >= 2.1

enumerator wkbSurface

Surface (abstract type).

ISO SQL/MM Part 3. GDAL >= 2.1

enumerator wkbPolyhedralSurface

a contiguous collection of polygons, which share common boundary segments, ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbTIN

a PolyhedralSurface consisting only of Triangle patches ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbTriangle

a Triangle.

ISO SQL/MM Part 3. GDAL >= 2.3

enumerator wkbNone

non-standard, for pure attribute records

enumerator wkbLinearRing

non-standard, just for createGeometry()

enumerator wkbCircularStringZ

wkbCircularString with Z component.

ISO SQL/MM Part 3. GDAL >= 2.0

enumerator wkbCompoundCurveZ

wkbCompoundCurve with Z component.

ISO SQL/MM Part 3. GDAL >= 2.0

enumerator wkbCurvePolygonZ

wkbCurvePolygon with Z component.

ISO SQL/MM Part 3. GDAL >= 2.0

enumerator wkbMultiCurveZ

wkbMultiCurve with Z component.

ISO SQL/MM Part 3. GDAL >= 2.0

enumerator wkbMultiSurfaceZ

wkbMultiSurface with Z component.

ISO SQL/MM Part 3. GDAL >= 2.0

enumerator wkbCurveZ

wkbCurve with Z component.

ISO SQL/MM Part 3. GDAL >= 2.1

enumerator wkbSurfaceZ

wkbSurface with Z component.

ISO SQL/MM Part 3. GDAL >= 2.1

enumerator wkbPolyhedralSurfaceZ

ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbTINZ

ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbTriangleZ

ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbPointM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbLineStringM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbPolygonM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbMultiPointM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbMultiLineStringM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbMultiPolygonM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbGeometryCollectionM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbCircularStringM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbCompoundCurveM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbCurvePolygonM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbMultiCurveM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbMultiSurfaceM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbCurveM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbSurfaceM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbPolyhedralSurfaceM

ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbTINM

ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbTriangleM

ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbPointZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbLineStringZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbPolygonZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbMultiPointZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbMultiLineStringZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbMultiPolygonZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbGeometryCollectionZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbCircularStringZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbCompoundCurveZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbCurvePolygonZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbMultiCurveZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbMultiSurfaceZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbCurveZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbSurfaceZM

ISO SQL/MM Part 3.

GDAL >= 2.1

enumerator wkbPolyhedralSurfaceZM

ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbTINZM

ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbTriangleZM

ISO SQL/MM Part 3.

GDAL >= 2.3

enumerator wkbPoint25D

2.5D extension as per 99-402

enumerator wkbLineString25D

2.5D extension as per 99-402

enumerator wkbPolygon25D

2.5D extension as per 99-402

enumerator wkbMultiPoint25D

2.5D extension as per 99-402

enumerator wkbMultiLineString25D

2.5D extension as per 99-402

enumerator wkbMultiPolygon25D

2.5D extension as per 99-402

enumerator wkbGeometryCollection25D

2.5D extension as per 99-402

enum OGRwkbVariant

Output variants of WKB we support.

99-402 was a short-lived extension to SFSQL 1.1 that used a high-bit flag to indicate the presence of Z coordinates in a WKB geometry.

SQL/MM Part 3 and SFSQL 1.2 use offsets of 1000 (Z), 2000 (M) and 3000 (ZM) to indicate the present of higher dimensional coordinates in a WKB geometry. Reference: 09-009_Committee_Draft_ISOIEC_CD_13249-3_SQLMM_Spatial.pdf, ISO/IEC JTC 1/SC 32 N 1820, ISO/IEC CD 13249-3:201x(E), Date: 2009-01-16. The codes are also found in §8.2.3 of

OGC 06-103r4 "OpenGIS® Implementation Standard for Geographic information -

Simple feature access - Part 1: Common architecture", v1.2.1

Values:

enumerator wkbVariantOldOgc

Old-style 99-402 extended dimension (Z) WKB types.

enumerator wkbVariantIso

SFSQL 1.2 and ISO SQL/MM Part 3 extended dimension (Z&M) WKB types.

enumerator wkbVariantPostGIS1

PostGIS 1.X has different codes for CurvePolygon, MultiCurve and MultiSurface.

enum OGRwkbByteOrder

Enumeration to describe byte order.

Values:

enumerator wkbXDR

MSB/Sun/Motorola: Most Significant Byte First

enumerator wkbNDR

LSB/Intel/Vax: Least Significant Byte First

enum OGRFieldType

List of feature field types.

This list is likely to be extended in the future ... avoid coding applications based on the assumption that all field types can be known.

Values:

enumerator OFTInteger

Simple 32bit integer.

enumerator OFTIntegerList

List of 32bit integers.

enumerator OFTReal

Double Precision floating point.

enumerator OFTRealList

List of doubles.

enumerator OFTString

String of ASCII chars.

enumerator OFTStringList

Array of strings.

enumerator OFTWideString

deprecated

enumerator OFTWideStringList

deprecated

enumerator OFTBinary

Raw Binary data.

enumerator OFTDate

Date.

enumerator OFTTime

Time.

enumerator OFTDateTime

Date and Time.

enumerator OFTInteger64

Single 64bit integer.

enumerator OFTInteger64List

List of 64bit integers.

enumerator OFTMaxType
enum OGRFieldSubType

List of field subtypes.

A subtype represents a hint, a restriction of the main type, that is not strictly necessary to consult. This list is likely to be extended in the future ... avoid coding applications based on the assumption that all field types can be known. Most subtypes only make sense for a restricted set of main types.

Since

GDAL 2.0

Values:

enumerator OFSTNone

No subtype.

This is the default value

enumerator OFSTBoolean

Boolean integer.

Only valid for OFTInteger and OFTIntegerList.

enumerator OFSTInt16

Signed 16-bit integer.

Only valid for OFTInteger and OFTIntegerList.

enumerator OFSTFloat32

Single precision (32 bit) floating point.

Only valid for OFTReal and OFTRealList.

enumerator OFSTJSON

JSON content.

Only valid for OFTString.

Since

GDAL 2.4

enumerator OFSTUUID

UUID string representation.

Only valid for OFTString.

Since

GDAL 3.3

enumerator OFSTMaxSubType
enum OGRJustification

Display justification for field values.

Values:

enumerator OJUndefined
enumerator OJLeft
enumerator OJRight
enum ogr_style_tool_class_id

OGRStyleTool derived class types (returned by GetType()).

Values:

enumerator OGRSTCNone

None.

enumerator OGRSTCPen

Pen.

enumerator OGRSTCBrush

Brush.

enumerator OGRSTCSymbol

Symbol.

enumerator OGRSTCLabel

Label.

enumerator OGRSTCVector

Vector.

enum ogr_style_tool_units_id

List of units supported by OGRStyleTools.

Values:

enumerator OGRSTUGround

Ground unit.

enumerator OGRSTUPixel

Pixel.

enumerator OGRSTUPoints

Points.

enumerator OGRSTUMM

Millimeter.

enumerator OGRSTUCM

Centimeter.

enumerator OGRSTUInches

Inch.

enum ogr_style_tool_param_pen_id

List of parameters for use with OGRStylePen.

Values:

enumerator OGRSTPenColor

Color.

enumerator OGRSTPenWidth

Width.

enumerator OGRSTPenPattern

Pattern.

enumerator OGRSTPenId

Id.

enumerator OGRSTPenPerOffset

Perpendicular offset.

enumerator OGRSTPenCap

Cap.

enumerator OGRSTPenJoin

Join.

enumerator OGRSTPenPriority

Priority.

enum ogr_style_tool_param_brush_id

List of parameters for use with OGRStyleBrush.

Values:

enumerator OGRSTBrushFColor

Foreground color.

enumerator OGRSTBrushBColor

Background color.

enumerator OGRSTBrushId

Id.

enumerator OGRSTBrushAngle

Angle.

enumerator OGRSTBrushSize

Size.

enumerator OGRSTBrushDx

Dx.

enumerator OGRSTBrushDy

Dy.

enumerator OGRSTBrushPriority

Priority.

enum ogr_style_tool_param_symbol_id

List of parameters for use with OGRStyleSymbol.

Values:

enumerator OGRSTSymbolId

Id.

enumerator OGRSTSymbolAngle

Angle.

enumerator OGRSTSymbolColor

Color.

enumerator OGRSTSymbolSize

Size.

enumerator OGRSTSymbolDx

Dx.

enumerator OGRSTSymbolDy

Dy.

enumerator OGRSTSymbolStep

Step.

enumerator OGRSTSymbolPerp

Perpendicular.

enumerator OGRSTSymbolOffset

Offset.

enumerator OGRSTSymbolPriority

Priority.

enumerator OGRSTSymbolFontName

Font name.

enumerator OGRSTSymbolOColor

Outline color.

enum ogr_style_tool_param_label_id

List of parameters for use with OGRStyleLabel.

Values:

enumerator OGRSTLabelFontName

Font name.

enumerator OGRSTLabelSize

Size.

enumerator OGRSTLabelTextString

Text string.

enumerator OGRSTLabelAngle

Angle.

enumerator OGRSTLabelFColor

Foreground color.

enumerator OGRSTLabelBColor

Background color.

enumerator OGRSTLabelPlacement

Placement.

enumerator OGRSTLabelAnchor

Anchor.

enumerator OGRSTLabelDx

Dx.

enumerator OGRSTLabelDy

Dy.

enumerator OGRSTLabelPerp

Perpendicular.

enumerator OGRSTLabelBold

Bold.

enumerator OGRSTLabelItalic

Italic.

enumerator OGRSTLabelUnderline

Underline.

enumerator OGRSTLabelPriority

Priority.

enumerator OGRSTLabelStrikeout

Strike out.

enumerator OGRSTLabelStretch

Stretch.

enumerator OGRSTLabelAdjHor

OBSOLETE; do not use.

enumerator OGRSTLabelAdjVert

OBSOLETE; do not use.

enumerator OGRSTLabelHColor

Highlight color.

enumerator OGRSTLabelOColor

Outline color.

enum OGRFieldDomainType

Type of field domain.

Since

GDAL 3.3

Values:

enumerator OFDT_CODED

Coded.

enumerator OFDT_RANGE

Range (min/max)

enumerator OFDT_GLOB

Glob (used by GeoPackage)

enum OGRFieldDomainSplitPolicy

Split policy for field domains.

When a feature is split in two, defines how the value of attributes following the domain are computed.

Since

GDAL 3.3

Values:

enumerator OFDSP_DEFAULT_VALUE

Default value.

enumerator OFDSP_DUPLICATE

Duplicate.

enumerator OFDSP_GEOMETRY_RATIO

New values are computed by the ratio of their area/length compared to the area/length of the original feature.

enum OGRFieldDomainMergePolicy

Merge policy for field domains.

When a feature is built by merging two features, defines how the value of attributes following the domain are computed.

Since

GDAL 3.3

Values:

enumerator OFDMP_DEFAULT_VALUE

Default value.

enumerator OFDMP_SUM

Sum.

enumerator OFDMP_GEOMETRY_WEIGHTED

New values are computed as the weighted average of the source values.

Functions

const char *OGRGeometryTypeToName(OGRwkbGeometryType eType)

Fetch a human readable name corresponding to an OGRwkbGeometryType value.

The returned value should not be modified, or freed by the application.

This function is C callable.

Parameters:

eType -- the geometry type.

Returns:

internal human readable string, or NULL on failure.

OGRwkbGeometryType OGRMergeGeometryTypes(OGRwkbGeometryType eMain, OGRwkbGeometryType eExtra)

Find common geometry type.

Given two geometry types, find the most specific common type. Normally used repeatedly with the geometries in a layer to try and establish the most specific geometry type that can be reported for the layer.

NOTE: wkbUnknown is the "worst case" indicating a mixture of geometry types with nothing in common but the base geometry type. wkbNone should be used to indicate that no geometries have been encountered yet, and means the first geometry encountered will establish the preliminary type.

Parameters:

  • eMain -- the first input geometry type.

  • eExtra -- the second input geometry type.

Returns:

the merged geometry type.

OGRwkbGeometryType OGRMergeGeometryTypesEx(OGRwkbGeometryType eMain, OGRwkbGeometryType eExtra, int bAllowPromotingToCurves)

Find common geometry type.

Given two geometry types, find the most specific common type. Normally used repeatedly with the geometries in a layer to try and establish the most specific geometry type that can be reported for the layer.

NOTE: wkbUnknown is the "worst case" indicating a mixture of geometry types with nothing in common but the base geometry type. wkbNone should be used to indicate that no geometries have been encountered yet, and means the first geometry encountered will establish the preliminary type.

If bAllowPromotingToCurves is set to TRUE, mixing Polygon and CurvePolygon will return CurvePolygon. Mixing LineString, CircularString, CompoundCurve will return CompoundCurve. Mixing MultiPolygon and MultiSurface will return MultiSurface. Mixing MultiCurve and MultiLineString will return MultiCurve.

Since

GDAL 2.0

Parameters:

  • eMain -- the first input geometry type.

  • eExtra -- the second input geometry type.

  • bAllowPromotingToCurves -- determine if promotion to curve type must be done.

Returns:

the merged geometry type.

OGRwkbGeometryType OGR_GT_Flatten(OGRwkbGeometryType eType)

Returns the 2D geometry type corresponding to the passed geometry type.

This function is intended to work with geometry types as old-style 99-402 extended dimension (Z) WKB types, as well as with newer SFSQL 1.2 and ISO SQL/MM Part 3 extended dimension (Z&M) WKB types.

Since

GDAL 2.0

Parameters:

eType -- Input geometry type

Returns:

2D geometry type corresponding to the passed geometry type.

OGRwkbGeometryType OGR_GT_SetZ(OGRwkbGeometryType eType)

Returns the 3D geometry type corresponding to the passed geometry type.

Since

GDAL 2.0

Parameters:

eType -- Input geometry type

Returns:

3D geometry type corresponding to the passed geometry type.

OGRwkbGeometryType OGR_GT_SetM(OGRwkbGeometryType eType)

Returns the measured geometry type corresponding to the passed geometry type.

Since

GDAL 2.1

Parameters:

eType -- Input geometry type

Returns:

measured geometry type corresponding to the passed geometry type.

OGRwkbGeometryType OGR_GT_SetModifier(OGRwkbGeometryType eType, int bSetZ, int bSetM)

Returns a XY, XYZ, XYM or XYZM geometry type depending on parameter.

Since

GDAL 2.0

Parameters:

  • eType -- Input geometry type

  • bHasZ -- TRUE if the output geometry type must be 3D.

  • bHasM -- TRUE if the output geometry type must be measured.

Returns:

Output geometry type.

int OGR_GT_HasZ(OGRwkbGeometryType eType)

Return if the geometry type is a 3D geometry type.

Since

GDAL 2.0

Parameters:

eType -- Input geometry type

Returns:

TRUE if the geometry type is a 3D geometry type.

int OGR_GT_HasM(OGRwkbGeometryType eType)

Return if the geometry type is a measured type.

Since

GDAL 2.1

Parameters:

eType -- Input geometry type

Returns:

TRUE if the geometry type is a measured type.

int OGR_GT_IsSubClassOf(OGRwkbGeometryType eType, OGRwkbGeometryType eSuperType)

Returns if a type is a subclass of another one.

Since

GDAL 2.0

Parameters:

  • eType -- Type.

  • eSuperType -- Super type

Returns:

TRUE if eType is a subclass of eSuperType.

int OGR_GT_IsCurve(OGRwkbGeometryType)

Return if a geometry type is an instance of Curve.

Such geometry type are wkbLineString, wkbCircularString, wkbCompoundCurve and their Z/M/ZM variant.

Since

GDAL 2.0

Parameters:

eGeomType -- the geometry type

Returns:

TRUE if the geometry type is an instance of Curve

int OGR_GT_IsSurface(OGRwkbGeometryType)

Return if a geometry type is an instance of Surface.

Such geometry type are wkbCurvePolygon and wkbPolygon and their Z/M/ZM variant.

Since

GDAL 2.0

Parameters:

eGeomType -- the geometry type

Returns:

TRUE if the geometry type is an instance of Surface

int OGR_GT_IsNonLinear(OGRwkbGeometryType)

Return if a geometry type is a non-linear geometry type.

Such geometry type are wkbCurve, wkbCircularString, wkbCompoundCurve, wkbSurface, wkbCurvePolygon, wkbMultiCurve, wkbMultiSurface and their Z/M variants.

Since

GDAL 2.0

Parameters:

eGeomType -- the geometry type

Returns:

TRUE if the geometry type is a non-linear geometry type.

OGRwkbGeometryType OGR_GT_GetCollection(OGRwkbGeometryType eType)

Returns the collection type that can contain the passed geometry type.

Handled conversions are : wkbNone->wkbNone, wkbPoint -> wkbMultiPoint, wkbLineString->wkbMultiLineString, wkbPolygon/wkbTriangle/wkbPolyhedralSurface/wkbTIN->wkbMultiPolygon, wkbCircularString->wkbMultiCurve, wkbCompoundCurve->wkbMultiCurve, wkbCurvePolygon->wkbMultiSurface. In other cases, wkbUnknown is returned

Passed Z, M, ZM flag is preserved.

Since

GDAL 2.0

Parameters:

eType -- Input geometry type

Returns:

the collection type that can contain the passed geometry type or wkbUnknown

OGRwkbGeometryType OGR_GT_GetCurve(OGRwkbGeometryType eType)

Returns the curve geometry type that can contain the passed geometry type.

Handled conversions are : wkbPolygon -> wkbCurvePolygon, wkbLineString->wkbCompoundCurve, wkbMultiPolygon->wkbMultiSurface and wkbMultiLineString->wkbMultiCurve. In other cases, the passed geometry is returned.

Passed Z, M, ZM flag is preserved.

Since

GDAL 2.0

Parameters:

eType -- Input geometry type

Returns:

the curve type that can contain the passed geometry type

OGRwkbGeometryType OGR_GT_GetLinear(OGRwkbGeometryType eType)

Returns the non-curve geometry type that can contain the passed geometry type.

Handled conversions are : wkbCurvePolygon -> wkbPolygon, wkbCircularString->wkbLineString, wkbCompoundCurve->wkbLineString, wkbMultiSurface->wkbMultiPolygon and wkbMultiCurve->wkbMultiLineString. In other cases, the passed geometry is returned.

Passed Z, M, ZM flag is preserved.

Since

GDAL 2.0

Parameters:

eType -- Input geometry type

Returns:

the non-curve type that can contain the passed geometry type

inline int OGR_GET_MS(float fSec)

Return the number of milliseconds from a datetime with decimal seconds.

int OGRParseDate(const char *pszInput, OGRField *psOutput, int nOptions)

Parse date string.

This function attempts to parse a date string in a variety of formats into the OGRField.Date format suitable for use with OGR. Generally speaking this function is expecting values like:

YYYY-MM-DD HH:MM:SS(.sss)?+nn or YYYY-MM-DDTHH:MM:SS(.sss)?Z (ISO 8601 format) or YYYY-MM-DDZ or THH:MM(:SS(.sss)?)?Z? (ISO 8601 extended format) or THHMM(SS(.sss)?)?Z? (ISO 8601 basic format)

The seconds may also have a decimal portion (parsed as milliseconds). And just dates (YYYY-MM-DD) or just times (HH:MM:SS[.sss]) are also supported. The date may also be in YYYY/MM/DD format. If the year is less than 100 and greater than 30 a "1900" century value will be set. If it is less than 30 and greater than -1 then a "2000" century value will be set. In the future this function may be generalized, and additional control provided through nOptions, but an nOptions value of "0" should always do a reasonable default form of processing.

The value of psField will be indeterminate if the function fails (returns FALSE).

Parameters:

  • pszInput -- the input date string.

  • psField -- the OGRField that will be updated with the parsed result.

  • nOptions -- parsing options. 0 or OGRPARSEDATE_OPTION_LAX

Returns:

TRUE if apparently successful or FALSE on failure.

class OGREnvelope
#include <ogr_core.h>

Simple container for a bounding region (rectangle)

Subclassed by OGREnvelope3D

Public Functions

inline OGREnvelope()

Default constructor.

Defines an empty rectangle

inline OGREnvelope(const OGREnvelope &oOther)

Copy constructor.

OGREnvelope &operator=(const OGREnvelope&) = default

Assignment operator.

inline int IsInit() const

Return whether the object has been initialized, that is, is non empty.

inline void Merge(OGREnvelope const &sOther)

Update the current object by computing its union with the other rectangle.

inline void Merge(double dfX, double dfY)

Update the current object by computing its union with the provided point.

inline void Intersect(OGREnvelope const &sOther)

Update the current object by computing its intersection with the other rectangle.

inline int Intersects(OGREnvelope const &other) const

Return whether the current object intersects with the other rectangle.

inline int Contains(OGREnvelope const &other) const

Return whether the current object contains the other rectangle.

inline bool operator==(const OGREnvelope &other) const

Return whether the current rectangle is equal to the other rectangle.

inline bool operator!=(const OGREnvelope &other) const

Return whether the current rectangle is not equal to the other rectangle.

Public Members

double MinX

Minimum X value.

double MaxX

Maximum X value.

double MinY

Minimum Y value.

double MaxY

Maximum Y value.

class OGREnvelope3D : public OGREnvelope
#include <ogr_core.h>

Simple container for a bounding region in 3D.

Public Functions

inline OGREnvelope3D()

Default constructor.

Defines an empty rectangle

inline OGREnvelope3D(const OGREnvelope3D &oOther)

Copy constructor.

OGREnvelope3D &operator=(const OGREnvelope3D&) = default

Assignment operator.

inline bool Is3D() const

Returns TRUE if MinZ and MaxZ are both valid numbers.

inline int IsInit() const

Return whether the object has been initialized, that is, is non empty.

inline void Merge(OGREnvelope3D const &sOther)

Update the current object by computing its union with the other rectangle.

inline void Merge(OGREnvelope const &sOther)

Update the current object by computing its union with the other rectangle.

inline void Merge(double dfX, double dfY, double dfZ)

Update the current object by computing its union with the provided point.

inline void Intersect(OGREnvelope3D const &sOther)

Update the current object by computing its intersection with the other rectangle.

inline int Intersects(OGREnvelope3D const &other) const

Return whether the current object intersects with the other rectangle.

inline int Contains(OGREnvelope3D const &other) const

Return whether the current object contains the other rectangle.

Public Members

double MinZ

Minimum Z value.

double MaxZ

Maximum Z value.

union OGRField
#include <ogr_core.h>

OGRFeature field attribute value union.

struct OGRCodedValue
#include <ogr_core.h>

Associates a code and a value.

Since

GDAL 3.3

Public Members

char *pszCode

Code.

Content should be of the type of the OGRFieldDomain

char *pszValue

Value.

Might be NULL

C API and defines for OGRFeature, OGRGeometry, and OGRDataSource related classes.

See also: ogr_geometry.h, ogr_feature.h, ogrsf_frmts.h, ogr_featurestyle.h

Defines

OGR_GEOM_COORD_PRECISION_UNKNOWN

Value for a unknown coordinate precision.

OGR_GEOS_PREC_NO_TOPO

This option causes OGR_G_SetPrecision() to not attempt at preserving the topology.

OGR_GEOS_PREC_KEEP_COLLAPSED

This option causes OGR_G_SetPrecision() to retain collapsed elements.

OGR_GGT_COUNT_NOT_NEEDED

Flag for OGR_L_GetGeometryTypes() indicating that OGRGeometryTypeCounter::nCount value is not needed.

OGR_GGT_STOP_IF_MIXED

Flag for OGR_L_GetGeometryTypes() indicating that iteration might stop as sooon as 2 distinct geometry types are found.

OGR_GGT_GEOMCOLLECTIONZ_TINZ

Flag for OGR_L_GetGeometryTypes() indicating that a GeometryCollectionZ whose first subgeometry is a TinZ should be reported as TinZ.

OGR_FOR_EACH_FEATURE_BEGIN(hFeat, hLayer)

Conveniency macro to iterate over features of a layer.

Typical usage is:

In C++, you might want to use instead range-based loop:

Since

GDAL 2.3

Parameters:

  • hFeat -- variable name for OGRFeatureH. The variable will be declared inside the macro body.

  • hLayer -- layer to iterate over.

OGR_FOR_EACH_FEATURE_END(hFeat)

End of iterator.

Typedefs

typedef void *OGRGeometryH

Opaque type for a geometry.

typedef struct OGRGeomCoordinatePrecision *OGRGeomCoordinatePrecisionH

Opaque type for OGRGeomCoordinatePrecision.

typedef struct OGRwkbExportOptions OGRwkbExportOptions

Opaque type for WKB export options.

typedef struct OGRGeomTransformer *OGRGeomTransformerH

Opaque type for a geometry transformer.

typedef struct _OGRPreparedGeometry *OGRPreparedGeometryH

Opaque type for a prepared geometry.

typedef void *OGRFieldDefnH

Opaque type for a field definition (OGRFieldDefn)

typedef void *OGRFeatureDefnH

Opaque type for a feature definition (OGRFeatureDefn)

typedef void *OGRFeatureH

Opaque type for a feature (OGRFeature)

typedef void *OGRStyleTableH

Opaque type for a style table (OGRStyleTable)

typedef struct OGRGeomFieldDefnHS *OGRGeomFieldDefnH

Opaque type for a geometry field definition (OGRGeomFieldDefn)

typedef struct OGRFieldDomainHS *OGRFieldDomainH

Opaque type for a field domain definition (OGRFieldDomain)

typedef void *OGRLayerH

Opaque type for a layer (OGRLayer)

typedef void *OGRDataSourceH

Opaque type for a OGR datasource (OGRDataSource)

typedef void *OGRSFDriverH

Opaque type for a OGR driver (OGRSFDriver)

typedef void *OGRStyleMgrH

Style manager opaque type.

typedef void *OGRStyleToolH

Style tool opaque type.

Functions

bool OGRGetGEOSVersion(int *pnMajor, int *pnMinor, int *pnPatch)

Get the GEOS version.

Since

GDAL 3.4.0

Parameters:

  • pnMajor -- Pointer to major version number, or NULL

  • pnMinor -- Pointer to minor version number, or NULL

  • pnPatch -- Pointer to patch version number, or NULL

Returns:

TRUE if GDAL is built against GEOS

OGRGeomCoordinatePrecisionH OGRGeomCoordinatePrecisionCreate(void)

Creates a new instance of OGRGeomCoordinatePrecision.

The default X,Y,Z,M resolutions are set to OGR_GEOM_COORD_PRECISION_UNKNOWN.

Since

GDAL 3.9

void OGRGeomCoordinatePrecisionDestroy(OGRGeomCoordinatePrecisionH)

Destroy a OGRGeomCoordinatePrecision.

Since

GDAL 3.9

Parameters:

hGeomCoordPrec -- OGRGeomCoordinatePrecision instance or nullptr

double OGRGeomCoordinatePrecisionGetXYResolution(OGRGeomCoordinatePrecisionH)

Get the X/Y resolution of a OGRGeomCoordinatePrecision.

Since

GDAL 3.9

Parameters:

hGeomCoordPrec -- OGRGeomCoordinatePrecision instance (must not be null)

Returns:

the the X/Y resolution of a OGRGeomCoordinatePrecision or OGR_GEOM_COORD_PRECISION_UNKNOWN

double OGRGeomCoordinatePrecisionGetZResolution(OGRGeomCoordinatePrecisionH)

Get the Z resolution of a OGRGeomCoordinatePrecision.

Since

GDAL 3.9

Parameters:

hGeomCoordPrec -- OGRGeomCoordinatePrecision instance (must not be null)

Returns:

the the Z resolution of a OGRGeomCoordinatePrecision or OGR_GEOM_COORD_PRECISION_UNKNOWN

double OGRGeomCoordinatePrecisionGetMResolution(OGRGeomCoordinatePrecisionH)

Get the M resolution of a OGRGeomCoordinatePrecision.

Since

GDAL 3.9

Parameters:

hGeomCoordPrec -- OGRGeomCoordinatePrecision instance (must not be null)

Returns:

the the M resolution of a OGRGeomCoordinatePrecision or OGR_GEOM_COORD_PRECISION_UNKNOWN

char **OGRGeomCoordinatePrecisionGetFormats(OGRGeomCoordinatePrecisionH)

Get the list of format names for coordinate precision format specific options.

An example of a supported value for pszFormatName is "FileGeodatabase" for layers of the OpenFileGDB driver.

The returned values may be used for the pszFormatName argument of OGRGeomCoordinatePrecisionGetFormatSpecificOptions().

Since

GDAL 3.9

Parameters:

hGeomCoordPrec -- OGRGeomCoordinatePrecision instance (must not be null)

Returns:

a null-terminated list to free with CSLDestroy(), or nullptr.

CSLConstList OGRGeomCoordinatePrecisionGetFormatSpecificOptions(OGRGeomCoordinatePrecisionH, const char *pszFormatName)

Get format specific coordinate precision options.

An example of a supported value for pszFormatName is "FileGeodatabase" for layers of the OpenFileGDB driver.

Since

GDAL 3.9

Parameters:

  • hGeomCoordPrec -- OGRGeomCoordinatePrecision instance (must not be null)

  • pszFormatName -- A format name (one of those returned by OGRGeomCoordinatePrecisionGetFormats())

Returns:

a null-terminated list, or nullptr. The list must not be freed, and is owned by hGeomCoordPrec

void OGRGeomCoordinatePrecisionSet(OGRGeomCoordinatePrecisionH, double dfXYResolution, double dfZResolution, double dfMResolution)

Set the resolution of the geometry coordinate components.

For the X, Y and Z ordinates, the precision should be expressed in the units of the CRS of the geometry. So typically degrees for geographic CRS, or meters/feet/US-feet for projected CRS. Users might use OGRGeomCoordinatePrecisionSetFromMeter() for an even more convenient interface.

For a projected CRS with meters as linear unit, 1e-3 corresponds to a millimetric precision. For a geographic CRS in 8.9e-9 corresponds to a millimetric precision (for a Earth CRS)

Resolution should be stricty positive, or set to OGR_GEOM_COORD_PRECISION_UNKNOWN when unknown.

Since

GDAL 3.9

Parameters:

  • hGeomCoordPrec -- OGRGeomCoordinatePrecision instance (must not be null)

  • dfXYResolution -- Resolution for for X and Y coordinates.

  • dfZResolution -- Resolution for for Z coordinates.

  • dfMResolution -- Resolution for for M coordinates.

void OGRGeomCoordinatePrecisionSetFromMeter(OGRGeomCoordinatePrecisionH, OGRSpatialReferenceH hSRS, double dfXYMeterResolution, double dfZMeterResolution, double dfMResolution)

Set the resolution of the geometry coordinate components.

For the X, Y and Z ordinates, the precision should be expressed in meter, e.g 1e-3 for millimetric precision.

Resolution should be stricty positive, or set to OGR_GEOM_COORD_PRECISION_UNKNOWN when unknown.

Since

GDAL 3.9

Parameters:

  • hGeomCoordPrec -- OGRGeomCoordinatePrecision instance (must not be null)

  • hSRS -- Spatial reference system, used for metric to SRS unit conversion (must not be null)

  • dfXYMeterResolution -- Resolution for for X and Y coordinates, in meter.

  • dfZMeterResolution -- Resolution for for Z coordinates, in meter.

  • dfMResolution -- Resolution for for M coordinates.

void OGRGeomCoordinatePrecisionSetFormatSpecificOptions(OGRGeomCoordinatePrecisionH, const char *pszFormatName, CSLConstList papszOptions)

Set format specific coordinate precision options.

Since

GDAL 3.9

Parameters:

  • hGeomCoordPrec -- OGRGeomCoordinatePrecision instance (must not be null)

  • pszFormatName -- A format name (must not be null)

  • papszOptions -- null-terminated list of options.

OGRErr OGR_G_CreateFromWkb(const void*, OGRSpatialReferenceH, OGRGeometryH*, int)

Create a geometry object of the appropriate type from its well known binary representation.

Note that if nBytes is passed as zero, no checking can be done on whether the pabyData is sufficient. This can result in a crash if the input data is corrupt. This function returns no indication of the number of bytes from the data source actually used to represent the returned geometry object. Use OGR_G_WkbSize() on the returned geometry to establish the number of bytes it required in WKB format.

The OGRGeometryFactory::createFromWkb() CPP method is the same as this function.

Parameters:

  • pabyData -- pointer to the input BLOB data.

  • hSRS -- handle to the spatial reference to be assigned to the created geometry object. This may be NULL.

  • phGeometry -- the newly created geometry object will be assigned to the indicated handle on return. This will be NULL in case of failure. If not NULL, *phGeometry should be freed with OGR_G_DestroyGeometry() after use.

  • nBytes -- the number of bytes of data available in pabyData, or -1 if it is not known, but assumed to be sufficient.

Returns:

OGRERR_NONE if all goes well, otherwise any of OGRERR_NOT_ENOUGH_DATA, OGRERR_UNSUPPORTED_GEOMETRY_TYPE, or OGRERR_CORRUPT_DATA may be returned.

OGRErr OGR_G_CreateFromWkbEx(const void*, OGRSpatialReferenceH, OGRGeometryH*, size_t)

Create a geometry object of the appropriate type from its well known binary representation.

Note that if nBytes is passed as zero, no checking can be done on whether the pabyData is sufficient. This can result in a crash if the input data is corrupt. This function returns no indication of the number of bytes from the data source actually used to represent the returned geometry object. Use OGR_G_WkbSizeEx() on the returned geometry to establish the number of bytes it required in WKB format.

The OGRGeometryFactory::createFromWkb() CPP method is the same as this function.

Since

GDAL 3.3

Parameters:

  • pabyData -- pointer to the input BLOB data.

  • hSRS -- handle to the spatial reference to be assigned to the created geometry object. This may be NULL.

  • phGeometry -- the newly created geometry object will be assigned to the indicated handle on return. This will be NULL in case of failure. If not NULL, *phGeometry should be freed with OGR_G_DestroyGeometry() after use.

  • nBytes -- the number of bytes of data available in pabyData, or -1 if it is not known, but assumed to be sufficient.

Returns:

OGRERR_NONE if all goes well, otherwise any of OGRERR_NOT_ENOUGH_DATA, OGRERR_UNSUPPORTED_GEOMETRY_TYPE, or OGRERR_CORRUPT_DATA may be returned.

OGRErr OGR_G_CreateFromWkt(char**, OGRSpatialReferenceH, OGRGeometryH*)

Create a geometry object of the appropriate type from its well known text representation.

The OGRGeometryFactory::createFromWkt CPP method is the same as this function.

Parameters:

  • ppszData -- input zero terminated string containing well known text representation of the geometry to be created. The pointer is updated to point just beyond that last character consumed.

  • hSRS -- handle to the spatial reference to be assigned to the created geometry object. This may be NULL.

  • phGeometry -- the newly created geometry object will be assigned to the indicated handle on return. This will be NULL if the method fails. If not NULL, *phGeometry should be freed with OGR_G_DestroyGeometry() after use.

Returns:

OGRERR_NONE if all goes well, otherwise any of OGRERR_NOT_ENOUGH_DATA, OGRERR_UNSUPPORTED_GEOMETRY_TYPE, or OGRERR_CORRUPT_DATA may be returned.

OGRErr OGR_G_CreateFromFgf(const void*, OGRSpatialReferenceH, OGRGeometryH*, int, int*)

Create a geometry object of the appropriate type from its FGF (FDO Geometry Format) binary representation.

See OGRGeometryFactory::createFromFgf()

void OGR_G_DestroyGeometry(OGRGeometryH)

Destroy geometry object.

Equivalent to invoking delete on a geometry, but it guaranteed to take place within the context of the GDAL/OGR heap.

This function is the same as the CPP method OGRGeometryFactory::destroyGeometry.

Parameters:

hGeom -- handle to the geometry to delete.

OGRGeometryH OGR_G_CreateGeometry(OGRwkbGeometryType)

Create an empty geometry of desired type.

This is equivalent to allocating the desired geometry with new, but the allocation is guaranteed to take place in the context of the GDAL/OGR heap.

This function is the same as the CPP method OGRGeometryFactory::createGeometry.

Parameters:

eGeometryType -- the type code of the geometry to be created.

Returns:

handle to the newly create geometry or NULL on failure. Should be freed with OGR_G_DestroyGeometry() after use.

OGRGeometryH OGR_G_ApproximateArcAngles(double dfCenterX, double dfCenterY, double dfZ, double dfPrimaryRadius, double dfSecondaryAxis, double dfRotation, double dfStartAngle, double dfEndAngle, double dfMaxAngleStepSizeDegrees)

Stroke arc to linestring.

Stroke an arc of a circle to a linestring based on a center point, radius, start angle and end angle, all angles in degrees.

If the dfMaxAngleStepSizeDegrees is zero, then a default value will be used. This is currently 4 degrees unless the user has overridden the value with the OGR_ARC_STEPSIZE configuration variable.

See also

CPLSetConfigOption()

Since

OGR 1.8.0

Parameters:

  • dfCenterX -- center X

  • dfCenterY -- center Y

  • dfZ -- center Z

  • dfPrimaryRadius -- X radius of ellipse.

  • dfSecondaryRadius -- Y radius of ellipse.

  • dfRotation -- rotation of the ellipse clockwise.

  • dfStartAngle -- angle to first point on arc (clockwise of X-positive)

  • dfEndAngle -- angle to last point on arc (clockwise of X-positive)

  • dfMaxAngleStepSizeDegrees -- the largest step in degrees along the arc, zero to use the default setting.

Returns:

OGRLineString geometry representing an approximation of the arc.

OGRGeometryH OGR_G_ForceToPolygon(OGRGeometryH)

Convert to polygon.

This function is the same as the C++ method OGRGeometryFactory::forceToPolygon().

Since

GDAL/OGR 1.8.0

Parameters:

hGeom -- handle to the geometry to convert (ownership surrendered).

Returns:

the converted geometry (ownership to caller).

OGRGeometryH OGR_G_ForceToLineString(OGRGeometryH)

Convert to line string.

This function is the same as the C++ method OGRGeometryFactory::forceToLineString().

Since

GDAL/OGR 1.10.0

Parameters:

hGeom -- handle to the geometry to convert (ownership surrendered).

Returns:

the converted geometry (ownership to caller).

OGRGeometryH OGR_G_ForceToMultiPolygon(OGRGeometryH)

Convert to multipolygon.

This function is the same as the C++ method OGRGeometryFactory::forceToMultiPolygon().

Since

GDAL/OGR 1.8.0

Parameters:

hGeom -- handle to the geometry to convert (ownership surrendered).

Returns:

the converted geometry (ownership to caller).

OGRGeometryH OGR_G_ForceToMultiPoint(OGRGeometryH)

Convert to multipoint.

This function is the same as the C++ method OGRGeometryFactory::forceToMultiPoint().

Since

GDAL/OGR 1.8.0

Parameters:

hGeom -- handle to the geometry to convert (ownership surrendered).

Returns:

the converted geometry (ownership to caller).

OGRGeometryH OGR_G_ForceToMultiLineString(OGRGeometryH)

Convert to multilinestring.

This function is the same as the C++ method OGRGeometryFactory::forceToMultiLineString().

Since

GDAL/OGR 1.8.0

Parameters:

hGeom -- handle to the geometry to convert (ownership surrendered).

Returns:

the converted geometry (ownership to caller).

OGRGeometryH OGR_G_ForceTo(OGRGeometryH hGeom, OGRwkbGeometryType eTargetType, char **papszOptions)

Convert to another geometry type.

This function is the same as the C++ method OGRGeometryFactory::forceTo().

Since

GDAL 2.0

Parameters:

  • hGeom -- the input geometry - ownership is passed to the method.

  • eTargetType -- target output geometry type.

  • papszOptions -- options as a null-terminated list of strings or NULL.

Returns:

new geometry.

OGRGeometryH OGR_G_RemoveLowerDimensionSubGeoms(const OGRGeometryH hGeom)

Remove sub-geometries from a geometry collection that do not have the maximum topological dimensionality of the collection.

This function is the same as the C++ method OGRGeometryFactory::removeLowerDimensionSubGeoms().

Since

GDAL 3.1.0

Parameters:

hGeom -- handle to the geometry to convert

Returns:

a new geometry.

int OGR_G_GetDimension(OGRGeometryH)

Get the dimension of this geometry.

This function corresponds to the SFCOM IGeometry::GetDimension() method. It indicates the dimension of the geometry, but does not indicate the dimension of the underlying space (as indicated by OGR_G_GetCoordinateDimension() function).

This function is the same as the CPP method OGRGeometry::getDimension().

Parameters:

hGeom -- handle on the geometry to get the dimension from.

Returns:

0 for points, 1 for lines and 2 for surfaces.

int OGR_G_GetCoordinateDimension(OGRGeometryH)

Get the dimension of the coordinates in this geometry.

This function is the same as the CPP method OGRGeometry::getCoordinateDimension().

Deprecated:

use OGR_G_CoordinateDimension(), OGR_G_Is3D(), or OGR_G_IsMeasured().

Parameters:

hGeom -- handle on the geometry to get the dimension of the coordinates from.

Returns:

this will return 2 or 3.

int OGR_G_CoordinateDimension(OGRGeometryH)

Get the dimension of the coordinates in this geometry.

This function is the same as the CPP method OGRGeometry::CoordinateDimension().

Since

GDAL 2.1

Parameters:

hGeom -- handle on the geometry to get the dimension of the coordinates from.

Returns:

this will return 2 for XY, 3 for XYZ and XYM, and 4 for XYZM data.

void OGR_G_SetCoordinateDimension(OGRGeometryH, int)

Set the coordinate dimension.

This method sets the explicit coordinate dimension. Setting the coordinate dimension of a geometry to 2 should zero out any existing Z values. Setting the dimension of a geometry collection, a compound curve, a polygon, etc. will affect the children geometries. This will also remove the M dimension if present before this call.

Deprecated:

use OGR_G_Set3D() or OGR_G_SetMeasured().

Parameters:

  • hGeom -- handle on the geometry to set the dimension of the coordinates.

  • nNewDimension -- New coordinate dimension value, either 2 or 3.

int OGR_G_Is3D(OGRGeometryH)

See whether this geometry has Z coordinates.

This function is the same as the CPP method OGRGeometry::Is3D().

Since

GDAL 2.1

Parameters:

hGeom -- handle on the geometry to check whether it has Z coordinates.

Returns:

TRUE if the geometry has Z coordinates.

int OGR_G_IsMeasured(OGRGeometryH)

See whether this geometry is measured.

This function is the same as the CPP method OGRGeometry::IsMeasured().

Since

GDAL 2.1

Parameters:

hGeom -- handle on the geometry to check whether it is measured.

Returns:

TRUE if the geometry has M coordinates.

void OGR_G_Set3D(OGRGeometryH, int)

Add or remove the Z coordinate dimension.

This method adds or removes the explicit Z coordinate dimension. Removing the Z coordinate dimension of a geometry will remove any existing Z values. Adding the Z dimension to a geometry collection, a compound curve, a polygon, etc. will affect the children geometries.

Since

GDAL 2.1

Parameters:

  • hGeom -- handle on the geometry to set or unset the Z dimension.

  • bIs3D -- Should the geometry have a Z dimension, either TRUE or FALSE.

void OGR_G_SetMeasured(OGRGeometryH, int)

Add or remove the M coordinate dimension.

This method adds or removes the explicit M coordinate dimension. Removing the M coordinate dimension of a geometry will remove any existing M values. Adding the M dimension to a geometry collection, a compound curve, a polygon, etc. will affect the children geometries.

Since

GDAL 2.1

Parameters:

  • hGeom -- handle on the geometry to set or unset the M dimension.

  • bIsMeasured -- Should the geometry have a M dimension, either TRUE or FALSE.

OGRGeometryH OGR_G_Clone(OGRGeometryH)

Make a copy of this object.

This function relates to the SFCOM IGeometry::clone() method.

This function is the same as the CPP method OGRGeometry::clone().

Parameters:

hGeom -- handle on the geometry to clone from.

Returns:

a handle on the copy of the geometry with the spatial reference system as the original.

void OGR_G_GetEnvelope(OGRGeometryH, OGREnvelope*)

Computes and returns the bounding envelope for this geometry in the passed psEnvelope structure.

This function is the same as the CPP method OGRGeometry::getEnvelope().

Parameters:

  • hGeom -- handle of the geometry to get envelope from.

  • psEnvelope -- the structure in which to place the results.

void OGR_G_GetEnvelope3D(OGRGeometryH, OGREnvelope3D*)

Computes and returns the bounding envelope (3D) for this geometry in the passed psEnvelope structure.

This function is the same as the CPP method OGRGeometry::getEnvelope().

Since

OGR 1.9.0

Parameters:

  • hGeom -- handle of the geometry to get envelope from.

  • psEnvelope -- the structure in which to place the results.

OGRErr OGR_G_ImportFromWkb(OGRGeometryH, const void*, int)

Assign geometry from well known binary data.

The object must have already been instantiated as the correct derived type of geometry object to match the binaries type.

This function relates to the SFCOM IWks::ImportFromWKB() method.

This function is the same as the CPP method OGRGeometry::importFromWkb().

Parameters:

  • hGeom -- handle on the geometry to assign the well know binary data to.

  • pabyData -- the binary input data.

  • nSize -- the size of pabyData in bytes, or -1 if not known.

Returns:

OGRERR_NONE if all goes well, otherwise any of OGRERR_NOT_ENOUGH_DATA, OGRERR_UNSUPPORTED_GEOMETRY_TYPE, or OGRERR_CORRUPT_DATA may be returned.

OGRErr OGR_G_ExportToWkb(OGRGeometryH, OGRwkbByteOrder, unsigned char*)

Convert a geometry well known binary format.

This function relates to the SFCOM IWks::ExportToWKB() method.

For backward compatibility purposes, it exports the Old-style 99-402 extended dimension (Z) WKB types for types Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon and GeometryCollection. For other geometry types, it is equivalent to OGR_G_ExportToIsoWkb().

This function is the same as the CPP method OGRGeometry::exportToWkb(OGRwkbByteOrder, unsigned char *,

OGRwkbVariant) with eWkbVariant = wkbVariantOldOgc.

Parameters:

  • hGeom -- handle on the geometry to convert to a well know binary data from.

  • eOrder -- One of wkbXDR or wkbNDR indicating MSB or LSB byte order respectively.

  • pabyDstBuffer -- a buffer into which the binary representation is written. This buffer must be at least OGR_G_WkbSize() byte in size.

Returns:

Currently OGRERR_NONE is always returned.

OGRErr OGR_G_ExportToIsoWkb(OGRGeometryH, OGRwkbByteOrder, unsigned char*)

Convert a geometry into SFSQL 1.2 / ISO SQL/MM Part 3 well known binary format.

This function relates to the SFCOM IWks::ExportToWKB() method. It exports the SFSQL 1.2 and ISO SQL/MM Part 3 extended dimension (Z&M) WKB types.

This function is the same as the CPP method OGRGeometry::exportToWkb(OGRwkbByteOrder, unsigned char *, OGRwkbVariant) with eWkbVariant = wkbVariantIso.

Since

GDAL 2.0

Parameters:

  • hGeom -- handle on the geometry to convert to a well know binary data from.

  • eOrder -- One of wkbXDR or wkbNDR indicating MSB or LSB byte order respectively.

  • pabyDstBuffer -- a buffer into which the binary representation is written. This buffer must be at least OGR_G_WkbSize() byte in size.

Returns:

Currently OGRERR_NONE is always returned.

OGRwkbExportOptions *OGRwkbExportOptionsCreate(void)

Create geometry WKB export options.

The default is Intel order, old-OGC wkb variant and 0 discarded lsb bits.

Since

GDAL 3.9

Returns:

object to be freed with OGRwkbExportOptionsDestroy().

void OGRwkbExportOptionsDestroy(OGRwkbExportOptions*)

Destroy object returned by OGRwkbExportOptionsCreate()

Since

GDAL 3.9

Parameters:

psOptions -- WKB export options

void OGRwkbExportOptionsSetByteOrder(OGRwkbExportOptions*, OGRwkbByteOrder)

Set the WKB byte order.

Since

GDAL 3.9

Parameters:

  • psOptions -- WKB export options

  • eByteOrder -- Byte order: wkbXDR (big-endian) or wkbNDR (little-endian, Intel)

void OGRwkbExportOptionsSetVariant(OGRwkbExportOptions*, OGRwkbVariant)

Set the WKB variant.

Since

GDAL 3.9

Parameters:

  • psOptions -- WKB export options

  • eWkbVariant -- variant: wkbVariantOldOgc, wkbVariantIso, wkbVariantPostGIS1

void OGRwkbExportOptionsSetPrecision(OGRwkbExportOptions*, OGRGeomCoordinatePrecisionH)

Set precision options.

Since

GDAL 3.9

Parameters:

  • psOptions -- WKB export options

  • hPrecisionOptions -- Precision options (might be null to reset them)

OGRErr OGR_G_ExportToWkbEx(OGRGeometryH, unsigned char*, const OGRwkbExportOptions*)

Convert a geometry into well known binary format.

This function relates to the SFCOM IWks::ExportToWKB() method.

This function is the same as the CPP method OGRGeometry::exportToWkb(unsigned char *, const OGRwkbExportOptions*)

Since

GDAL 3.9

Parameters:

  • hGeom -- handle on the geometry to convert to a well know binary data from.

  • pabyDstBuffer -- a buffer into which the binary representation is written. This buffer must be at least OGR_G_WkbSize() byte in size.

  • psOptions -- WKB export options.

Returns:

Currently OGRERR_NONE is always returned.

int OGR_G_WkbSize(OGRGeometryH hGeom)

Returns size of related binary representation.

This function returns the exact number of bytes required to hold the well known binary representation of this geometry object. Its computation may be slightly expensive for complex geometries.

This function relates to the SFCOM IWks::WkbSize() method.

This function is the same as the CPP method OGRGeometry::WkbSize().

Use OGR_G_WkbSizeEx() if called on huge geometries (> 2 GB serialized)

Parameters:

hGeom -- handle on the geometry to get the binary size from.

Returns:

size of binary representation in bytes.

size_t OGR_G_WkbSizeEx(OGRGeometryH hGeom)

Returns size of related binary representation.

This function returns the exact number of bytes required to hold the well known binary representation of this geometry object. Its computation may be slightly expensive for complex geometries.

This function relates to the SFCOM IWks::WkbSize() method.

This function is the same as the CPP method OGRGeometry::WkbSize().

Since

GDAL 3.3

Parameters:

hGeom -- handle on the geometry to get the binary size from.

Returns:

size of binary representation in bytes.

OGRErr OGR_G_ImportFromWkt(OGRGeometryH, char**)

Assign geometry from well known text data.

The object must have already been instantiated as the correct derived type of geometry object to match the text type.

This function relates to the SFCOM IWks::ImportFromWKT() method.

This function is the same as the CPP method OGRGeometry::importFromWkt().

Parameters:

  • hGeom -- handle on the geometry to assign well know text data to.

  • ppszSrcText -- pointer to a pointer to the source text. The pointer is updated to pointer after the consumed text.

Returns:

OGRERR_NONE if all goes well, otherwise any of OGRERR_NOT_ENOUGH_DATA, OGRERR_UNSUPPORTED_GEOMETRY_TYPE, or OGRERR_CORRUPT_DATA may be returned.

OGRErr OGR_G_ExportToWkt(OGRGeometryH, char**)

Convert a geometry into well known text format.

This function relates to the SFCOM IWks::ExportToWKT() method.

For backward compatibility purposes, it exports the Old-style 99-402 extended dimension (Z) WKB types for types Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon and GeometryCollection. For other geometry types, it is equivalent to OGR_G_ExportToIsoWkt().

This function is the same as the CPP method OGRGeometry::exportToWkt().

Parameters:

  • hGeom -- handle on the geometry to convert to a text format from.

  • ppszSrcText -- a text buffer is allocated by the program, and assigned to the passed pointer. After use, *ppszDstText should be freed with CPLFree().

Returns:

Currently OGRERR_NONE is always returned.

OGRErr OGR_G_ExportToIsoWkt(OGRGeometryH, char**)

Convert a geometry into SFSQL 1.2 / ISO SQL/MM Part 3 well known text format.

This function relates to the SFCOM IWks::ExportToWKT() method. It exports the SFSQL 1.2 and ISO SQL/MM Part 3 extended dimension (Z&M) WKB types.

This function is the same as the CPP method OGRGeometry::exportToWkt(wkbVariantIso).

Since

GDAL 2.0

Parameters:

  • hGeom -- handle on the geometry to convert to a text format from.

  • ppszSrcText -- a text buffer is allocated by the program, and assigned to the passed pointer. After use, *ppszDstText should be freed with CPLFree().

Returns:

Currently OGRERR_NONE is always returned.

OGRwkbGeometryType OGR_G_GetGeometryType(OGRGeometryH)

Fetch geometry type.

Note that the geometry type may include the 2.5D flag. To get a 2D flattened version of the geometry type apply the wkbFlatten() macro to the return result.

This function is the same as the CPP method OGRGeometry::getGeometryType().

Parameters:

hGeom -- handle on the geometry to get type from.

Returns:

the geometry type code.

const char *OGR_G_GetGeometryName(OGRGeometryH)

Fetch WKT name for geometry type.

There is no SFCOM analog to this function.

This function is the same as the CPP method OGRGeometry::getGeometryName().

Parameters:

hGeom -- handle on the geometry to get name from.

Returns:

name used for this geometry type in well known text format.

void OGR_G_DumpReadable(OGRGeometryH, FILE*, const char*)

Dump geometry in well known text format to indicated output file.

This method is the same as the CPP method OGRGeometry::dumpReadable.

Parameters:

  • hGeom -- handle on the geometry to dump.

  • fp -- the text file to write the geometry to.

  • pszPrefix -- the prefix to put on each line of output.

void OGR_G_FlattenTo2D(OGRGeometryH)

Convert geometry to strictly 2D.

In a sense this converts all Z coordinates to 0.0.

This function is the same as the CPP method OGRGeometry::flattenTo2D().

Parameters:

hGeom -- handle on the geometry to convert.

void OGR_G_CloseRings(OGRGeometryH)

Force rings to be closed.

If this geometry, or any contained geometries has polygon rings that are not closed, they will be closed by adding the starting point at the end.

Parameters:

hGeom -- handle to the geometry.

OGRGeometryH OGR_G_CreateFromGML(const char*)

Create geometry from GML.

This method translates a fragment of GML containing only the geometry portion into a corresponding OGRGeometry. There are many limitations on the forms of GML geometries supported by this parser, but they are too numerous to list here.

The following GML2 elements are parsed : Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, MultiGeometry.

The following GML3 elements are parsed : Surface, MultiSurface, PolygonPatch, Triangle, Rectangle, Curve, MultiCurve, CompositeCurve, LineStringSegment, Arc, Circle, CompositeSurface, OrientableSurface, Solid, Tin, TriangulatedSurface.

Arc and Circle elements are returned as curves by default. Stroking to linestrings can be done with OGR_G_ForceTo(hGeom, OGR_GT_GetLinear(OGR_G_GetGeometryType(hGeom)), NULL). A 4 degrees step is used by default, unless the user has overridden the value with the OGR_ARC_STEPSIZE configuration variable.

The C++ method OGRGeometryFactory::createFromGML() is the same as this function.

See also

OGR_G_ForceTo()

See also

OGR_GT_GetLinear()

See also

OGR_G_GetGeometryType()

Parameters:

pszGML -- The GML fragment for the geometry.

Returns:

a geometry on success, or NULL on error.

char *OGR_G_ExportToGML(OGRGeometryH)

Convert a geometry into GML format.

The GML geometry is expressed directly in terms of GML basic data types assuming the this is available in the gml namespace. The returned string should be freed with CPLFree() when no longer required.

This method is the same as the C++ method OGRGeometry::exportToGML().

Parameters:

hGeometry -- handle to the geometry.

Returns:

A GML fragment or NULL in case of error.

char *OGR_G_ExportToGMLEx(OGRGeometryH, char **papszOptions)

Convert a geometry into GML format.

The GML geometry is expressed directly in terms of GML basic data types assuming the this is available in the gml namespace. The returned string should be freed with CPLFree() when no longer required.

The supported options are :

  • FORMAT=GML2/GML3/GML32 (GML2 or GML32 added in GDAL 2.1). If not set, it will default to GML 2.1.2 output.

  • GML3_LINESTRING_ELEMENT=curve. (Only valid for FORMAT=GML3) To use gml:Curve element for linestrings. Otherwise gml:LineString will be used .

  • GML3_LONGSRS=YES/NO. (Only valid for FORMAT=GML3, deprecated by SRSNAME_FORMAT in GDAL >=2.2). Defaults to YES. If YES, SRS with EPSG authority will be written with the "urn:ogc:def:crs:EPSG::" prefix. In the case the SRS should be treated as lat/long or northing/easting, then the function will take care of coordinate order swapping if the data axis to CRS axis mapping indicates it. If set to NO, SRS with EPSG authority will be written with the "EPSG:" prefix, even if they are in lat/long order.

  • SRSNAME_FORMAT=SHORT/OGC_URN/OGC_URL (Only valid for FORMAT=GML3, added in GDAL 2.2). Defaults to OGC_URN. If SHORT, then srsName will be in the form AUTHORITY_NAME:AUTHORITY_CODE. If OGC_URN, then srsName will be in the form urn:ogc:def:crs:AUTHORITY_NAME::AUTHORITY_CODE. If OGC_URL, then srsName will be in the form http://www.opengis.net/def/crs/AUTHORITY_NAME/0/AUTHORITY_CODE. For OGC_URN and OGC_URL, in the case the SRS should be treated as lat/long or northing/easting, then the function will take care of coordinate order swapping if the data axis to CRS axis mapping indicates it.

  • GMLID=astring. If specified, a gml:id attribute will be written in the top-level geometry element with the provided value. Required for GML 3.2 compatibility.

  • SRSDIMENSION_LOC=POSLIST/GEOMETRY/GEOMETRY,POSLIST. (Only valid for FORMAT=GML3/GML32, GDAL >= 2.0) Default to POSLIST. For 2.5D geometries, define the location where to attach the srsDimension attribute. There are diverging implementations. Some put in on the <gml:posList> element, other on the top geometry element.

  • NAMESPACE_DECL=YES/NO. If set to YES, xmlns:gml="http://www.opengis.net/gml" will be added to the root node for GML < 3.2 or xmlns:gml="http://www.opengis.net/gml/3.2" for GML 3.2

  • XY_COORD_RESOLUTION=double (added in GDAL 3.9): Resolution for the coordinate precision of the X and Y coordinates. Expressed in the units of the X and Y axis of the SRS. eg 1e-5 for up to 5 decimal digits. 0 for the default behavior.

  • Z_COORD_RESOLUTION=double (added in GDAL 3.9): Resolution for the coordinate precision of the Z coordinates. Expressed in the units of the Z axis of the SRS. 0 for the default behavior.

Note that curve geometries like CIRCULARSTRING, COMPOUNDCURVE, CURVEPOLYGON, MULTICURVE or MULTISURFACE are not supported in GML 2.

This method is the same as the C++ method OGRGeometry::exportToGML().

Since

OGR 1.8.0

Parameters:

  • hGeometry -- handle to the geometry.

  • papszOptions -- NULL-terminated list of options.

Returns:

A GML fragment or NULL in case of error.

OGRGeometryH OGR_G_CreateFromGMLTree(const CPLXMLNode*)

Create geometry from GML.

CPLXMLNode *OGR_G_ExportToGMLTree(OGRGeometryH)

Convert a geometry into GML format.

CPLXMLNode *OGR_G_ExportEnvelopeToGMLTree(OGRGeometryH)

Export the envelope of a geometry as a gml:Box.

char *OGR_G_ExportToKML(OGRGeometryH, const char *pszAltitudeMode)

Convert a geometry into KML format.

The returned string should be freed with CPLFree() when no longer required.

This method is the same as the C++ method OGRGeometry::exportToKML().

Parameters:

  • hGeometry -- handle to the geometry.

  • pszAltitudeMode -- value to write in altitudeMode element, or NULL.

Returns:

A KML fragment or NULL in case of error.

char *OGR_G_ExportToJson(OGRGeometryH)

Convert a geometry into GeoJSON format.

The returned string should be freed with CPLFree() when no longer required.

This method is the same as the C++ method OGRGeometry::exportToJson().

Parameters:

hGeometry -- handle to the geometry.

Returns:

A GeoJSON fragment or NULL in case of error.

char *OGR_G_ExportToJsonEx(OGRGeometryH, char **papszOptions)

Convert a geometry into GeoJSON format.

The returned string should be freed with CPLFree() when no longer required.

The following options are supported :

  • COORDINATE_PRECISION=number: maximum number of figures after decimal separator to write in coordinates.

  • XY_COORD_PRECISION=integer: number of decimal figures for X,Y coordinates (added in GDAL 3.9)

  • Z_COORD_PRECISION=integer: number of decimal figures for Z coordinates (added in GDAL 3.9)

  • SIGNIFICANT_FIGURES=number: maximum number of significant figures (GDAL >= 2.1).

If XY_COORD_PRECISION or Z_COORD_PRECISION is specified, COORDINATE_PRECISION or SIGNIFICANT_FIGURES will be ignored if specified. If COORDINATE_PRECISION is defined, SIGNIFICANT_FIGURES will be ignored if specified. When none are defined, the default is COORDINATE_PRECISION=15.

This method is the same as the C++ method OGRGeometry::exportToJson().

Since

OGR 1.9.0

Parameters:

  • hGeometry -- handle to the geometry.

  • papszOptions -- a null terminated list of options.

Returns:

A GeoJSON fragment or NULL in case of error.

OGRGeometryH OGR_G_CreateGeometryFromJson(const char*)

Create a OGR geometry from a GeoJSON geometry object.

OGRGeometryH OGR_G_CreateGeometryFromEsriJson(const char*)

Create a OGR geometry from a ESRI JSON geometry object.

void OGR_G_AssignSpatialReference(OGRGeometryH, OGRSpatialReferenceH)

Assign spatial reference to this object.

Any existing spatial reference is replaced, but under no circumstances does this result in the object being reprojected. It is just changing the interpretation of the existing geometry. Note that assigning a spatial reference increments the reference count on the OGRSpatialReference, but does not copy it.

Starting with GDAL 2.3, this will also assign the spatial reference to potential sub-geometries of the geometry (OGRGeometryCollection, OGRCurvePolygon/OGRPolygon, OGRCompoundCurve, OGRPolyhedralSurface and their derived classes).

This is similar to the SFCOM IGeometry::put_SpatialReference() method.

This function is the same as the CPP method OGRGeometry::assignSpatialReference.

Parameters:

  • hGeom -- handle on the geometry to apply the new spatial reference system.

  • hSRS -- handle on the new spatial reference system to apply.

OGRSpatialReferenceH OGR_G_GetSpatialReference(OGRGeometryH)

Returns spatial reference system for geometry.

This function relates to the SFCOM IGeometry::get_SpatialReference() method.

This function is the same as the CPP method OGRGeometry::getSpatialReference().

Parameters:

hGeom -- handle on the geometry to get spatial reference from.

Returns:

a reference to the spatial reference geometry, which should not be modified.

OGRErr OGR_G_Transform(OGRGeometryH, OGRCoordinateTransformationH)

Apply arbitrary coordinate transformation to geometry.

This function will transform the coordinates of a geometry from their current spatial reference system to a new target spatial reference system. Normally this means reprojecting the vectors, but it could include datum shifts, and changes of units.

Note that this function does not require that the geometry already have a spatial reference system. It will be assumed that they can be treated as having the source spatial reference system of the OGRCoordinateTransformation object, and the actual SRS of the geometry will be ignored. On successful completion the output OGRSpatialReference of the OGRCoordinateTransformation will be assigned to the geometry.

This function only does reprojection on a point-by-point basis. It does not include advanced logic to deal with discontinuities at poles or antimeridian. For that, use the OGR_GeomTransformer_Create() and OGR_GeomTransformer_Transform() functions.

This function is the same as the CPP method OGRGeometry::transform.

Parameters:

  • hGeom -- handle on the geometry to apply the transform to.

  • hTransform -- handle on the transformation to apply.

Returns:

OGRERR_NONE on success or an error code.

OGRErr OGR_G_TransformTo(OGRGeometryH, OGRSpatialReferenceH)

Transform geometry to new spatial reference system.

This function will transform the coordinates of a geometry from their current spatial reference system to a new target spatial reference system. Normally this means reprojecting the vectors, but it could include datum shifts, and changes of units.

This function will only work if the geometry already has an assigned spatial reference system, and if it is transformable to the target coordinate system.

Because this function requires internal creation and initialization of an OGRCoordinateTransformation object it is significantly more expensive to use this function to transform many geometries than it is to create the OGRCoordinateTransformation in advance, and call transform() with that transformation. This function exists primarily for convenience when only transforming a single geometry.

This function is the same as the CPP method OGRGeometry::transformTo.

Parameters:

  • hGeom -- handle on the geometry to apply the transform to.

  • hSRS -- handle on the spatial reference system to apply.

Returns:

OGRERR_NONE on success, or an error code.

OGRGeomTransformerH OGR_GeomTransformer_Create(OGRCoordinateTransformationH, CSLConstList papszOptions)

Create a geometry transformer.

This is a enhanced version of OGR_G_Transform().

When reprojecting geometries from a Polar Stereographic projection or a projection naturally crossing the antimeridian (like UTM Zone 60) to a geographic CRS, it will cut geometries along the antimeridian. So a LineString might be returned as a MultiLineString.

The WRAPDATELINE=YES option might be specified for circumstances to correct geometries that incorrectly go from a longitude on a side of the antimeridian to the other side, like a LINESTRING(-179 0,179 0) will be transformed to a MULTILINESTRING ((-179 0,-180 0),(180 0,179 0)). For that use case, hCT might be NULL.

Since

GDAL 3.1

Parameters:

  • hCT -- Coordinate transformation object (will be cloned) or NULL.

  • papszOptions -- NULL terminated list of options, or NULL. Supported options are:

    • WRAPDATELINE=YES

    • DATELINEOFFSET=longitude_gap_in_degree. Defaults to 10.

Returns:

transformer object to free with OGR_GeomTransformer_Destroy()

OGRGeometryH OGR_GeomTransformer_Transform(OGRGeomTransformerH hTransformer, OGRGeometryH hGeom)

Transforms a geometry.

Since

GDAL 3.1

Parameters:

  • hTransformer -- transformer object.

  • hGeom -- Source geometry.

Returns:

a new geometry (or NULL) to destroy with OGR_G_DestroyGeometry()

void OGR_GeomTransformer_Destroy(OGRGeomTransformerH hTransformer)

Destroy a geometry transformer allocated with OGR_GeomTransformer_Create()

Since

GDAL 3.1

Parameters:

hTransformer -- transformer object.

OGRGeometryH OGR_G_Simplify(OGRGeometryH hThis, double tolerance)

Compute a simplified geometry.

This function is the same as the C++ method OGRGeometry::Simplify().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Since

OGR 1.8.0

Parameters:

  • hThis -- the geometry.

  • dTolerance -- the distance tolerance for the simplification.

Returns:

the simplified geometry or NULL if an error occurs.

OGRGeometryH OGR_G_SimplifyPreserveTopology(OGRGeometryH hThis, double tolerance)

Simplify the geometry while preserving topology.

This function is the same as the C++ method OGRGeometry::SimplifyPreserveTopology().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Since

OGR 1.9.0

Parameters:

  • hThis -- the geometry.

  • dTolerance -- the distance tolerance for the simplification.

Returns:

the simplified geometry or NULL if an error occurs.

OGRGeometryH OGR_G_DelaunayTriangulation(OGRGeometryH hThis, double dfTolerance, int bOnlyEdges)

Return a Delaunay triangulation of the vertices of the geometry.

This function is the same as the C++ method OGRGeometry::DelaunayTriangulation().

This function is built on the GEOS library, v3.4 or above. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Since

OGR 2.1

Parameters:

  • hThis -- the geometry.

  • dfTolerance -- optional snapping tolerance to use for improved robustness

  • bOnlyEdges -- if TRUE, will return a MULTILINESTRING, otherwise it will return a GEOMETRYCOLLECTION containing triangular POLYGONs.

Returns:

the geometry resulting from the Delaunay triangulation or NULL if an error occurs.

void OGR_G_Segmentize(OGRGeometryH hGeom, double dfMaxLength)

Modify the geometry such it has no segment longer then the given distance.

Interpolated points will have Z and M values (if needed) set to 0. Distance computation is performed in 2d only.

This function is the same as the CPP method OGRGeometry::segmentize().

Parameters:

  • hGeom -- handle on the geometry to segmentize

  • dfMaxLength -- the maximum distance between 2 points after segmentization

int OGR_G_Intersects(OGRGeometryH, OGRGeometryH)

Do these features intersect?

Determines whether two geometries intersect. If GEOS is enabled, then this is done in rigorous fashion otherwise TRUE is returned if the envelopes (bounding boxes) of the two geometries overlap.

This function is the same as the CPP method OGRGeometry::Intersects.

Parameters:

  • hGeom -- handle on the first geometry.

  • hOtherGeom -- handle on the other geometry to test against.

Returns:

TRUE if the geometries intersect, otherwise FALSE.

int OGR_G_Equals(OGRGeometryH, OGRGeometryH)

Returns TRUE if two geometries are equivalent.

This operation implements the SQL/MM ST_OrderingEquals() operation.

The comparison is done in a structural way, that is to say that the geometry types must be identical, as well as the number and ordering of sub-geometries and vertices. Or equivalently, two geometries are considered equal by this method if their WKT/WKB representation is equal. Note: this must be distinguished for equality in a spatial way (which is the purpose of the ST_Equals() operation).

This function is the same as the CPP method OGRGeometry::Equals() method.

Parameters:

  • hGeom -- handle on the first geometry.

  • hOther -- handle on the other geometry to test against.

Returns:

TRUE if equivalent or FALSE otherwise.

int OGR_G_Disjoint(OGRGeometryH, OGRGeometryH)

Test for disjointness.

Tests if this geometry and the other geometry are disjoint.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::Disjoint().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hThis -- the geometry to compare.

  • hOther -- the other geometry to compare.

Returns:

TRUE if they are disjoint, otherwise FALSE.

int OGR_G_Touches(OGRGeometryH, OGRGeometryH)

Test for touching.

Tests if this geometry and the other geometry are touching.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::Touches().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hThis -- the geometry to compare.

  • hOther -- the other geometry to compare.

Returns:

TRUE if they are touching, otherwise FALSE.

int OGR_G_Crosses(OGRGeometryH, OGRGeometryH)

Test for crossing.

Tests if this geometry and the other geometry are crossing.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::Crosses().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hThis -- the geometry to compare.

  • hOther -- the other geometry to compare.

Returns:

TRUE if they are crossing, otherwise FALSE.

int OGR_G_Within(OGRGeometryH, OGRGeometryH)

Test for containment.

Tests if this geometry is within the other geometry.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::Within().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hThis -- the geometry to compare.

  • hOther -- the other geometry to compare.

Returns:

TRUE if hThis is within hOther, otherwise FALSE.

int OGR_G_Contains(OGRGeometryH, OGRGeometryH)

Test for containment.

Tests if this geometry contains the other geometry.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::Contains().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hThis -- the geometry to compare.

  • hOther -- the other geometry to compare.

Returns:

TRUE if hThis contains hOther geometry, otherwise FALSE.

int OGR_G_Overlaps(OGRGeometryH, OGRGeometryH)

Test for overlap.

Tests if this geometry and the other geometry overlap, that is their intersection has a non-zero area.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::Overlaps().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hThis -- the geometry to compare.

  • hOther -- the other geometry to compare.

Returns:

TRUE if they are overlapping, otherwise FALSE.

OGRGeometryH OGR_G_Boundary(OGRGeometryH)

Compute boundary.

A new geometry object is created and returned containing the boundary of the geometry on which the method is invoked.

This function is the same as the C++ method OGR_G_Boundary().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Since

OGR 1.8.0

Parameters:

hTarget -- The Geometry to calculate the boundary of.

Returns:

a handle to a newly allocated geometry now owned by the caller, or NULL on failure.

OGRGeometryH OGR_G_ConvexHull(OGRGeometryH)

Compute convex hull.

A new geometry object is created and returned containing the convex hull of the geometry on which the method is invoked.

This function is the same as the C++ method OGRGeometry::ConvexHull().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

hTarget -- The Geometry to calculate the convex hull of.

Returns:

a handle to a newly allocated geometry now owned by the caller, or NULL on failure.

OGRGeometryH OGR_G_ConcaveHull(OGRGeometryH, double dfRatio, bool bAllowHoles)

Compute "concave hull" of a geometry.

The concave hull is fully contained within the convex hull and also contains all the points of the input, but in a smaller area. The area ratio is the ratio of the area of the convex hull and the concave hull. Frequently used to convert a multi-point into a polygonal area. that contains all the points in the input Geometry.

A new geometry object is created and returned containing the convex hull of the geometry on which the function is invoked.

This function is the same as the C++ method OGRGeometry::ConcaveHull().

This function is built on the GEOS >= 3.11 library If OGR is built without the GEOS >= 3.11 librray, this function will always fail, issuing a CPLE_NotSupported error.

Since

GDAL 3.6

Parameters:

  • hTarget -- The Geometry to calculate the concave hull of.

  • dfRatio -- Ratio of the area of the convex hull and the concave hull.

  • bAllowHoles -- Whether holes are allowed.

Returns:

a handle to a newly allocated geometry now owned by the caller, or NULL on failure.

OGRGeometryH OGR_G_Buffer(OGRGeometryH, double, int)

Compute buffer of geometry.

Builds a new geometry containing the buffer region around the geometry on which it is invoked. The buffer is a polygon containing the region within the buffer distance of the original geometry.

Some buffer sections are properly described as curves, but are converted to approximate polygons. The nQuadSegs parameter can be used to control how many segments should be used to define a 90 degree curve - a quadrant of a circle. A value of 30 is a reasonable default. Large values result in large numbers of vertices in the resulting buffer geometry while small numbers reduce the accuracy of the result.

This function is the same as the C++ method OGRGeometry::Buffer().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hTarget -- the geometry.

  • dfDist -- the buffer distance to be applied. Should be expressed into the same unit as the coordinates of the geometry.

  • nQuadSegs -- the number of segments used to approximate a 90 degree (quadrant) of curvature.

Returns:

the newly created geometry, or NULL if an error occurs.

OGRGeometryH OGR_G_Intersection(OGRGeometryH, OGRGeometryH)

Compute intersection.

Generates a new geometry which is the region of intersection of the two geometries operated on. The OGR_G_Intersects() function can be used to test if two geometries intersect.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::Intersection().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hThis -- the geometry.

  • hOther -- the other geometry.

Returns:

a new geometry representing the intersection or NULL if there is no intersection or an error occurs.

OGRGeometryH OGR_G_Union(OGRGeometryH, OGRGeometryH)

Compute union.

Generates a new geometry which is the region of union of the two geometries operated on.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::Union().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hThis -- the geometry.

  • hOther -- the other geometry.

Returns:

a new geometry representing the union or NULL if an error occurs.

OGRGeometryH OGR_G_UnionCascaded(OGRGeometryH)

Compute union using cascading.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

The input geometry must be a MultiPolygon.

This function is the same as the C++ method OGRGeometry::UnionCascaded().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Deprecated:

Use OGR_G_UnaryUnion() instead

Parameters:

hThis -- the geometry.

Returns:

a new geometry representing the union or NULL if an error occurs.

OGRGeometryH OGR_G_UnaryUnion(OGRGeometryH)

Returns the union of all components of a single geometry.

Usually used to convert a collection into the smallest set of polygons that cover the same area.

See https://postgis.net/docs/ST_UnaryUnion.html for more details.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::UnaryUnion().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Since

GDAL 3.7

Parameters:

hThis -- the geometry.

Returns:

a new geometry representing the union or NULL if an error occurs.

OGRGeometryH OGR_G_PointOnSurface(OGRGeometryH)

Returns a point guaranteed to lie on the surface.

This method relates to the SFCOM ISurface::get_PointOnSurface() method however the current implementation based on GEOS can operate on other geometry types than the types that are supported by SQL/MM-Part 3 : surfaces (polygons) and multisurfaces (multipolygons).

This method is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this method will always fail, issuing a CPLE_NotSupported error.

Since

OGR 1.10

Parameters:

hGeom -- the geometry to operate on.

Returns:

a point guaranteed to lie on the surface or NULL if an error occurred.

OGRGeometryH OGR_G_Difference(OGRGeometryH, OGRGeometryH)

Compute difference.

Generates a new geometry which is the region of this geometry with the region of the other geometry removed.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::Difference().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hThis -- the geometry.

  • hOther -- the other geometry.

Returns:

a new geometry representing the difference or NULL if the difference is empty or an error occurs.

OGRGeometryH OGR_G_SymDifference(OGRGeometryH, OGRGeometryH)

Compute symmetric difference.

Generates a new geometry which is the symmetric difference of this geometry and the other geometry.

Geometry validity is not checked. In case you are unsure of the validity of the input geometries, call IsValid() before, otherwise the result might be wrong.

This function is the same as the C++ method OGRGeometry::SymmetricDifference().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Since

OGR 1.8.0

Parameters:

  • hThis -- the geometry.

  • hOther -- the other geometry.

Returns:

a new geometry representing the symmetric difference or NULL if the difference is empty or an error occurs.

double OGR_G_Distance(OGRGeometryH, OGRGeometryH)

Compute distance between two geometries.

Returns the shortest distance between the two geometries. The distance is expressed into the same unit as the coordinates of the geometries.

This function is the same as the C++ method OGRGeometry::Distance().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Parameters:

  • hFirst -- the first geometry to compare against.

  • hOther -- the other geometry to compare against.

Returns:

the distance between the geometries or -1 if an error occurs.

double OGR_G_Distance3D(OGRGeometryH, OGRGeometryH)

Returns the 3D distance between two geometries.

The distance is expressed into the same unit as the coordinates of the geometries.

This method is built on the SFCGAL library, check it for the definition of the geometry operation. If OGR is built without the SFCGAL library, this method will always return -1.0

This function is the same as the C++ method OGRGeometry::Distance3D().

Since

GDAL 2.2

Parameters:

  • hFirst -- the first geometry to compare against.

  • hOther -- the other geometry to compare against.

Returns:

distance between the two geometries

Returns:

the distance between the geometries or -1 if an error occurs.

double OGR_G_Length(OGRGeometryH)

Compute length of a geometry.

Computes the length for OGRCurve or MultiCurve objects. Undefined for all other geometry types (returns zero).

This function utilizes the C++ get_Length() method.

Since

OGR 1.8.0

Parameters:

hGeom -- the geometry to operate on.

Returns:

the length or 0.0 for unsupported geometry types.

double OGR_G_Area(OGRGeometryH)

Compute geometry area.

The returned area is a 2D Cartesian (planar) area in square units of the spatial reference system in use, so potentially "square degrees" for a geometry expressed in a geographic SRS.

Computes the area for surfaces or closed curves. Undefined for all other geometry types (returns 0.0).

This function utilizes the C++ OGRSurface::get_Area() method.

See also

OGR_G_GeodesicArea() for an alternative function returning areas computed on the ellipsoid, an in square meters.

Since

OGR 1.8.0

Parameters:

hGeom -- the geometry to operate on.

Returns:

the area of the geometry in square units of the spatial reference system in use, or 0.0 for unsupported geometry types.

double OGR_G_GeodesicArea(OGRGeometryH)

Compute geometry area, considered as a surface on the underlying ellipsoid of the SRS attached to the geometry.

The returned area will always be in square meters, and assumes that polygon edges describe geodesic lines on the ellipsoid.

If the geometry' SRS is not a geographic one, geometries are reprojected to the underlying geographic SRS of the geometry' SRS. OGRSpatialReference::GetDataAxisToSRSAxisMapping() is honored.

Computes the area for surfaces or closed curves. Undefined for all other geometry types (returns a negative value).

Note that geometries with circular arcs will be linearized in their original coordinate space first, so the resulting geodesic area will be an approximation.

This function utilizes the C++ OGRSurface::get_GeodesicArea() method.

See also

OGR_G_Area() for an alternative method returning areas computed in 2D Cartesian space.

Since

OGR 3.9.0

Parameters:

hGeom -- the geometry to operate on.

Returns:

the area, or a negative value in case of error (unsupported geometry type, no SRS attached, etc.)

bool OGR_G_IsClockwise(OGRGeometryH hGeom)

Returns true if the ring has clockwise winding (or less than 2 points)

Assumes that the ring is closed.

Since

GDAL 3.8

Parameters:

hGeom -- handle to a curve geometry

int OGR_G_Centroid(OGRGeometryH, OGRGeometryH)

Compute the geometry centroid.

The centroid location is applied to the passed in OGRPoint object. The centroid is not necessarily within the geometry.

This method relates to the SFCOM ISurface::get_Centroid() method however the current implementation based on GEOS can operate on other geometry types such as multipoint, linestring, geometrycollection such as multipolygons. OGC SF SQL 1.1 defines the operation for surfaces (polygons). SQL/MM-Part 3 defines the operation for surfaces and multisurfaces (multipolygons).

This function is the same as the C++ method OGRGeometry::Centroid().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Returns:

OGRERR_NONE on success or OGRERR_FAILURE on error.

OGRGeometryH OGR_G_Value(OGRGeometryH, double dfDistance)

Fetch point at given distance along curve.

This function relates to the SF COM ICurve::get_Value() method.

This function is the same as the C++ method OGRCurve::Value().

Since

GDAL 2.0

Parameters:

  • hGeom -- curve geometry.

  • dfDistance -- distance along the curve at which to sample position. This distance should be between zero and get_Length() for this curve.

Returns:

a point or NULL.

void OGR_G_Empty(OGRGeometryH)

Clear geometry information.

This restores the geometry to its initial state after construction, and before assignment of actual geometry.

This function relates to the SFCOM IGeometry::Empty() method.

This function is the same as the CPP method OGRGeometry::empty().

Parameters:

hGeom -- handle on the geometry to empty.

int OGR_G_IsEmpty(OGRGeometryH)

Test if the geometry is empty.

This method is the same as the CPP method OGRGeometry::IsEmpty().

Parameters:

hGeom -- The Geometry to test.

Returns:

TRUE if the geometry has no points, otherwise FALSE.

int OGR_G_IsValid(OGRGeometryH)

Test if the geometry is valid.

This function is the same as the C++ method OGRGeometry::IsValid().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always return FALSE.

Parameters:

hGeom -- The Geometry to test.

Returns:

TRUE if the geometry has no points, otherwise FALSE.

OGRGeometryH OGR_G_MakeValid(OGRGeometryH)

Attempts to make an invalid geometry valid without losing vertices.

Already-valid geometries are cloned without further intervention.

This function is the same as the C++ method OGRGeometry::MakeValid().

This function is built on the GEOS >= 3.8 library, check it for the definition of the geometry operation. If OGR is built without the GEOS >= 3.8 library, this function will return a clone of the input geometry if it is valid, or NULL if it is invalid

Since

GDAL 3.0

Parameters:

hGeom -- The Geometry to make valid.

Returns:

a newly allocated geometry now owned by the caller, or NULL on failure.

OGRGeometryH OGR_G_MakeValidEx(OGRGeometryH, CSLConstList)

Attempts to make an invalid geometry valid without losing vertices.

Already-valid geometries are cloned without further intervention.

This function is the same as the C++ method OGRGeometry::MakeValid().

See documentation of that method for possible options.

Since

GDAL 3.4

Parameters:

  • hGeom -- The Geometry to make valid.

  • papszOptions -- Options.

Returns:

a newly allocated geometry now owned by the caller, or NULL on failure.

OGRGeometryH OGR_G_Normalize(OGRGeometryH)

Attempts to bring geometry into normalized/canonical form.

This function is the same as the C++ method OGRGeometry::Normalize().

This function is built on the GEOS library; check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Since

GDAL 3.3

Parameters:

hGeom -- The Geometry to normalize.

Returns:

a newly allocated geometry now owned by the caller, or NULL on failure.

int OGR_G_IsSimple(OGRGeometryH)

Returns TRUE if the geometry is simple.

Returns TRUE if the geometry has no anomalous geometric points, such as self intersection or self tangency. The description of each instantiable geometric class will include the specific conditions that cause an instance of that class to be classified as not simple.

This function is the same as the C++ method OGRGeometry::IsSimple() method.

If OGR is built without the GEOS library, this function will always return FALSE.

Parameters:

hGeom -- The Geometry to test.

Returns:

TRUE if object is simple, otherwise FALSE.

int OGR_G_IsRing(OGRGeometryH)

Test if the geometry is a ring.

This function is the same as the C++ method OGRGeometry::IsRing().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always return FALSE.

Parameters:

hGeom -- The Geometry to test.

Returns:

TRUE if the geometry has no points, otherwise FALSE.

OGRGeometryH OGR_G_SetPrecision(OGRGeometryH, double dfGridSize, int nFlags)

Set the geometry's precision, rounding all its coordinates to the precision grid, and making sure the geometry is still valid.

This is a stronger version of roundCoordinates().

Note that at time of writing GEOS does no supported curve geometries. So currently if this function is called on such a geometry, OGR will first call getLinearGeometry() on the input and getCurveGeometry() on the output, but that it is unlikely to yield to the expected result.

This function is the same as the C++ method OGRGeometry::SetPrecision().

This function is built on the GEOSGeom_setPrecision_r() function of the GEOS library. Check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Since

GDAL 3.9

Parameters:

  • hThis -- the geometry.

  • dfGridSize -- size of the precision grid, or 0 for FLOATING precision.

  • nFlags -- The bitwise OR of zero, one or several of OGR_GEOS_PREC_NO_TOPO and OGR_GEOS_PREC_KEEP_COLLAPSED

Returns:

a new geometry or NULL if an error occurs.

OGRGeometryH OGR_G_Polygonize(OGRGeometryH)

Polygonizes a set of sparse edges.

A new geometry object is created and returned containing a collection of reassembled Polygons: NULL will be returned if the input collection doesn't corresponds to a MultiLinestring, or when reassembling Edges into Polygons is impossible due to topological inconsistencies.

This function is the same as the C++ method OGRGeometry::Polygonize().

This function is built on the GEOS library, check it for the definition of the geometry operation. If OGR is built without the GEOS library, this function will always fail, issuing a CPLE_NotSupported error.

Since

OGR 1.9.0

Parameters:

hTarget -- The Geometry to be polygonized.

Returns:

a handle to a newly allocated geometry now owned by the caller, or NULL on failure.

int OGR_G_GetPointCount(OGRGeometryH)

Fetch number of points from a Point or a LineString/LinearRing geometry.

Only wkbPoint[25D] or wkbLineString[25D] may return a valid value. Other geometry types will silently return 0.

Parameters:

hGeom -- handle to the geometry from which to get the number of points.

Returns:

the number of points.

int OGR_G_GetPoints(OGRGeometryH hGeom, void *pabyX, int nXStride, void *pabyY, int nYStride, void *pabyZ, int nZStride)

Returns all points of line string.

This method copies all points into user arrays. The user provides the stride between 2 consecutive elements of the array.

On some CPU architectures, care must be taken so that the arrays are properly aligned.

Since

OGR 1.9.0

Parameters:

  • hGeom -- handle to the geometry from which to get the coordinates.

  • pabyX -- a buffer of at least (sizeof(double) * nXStride * nPointCount) bytes, may be NULL.

  • nXStride -- the number of bytes between 2 elements of pabyX.

  • pabyY -- a buffer of at least (sizeof(double) * nYStride * nPointCount) bytes, may be NULL.

  • nYStride -- the number of bytes between 2 elements of pabyY.

  • pabyZ -- a buffer of at last size (sizeof(double) * nZStride * nPointCount) bytes, may be NULL.

  • nZStride -- the number of bytes between 2 elements of pabyZ.

Returns:

the number of points

int OGR_G_GetPointsZM(OGRGeometryH hGeom, void *pabyX, int nXStride, void *pabyY, int nYStride, void *pabyZ, int nZStride, void *pabyM, int nMStride)

Returns all points of line string.

This method copies all points into user arrays. The user provides the stride between 2 consecutive elements of the array.

On some CPU architectures, care must be taken so that the arrays are properly aligned.

Since

OGR 1.9.0

Parameters:

  • hGeom -- handle to the geometry from which to get the coordinates.

  • pabyX -- a buffer of at least (nXStride * nPointCount) bytes, may be NULL.

  • nXStride -- the number of bytes between 2 elements of pabyX.

  • pabyY -- a buffer of at least (nYStride * nPointCount) bytes, may be NULL.

  • nYStride -- the number of bytes between 2 elements of pabyY.

  • pabyZ -- a buffer of at last size (nZStride * nPointCount) bytes, may be NULL.

  • nZStride -- the number of bytes between 2 elements of pabyZ.

  • pabyM -- a buffer of at last size (nMStride * nPointCount) bytes, may be NULL.

  • nMStride -- the number of bytes between 2 elements of pabyM.

Returns:

the number of points

double OGR_G_GetX(OGRGeometryH, int)

Fetch the x coordinate of a point from a Point or a LineString/LinearRing geometry.

Parameters:

  • hGeom -- handle to the geometry from which to get the x coordinate.

  • i -- point to get the x coordinate.

Returns:

the X coordinate of this point.

double OGR_G_GetY(OGRGeometryH, int)

Fetch the x coordinate of a point from a Point or a LineString/LinearRing geometry.

Parameters:

  • hGeom -- handle to the geometry from which to get the y coordinate.

  • i -- point to get the Y coordinate.

Returns:

the Y coordinate of this point.

double OGR_G_GetZ(OGRGeometryH, int)

Fetch the z coordinate of a point from a Point or a LineString/LinearRing geometry.

Parameters:

  • hGeom -- handle to the geometry from which to get the Z coordinate.

  • i -- point to get the Z coordinate.

Returns:

the Z coordinate of this point.

double OGR_G_GetM(OGRGeometryH, int)

Fetch the m coordinate of a point from a geometry.

Parameters:

  • hGeom -- handle to the geometry from which to get the M coordinate.

  • i -- point to get the M coordinate.

Returns:

the M coordinate of this point.

void OGR_G_GetPoint(OGRGeometryH, int iPoint, double*, double*, double*)

Fetch a point in line string or a point geometry.

Parameters:

  • hGeom -- handle to the geometry from which to get the coordinates.

  • i -- the vertex to fetch, from 0 to getNumPoints()-1, zero for a point.

  • pdfX -- value of x coordinate.

  • pdfY -- value of y coordinate.

  • pdfZ -- value of z coordinate.

void OGR_G_GetPointZM(OGRGeometryH, int iPoint, double*, double*, double*, double*)

Fetch a point in line string or a point geometry.

Parameters:

  • hGeom -- handle to the geometry from which to get the coordinates.

  • i -- the vertex to fetch, from 0 to getNumPoints()-1, zero for a point.

  • pdfX -- value of x coordinate.

  • pdfY -- value of y coordinate.

  • pdfZ -- value of z coordinate.

  • pdfM -- value of m coordinate.

void OGR_G_SetPointCount(OGRGeometryH hGeom, int nNewPointCount)

Set number of points in a geometry.

This method primary exists to preset the number of points in a linestring geometry before setPoint() is used to assign them to avoid reallocating the array larger with each call to addPoint().

Parameters:

  • hGeom -- handle to the geometry.

  • nNewPointCount -- the new number of points for geometry.

void OGR_G_SetPoint(OGRGeometryH, int iPoint, double, double, double)

Set the location of a vertex in a point or linestring geometry.

If iPoint is larger than the number of existing points in the linestring, the point count will be increased to accommodate the request.

Parameters:

  • hGeom -- handle to the geometry to add a vertex to.

  • i -- the index of the vertex to assign (zero based) or zero for a point.

  • dfX -- input X coordinate to assign.

  • dfY -- input Y coordinate to assign.

  • dfZ -- input Z coordinate to assign (defaults to zero).

void OGR_G_SetPoint_2D(OGRGeometryH, int iPoint, double, double)

Set the location of a vertex in a point or linestring geometry.

If iPoint is larger than the number of existing points in the linestring, the point count will be increased to accommodate the request.

Parameters:

  • hGeom -- handle to the geometry to add a vertex to.

  • i -- the index of the vertex to assign (zero based) or zero for a point.

  • dfX -- input X coordinate to assign.

  • dfY -- input Y coordinate to assign.

void OGR_G_SetPointM(OGRGeometryH, int iPoint, double, double, double)

Set the location of a vertex in a point or linestring geometry.

If iPoint is larger than the number of existing points in the linestring, the point count will be increased to accommodate the request.

Parameters:

  • hGeom -- handle to the geometry to add a vertex to.

  • i -- the index of the vertex to assign (zero based) or zero for a point.

  • dfX -- input X coordinate to assign.

  • dfY -- input Y coordinate to assign.

  • dfM -- input M coordinate to assign.

void OGR_G_SetPointZM(OGRGeometryH, int iPoint, double, double, double, double)

Set the location of a vertex in a point or linestring geometry.

If iPoint is larger than the number of existing points in the linestring, the point count will be increased to accommodate the request.

Parameters:

  • hGeom -- handle to the geometry to add a vertex to.

  • i -- the index of the vertex to assign (zero based) or zero for a point.

  • dfX -- input X coordinate to assign.

  • dfY -- input Y coordinate to assign.

  • dfZ -- input Z coordinate to assign.

  • dfM -- input M coordinate to assign.

void OGR_G_AddPoint(OGRGeometryH, double, double, double)

Add a point to a geometry (line string or point).

The vertex count of the line string is increased by one, and assigned from the passed location value.

Parameters:

  • hGeom -- handle to the geometry to add a point to.

  • dfX -- x coordinate of point to add.

  • dfY -- y coordinate of point to add.

  • dfZ -- z coordinate of point to add.

void OGR_G_AddPoint_2D(OGRGeometryH, double, double)

Add a point to a geometry (line string or point).

The vertex count of the line string is increased by one, and assigned from the passed location value.

Parameters:

  • hGeom -- handle to the geometry to add a point to.

  • dfX -- x coordinate of point to add.

  • dfY -- y coordinate of point to add.

void OGR_G_AddPointM(OGRGeometryH, double, double, double)

Add a point to a geometry (line string or point).

The vertex count of the line string is increased by one, and assigned from the passed location value.

Parameters:

  • hGeom -- handle to the geometry to add a point to.

  • dfX -- x coordinate of point to add.

  • dfY -- y coordinate of point to add.

  • dfM -- m coordinate of point to add.

void OGR_G_AddPointZM(OGRGeometryH, double, double, double, double)

Add a point to a geometry (line string or point).

The vertex count of the line string is increased by one, and assigned from the passed location value.

Parameters:

  • hGeom -- handle to the geometry to add a point to.

  • dfX -- x coordinate of point to add.

  • dfY -- y coordinate of point to add.

  • dfZ -- z coordinate of point to add.

  • dfM -- m coordinate of point to add.

void OGR_G_SetPoints(OGRGeometryH hGeom, int nPointsIn, const void *pabyX, int nXStride, const void *pabyY, int nYStride, const void *pabyZ, int nZStride)

Assign all points in a point or a line string geometry.

This method clear any existing points assigned to this geometry, and assigns a whole new set.

Parameters:

  • hGeom -- handle to the geometry to set the coordinates.

  • nPointsIn -- number of points being passed in padfX and padfY.

  • pabyX -- list of X coordinates (double values) of points being assigned.

  • nXStride -- the number of bytes between 2 elements of pabyX.

  • pabyY -- list of Y coordinates (double values) of points being assigned.

  • nYStride -- the number of bytes between 2 elements of pabyY.

  • pabyZ -- list of Z coordinates (double values) of points being assigned (defaults to NULL for 2D objects).

  • nZStride -- the number of bytes between 2 elements of pabyZ.

void OGR_G_SetPointsZM(OGRGeometryH hGeom, int nPointsIn, const void *pabyX, int nXStride, const void *pabyY, int nYStride, const void *pabyZ, int nZStride, const void *pabyM, int nMStride)

Assign all points in a point or a line string geometry.

This method clear any existing points assigned to this geometry, and assigns a whole new set.

Parameters:

  • hGeom -- handle to the geometry to set the coordinates.

  • nPointsIn -- number of points being passed in padfX and padfY.

  • pX -- list of X coordinates (double values) of points being assigned.

  • nXStride -- the number of bytes between 2 elements of pX.

  • pY -- list of Y coordinates (double values) of points being assigned.

  • nYStride -- the number of bytes between 2 elements of pY.

  • pZ -- list of Z coordinates (double values) of points being assigned (if not NULL, upgrades the geometry to have Z coordinate).

  • nZStride -- the number of bytes between 2 elements of pZ.

  • pM -- list of M coordinates (double values) of points being assigned (if not NULL, upgrades the geometry to have M coordinate).

  • nMStride -- the number of bytes between 2 elements of pM.

void OGR_G_SwapXY(OGRGeometryH hGeom)

Swap x and y coordinates.

Since

OGR 2.3.0

Parameters:

hGeom -- geometry.

int OGR_G_GetGeometryCount(OGRGeometryH)

Fetch the number of elements in a geometry or number of geometries in container.

Only geometries of type wkbPolygon[25D], wkbMultiPoint[25D], wkbMultiLineString[25D], wkbMultiPolygon[25D] or wkbGeometryCollection[25D] may return a valid value. Other geometry types will silently return 0.

For a polygon, the returned number is the number of rings (exterior ring + interior rings).

Parameters:

hGeom -- single geometry or geometry container from which to get the number of elements.

Returns:

the number of elements.

OGRGeometryH OGR_G_GetGeometryRef(OGRGeometryH, int)

Fetch geometry from a geometry container.

This function returns a handle to a geometry within the container. The returned geometry remains owned by the container, and should not be modified. The handle is only valid until the next change to the geometry container. Use OGR_G_Clone() to make a copy.

This function relates to the SFCOM IGeometryCollection::get_Geometry() method.

This function is the same as the CPP method OGRGeometryCollection::getGeometryRef().

For a polygon, OGR_G_GetGeometryRef(iSubGeom) returns the exterior ring if iSubGeom == 0, and the interior rings for iSubGeom > 0.

Parameters:

  • hGeom -- handle to the geometry container from which to get a geometry from.

  • iSubGeom -- the index of the geometry to fetch, between 0 and getNumGeometries() - 1.

Returns:

handle to the requested geometry.

OGRErr OGR_G_AddGeometry(OGRGeometryH, OGRGeometryH)

Add a geometry to a geometry container.

Some subclasses of OGRGeometryCollection restrict the types of geometry that can be added, and may return an error. The passed geometry is cloned to make an internal copy.

There is no SFCOM analog to this method.

This function is the same as the CPP method OGRGeometryCollection::addGeometry.

For a polygon, hNewSubGeom must be a linearring. If the polygon is empty, the first added subgeometry will be the exterior ring. The next ones will be the interior rings.

Parameters:

  • hGeom -- existing geometry container.

  • hNewSubGeom -- geometry to add to the container.

Returns:

OGRERR_NONE if successful, or OGRERR_UNSUPPORTED_GEOMETRY_TYPE if the geometry type is illegal for the type of existing geometry.

OGRErr OGR_G_AddGeometryDirectly(OGRGeometryH, OGRGeometryH)

Add a geometry directly to an existing geometry container.

Some subclasses of OGRGeometryCollection restrict the types of geometry that can be added, and may return an error. Ownership of the passed geometry is taken by the container rather than cloning as addGeometry() does.

This function is the same as the CPP method OGRGeometryCollection::addGeometryDirectly.

There is no SFCOM analog to this method.

For a polygon, hNewSubGeom must be a linearring. If the polygon is empty, the first added subgeometry will be the exterior ring. The next ones will be the interior rings.

Parameters:

  • hGeom -- existing geometry.

  • hNewSubGeom -- geometry to add to the existing geometry.

Returns:

OGRERR_NONE if successful, or OGRERR_UNSUPPORTED_GEOMETRY_TYPE if the geometry type is illegal for the type of geometry container.

OGRErr OGR_G_RemoveGeometry(OGRGeometryH, int, int)

Remove a geometry from an exiting geometry container.

Removing a geometry will cause the geometry count to drop by one, and all "higher" geometries will shuffle down one in index.

There is no SFCOM analog to this method.

This function is the same as the CPP method OGRGeometryCollection::removeGeometry() for geometry collections, OGRCurvePolygon::removeRing() for polygons / curve polygons and OGRPolyhedralSurface::removeGeometry() for polyhedral surfaces and TINs.

Parameters:

  • hGeom -- the existing geometry to delete from.

  • iGeom -- the index of the geometry to delete. A value of -1 is a special flag meaning that all geometries should be removed.

  • bDelete -- if TRUE the geometry will be destroyed, otherwise it will not. The default is TRUE as the existing geometry is considered to own the geometries in it.

Returns:

OGRERR_NONE if successful, or OGRERR_FAILURE if the index is out of range.

int OGR_G_HasCurveGeometry(OGRGeometryH, int bLookForNonLinear)

Returns if this geometry is or has curve geometry.

Returns if a geometry is or has CIRCULARSTRING, COMPOUNDCURVE, CURVEPOLYGON, MULTICURVE or MULTISURFACE in it.

If bLookForNonLinear is set to TRUE, it will be actually looked if the geometry or its subgeometries are or contain a non-linear geometry in them. In which case, if the method returns TRUE, it means that OGR_G_GetLinearGeometry() would return an approximate version of the geometry. Otherwise, OGR_G_GetLinearGeometry() would do a conversion, but with just converting container type, like COMPOUNDCURVE -> LINESTRING, MULTICURVE -> MULTILINESTRING or MULTISURFACE -> MULTIPOLYGON, resulting in a "loss-less" conversion.

This function is the same as C++ method OGRGeometry::hasCurveGeometry().

Since

GDAL 2.0

Parameters:

  • hGeom -- the geometry to operate on.

  • bLookForNonLinear -- set it to TRUE to check if the geometry is or contains a CIRCULARSTRING.

Returns:

TRUE if this geometry is or has curve geometry.

OGRGeometryH OGR_G_GetLinearGeometry(OGRGeometryH hGeom, double dfMaxAngleStepSizeDegrees, char **papszOptions)

Return, possibly approximate, linear version of this geometry.

Returns a geometry that has no CIRCULARSTRING, COMPOUNDCURVE, CURVEPOLYGON, MULTICURVE or MULTISURFACE in it, by approximating curve geometries.

The ownership of the returned geometry belongs to the caller.

The reverse function is OGR_G_GetCurveGeometry().

This method relates to the ISO SQL/MM Part 3 ICurve::CurveToLine() and CurvePolygon::CurvePolyToPoly() methods.

This function is the same as C++ method OGRGeometry::getLinearGeometry().

Since

GDAL 2.0

Parameters:

  • hGeom -- the geometry to operate on.

  • dfMaxAngleStepSizeDegrees -- the largest step in degrees along the arc, zero to use the default setting.

  • papszOptions -- options as a null-terminated list of strings or NULL. See OGRGeometryFactory::curveToLineString() for valid options.

Returns:

a new geometry.

OGRGeometryH OGR_G_GetCurveGeometry(OGRGeometryH hGeom, char **papszOptions)

Return curve version of this geometry.

Returns a geometry that has possibly CIRCULARSTRING, COMPOUNDCURVE, CURVEPOLYGON, MULTICURVE or MULTISURFACE in it, by de-approximating linear into curve geometries.

If the geometry has no curve portion, the returned geometry will be a clone of it.

The ownership of the returned geometry belongs to the caller.

The reverse function is OGR_G_GetLinearGeometry().

This function is the same as C++ method OGRGeometry::getCurveGeometry().

Since

GDAL 2.0

Parameters:

  • hGeom -- the geometry to operate on.

  • papszOptions -- options as a null-terminated list of strings. Unused for now. Must be set to NULL.

Returns:

a new geometry.

OGRGeometryH OGRBuildPolygonFromEdges(OGRGeometryH hLinesAsCollection, int bBestEffort, int bAutoClose, double dfTolerance, OGRErr *peErr)

Build a ring from a bunch of arcs.

Parameters:

  • hLines -- handle to an OGRGeometryCollection (or OGRMultiLineString) containing the line string geometries to be built into rings.

  • bBestEffort -- not yet implemented???.

  • bAutoClose -- indicates if the ring should be close when first and last points of the ring are the same.

  • dfTolerance -- tolerance into which two arcs are considered close enough to be joined.

  • peErr -- OGRERR_NONE on success, or OGRERR_FAILURE on failure.

Returns:

a handle to the new geometry, a polygon.

void OGRSetNonLinearGeometriesEnabledFlag(int bFlag)

Set flag to enable/disable returning non-linear geometries in the C API.

This flag has only an effect on the OGR_F_GetGeometryRef(), OGR_F_GetGeomFieldRef(), OGR_L_GetGeomType(), OGR_GFld_GetType() and OGR_FD_GetGeomType() C API, and corresponding methods in the SWIG bindings. It is meant as making it simple for applications using the OGR C API not to have to deal with non-linear geometries, even if such geometries might be returned by drivers. In which case, they will be transformed into their closest linear geometry, by doing linear approximation, with OGR_G_ForceTo().

Libraries should generally not use that method, since that could interfere with other libraries or applications.

Note that it does not affect the behavior of the C++ API.

Since

GDAL 2.0

Parameters:

bFlag -- TRUE if non-linear geometries might be returned (default value). FALSE to ask for non-linear geometries to be approximated as linear geometries.

int OGRGetNonLinearGeometriesEnabledFlag(void)

Get flag to enable/disable returning non-linear geometries in the C API.

return TRUE if non-linear geometries might be returned (default value is TRUE).

See also

OGRSetNonLinearGeometriesEnabledFlag()

Since

GDAL 2.0

int OGRHasPreparedGeometrySupport(void)

Returns if GEOS has prepared geometry support.

Returns:

TRUE or FALSE

OGRPreparedGeometryH OGRCreatePreparedGeometry(OGRGeometryH hGeom)

Creates a prepared geometry.

To free with OGRDestroyPreparedGeometry()

Since

GDAL 3.3

Parameters:

hGeom -- input geometry to prepare.

Returns:

handle to a prepared geometry.

void OGRDestroyPreparedGeometry(OGRPreparedGeometryH hPreparedGeom)

Destroys a prepared geometry.

Since

GDAL 3.3

Parameters:

hPreparedGeom -- preprated geometry.

int OGRPreparedGeometryIntersects(OGRPreparedGeometryH hPreparedGeom, OGRGeometryH hOtherGeom)

Returns whether a prepared geometry intersects with a geometry.

Since

GDAL 3.3

Parameters:

  • hPreparedGeom -- prepared geometry.

  • hOtherGeom -- other geometry.

Returns:

TRUE or FALSE.

int OGRPreparedGeometryContains(OGRPreparedGeometryH hPreparedGeom, OGRGeometryH hOtherGeom)

Returns whether a prepared geometry contains a geometry.

Parameters:

  • hPreparedGeom -- prepared geometry.

  • hOtherGeom -- other geometry.

Returns:

TRUE or FALSE.

OGRFieldDefnH OGR_Fld_Create(const char*, OGRFieldType)

Create a new field definition.

By default, fields have no width, precision, are nullable and not ignored.

This function is the same as the CPP method OGRFieldDefn::OGRFieldDefn().

Parameters:

  • pszName -- the name of the new field definition.

  • eType -- the type of the new field definition.

Returns:

handle to the new field definition.

void OGR_Fld_Destroy(OGRFieldDefnH)

Destroy a field definition.

Parameters:

hDefn -- handle to the field definition to destroy.

void OGR_Fld_SetName(OGRFieldDefnH, const char*)

Reset the name of this field.

This function is the same as the CPP method OGRFieldDefn::SetName().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters:

  • hDefn -- handle to the field definition to apply the new name to.

  • pszName -- the new name to apply.

const char *OGR_Fld_GetNameRef(OGRFieldDefnH)

Fetch name of this field.

This function is the same as the CPP method OGRFieldDefn::GetNameRef().

Parameters:

hDefn -- handle to the field definition.

Returns:

the name of the field definition.

void OGR_Fld_SetAlternativeName(OGRFieldDefnH, const char*)

Reset the alternative name (or "alias") for this field.

The alternative name is an optional attribute for a field which can provide a more user-friendly, descriptive name of a field which is not subject to the usual naming constraints defined by the data provider.

This is a metadata style attribute only: the alternative name cannot be used in place of the actual field name during SQL queries or other field name dependent API calls.

This function is the same as the CPP method OGRFieldDefn::SetAlternativeName().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Since

GDAL 3.2

Parameters:

  • hDefn -- handle to the field definition to apply the new alternative name to.

  • pszAlternativeName -- the new alternative name to apply.

const char *OGR_Fld_GetAlternativeNameRef(OGRFieldDefnH)

Fetch the alternative name (or "alias") for this field.

The alternative name is an optional attribute for a field which can provide a more user-friendly, descriptive name of a field which is not subject to the usual naming constraints defined by the data provider.

This is a metadata style attribute only: the alternative name cannot be used in place of the actual field name during SQL queries or other field name dependent API calls.

This function is the same as the CPP method OGRFieldDefn::GetAlternativeNameRef().

Since

GDAL 3.2

Parameters:

hDefn -- handle to the field definition.

Returns:

the alternative name of the field definition.

OGRFieldType OGR_Fld_GetType(OGRFieldDefnH)

Fetch type of this field.

This function is the same as the CPP method OGRFieldDefn::GetType().

Parameters:

hDefn -- handle to the field definition to get type from.

Returns:

field type.

void OGR_Fld_SetType(OGRFieldDefnH, OGRFieldType)

Set the type of this field.

This should never be done to an OGRFieldDefn that is already part of an OGRFeatureDefn.

This function is the same as the CPP method OGRFieldDefn::SetType().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters:

  • hDefn -- handle to the field definition to set type to.

  • eType -- the new field type.

OGRFieldSubType OGR_Fld_GetSubType(OGRFieldDefnH)

Fetch subtype of this field.

This function is the same as the CPP method OGRFieldDefn::GetSubType().

Since

GDAL 2.0

Parameters:

hDefn -- handle to the field definition to get subtype from.

Returns:

field subtype.

void OGR_Fld_SetSubType(OGRFieldDefnH, OGRFieldSubType)

Set the subtype of this field.

This should never be done to an OGRFieldDefn that is already part of an OGRFeatureDefn.

This function is the same as the CPP method OGRFieldDefn::SetSubType().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Since

GDAL 2.0

Parameters:

  • hDefn -- handle to the field definition to set type to.

  • eSubType -- the new field subtype.

OGRJustification OGR_Fld_GetJustify(OGRFieldDefnH)

Get the justification for this field.

This function is the same as the CPP method OGRFieldDefn::GetJustify().

Note: no driver is know to use the concept of field justification.

Parameters:

hDefn -- handle to the field definition to get justification from.

Returns:

the justification.

void OGR_Fld_SetJustify(OGRFieldDefnH, OGRJustification)

Set the justification for this field.

Note: no driver is know to use the concept of field justification.

This function is the same as the CPP method OGRFieldDefn::SetJustify().

Parameters:

  • hDefn -- handle to the field definition to set justification to.

  • eJustify -- the new justification.

int OGR_Fld_GetWidth(OGRFieldDefnH)

Get the formatting width for this field.

This function is the same as the CPP method OGRFieldDefn::GetWidth().

Parameters:

hDefn -- handle to the field definition to get width from.

Returns:

the width, zero means no specified width.

void OGR_Fld_SetWidth(OGRFieldDefnH, int)

Set the formatting width for this field in characters.

This function is the same as the CPP method OGRFieldDefn::SetWidth().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters:

  • hDefn -- handle to the field definition to set width to.

  • nNewWidth -- the new width.

int OGR_Fld_GetPrecision(OGRFieldDefnH)

Get the formatting precision for this field.

This should normally be zero for fields of types other than OFTReal.

This function is the same as the CPP method OGRFieldDefn::GetPrecision().

Parameters:

hDefn -- handle to the field definition to get precision from.

Returns:

the precision.

void OGR_Fld_SetPrecision(OGRFieldDefnH, int)

Set the formatting precision for this field in characters.

This should normally be zero for fields of types other than OFTReal.

This function is the same as the CPP method OGRFieldDefn::SetPrecision().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters:

  • hDefn -- handle to the field definition to set precision to.

  • nPrecision -- the new precision.

int OGR_Fld_GetTZFlag(OGRFieldDefnH)

Get the time zone flag.

Only applies to OFTTime, OFTDate and OFTDateTime fields.

Cf OGR_TZFLAG_UNKNOWN, OGR_TZFLAG_LOCALTIME, OGR_TZFLAG_MIXED_TZ and OGR_TZFLAG_UTC

Since

GDAL 3.8

Parameters:

hDefn -- handle to the field definition .

Returns:

the time zone flag.

void OGR_Fld_SetTZFlag(OGRFieldDefnH, int)

Set the formatting precision for this field in characters.

Set the time zone flag.

Only applies to OFTTime, OFTDate and OFTDateTime fields.

Cf OGR_TZFLAG_UNKNOWN, OGR_TZFLAG_LOCALTIME, OGR_TZFLAG_MIXED_TZ and OGR_TZFLAG_UTC

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Since

GDAL 3.8

Parameters:

  • hDefn -- handle to the field definition to set precision to.

  • nTZFlag -- the new time zone flag.

void OGR_Fld_Set(OGRFieldDefnH, const char*, OGRFieldType, int, int, OGRJustification)

Set defining parameters for a field in one call.

This function is the same as the CPP method OGRFieldDefn::Set().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters:

  • hDefn -- handle to the field definition to set to.

  • pszNameIn -- the new name to assign.

  • eTypeIn -- the new type (one of the OFT values like OFTInteger).

  • nWidthIn -- the preferred formatting width. Defaults to zero indicating undefined.

  • nPrecisionIn -- number of decimals places for formatting, defaults to zero indicating undefined.

  • eJustifyIn -- the formatting justification (OJLeft or OJRight), defaults to OJUndefined.

int OGR_Fld_IsIgnored(OGRFieldDefnH hDefn)

Return whether this field should be omitted when fetching features.

This method is the same as the C++ method OGRFieldDefn::IsIgnored().

Parameters:

hDefn -- handle to the field definition

Returns:

ignore state

void OGR_Fld_SetIgnored(OGRFieldDefnH hDefn, int)

Set whether this field should be omitted when fetching features.

This method is the same as the C++ method OGRFieldDefn::SetIgnored().

This method should not be called on a object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, the OGRLayer::SetIgnoredFields() method should be called.

Parameters:

  • hDefn -- handle to the field definition

  • ignore -- ignore state

int OGR_Fld_IsNullable(OGRFieldDefnH hDefn)

Return whether this field can receive null values.

By default, fields are nullable.

Even if this method returns FALSE (i.e not-nullable field), it doesn't mean that OGRFeature::IsFieldSet() will necessary return TRUE, as fields can be temporary unset and null/not-null validation is usually done when OGRLayer::CreateFeature()/SetFeature() is called.

This method is the same as the C++ method OGRFieldDefn::IsNullable().

Since

GDAL 2.0

Parameters:

hDefn -- handle to the field definition

Returns:

TRUE if the field is authorized to be null.

void OGR_Fld_SetNullable(OGRFieldDefnH hDefn, int)

Set whether this field can receive null values.

By default, fields are nullable, so this method is generally called with FALSE to set a not-null constraint.

Drivers that support writing not-null constraint will advertise the GDAL_DCAP_NOTNULL_FIELDS driver metadata item.

This method is the same as the C++ method OGRFieldDefn::SetNullable().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Since

GDAL 2.0

Parameters:

  • hDefn -- handle to the field definition

  • bNullableIn -- FALSE if the field must have a not-null constraint.

int OGR_Fld_IsUnique(OGRFieldDefnH hDefn)

Return whether this field has a unique constraint.

By default, fields have no unique constraint.

This method is the same as the C++ method OGRFieldDefn::IsUnique().

Since

GDAL 3.2

Parameters:

hDefn -- handle to the field definition

Returns:

TRUE if the field has a unique constraint.

void OGR_Fld_SetUnique(OGRFieldDefnH hDefn, int)

Set whether this field has a unique constraint.

By default, fields have no unique constraint, so this method is generally called with TRUE to set a unique constraint.

Drivers that support writing unique constraint will advertise the GDAL_DCAP_UNIQUE_FIELDS driver metadata item. field can receive null values.

This method is the same as the C++ method OGRFieldDefn::SetUnique().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Since

GDAL 3.2

Parameters:

  • hDefn -- handle to the field definition

  • bUniqueIn -- TRUE if the field must have a unique constraint.

const char *OGR_Fld_GetDefault(OGRFieldDefnH hDefn)

Get default field value.

This function is the same as the C++ method OGRFieldDefn::GetDefault().

Since

GDAL 2.0

Parameters:

hDefn -- handle to the field definition.

Returns:

default field value or NULL.

void OGR_Fld_SetDefault(OGRFieldDefnH hDefn, const char*)

Set default field value.

The default field value is taken into account by drivers (generally those with a SQL interface) that support it at field creation time. OGR will generally not automatically set the default field value to null fields by itself when calling OGRFeature::CreateFeature() / OGRFeature::SetFeature(), but will let the low-level layers to do the job. So retrieving the feature from the layer is recommended.

The accepted values are NULL, a numeric value, a literal value enclosed between single quote characters (and inner single quote characters escaped by repetition of the single quote character), CURRENT_TIMESTAMP, CURRENT_TIME, CURRENT_DATE or a driver specific expression (that might be ignored by other drivers). For a datetime literal value, format should be 'YYYY/MM/DD HH:MM:SS[.sss]' (considered as UTC time).

Drivers that support writing DEFAULT clauses will advertise the GDAL_DCAP_DEFAULT_FIELDS driver metadata item.

This function is the same as the C++ method OGRFieldDefn::SetDefault().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Since

GDAL 2.0

Parameters:

  • hDefn -- handle to the field definition.

  • pszDefault -- new default field value or NULL pointer.

int OGR_Fld_IsDefaultDriverSpecific(OGRFieldDefnH hDefn)

Returns whether the default value is driver specific.

Driver specific default values are those that are not NULL, a numeric value, a literal value enclosed between single quote characters, CURRENT_TIMESTAMP, CURRENT_TIME, CURRENT_DATE or datetime literal value.

This function is the same as the C++ method OGRFieldDefn::IsDefaultDriverSpecific().

Since

GDAL 2.0

Parameters:

hDefn -- handle to the field definition

Returns:

TRUE if the default value is driver specific.

const char *OGR_Fld_GetDomainName(OGRFieldDefnH hDefn)

Return the name of the field domain for this field.

By default, none (empty string) is returned.

Field domains (OGRFieldDomain class) are attached at the GDALDataset level and should be retrieved with GDALDatasetGetFieldDomain().

This method is the same as the C++ method OGRFieldDefn::GetDomainName().

Since

GDAL 3.3

Parameters:

hDefn -- handle to the field definition

Returns:

the field domain name, or an empty string if there is none.

void OGR_Fld_SetDomainName(OGRFieldDefnH hDefn, const char*)

Set the name of the field domain for this field.

Field domains (OGRFieldDomain) are attached at the GDALDataset level.

This method is the same as the C++ method OGRFieldDefn::SetDomainName().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Since

GDAL 3.3

Parameters:

  • hDefn -- handle to the field definition

  • pszFieldName -- Field domain name.

const char *OGR_Fld_GetComment(OGRFieldDefnH hDefn)

Return the (optional) comment for this field.

By default, none (empty string) is returned.

This method is the same as the C++ method OGRFieldDefn::GetComment().

Since

GDAL 3.7

Parameters:

hDefn -- handle to the field definition

Returns:

the comment, or an empty string if there is none.

void OGR_Fld_SetComment(OGRFieldDefnH hDefn, const char*)

Set the comment for this field.

This method is the same as the C++ method OGRFieldDefn::SetComment().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Since

GDAL 3.7

Parameters:

  • hDefn -- handle to the field definition

  • pszComment -- Field comment.

const char *OGR_GetFieldTypeName(OGRFieldType)

Fetch human readable name for a field type.

This function is the same as the CPP method OGRFieldDefn::GetFieldTypeName().

Parameters:

eType -- the field type to get name for.

Returns:

the name.

const char *OGR_GetFieldSubTypeName(OGRFieldSubType)

Fetch human readable name for a field subtype.

This function is the same as the CPP method OGRFieldDefn::GetFieldSubTypeName().

Since

GDAL 2.0

Parameters:

eSubType -- the field subtype to get name for.

Returns:

the name.

int OGR_AreTypeSubTypeCompatible(OGRFieldType eType, OGRFieldSubType eSubType)

Return if type and subtype are compatible.

Since

GDAL 2.0

Parameters:

  • eType -- the field type.

  • eSubType -- the field subtype.

Returns:

TRUE if type and subtype are compatible

OGRGeomFieldDefnH OGR_GFld_Create(const char*, OGRwkbGeometryType)

Create a new field geometry definition.

This function is the same as the CPP method OGRGeomFieldDefn::OGRGeomFieldDefn().

Since

GDAL 1.11

Parameters:

  • pszName -- the name of the new field definition.

  • eType -- the type of the new field definition.

Returns:

handle to the new field definition.

void OGR_GFld_Destroy(OGRGeomFieldDefnH)

Destroy a geometry field definition.

Since

GDAL 1.11

Parameters:

hDefn -- handle to the geometry field definition to destroy.

void OGR_GFld_SetName(OGRGeomFieldDefnH, const char*)

Reset the name of this field.

This function is the same as the CPP method OGRGeomFieldDefn::SetName().

Note that once a OGRGeomFieldDefn has been added to a layer definition with OGRLayer::AddGeomFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetGeomFieldDefn(). Instead, OGRLayer::AlterGeomFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Since

GDAL 1.11

Parameters:

  • hDefn -- handle to the geometry field definition to apply the new name to.

  • pszName -- the new name to apply.

const char *OGR_GFld_GetNameRef(OGRGeomFieldDefnH)

Fetch name of this field.

This function is the same as the CPP method OGRGeomFieldDefn::GetNameRef().

Since

GDAL 1.11

Parameters:

hDefn -- handle to the geometry field definition.

Returns:

the name of the geometry field definition.

OGRwkbGeometryType OGR_GFld_GetType(OGRGeomFieldDefnH)

Fetch geometry type of this field.

This function is the same as the CPP method OGRGeomFieldDefn::GetType().

Since

GDAL 1.11

Parameters:

hDefn -- handle to the geometry field definition to get type from.

Returns:

field geometry type.

void OGR_GFld_SetType(OGRGeomFieldDefnH, OGRwkbGeometryType)

Set the geometry type of this field.

This should never be done to an OGRGeomFieldDefn that is already part of an OGRFeatureDefn.

This function is the same as the CPP method OGRGeomFieldDefn::SetType().

Note that once a OGRGeomFieldDefn has been added to a layer definition with OGRLayer::AddGeomFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetGeomFieldDefn(). Instead, OGRLayer::AlterGeomFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Since

GDAL 1.11

Parameters:

  • hDefn -- handle to the geometry field definition to set type to.

  • eType -- the new field geometry type.

OGRSpatialReferenceH OGR_GFld_GetSpatialRef(OGRGeomFieldDefnH)

Fetch spatial reference system of this field.

This function is the same as the C++ method OGRGeomFieldDefn::GetSpatialRef().

Since

GDAL 1.11

Parameters:

hDefn -- handle to the geometry field definition

Returns:

a reference to the field spatial reference system. It should not be modified.

void OGR_GFld_SetSpatialRef(OGRGeomFieldDefnH, OGRSpatialReferenceH hSRS)

Set the spatial reference of this field.

This function is the same as the C++ method OGRGeomFieldDefn::SetSpatialRef().

This function drops the reference of the previously set SRS object and acquires a new reference on the passed object (if non-NULL).

Note that once a OGRGeomFieldDefn has been added to a layer definition with OGRLayer::AddGeomFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetGeomFieldDefn(). Instead, OGRLayer::AlterGeomFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Since

GDAL 1.11

Parameters:

  • hDefn -- handle to the geometry field definition

  • hSRS -- the new SRS to apply.

int OGR_GFld_IsNullable(OGRGeomFieldDefnH hDefn)

Return whether this geometry field can receive null values.

By default, fields are nullable.

Even if this method returns FALSE (i.e not-nullable field), it doesn't mean that OGRFeature::IsFieldSet() will necessary return TRUE, as fields can be temporary unset and null/not-null validation is usually done when OGRLayer::CreateFeature()/SetFeature() is called.

Note that not-nullable geometry fields might also contain 'empty' geometries.

This method is the same as the C++ method OGRGeomFieldDefn::IsNullable().

Note that once a OGRGeomFieldDefn has been added to a layer definition with OGRLayer::AddGeomFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetGeomFieldDefn(). Instead, OGRLayer::AlterGeomFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Since

GDAL 2.0

Parameters:

hDefn -- handle to the field definition

Returns:

TRUE if the field is authorized to be null.

void OGR_GFld_SetNullable(OGRGeomFieldDefnH hDefn, int)

Set whether this geometry field can receive null values.

By default, fields are nullable, so this method is generally called with FALSE to set a not-null constraint.

Drivers that support writing not-null constraint will advertise the GDAL_DCAP_NOTNULL_GEOMFIELDS driver metadata item.

This method is the same as the C++ method OGRGeomFieldDefn::SetNullable().

Since

GDAL 2.0

Parameters:

  • hDefn -- handle to the field definition

  • bNullableIn -- FALSE if the field must have a not-null constraint.

int OGR_GFld_IsIgnored(OGRGeomFieldDefnH hDefn)

Return whether this field should be omitted when fetching features.

This method is the same as the C++ method OGRGeomFieldDefn::IsIgnored().

Since

GDAL 1.11

Parameters:

hDefn -- handle to the geometry field definition

Returns:

ignore state

void OGR_GFld_SetIgnored(OGRGeomFieldDefnH hDefn, int)

Set whether this field should be omitted when fetching features.

This method is the same as the C++ method OGRGeomFieldDefn::SetIgnored().

This method should not be called on a object returned with OGRLayer::GetLayerDefn()->GetGeomFieldDefn(). Instead, the OGRLayer::SetIgnoredFields() method should be called.

Since

GDAL 1.11

Parameters:

  • hDefn -- handle to the geometry field definition

  • ignore -- ignore state

OGRGeomCoordinatePrecisionH OGR_GFld_GetCoordinatePrecision(OGRGeomFieldDefnH)

Return the coordinate precision associated to this geometry field.

This method is the same as the C++ method OGRGeomFieldDefn::GetCoordinatePrecision()

Since

GDAL 3.9

Parameters:

hDefn -- handle to the field definition

Returns:

the coordinate precision

void OGR_GFld_SetCoordinatePrecision(OGRGeomFieldDefnH, OGRGeomCoordinatePrecisionH)

Set coordinate precision associated to this geometry field.

This method is the same as the C++ method OGRGeomFieldDefn::SetCoordinatePrecision()

Note that once a OGRGeomFieldDefn has been added to a layer definition with OGRLayer::AddGeomFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetGeomFieldDefn().

Since

GDAL 3.9

Parameters:

  • hDefn -- handle to the field definition. Must not be NULL.

  • hGeomCoordPrec -- Coordinate precision. Must not be NULL.

OGRFeatureDefnH OGR_FD_Create(const char*)

Create a new feature definition object to hold the field definitions.

The OGRFeatureDefn maintains a reference count, but this starts at zero, and should normally be incremented by the owner.

This function is the same as the C++ method OGRFeatureDefn::OGRFeatureDefn().

Parameters:

pszName -- the name to be assigned to this layer/class. It does not need to be unique.

Returns:

handle to the newly created feature definition.

void OGR_FD_Destroy(OGRFeatureDefnH)

Destroy a feature definition object and release all memory associated with it.

This function is the same as the C++ method OGRFeatureDefn::~OGRFeatureDefn().

Parameters:

hDefn -- handle to the feature definition to be destroyed.

void OGR_FD_Release(OGRFeatureDefnH)

Drop a reference, and destroy if unreferenced.

This function is the same as the C++ method OGRFeatureDefn::Release().

Parameters:

hDefn -- handle to the feature definition to be released.

const char *OGR_FD_GetName(OGRFeatureDefnH)

Get name of the OGRFeatureDefn passed as an argument.

This function is the same as the C++ method OGRFeatureDefn::GetName().

Parameters:

hDefn -- handle to the feature definition to get the name from.

Returns:

the name. This name is internal and should not be modified, or freed.

int OGR_FD_GetFieldCount(OGRFeatureDefnH)

Fetch number of fields on the passed feature definition.

This function is the same as the C++ OGRFeatureDefn::GetFieldCount().

Parameters:

hDefn -- handle to the feature definition to get the fields count from.

Returns:

count of fields.

OGRFieldDefnH OGR_FD_GetFieldDefn(OGRFeatureDefnH, int)

Fetch field definition of the passed feature definition.

This function is the same as the C++ method OGRFeatureDefn::GetFieldDefn().

Parameters:

  • hDefn -- handle to the feature definition to get the field definition from.

  • iField -- the field to fetch, between 0 and GetFieldCount()-1.

Returns:

a handle to an internal field definition object or NULL if invalid index. This object should not be modified or freed by the application.

int OGR_FD_GetFieldIndex(OGRFeatureDefnH, const char*)

Find field by name.

The field index of the first field matching the passed field name (case insensitively) is returned.

This function is the same as the C++ method OGRFeatureDefn::GetFieldIndex.

Parameters:

  • hDefn -- handle to the feature definition to get field index from.

  • pszFieldName -- the field name to search for.

Returns:

the field index, or -1 if no match found.

void OGR_FD_AddFieldDefn(OGRFeatureDefnH, OGRFieldDefnH)

Add a new field definition to the passed feature definition.

To add a new field definition to a layer definition, do not use this function directly, but use OGR_L_CreateField() instead.

This function should only be called while there are no OGRFeature objects in existence based on this OGRFeatureDefn. The OGRFieldDefn passed in is copied, and remains the responsibility of the caller.

This function is the same as the C++ method OGRFeatureDefn::AddFieldDefn().

Parameters:

  • hDefn -- handle to the feature definition to add the field definition to.

  • hNewField -- handle to the new field definition.

OGRErr OGR_FD_DeleteFieldDefn(OGRFeatureDefnH hDefn, int iField)

Delete an existing field definition.

To delete an existing field definition from a layer definition, do not use this function directly, but use OGR_L_DeleteField() instead.

This method should only be called while there are no OGRFeature objects in existence based on this OGRFeatureDefn.

This method is the same as the C++ method OGRFeatureDefn::DeleteFieldDefn().

Since

OGR 1.9.0

Parameters:

  • hDefn -- handle to the feature definition.

  • iField -- the index of the field definition.

Returns:

OGRERR_NONE in case of success.

OGRErr OGR_FD_ReorderFieldDefns(OGRFeatureDefnH hDefn, const int *panMap)

Reorder the field definitions in the array of the feature definition.

To reorder the field definitions in a layer definition, do not use this function directly, but use OGR_L_ReorderFields() instead.

This method should only be called while there are no OGRFeature objects in existence based on this OGRFeatureDefn.

This method is the same as the C++ method OGRFeatureDefn::ReorderFieldDefns().

Since

OGR 2.1.0

Parameters:

  • hDefn -- handle to the feature definition.

  • panMap -- an array of GetFieldCount() elements which is a permutation of [0, GetFieldCount()-1]. panMap is such that, for each field definition at position i after reordering, its position before reordering was panMap[i].

Returns:

OGRERR_NONE in case of success.

OGRwkbGeometryType OGR_FD_GetGeomType(OGRFeatureDefnH)

Fetch the geometry base type of the passed feature definition.

This function is the same as the C++ method OGRFeatureDefn::GetGeomType().

Starting with GDAL 1.11, this method returns GetGeomFieldDefn(0)->GetType().

Parameters:

hDefn -- handle to the feature definition to get the geometry type from.

Returns:

the base type for all geometry related to this definition.

void OGR_FD_SetGeomType(OGRFeatureDefnH, OGRwkbGeometryType)

Assign the base geometry type for the passed layer (the same as the feature definition).

All geometry objects using this type must be of the defined type or a derived type. The default upon creation is wkbUnknown which allows for any geometry type. The geometry type should generally not be changed after any OGRFeatures have been created against this definition.

This function is the same as the C++ method OGRFeatureDefn::SetGeomType().

Starting with GDAL 1.11, this method calls GetGeomFieldDefn(0)->SetType().

Parameters:

  • hDefn -- handle to the layer or feature definition to set the geometry type to.

  • eType -- the new type to assign.

int OGR_FD_IsGeometryIgnored(OGRFeatureDefnH)

Determine whether the geometry can be omitted when fetching features.

This function is the same as the C++ method OGRFeatureDefn::IsGeometryIgnored().

Starting with GDAL 1.11, this method returns GetGeomFieldDefn(0)->IsIgnored().

Parameters:

hDefn -- handle to the feature definition on witch OGRFeature are based on.

Returns:

ignore state

void OGR_FD_SetGeometryIgnored(OGRFeatureDefnH, int)

Set whether the geometry can be omitted when fetching features.

This function is the same as the C++ method OGRFeatureDefn::SetGeometryIgnored().

Starting with GDAL 1.11, this method calls GetGeomFieldDefn(0)->SetIgnored().

Parameters:

  • hDefn -- handle to the feature definition on witch OGRFeature are based on.

  • bIgnore -- ignore state

int OGR_FD_IsStyleIgnored(OGRFeatureDefnH)

Determine whether the style can be omitted when fetching features.

This function is the same as the C++ method OGRFeatureDefn::IsStyleIgnored().

Parameters:

hDefn -- handle to the feature definition on which OGRFeature are based on.

Returns:

ignore state

void OGR_FD_SetStyleIgnored(OGRFeatureDefnH, int)

Set whether the style can be omitted when fetching features.

This function is the same as the C++ method OGRFeatureDefn::SetStyleIgnored().

Parameters:

  • hDefn -- handle to the feature definition on witch OGRFeature are based on.

  • bIgnore -- ignore state

int OGR_FD_Reference(OGRFeatureDefnH)

Increments the reference count by one.

The reference count is used keep track of the number of OGRFeature objects referencing this definition.

This function is the same as the C++ method OGRFeatureDefn::Reference().

Parameters:

hDefn -- handle to the feature definition on witch OGRFeature are based on.

Returns:

the updated reference count.

int OGR_FD_Dereference(OGRFeatureDefnH)

Decrements the reference count by one.

This function is the same as the C++ method OGRFeatureDefn::Dereference().

Parameters:

hDefn -- handle to the feature definition on witch OGRFeature are based on.

Returns:

the updated reference count.

int OGR_FD_GetReferenceCount(OGRFeatureDefnH)

Fetch current reference count.

This function is the same as the C++ method OGRFeatureDefn::GetReferenceCount().

Parameters:

hDefn -- handle to the feature definition on witch OGRFeature are based on.

Returns:

the current reference count.

int OGR_FD_GetGeomFieldCount(OGRFeatureDefnH hFDefn)

Fetch number of geometry fields on the passed feature definition.

This function is the same as the C++ OGRFeatureDefn::GetGeomFieldCount().

Since

GDAL 1.11

Parameters:

hDefn -- handle to the feature definition to get the fields count from.

Returns:

count of geometry fields.

OGRGeomFieldDefnH OGR_FD_GetGeomFieldDefn(OGRFeatureDefnH hFDefn, int i)

Fetch geometry field definition of the passed feature definition.

This function is the same as the C++ method OGRFeatureDefn::GetGeomFieldDefn().

Since

GDAL 1.11

Parameters:

  • hDefn -- handle to the feature definition to get the field definition from.

  • iGeomField -- the geometry field to fetch, between 0 and GetGeomFieldCount() - 1.

Returns:

a handle to an internal field definition object or NULL if invalid index. This object should not be modified or freed by the application.

int OGR_FD_GetGeomFieldIndex(OGRFeatureDefnH hFDefn, const char *pszName)

Find geometry field by name.

The geometry field index of the first geometry field matching the passed field name (case insensitively) is returned.

This function is the same as the C++ method OGRFeatureDefn::GetGeomFieldIndex.

Parameters:

  • hDefn -- handle to the feature definition to get field index from.

  • pszGeomFieldName -- the geometry field name to search for.

Returns:

the geometry field index, or -1 if no match found.

void OGR_FD_AddGeomFieldDefn(OGRFeatureDefnH hFDefn, OGRGeomFieldDefnH hGFldDefn)

Add a new field definition to the passed feature definition.

To add a new field definition to a layer definition, do not use this function directly, but use OGR_L_CreateGeomField() instead.

This function should only be called while there are no OGRFeature objects in existence based on this OGRFeatureDefn. The OGRGeomFieldDefn passed in is copied, and remains the responsibility of the caller.

This function is the same as the C++ method OGRFeatureDefn::AddGeomFieldDefn().

Since

GDAL 1.11

Parameters:

  • hDefn -- handle to the feature definition to add the geometry field definition to.

  • hNewGeomField -- handle to the new field definition.

OGRErr OGR_FD_DeleteGeomFieldDefn(OGRFeatureDefnH hFDefn, int iGeomField)

Delete an existing geometry field definition.

To delete an existing geometry field definition from a layer definition, do not use this function directly, but use OGR_L_DeleteGeomField() instead (not implemented yet).

This method should only be called while there are no OGRFeature objects in existence based on this OGRFeatureDefn.

This method is the same as the C++ method OGRFeatureDefn::DeleteGeomFieldDefn().

Since

GDAL 1.11

Parameters:

  • hDefn -- handle to the feature definition.

  • iGeomField -- the index of the geometry field definition.

Returns:

OGRERR_NONE in case of success.

int OGR_FD_IsSame(OGRFeatureDefnH hFDefn, OGRFeatureDefnH hOtherFDefn)

Test if the feature definition is identical to the other one.

Since

OGR 1.11

Parameters:

  • hFDefn -- handle to the feature definition on witch OGRFeature are based on.

  • hOtherFDefn -- handle to the other feature definition to compare to.

Returns:

TRUE if the feature definition is identical to the other one.

OGRFeatureH OGR_F_Create(OGRFeatureDefnH)

Feature factory.

Note that the OGRFeature will increment the reference count of its defining OGRFeatureDefn. Destruction of the OGRFeatureDefn before destruction of all OGRFeatures that depend on it is likely to result in a crash.

This function is the same as the C++ method OGRFeature::OGRFeature().

Parameters:

hDefn -- handle to the feature class (layer) definition to which the feature will adhere.

Returns:

a handle to the new feature object with null fields and no geometry, or, starting with GDAL 2.1, NULL in case out of memory situation.

void OGR_F_Destroy(OGRFeatureH)

Destroy feature.

The feature is deleted, but within the context of the GDAL/OGR heap. This is necessary when higher level applications use GDAL/OGR from a DLL and they want to delete a feature created within the DLL. If the delete is done in the calling application the memory will be freed onto the application heap which is inappropriate.

This function is the same as the C++ method OGRFeature::DestroyFeature().

Parameters:

hFeat -- handle to the feature to destroy.

OGRFeatureDefnH OGR_F_GetDefnRef(OGRFeatureH)

Fetch feature definition.

This function is the same as the C++ method OGRFeature::GetDefnRef().

Parameters:

hFeat -- handle to the feature to get the feature definition from.

Returns:

a handle to the feature definition object on which feature depends.

OGRErr OGR_F_SetGeometryDirectly(OGRFeatureH, OGRGeometryH)

Set feature geometry.

This function updates the features geometry, and operate exactly as SetGeometry(), except that this function assumes ownership of the passed geometry (even in case of failure of that function).

This function is the same as the C++ method OGRFeature::SetGeometryDirectly.

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature on which to apply the geometry.

  • hGeom -- handle to the new geometry to apply to feature.

Returns:

OGRERR_NONE if successful, or OGR_UNSUPPORTED_GEOMETRY_TYPE if the geometry type is illegal for the OGRFeatureDefn (checking not yet implemented).

OGRErr OGR_F_SetGeometry(OGRFeatureH, OGRGeometryH)

Set feature geometry.

This function updates the features geometry, and operate exactly as SetGeometryDirectly(), except that this function does not assume ownership of the passed geometry, but instead makes a copy of it.

This function is the same as the C++ OGRFeature::SetGeometry().

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature on which new geometry is applied to.

  • hGeom -- handle to the new geometry to apply to feature.

Returns:

OGRERR_NONE if successful, or OGR_UNSUPPORTED_GEOMETRY_TYPE if the geometry type is illegal for the OGRFeatureDefn (checking not yet implemented).

OGRGeometryH OGR_F_GetGeometryRef(OGRFeatureH)

Fetch a handle to feature geometry.

This function is essentially the same as the C++ method OGRFeature::GetGeometryRef() (the only difference is that this C function honours OGRGetNonLinearGeometriesEnabledFlag())

Parameters:

hFeat -- handle to the feature to get geometry from.

Returns:

a handle to internal feature geometry. This object should not be modified.

OGRGeometryH OGR_F_StealGeometry(OGRFeatureH)

Take away ownership of geometry.

Fetch the geometry from this feature, and clear the reference to the geometry on the feature. This is a mechanism for the application to take over ownership of the geometry from the feature without copying. Sort of an inverse to OGR_FSetGeometryDirectly().

After this call the OGRFeature will have a NULL geometry.

Parameters:

hFeat -- feature from which to steal the first geometry.

Returns:

the pointer to the stolen geometry.

OGRGeometryH OGR_F_StealGeometryEx(OGRFeatureH, int iGeomField)

Take away ownership of geometry.

Fetch the geometry from this feature, and clear the reference to the geometry on the feature. This is a mechanism for the application to take over ownership of the geometry from the feature without copying. This is the functional opposite of OGR_F_SetGeomFieldDirectly.

After this call the OGRFeature will have a NULL geometry for the geometry field of index iGeomField.

Since

GDAL 3.5

Parameters:

  • hFeat -- feature from which to steal a geometry.

  • iGeomField -- index of the geometry field to steal.

Returns:

the pointer to the stolen geometry.

OGRFeatureH OGR_F_Clone(OGRFeatureH)

Duplicate feature.

The newly created feature is owned by the caller, and will have its own reference to the OGRFeatureDefn.

This function is the same as the C++ method OGRFeature::Clone().

Parameters:

hFeat -- handle to the feature to clone.

Returns:

a handle to the new feature, exactly matching this feature.

int OGR_F_Equal(OGRFeatureH, OGRFeatureH)

Test if two features are the same.

Two features are considered equal if the share them (handle equality) same OGRFeatureDefn, have the same field values, and the same geometry (as tested by OGR_G_Equal()) as well as the same feature id.

This function is the same as the C++ method OGRFeature::Equal().

Parameters:

  • hFeat -- handle to one of the feature.

  • hOtherFeat -- handle to the other feature to test this one against.

Returns:

TRUE if they are equal, otherwise FALSE.

int OGR_F_GetFieldCount(OGRFeatureH)

Fetch number of fields on this feature This will always be the same as the field count for the OGRFeatureDefn.

This function is the same as the C++ method OGRFeature::GetFieldCount().

Parameters:

hFeat -- handle to the feature to get the fields count from.

Returns:

count of fields.

OGRFieldDefnH OGR_F_GetFieldDefnRef(OGRFeatureH, int)

Fetch definition for this field.

This function is the same as the C++ method OGRFeature::GetFieldDefnRef().

Parameters:

  • hFeat -- handle to the feature on which the field is found.

  • i -- the field to fetch, from 0 to GetFieldCount()-1.

Returns:

a handle to the field definition (from the OGRFeatureDefn). This is an internal reference, and should not be deleted or modified.

int OGR_F_GetFieldIndex(OGRFeatureH, const char*)

Fetch the field index given field name.

This is a cover for the OGRFeatureDefn::GetFieldIndex() method.

This function is the same as the C++ method OGRFeature::GetFieldIndex().

Parameters:

  • hFeat -- handle to the feature on which the field is found.

  • pszName -- the name of the field to search for.

Returns:

the field index, or -1 if no matching field is found.

int OGR_F_IsFieldSet(OGRFeatureH, int)

Test if a field has ever been assigned a value or not.

This function is the same as the C++ method OGRFeature::IsFieldSet().

Parameters:

  • hFeat -- handle to the feature on which the field is.

  • iField -- the field to test.

Returns:

TRUE if the field has been set, otherwise false.

void OGR_F_UnsetField(OGRFeatureH, int)

Clear a field, marking it as unset.

This function is the same as the C++ method OGRFeature::UnsetField().

Parameters:

  • hFeat -- handle to the feature on which the field is.

  • iField -- the field to unset.

int OGR_F_IsFieldNull(OGRFeatureH, int)

Test if a field is null.

This function is the same as the C++ method OGRFeature::IsFieldNull().

Since

GDAL 2.2

Parameters:

  • hFeat -- handle to the feature on which the field is.

  • iField -- the field to test.

Returns:

TRUE if the field is null, otherwise false.

int OGR_F_IsFieldSetAndNotNull(OGRFeatureH, int)

Test if a field is set and not null.

This function is the same as the C++ method OGRFeature::IsFieldSetAndNotNull().

Since

GDAL 2.2

Parameters:

  • hFeat -- handle to the feature on which the field is.

  • iField -- the field to test.

Returns:

TRUE if the field is set and not null, otherwise false.

void OGR_F_SetFieldNull(OGRFeatureH, int)

Clear a field, marking it as null.

This function is the same as the C++ method OGRFeature::SetFieldNull().

Since

GDAL 2.2

Parameters:

  • hFeat -- handle to the feature on which the field is.

  • iField -- the field to set to null.

OGRField *OGR_F_GetRawFieldRef(OGRFeatureH, int)

Fetch a handle to the internal field value given the index.

This function is the same as the C++ method OGRFeature::GetRawFieldRef().

Parameters:

  • hFeat -- handle to the feature on which field is found.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

Returns:

the returned handle is to an internal data structure, and should not be freed, or modified.

int OGR_RawField_IsUnset(const OGRField*)

Returns whether a raw field is unset.

Note: this function is rather low-level and should be rarely used in client code. Use instead OGR_F_IsFieldSet().

Since

GDAL 2.2

Parameters:

puField -- pointer to raw field.

int OGR_RawField_IsNull(const OGRField*)

Returns whether a raw field is null.

Note: this function is rather low-level and should be rarely used in client code. Use instead OGR_F_IsFieldNull().

Since

GDAL 2.2

Parameters:

puField -- pointer to raw field.

void OGR_RawField_SetUnset(OGRField*)

Mark a raw field as unset.

This should be called on a un-initialized field. In particular this will not free any memory dynamically allocated.

Note: this function is rather low-level and should be rarely used in client code. Use instead OGR_F_UnsetField().

Since

GDAL 2.2

Parameters:

puField -- pointer to raw field.

void OGR_RawField_SetNull(OGRField*)

Mark a raw field as null.

This should be called on a un-initialized field. In particular this will not free any memory dynamically allocated.

Note: this function is rather low-level and should be rarely used in client code. Use instead OGR_F_SetFieldNull().

Since

GDAL 2.2

Parameters:

puField -- pointer to raw field.

int OGR_F_GetFieldAsInteger(OGRFeatureH, int)

Fetch field value as integer.

OFTString features will be translated using atoi(). OFTReal fields will be cast to integer. Other field types, or errors will result in a return value of zero.

This function is the same as the C++ method OGRFeature::GetFieldAsInteger().

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

Returns:

the field value.

GIntBig OGR_F_GetFieldAsInteger64(OGRFeatureH, int)

Fetch field value as integer 64 bit.

OFTInteger are promoted to 64 bit. OFTString features will be translated using CPLAtoGIntBig(). OFTReal fields will be cast to integer. Other field types, or errors will result in a return value of zero.

This function is the same as the C++ method OGRFeature::GetFieldAsInteger64().

Since

GDAL 2.0

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

Returns:

the field value.

double OGR_F_GetFieldAsDouble(OGRFeatureH, int)

Fetch field value as a double.

OFTString features will be translated using CPLAtof(). OFTInteger fields will be cast to double. Other field types, or errors will result in a return value of zero.

This function is the same as the C++ method OGRFeature::GetFieldAsDouble().

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

Returns:

the field value.

const char *OGR_F_GetFieldAsString(OGRFeatureH, int)

Fetch field value as a string.

OFTReal and OFTInteger fields will be translated to string using sprintf(), but not necessarily using the established formatting rules. Other field types, or errors will result in a return value of zero.

This function is the same as the C++ method OGRFeature::GetFieldAsString().

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

Returns:

the field value. This string is internal, and should not be modified, or freed. Its lifetime may be very brief.

const char *OGR_F_GetFieldAsISO8601DateTime(OGRFeatureH, int, CSLConstList)

Fetch OFTDateTime field value as a ISO8601 representation.

Return a string like "YYYY-MM6DDTHH:MM:SS(.sss)?(Z|([+|-]HH:MM))?" Milliseconds are omitted if equal to zero. Other field types, or errors will result in a return of an empty string.

This function is the same as the C++ method OGRFeature::GetFieldAsISO8601DateTime().

Since

GDAL 3.7

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • papszOptions -- NULL terminated list of strings, or NULL. No options are defined currently.

Returns:

the field value. This string is internal, and should not be modified, or freed. Its lifetime may be very brief.

const int *OGR_F_GetFieldAsIntegerList(OGRFeatureH, int, int*)

Fetch field value as a list of integers.

Currently this function only works for OFTIntegerList fields.

This function is the same as the C++ method OGRFeature::GetFieldAsIntegerList().

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • pnCount -- an integer to put the list count (number of integers) into.

Returns:

the field value. This list is internal, and should not be modified, or freed. Its lifetime may be very brief. If *pnCount is zero on return the returned pointer may be NULL or non-NULL.

const GIntBig *OGR_F_GetFieldAsInteger64List(OGRFeatureH, int, int*)

Fetch field value as a list of 64 bit integers.

Currently this function only works for OFTInteger64List fields.

This function is the same as the C++ method OGRFeature::GetFieldAsInteger64List().

Since

GDAL 2.0

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • pnCount -- an integer to put the list count (number of integers) into.

Returns:

the field value. This list is internal, and should not be modified, or freed. Its lifetime may be very brief. If *pnCount is zero on return the returned pointer may be NULL or non-NULL.

const double *OGR_F_GetFieldAsDoubleList(OGRFeatureH, int, int*)

Fetch field value as a list of doubles.

Currently this function only works for OFTRealList fields.

This function is the same as the C++ method OGRFeature::GetFieldAsDoubleList().

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • pnCount -- an integer to put the list count (number of doubles) into.

Returns:

the field value. This list is internal, and should not be modified, or freed. Its lifetime may be very brief. If *pnCount is zero on return the returned pointer may be NULL or non-NULL.

char **OGR_F_GetFieldAsStringList(OGRFeatureH, int)

Fetch field value as a list of strings.

Currently this method only works for OFTStringList fields.

The returned list is terminated by a NULL pointer. The number of elements can also be calculated using CSLCount().

This function is the same as the C++ method OGRFeature::GetFieldAsStringList().

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

Returns:

the field value. This list is internal, and should not be modified, or freed. Its lifetime may be very brief.

GByte *OGR_F_GetFieldAsBinary(OGRFeatureH, int, int*)

Fetch field value as binary.

This method only works for OFTBinary and OFTString fields.

This function is the same as the C++ method OGRFeature::GetFieldAsBinary().

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • pnBytes -- location to place count of bytes returned.

Returns:

the field value. This list is internal, and should not be modified, or freed. Its lifetime may be very brief.

int OGR_F_GetFieldAsDateTime(OGRFeatureH, int, int*, int*, int*, int*, int*, int*, int*)

Fetch field value as date and time.

Currently this method only works for OFTDate, OFTTime and OFTDateTime fields.

This function is the same as the C++ method OGRFeature::GetFieldAsDateTime().

See also

Use OGR_F_GetFieldAsDateTimeEx() for second with millisecond accuracy.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • pnYear -- (including century)

  • pnMonth -- (1-12)

  • pnDay -- (1-31)

  • pnHour -- (0-23)

  • pnMinute -- (0-59)

  • pnSecond -- (0-59)

  • pnTZFlag -- (0=unknown, 1=localtime, 100=GMT, see data model for details)

Returns:

TRUE on success or FALSE on failure.

int OGR_F_GetFieldAsDateTimeEx(OGRFeatureH hFeat, int iField, int *pnYear, int *pnMonth, int *pnDay, int *pnHour, int *pnMinute, float *pfSecond, int *pnTZFlag)

Fetch field value as date and time.

Currently this method only works for OFTDate, OFTTime and OFTDateTime fields.

This function is the same as the C++ method OGRFeature::GetFieldAsDateTime().

Since

GDAL 2.0

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • pnYear -- (including century)

  • pnMonth -- (1-12)

  • pnDay -- (1-31)

  • pnHour -- (0-23)

  • pnMinute -- (0-59)

  • pfSecond -- (0-59 with millisecond accuracy)

  • pnTZFlag -- (0=unknown, 1=localtime, 100=GMT, see data model for details)

Returns:

TRUE on success or FALSE on failure.

void OGR_F_SetFieldInteger(OGRFeatureH, int, int)

Set field to integer value.

OFTInteger, OFTInteger64 and OFTReal fields will be set directly. OFTString fields will be assigned a string representation of the value, but not necessarily taking into account formatting constraints on this field. Other field types may be unaffected.

This function is the same as the C++ method OGRFeature::SetField().

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • nValue -- the value to assign.

void OGR_F_SetFieldInteger64(OGRFeatureH, int, GIntBig)

Set field to 64 bit integer value.

OFTInteger, OFTInteger64 and OFTReal fields will be set directly. OFTString fields will be assigned a string representation of the value, but not necessarily taking into account formatting constraints on this field. Other field types may be unaffected.

This function is the same as the C++ method OGRFeature::SetField().

Since

GDAL 2.0

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • nValue -- the value to assign.

void OGR_F_SetFieldDouble(OGRFeatureH, int, double)

Set field to double value.

OFTInteger, OFTInteger64 and OFTReal fields will be set directly. OFTString fields will be assigned a string representation of the value, but not necessarily taking into account formatting constraints on this field. Other field types may be unaffected.

This function is the same as the C++ method OGRFeature::SetField().

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • dfValue -- the value to assign.

void OGR_F_SetFieldString(OGRFeatureH, int, const char*)

Set field to string value.

OFTInteger fields will be set based on an atoi() conversion of the string. OFTInteger64 fields will be set based on an CPLAtoGIntBig() conversion of the string. OFTReal fields will be set based on an CPLAtof() conversion of the string. Other field types may be unaffected.

This function is the same as the C++ method OGRFeature::SetField().

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • pszValue -- the value to assign.

void OGR_F_SetFieldIntegerList(OGRFeatureH, int, int, const int*)

Set field to list of integers value.

This function currently on has an effect of OFTIntegerList, OFTInteger64List and OFTRealList fields.

This function is the same as the C++ method OGRFeature::SetField().

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to set, from 0 to GetFieldCount()-1.

  • nCount -- the number of values in the list being assigned.

  • panValues -- the values to assign.

void OGR_F_SetFieldInteger64List(OGRFeatureH, int, int, const GIntBig*)

Set field to list of 64 bit integers value.

This function currently on has an effect of OFTIntegerList, OFTInteger64List and OFTRealList fields.

This function is the same as the C++ method OGRFeature::SetField().

Since

GDAL 2.0

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to set, from 0 to GetFieldCount()-1.

  • nCount -- the number of values in the list being assigned.

  • panValues -- the values to assign.

void OGR_F_SetFieldDoubleList(OGRFeatureH, int, int, const double*)

Set field to list of doubles value.

This function currently on has an effect of OFTIntegerList, OFTInteger64List, OFTRealList fields.

This function is the same as the C++ method OGRFeature::SetField().

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to set, from 0 to GetFieldCount()-1.

  • nCount -- the number of values in the list being assigned.

  • padfValues -- the values to assign.

void OGR_F_SetFieldStringList(OGRFeatureH, int, CSLConstList)

Set field to list of strings value.

This function currently on has an effect of OFTStringList fields.

This function is the same as the C++ method OGRFeature::SetField().

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to set, from 0 to GetFieldCount()-1.

  • papszValues -- the values to assign. List of NUL-terminated string, ending with a NULL pointer.

void OGR_F_SetFieldRaw(OGRFeatureH, int, const OGRField*)

Set field.

The passed value OGRField must be of exactly the same type as the target field, or an application crash may occur. The passed value is copied, and will not be affected. It remains the responsibility of the caller.

This function is the same as the C++ method OGRFeature::SetField().

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to fetch, from 0 to GetFieldCount()-1.

  • psValue -- handle on the value to assign.

void OGR_F_SetFieldBinary(OGRFeatureH, int, int, const void*)

Set field to binary data.

This function currently on has an effect of OFTBinary fields.

This function is the same as the C++ method OGRFeature::SetField().

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to set, from 0 to GetFieldCount()-1.

  • nBytes -- the number of bytes in pabyData array.

  • pabyData -- the data to apply.

void OGR_F_SetFieldDateTime(OGRFeatureH, int, int, int, int, int, int, int, int)

Set field to datetime.

This method currently only has an effect for OFTDate, OFTTime and OFTDateTime fields.

See also

Use OGR_F_SetFieldDateTimeEx() for second with millisecond accuracy.

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to set, from 0 to GetFieldCount()-1.

  • nYear -- (including century)

  • nMonth -- (1-12)

  • nDay -- (1-31)

  • nHour -- (0-23)

  • nMinute -- (0-59)

  • nSecond -- (0-59)

  • nTZFlag -- (0=unknown, 1=localtime, 100=GMT, see data model for details)

void OGR_F_SetFieldDateTimeEx(OGRFeatureH, int, int, int, int, int, int, float, int)

Set field to datetime.

This method currently only has an effect for OFTDate, OFTTime and OFTDateTime fields.

Since

GDAL 2.0

Note

This method has only an effect on the in-memory feature object. If this object comes from a layer and the modifications must be serialized back to the datasource, OGR_L_SetFeature() must be used afterwards. Or if this is a new feature, OGR_L_CreateFeature() must be used afterwards.

Parameters:

  • hFeat -- handle to the feature that owned the field.

  • iField -- the field to set, from 0 to GetFieldCount()-1.

  • nYear -- (including century)

  • nMonth -- (1-12)

  • nDay -- (1-31)

  • nHour -- (0-23)

  • nMinute -- (0-59)

  • fSecond -- (0-59, with millisecond accuracy)

  • nTZFlag -- (0=unknown, 1=localtime, 100=GMT, see data model for details)

int OGR_F_GetGeomFieldCount(OGRFeatureH hFeat)

Fetch number of geometry fields on this feature This will always be the same as the geometry field count for the OGRFeatureDefn.

This function is the same as the C++ method OGRFeature::GetGeomFieldCount().

Since

GDAL 1.11

Parameters:

hFeat -- handle to the feature to get the geometry fields count from.

Returns:

count of geometry fields.

OGRGeomFieldDefnH OGR_F_GetGeomFieldDefnRef(OGRFeatureH hFeat, int iField)

Fetch definition for this geometry field.

This function is the same as the C++ method OGRFeature::GetGeomFieldDefnRef().

Since

GDAL 1.11

Parameters:

  • hFeat -- handle to the feature on which the field is found.

  • i -- the field to fetch, from 0 to GetGeomFieldCount()-1.

Returns:

a handle to the field definition (from the OGRFeatureDefn). This is an internal reference, and should not be deleted or modified.

int OGR_F_GetGeomFieldIndex(OGRFeatureH hFeat, const char *pszName)

Fetch the geometry field index given geometry field name.

This is a cover for the OGRFeatureDefn::GetGeomFieldIndex() method.

This function is the same as the C++ method OGRFeature::GetGeomFieldIndex().

Since

GDAL 1.11

Parameters:

  • hFeat -- handle to the feature on which the geometry field is found.

  • pszName -- the name of the geometry field to search for.

Returns:

the geometry field index, or -1 if no matching geometry field is found.

OGRGeometryH OGR_F_GetGeomFieldRef(OGRFeatureH hFeat, int iField)

Fetch a handle to feature geometry.

This function is the same as the C++ method OGRFeature::GetGeomFieldRef().

Since

GDAL 1.11

Parameters:

  • hFeat -- handle to the feature to get geometry from.

  • iField -- geometry field to get.

Returns:

a handle to internal feature geometry. This object should not be modified.

OGRErr OGR_F_SetGeomFieldDirectly(OGRFeatureH hFeat, int iField, OGRGeometryH hGeom)

Set feature geometry of a specified geometry field.

This function updates the features geometry, and operate exactly as SetGeomField(), except that this function assumes ownership of the passed geometry (even in case of failure of that function).

This function is the same as the C++ method OGRFeature::SetGeomFieldDirectly.

Since

GDAL 1.11

Parameters:

  • hFeat -- handle to the feature on which to apply the geometry.

  • iField -- geometry field to set.

  • hGeom -- handle to the new geometry to apply to feature.

Returns:

OGRERR_NONE if successful, or OGRERR_FAILURE if the index is invalid, or OGR_UNSUPPORTED_GEOMETRY_TYPE if the geometry type is illegal for the OGRFeatureDefn (checking not yet implemented).

OGRErr OGR_F_SetGeomField(OGRFeatureH hFeat, int iField, OGRGeometryH hGeom)

Set feature geometry of a specified geometry field.

This function updates the features geometry, and operate exactly as SetGeometryDirectly(), except that this function does not assume ownership of the passed geometry, but instead makes a copy of it.

This function is the same as the C++ OGRFeature::SetGeomField().

Parameters:

  • hFeat -- handle to the feature on which new geometry is applied to.

  • iField -- geometry field to set.

  • hGeom -- handle to the new geometry to apply to feature.

Returns:

OGRERR_NONE if successful, or OGR_UNSUPPORTED_GEOMETRY_TYPE if the geometry type is illegal for the OGRFeatureDefn (checking not yet implemented).

GIntBig OGR_F_GetFID(OGRFeatureH)

Get feature identifier.

This function is the same as the C++ method OGRFeature::GetFID(). Note: since GDAL 2.0, this method returns a GIntBig (previously a long)

Parameters:

hFeat -- handle to the feature from which to get the feature identifier.

Returns:

feature id or OGRNullFID if none has been assigned.

OGRErr OGR_F_SetFID(OGRFeatureH, GIntBig)

Set the feature identifier.

For specific types of features this operation may fail on illegal features ids. Generally it always succeeds. Feature ids should be greater than or equal to zero, with the exception of OGRNullFID (-1) indicating that the feature id is unknown.

This function is the same as the C++ method OGRFeature::SetFID().

Parameters:

  • hFeat -- handle to the feature to set the feature id to.

  • nFID -- the new feature identifier value to assign.

Returns:

On success OGRERR_NONE, or on failure some other value.

void OGR_F_DumpReadable(OGRFeatureH, FILE*)

Dump this feature in a human readable form.

This dumps the attributes, and geometry; however, it doesn't definition information (other than field types and names), nor does it report the geometry spatial reference system.

This function is the same as the C++ method OGRFeature::DumpReadable().

Parameters:

  • hFeat -- handle to the feature to dump.

  • fpOut -- the stream to write to, such as strout.

char *OGR_F_DumpReadableAsString(OGRFeatureH, CSLConstList)

Dump this feature in a human readable form.

This dumps the attributes, and geometry; however, it doesn't include definition information (other than field types and names), nor does it report the geometry spatial reference system.

A few options can be defined to change the default dump :

  • DISPLAY_FIELDS=NO : to hide the dump of the attributes

  • DISPLAY_STYLE=NO : to hide the dump of the style string

  • DISPLAY_GEOMETRY=NO : to hide the dump of the geometry

  • DISPLAY_GEOMETRY=SUMMARY : to get only a summary of the geometry

Since

GDAL 3.8

Parameters:

  • hFeat -- handle to the feature to dump.

  • papszOptions -- NULL terminated list of options (may be NULL)

Returns:

a string with the feature representation (to be freed with CPLFree())

OGRErr OGR_F_SetFrom(OGRFeatureH, OGRFeatureH, int)

Set one feature from another.

Overwrite the contents of this feature from the geometry and attributes of another. The hOtherFeature does not need to have the same OGRFeatureDefn. Field values are copied by corresponding field names. Field types do not have to exactly match. OGR_F_SetField*() function conversion rules will be applied as needed.

This function is the same as the C++ method OGRFeature::SetFrom().

Parameters:

  • hFeat -- handle to the feature to set to.

  • hOtherFeat -- handle to the feature from which geometry, and field values will be copied.

  • bForgiving -- TRUE if the operation should continue despite lacking output fields matching some of the source fields.

Returns:

OGRERR_NONE if the operation succeeds, even if some values are not transferred, otherwise an error code.

OGRErr OGR_F_SetFromWithMap(OGRFeatureH, OGRFeatureH, int, const int*)

Set one feature from another.

Overwrite the contents of this feature from the geometry and attributes of another. The hOtherFeature does not need to have the same OGRFeatureDefn. Field values are copied according to the provided indices map. Field types do not have to exactly match. OGR_F_SetField*() function conversion rules will be applied as needed. This is more efficient than OGR_F_SetFrom() in that this doesn't lookup the fields by their names. Particularly useful when the field names don't match.

This function is the same as the C++ method OGRFeature::SetFrom().

Parameters:

  • hFeat -- handle to the feature to set to.

  • hOtherFeat -- handle to the feature from which geometry, and field values will be copied.

  • panMap -- Array of the indices of the destination feature's fields stored at the corresponding index of the source feature's fields. A value of -1 should be used to ignore the source's field. The array should not be NULL and be as long as the number of fields in the source feature.

  • bForgiving -- TRUE if the operation should continue despite lacking output fields matching some of the source fields.

Returns:

OGRERR_NONE if the operation succeeds, even if some values are not transferred, otherwise an error code.

const char *OGR_F_GetStyleString(OGRFeatureH)

Fetch style string for this feature.

Set the OGR Feature Style Specification for details on the format of this string, and ogr_featurestyle.h for services available to parse it.

This function is the same as the C++ method OGRFeature::GetStyleString().

Parameters:

hFeat -- handle to the feature to get the style from.

Returns:

a reference to a representation in string format, or NULL if there isn't one.

void OGR_F_SetStyleString(OGRFeatureH, const char*)

Set feature style string.

This method operate exactly as OGR_F_SetStyleStringDirectly() except that it does not assume ownership of the passed string, but instead makes a copy of it.

This function is the same as the C++ method OGRFeature::SetStyleString().

Parameters:

  • hFeat -- handle to the feature to set style to.

  • pszStyle -- the style string to apply to this feature, cannot be NULL.

void OGR_F_SetStyleStringDirectly(OGRFeatureH, char*)

Set feature style string.

This method operate exactly as OGR_F_SetStyleString() except that it assumes ownership of the passed string.

This function is the same as the C++ method OGRFeature::SetStyleStringDirectly().

Parameters:

  • hFeat -- handle to the feature to set style to.

  • pszStyle -- the style string to apply to this feature, cannot be NULL.

OGRStyleTableH OGR_F_GetStyleTable(OGRFeatureH)

Return style table.

void OGR_F_SetStyleTableDirectly(OGRFeatureH, OGRStyleTableH)

Set style table and take ownership.

void OGR_F_SetStyleTable(OGRFeatureH, OGRStyleTableH)

Set style table.

const char *OGR_F_GetNativeData(OGRFeatureH)

Returns the native data for the feature.

The native data is the representation in a "natural" form that comes from the driver that created this feature, or that is aimed at an output driver. The native data may be in different format, which is indicated by OGR_F_GetNativeMediaType().

Note that most drivers do not support storing the native data in the feature object, and if they do, generally the NATIVE_DATA open option must be passed at dataset opening.

The "native data" does not imply it is something more performant or powerful than what can be obtained with the rest of the API, but it may be useful in round-tripping scenarios where some characteristics of the underlying format are not captured otherwise by the OGR abstraction.

This function is the same as the C++ method OGRFeature::GetNativeData().

See also

https://trac.osgeo.org/gdal/wiki/rfc60_improved_roundtripping_in_ogr

Since

GDAL 2.1

Parameters:

hFeat -- handle to the feature.

Returns:

a string with the native data, or NULL if there is none.

void OGR_F_SetNativeData(OGRFeatureH, const char*)

Sets the native data for the feature.

The native data is the representation in a "natural" form that comes from the driver that created this feature, or that is aimed at an output driver. The native data may be in different format, which is indicated by OGR_F_GetNativeMediaType().

This function is the same as the C++ method OGRFeature::SetNativeData().

See also

https://trac.osgeo.org/gdal/wiki/rfc60_improved_roundtripping_in_ogr

Since

GDAL 2.1

Parameters:

  • hFeat -- handle to the feature.

  • pszNativeData -- a string with the native data, or NULL if there is none.

const char *OGR_F_GetNativeMediaType(OGRFeatureH)

Returns the native media type for the feature.

The native media type is the identifier for the format of the native data. It follows the IANA RFC 2045 (see https://en.wikipedia.org/wiki/Media_type), e.g. "application/vnd.geo+json" for JSon.

This function is the same as the C function OGR_F_GetNativeMediaType().

See also

https://trac.osgeo.org/gdal/wiki/rfc60_improved_roundtripping_in_ogr

Since

GDAL 2.1

Parameters:

hFeat -- handle to the feature.

Returns:

a string with the native media type, or NULL if there is none.

void OGR_F_SetNativeMediaType(OGRFeatureH, const char*)

Sets the native media type for the feature.

The native media type is the identifier for the format of the native data. It follows the IANA RFC 2045 (see https://en.wikipedia.org/wiki/Media_type), e.g. "application/vnd.geo+json" for JSon.

This function is the same as the C++ method OGRFeature::SetNativeMediaType().

See also

https://trac.osgeo.org/gdal/wiki/rfc60_improved_roundtripping_in_ogr

Since

GDAL 2.1

Parameters:

  • hFeat -- handle to the feature.

  • pszNativeMediaType -- a string with the native media type, or NULL if there is none.

void OGR_F_FillUnsetWithDefault(OGRFeatureH hFeat, int bNotNullableOnly, char **papszOptions)

Fill unset fields with default values that might be defined.

This function is the same as the C++ method OGRFeature::FillUnsetWithDefault().

Since

GDAL 2.0

Parameters:

  • hFeat -- handle to the feature.

  • bNotNullableOnly -- if we should fill only unset fields with a not-null constraint.

  • papszOptions -- unused currently. Must be set to NULL.

int OGR_F_Validate(OGRFeatureH, int nValidateFlags, int bEmitError)

Validate that a feature meets constraints of its schema.

The scope of test is specified with the nValidateFlags parameter.

Regarding OGR_F_VAL_WIDTH, the test is done assuming the string width must be interpreted as the number of UTF-8 characters. Some drivers might interpret the width as the number of bytes instead. So this test is rather conservative (if it fails, then it will fail for all interpretations).

This function is the same as the C++ method OGRFeature::Validate().

Since

GDAL 2.0

Parameters:

  • hFeat -- handle to the feature to validate.

  • nValidateFlags -- OGR_F_VAL_ALL or combination of OGR_F_VAL_NULL, OGR_F_VAL_GEOM_TYPE, OGR_F_VAL_WIDTH and OGR_F_VAL_ALLOW_NULL_WHEN_DEFAULT with '|' operator

  • bEmitError -- TRUE if a CPLError() must be emitted when a check fails

Returns:

TRUE if all enabled validation tests pass.

void OGR_FldDomain_Destroy(OGRFieldDomainH)

Destroy a field domain.

This is the same as the C++ method OGRFieldDomain::~OGRFieldDomain()

Since

GDAL 3.3

Parameters:

hFieldDomain -- the field domain.

const char *OGR_FldDomain_GetName(OGRFieldDomainH)

Get the name of the field domain.

This is the same as the C++ method OGRFieldDomain::GetName()

Since

GDAL 3.3

Parameters:

hFieldDomain -- Field domain handle.

Returns:

the field domain name.

const char *OGR_FldDomain_GetDescription(OGRFieldDomainH)

Get the description of the field domain.

This is the same as the C++ method OGRFieldDomain::GetDescription()

Since

GDAL 3.3

Parameters:

hFieldDomain -- Field domain handle.

Returns:

the field domain description (might be empty string).

OGRFieldDomainType OGR_FldDomain_GetDomainType(OGRFieldDomainH)

Get the type of the field domain.

This is the same as the C++ method OGRFieldDomain::GetDomainType()

Since

GDAL 3.3

Parameters:

hFieldDomain -- Field domain handle.

Returns:

the type of the field domain.

OGRFieldType OGR_FldDomain_GetFieldType(OGRFieldDomainH)

Get the field type of the field domain.

This is the same as the C++ method OGRFieldDomain::GetFieldType()

Since

GDAL 3.3

Parameters:

hFieldDomain -- Field domain handle.

Returns:

the field type of the field domain.

OGRFieldSubType OGR_FldDomain_GetFieldSubType(OGRFieldDomainH)

Get the field subtype of the field domain.

This is the same as OGRFieldDomain::GetFieldSubType()

Since

GDAL 3.3

Parameters:

hFieldDomain -- Field domain handle.

Returns:

the field subtype of the field domain.

OGRFieldDomainSplitPolicy OGR_FldDomain_GetSplitPolicy(OGRFieldDomainH)

Get the split policy of the field domain.

This is the same as the C++ method OGRFieldDomain::GetSplitPolicy()

Since

GDAL 3.3

Parameters:

hFieldDomain -- Field domain handle.

Returns:

the split policy of the field domain.

void OGR_FldDomain_SetSplitPolicy(OGRFieldDomainH, OGRFieldDomainSplitPolicy)

Set the split policy of the field domain.

This is the same as the C++ method OGRFieldDomain::SetSplitPolicy()

Since

GDAL 3.3

Parameters:

  • hFieldDomain -- Field domain handle.

  • policy -- the split policy of the field domain.

OGRFieldDomainMergePolicy OGR_FldDomain_GetMergePolicy(OGRFieldDomainH)

Get the merge policy of the field domain.

This is the same as the C++ method OGRFieldDomain::GetMergePolicy()

Since

GDAL 3.3

Parameters:

hFieldDomain -- Field domain handle.

Returns:

the merge policy of the field domain.

void OGR_FldDomain_SetMergePolicy(OGRFieldDomainH, OGRFieldDomainMergePolicy)

Set the merge policy of the field domain.

This is the same as the C++ method OGRFieldDomain::SetMergePolicy()

Since

GDAL 3.3

Parameters:

  • hFieldDomain -- Field domain handle.

  • policy -- the merge policy of the field domain.

OGRFieldDomainH OGR_CodedFldDomain_Create(const char *pszName, const char *pszDescription, OGRFieldType eFieldType, OGRFieldSubType eFieldSubType, const OGRCodedValue *enumeration)

Creates a new coded field domain.

This is the same as the C++ method OGRCodedFieldDomain::OGRCodedFieldDomain() (except that the C function copies the enumeration, whereas the C++ method moves it)

Since

GDAL 3.3

Parameters:

  • pszName -- Domain name. Should not be NULL.

  • pszDescription -- Domain description (can be NULL)

  • eFieldType -- Field type. Generally numeric. Potentially OFTDateTime

  • eFieldSubType -- Field subtype.

  • enumeration -- Enumeration as (code, value) pairs. Should not be NULL. The end of the enumeration is marked by a code set to NULL. The enumeration will be copied. Each code should appear only once, but it is the responsibility of the user to check it.

Returns:

a new handle that should be freed with OGR_FldDomain_Destroy(), or NULL in case of error.

const OGRCodedValue *OGR_CodedFldDomain_GetEnumeration(OGRFieldDomainH)

Get the enumeration as (code, value) pairs.

The end of the enumeration is signaled by code == NULL

This is the same as the C++ method OGRCodedFieldDomain::GetEnumeration()

Since

GDAL 3.3

Parameters:

hFieldDomain -- Field domain handle.

Returns:

the (code, value) pairs, or nullptr in case of error.

OGRFieldDomainH OGR_RangeFldDomain_Create(const char *pszName, const char *pszDescription, OGRFieldType eFieldType, OGRFieldSubType eFieldSubType, const OGRField *psMin, bool bMinIsInclusive, const OGRField *psMax, bool bMaxIsInclusive)

Creates a new range field domain.

This is the same as the C++ method OGRRangeFieldDomain::OGRRangeFieldDomain().

Since

GDAL 3.3

Parameters:

  • pszName -- Domain name. Should not be NULL.

  • pszDescription -- Domain description (can be NULL)

  • eFieldType -- Field type. Among OFTInteger, OFTInteger64, OFTReal and OFTDateTime.

  • eFieldSubType -- Field subtype.

  • psMin -- Minimum value (can be NULL). The member in the union that is read is consistent with eFieldType

  • bMinIsInclusive -- Whether the minimum value is included in the range.

  • psMax -- Maximum value (can be NULL). The member in the union that is read is consistent with eFieldType

  • bMaxIsInclusive -- Whether the maximum value is included in the range.

Returns:

a new handle that should be freed with OGR_FldDomain_Destroy()

const OGRField *OGR_RangeFldDomain_GetMin(OGRFieldDomainH, bool *pbIsInclusiveOut)

Get the minimum value.

Which member in the returned OGRField enum must be read depends on the field type.

If no minimum value is set, the OGR_RawField_IsUnset() will return true when called on the result.

This is the same as the C++ method OGRRangeFieldDomain::GetMin()

Since

GDAL 3.3

Parameters:

  • hFieldDomain -- Field domain handle.

  • pbIsInclusiveOut -- set to true if the minimum is included in the range.

Returns:

the minimum value.

const OGRField *OGR_RangeFldDomain_GetMax(OGRFieldDomainH, bool *pbIsInclusiveOut)

Get the maximum value.

Which member in the returned OGRField enum must be read depends on the field type.

If no maximum value is set, the OGR_RawField_IsUnset() will return true when called on the result.

This is the same as the C++ method OGRRangeFieldDomain::GetMax()

Since

GDAL 3.3

Parameters:

  • hFieldDomain -- Field domain handle.

  • pbIsInclusiveOut -- set to true if the maximum is included in the range.

Returns:

the maximum value.

OGRFieldDomainH OGR_GlobFldDomain_Create(const char *pszName, const char *pszDescription, OGRFieldType eFieldType, OGRFieldSubType eFieldSubType, const char *pszGlob)

Creates a new glob field domain.

This is the same as the C++ method OGRGlobFieldDomain::OGRGlobFieldDomain()

Since

GDAL 3.3

Parameters:

  • pszName -- Domain name. Should not be NULL.

  • pszDescription -- Domain description (can be NULL)

  • eFieldType -- Field type.

  • eFieldSubType -- Field subtype.

  • pszGlob -- Glob expression. Should not be NULL.

Returns:

a new handle that should be freed with OGR_FldDomain_Destroy()

const char *OGR_GlobFldDomain_GetGlob(OGRFieldDomainH)

Get the glob expression.

This is the same as the C++ method OGRGlobFieldDomain::GetGlob()

Since

GDAL 3.3

Parameters:

hFieldDomain -- Field domain handle.

Returns:

the glob expression, or nullptr in case of error

const char *OGR_L_GetName(OGRLayerH)

Return the layer name.

This returns the same content as OGR_FD_GetName(OGR_L_GetLayerDefn(hLayer)), but for a few drivers, calling OGR_L_GetName() directly can avoid lengthy layer definition initialization.

This function is the same as the C++ method OGRLayer::GetName().

Since

OGR 1.8.0

Parameters:

hLayer -- handle to the layer.

Returns:

the layer name (must not been freed)

OGRwkbGeometryType OGR_L_GetGeomType(OGRLayerH)

Return the layer geometry type.

This returns the same result as OGR_FD_GetGeomType(OGR_L_GetLayerDefn(hLayer)), but for a few drivers, calling OGR_L_GetGeomType() directly can avoid lengthy layer definition initialization.

For layers with multiple geometry fields, this method only returns the geometry type of the first geometry column. For other columns, use OGR_GFld_GetType(OGR_FD_GetGeomFieldDefn(OGR_L_GetLayerDefn(hLayer), i)). For layers without any geometry field, this method returns wkbNone.

This function is the same as the C++ method OGRLayer::GetGeomType().

Since

OGR 1.8.0

Parameters:

hLayer -- handle to the layer.

Returns:

the geometry type

OGRGeometryTypeCounter *OGR_L_GetGeometryTypes(OGRLayerH hLayer, int iGeomField, int nFlags, int *pnEntryCount, GDALProgressFunc pfnProgress, void *pProgressData)

Get actual geometry types found in features.

See OGRLayer::GetGeometryTypes() for details.

Since

GDAL 3.6

Parameters:

  • hLayer -- Layer.

  • iGeomField -- Geometry field index.

  • nFlags -- Hint flags. 0, or combination of OGR_GGT_COUNT_NOT_NEEDED, OGR_GGT_STOP_IF_MIXED, OGR_GGT_GEOMCOLLECTIONZ_TINZ

  • pnEntryCount -- [out] Pointer to the number of entries in the returned array. Must not be NULL.

  • pfnProgress -- Cancellation callback. May be NULL.

  • pProgressData -- User data for the cancellation callback. May be NULL.

Returns:

an array of *pnEntryCount that must be freed with CPLFree(), or NULL in case of error

OGRGeometryH OGR_L_GetSpatialFilter(OGRLayerH)

This function returns the current spatial filter for this layer.

The returned pointer is to an internally owned object, and should not be altered or deleted by the caller.

This function is the same as the C++ method OGRLayer::GetSpatialFilter().

Parameters:

hLayer -- handle to the layer to get the spatial filter from.

Returns:

a handle to the spatial filter geometry.

void OGR_L_SetSpatialFilter(OGRLayerH, OGRGeometryH)

Set a new spatial filter.

This function set the geometry to be used as a spatial filter when fetching features via the OGR_L_GetNextFeature() function. Only features that geometrically intersect the filter geometry will be returned.

Currently this test is may be inaccurately implemented, but it is guaranteed that all features whose envelope (as returned by OGR_G_GetEnvelope()) overlaps the envelope of the spatial filter will be returned. This can result in more shapes being returned that should strictly be the case.

Starting with GDAL 2.3, features with null or empty geometries will never be considered as matching a spatial filter.

This function makes an internal copy of the passed geometry. The passed geometry remains the responsibility of the caller, and may be safely destroyed.

For the time being the passed filter geometry should be in the same SRS as the layer (as returned by OGR_L_GetSpatialRef()). In the future this may be generalized.

This function is the same as the C++ method OGRLayer::SetSpatialFilter.

Parameters:

  • hLayer -- handle to the layer on which to set the spatial filter.

  • hGeom -- handle to the geometry to use as a filtering region. NULL may be passed indicating that the current spatial filter should be cleared, but no new one instituted.

void OGR_L_SetSpatialFilterRect(OGRLayerH, double, double, double, double)

Set a new rectangular spatial filter.

This method set rectangle to be used as a spatial filter when fetching features via the OGR_L_GetNextFeature() method. Only features that geometrically intersect the given rectangle will be returned.

The x/y values should be in the same coordinate system as the layer as a whole (as returned by OGRLayer::GetSpatialRef()). Internally this method is normally implemented as creating a 5 vertex closed rectangular polygon and passing it to OGRLayer::SetSpatialFilter(). It exists as a convenience.

The only way to clear a spatial filter set with this method is to call OGRLayer::SetSpatialFilter(NULL).

This method is the same as the C++ method OGRLayer::SetSpatialFilterRect().

Parameters:

  • hLayer -- handle to the layer on which to set the spatial filter.

  • dfMinX -- the minimum X coordinate for the rectangular region.

  • dfMinY -- the minimum Y coordinate for the rectangular region.

  • dfMaxX -- the maximum X coordinate for the rectangular region.

  • dfMaxY -- the maximum Y coordinate for the rectangular region.

void OGR_L_SetSpatialFilterEx(OGRLayerH, int iGeomField, OGRGeometryH hGeom)

Set a new spatial filter.

This function set the geometry to be used as a spatial filter when fetching features via the OGR_L_GetNextFeature() function. Only features that geometrically intersect the filter geometry will be returned.

Currently this test is may be inaccurately implemented, but it is guaranteed that all features who's envelope (as returned by OGR_G_GetEnvelope()) overlaps the envelope of the spatial filter will be returned. This can result in more shapes being returned that should strictly be the case.

This function makes an internal copy of the passed geometry. The passed geometry remains the responsibility of the caller, and may be safely destroyed.

For the time being the passed filter geometry should be in the same SRS as the geometry field definition it corresponds to (as returned by GetLayerDefn()->OGRFeatureDefn::GetGeomFieldDefn(iGeomField)->GetSpatialRef()). In the future this may be generalized.

Note that only the last spatial filter set is applied, even if several successive calls are done with different iGeomField values.

This function is the same as the C++ method OGRLayer::SetSpatialFilter.

Since

GDAL 1.11

Parameters:

  • hLayer -- handle to the layer on which to set the spatial filter.

  • iGeomField -- index of the geometry field on which the spatial filter operates.

  • hGeom -- handle to the geometry to use as a filtering region. NULL may be passed indicating that the current spatial filter should be cleared, but no new one instituted.

void OGR_L_SetSpatialFilterRectEx(OGRLayerH, int iGeomField, double dfMinX, double dfMinY, double dfMaxX, double dfMaxY)

Set a new rectangular spatial filter.

This method set rectangle to be used as a spatial filter when fetching features via the OGR_L_GetNextFeature() method. Only features that geometrically intersect the given rectangle will be returned.

The x/y values should be in the same coordinate system as as the geometry field definition it corresponds to (as returned by GetLayerDefn()->OGRFeatureDefn::GetGeomFieldDefn(iGeomField)->GetSpatialRef()). Internally this method is normally implemented as creating a 5 vertex closed rectangular polygon and passing it to OGRLayer::SetSpatialFilter(). It exists as a convenience.

The only way to clear a spatial filter set with this method is to call OGRLayer::SetSpatialFilter(NULL).

This method is the same as the C++ method OGRLayer::SetSpatialFilterRect().

Since

GDAL 1.11

Parameters:

  • hLayer -- handle to the layer on which to set the spatial filter.

  • iGeomField -- index of the geometry field on which the spatial filter operates.

  • dfMinX -- the minimum X coordinate for the rectangular region.

  • dfMinY -- the minimum Y coordinate for the rectangular region.

  • dfMaxX -- the maximum X coordinate for the rectangular region.

  • dfMaxY -- the maximum Y coordinate for the rectangular region.

OGRErr OGR_L_SetAttributeFilter(OGRLayerH, const char*)

Set a new attribute query.

This function sets the attribute query string to be used when fetching features via the OGR_L_GetNextFeature() function. Only features for which the query evaluates as true will be returned.

The query string should be in the format of an SQL WHERE clause. For instance "population > 1000000 and population < 5000000" where population is an attribute in the layer. The query format is normally a SQL WHERE clause as described in the "WHERE" section of the OGR SQL dialect documentation. In some cases (RDBMS backed drivers, SQLite, GeoPackage) the native capabilities of the database may be used to to interpret the WHERE clause, in which case the capabilities will be broader than those of OGR SQL.

Note that installing a query string will generally result in resetting the current reading position (ala OGR_L_ResetReading()).

This function is the same as the C++ method OGRLayer::SetAttributeFilter().

Parameters:

  • hLayer -- handle to the layer on which attribute query will be executed.

  • pszQuery -- query in restricted SQL WHERE format, or NULL to clear the current query.

Returns:

OGRERR_NONE if successfully installed, or an error code if the query expression is in error, or some other failure occurs.

void OGR_L_ResetReading(OGRLayerH)

Reset feature reading to start on the first feature.

This affects GetNextFeature() and GetArrowStream().

This function is the same as the C++ method OGRLayer::ResetReading().

Parameters:

hLayer -- handle to the layer on which features are read.

OGRFeatureH OGR_L_GetNextFeature(OGRLayerH)

Fetch the next available feature from this layer.

The returned feature becomes the responsibility of the caller to delete with OGR_F_Destroy(). It is critical that all features associated with an OGRLayer (more specifically an OGRFeatureDefn) be deleted before that layer/datasource is deleted.

Only features matching the current spatial filter (set with SetSpatialFilter()) will be returned.

This function implements sequential access to the features of a layer. The OGR_L_ResetReading() function can be used to start at the beginning again.

Starting with GDAL 3.6, it is possible to retrieve them by batches, with a column-oriented memory layout, using the OGR_L_GetArrowStream() function.

Features returned by OGR_GetNextFeature() may or may not be affected by concurrent modifications depending on drivers. A guaranteed way of seeing modifications in effect is to call OGR_L_ResetReading() on layers where OGR_GetNextFeature() has been called, before reading again. Structural changes in layers (field addition, deletion, ...) when a read is in progress may or may not be possible depending on drivers. If a transaction is committed/aborted, the current sequential reading may or may not be valid after that operation and a call to OGR_L_ResetReading() might be needed.

This function is the same as the C++ method OGRLayer::GetNextFeature().

Parameters:

hLayer -- handle to the layer from which feature are read.

Returns:

a handle to a feature, or NULL if no more features are available.

bool OGR_L_GetArrowStream(OGRLayerH hLayer, struct ArrowArrayStream *out_stream, char **papszOptions)

Get a Arrow C stream.

On successful return, and when the stream interfaces is no longer needed, it must be freed with out_stream->release(out_stream). Please carefully read https://arrow.apache.org/docs/format/CStreamInterface.html for more details on using Arrow C stream.

The method may take into account ignored fields set with SetIgnoredFields() (the default implementation does), and should take into account filters set with SetSpatialFilter() and SetAttributeFilter(). Note however that specialized implementations may fallback to the default (slower) implementation when filters are set. Drivers that have a specialized implementation should advertise the OLCFastGetArrowStream capability.

There are extra precautions to take into account in a OGR context. Unless otherwise specified by a particular driver implementation, the get_schema(), get_next() and get_last_error() function pointers of the ArrowArrayStream structure should no longer be used after the OGRLayer, from which the ArrowArrayStream structure was initialized, has been destroyed (typically at dataset closing). The reason is that those function pointers will typically point to methods of the OGRLayer instance. However, the ArrowSchema and ArrowArray structures filled from those callbacks can be used and must be released independently from the ArrowArrayStream or the layer.

Furthermore, unless otherwise specified by a particular driver implementation, only one ArrowArrayStream can be active at a time on a given layer (that is the last active one must be explicitly released before a next one is asked). Changing filter state, ignored columns, modifying the schema or using ResetReading()/GetNextFeature() while using a ArrowArrayStream is strongly discouraged and may lead to unexpected results. As a rule of thumb, no OGRLayer methods that affect the state of a layer should be called on a layer, while an ArrowArrayStream on it is active.

Starting with GDAL 3.8, the ArrowSchema::metadata field filled by the get_schema() callback may be set with the potential following items:

A potential usage can be: 

struct ArrowArrayStream stream;
if( !OGR_L_GetArrowStream(hLayer, &stream, nullptr))
{
    CPLError(CE_Failure, CPLE_AppDefined,
             "OGR_L_GetArrowStream() failed\n");
    exit(1);
}
struct ArrowSchema schema;
if( stream.get_schema(&stream, &schema) == 0 )
{
    // Do something useful
    schema.release(schema);
}
while( true )
{
    struct ArrowArray array;
    // Look for an error (get_next() returning a non-zero code), or
    // end of iteration (array.release == nullptr)
    if( stream.get_next(&stream, &array) != 0 ||
        array.release == nullptr )
    {
        break;
    }
    // Do something useful
    array.release(&array);
}
stream.release(&stream);

A full example is available in the Reading From OGR using the Arrow C Stream data interface tutorial.

Options may be driver specific. The default implementation recognizes the following options:

  • INCLUDE_FID=YES/NO. Whether to include the FID column. Defaults to YES.

  • MAX_FEATURES_IN_BATCH=integer. Maximum number of features to retrieve in a ArrowArray batch. Defaults to 65 536.

  • TIMEZONE="unknown", "UTC", "(+|:)HH:MM" or any other value supported by Arrow. (GDAL >= 3.8) Override the timezone flag nominally provided by OGRFieldDefn::GetTZFlag(), and used for the Arrow field timezone declaration, with a user specified timezone. Note that datetime values in Arrow arrays are always stored in UTC, and that the time zone flag used by GDAL to convert to UTC is the one of the OGRField::Date::TZFlag member at the OGRFeature level. The conversion to UTC of a OGRField::Date is only done if both the timezone indicated by OGRField::Date::TZFlag and the one at the OGRFieldDefn level (or set by this TIMEZONE option) are not unknown.

  • GEOMETRY_METADATA_ENCODING=OGC/GEOARROW (GDAL >= 3.8). The default is OGC, which will lead to setting the Arrow geometry column metadata to ARROW:extension:name=ogc.wkb. If setting to GEOMETRY_METADATA_ENCODING to GEOARROW, ARROW:extension:name=geoarrow.wkb and ARROW:extension:metadata={"crs": <projjson CRS representation>> are set.

The Arrow/Parquet drivers recognize the following option:

  • GEOMETRY_ENCODING=WKB. To force a fallback to the generic implementation when the native geometry encoding is not WKB. Otherwise the geometry will be returned with its native Arrow encoding (possibly using GeoArrow encoding).

Since

GDAL 3.6

Parameters:

  • hLayer -- Layer

  • out_stream -- Output stream. Must not be NULL. The content of the structure does not need to be initialized.

  • papszOptions -- NULL terminated list of key=value options.

Returns:

true in case of success.

bool OGR_L_IsArrowSchemaSupported(OGRLayerH hLayer, const struct ArrowSchema *schema, char **papszOptions, char **ppszErrorMsg)

Returns whether the provided ArrowSchema is supported for writing.

This function exists since not all drivers may support all Arrow data types.

The ArrowSchema must be of type struct (format=+s)

It is recommended to call this function before calling OGR_L_WriteArrowBatch().

This is the same as the C++ method OGRLayer::IsArrowSchemaSupported().

Since

3.8

Parameters:

  • hLayer -- Layer.

  • schema -- Schema of type struct (format = '+s')

  • papszOptions -- Options (none currently). Null terminated list, or nullptr.

  • ppszErrorMsg -- [out] nullptr, or pointer to a string that will contain the reason of the failure, when this function returns false.

Returns:

true if the ArrowSchema is supported for writing.

bool OGR_L_CreateFieldFromArrowSchema(OGRLayerH hLayer, const struct ArrowSchema *schema, char **papszOptions)

Creates a field from an ArrowSchema.

This should only be used for attribute fields. Geometry fields should be created with CreateGeomField(). The FID field should also not be passed with this method.

Contrary to the IsArrowSchemaSupported() and WriteArrowBatch() methods, the passed schema must be for an individual field, and thus, is not of type struct (format=+s) (unless writing a set of fields grouped together in the same structure).

Additional field metadata can be speciffed through the ArrowSchema::metadata field with the potential following items:

This method and CreateField() are mutually exclusive in the same session.

This method is the same as the C++ method OGRLayer::CreateFieldFromArrowSchema().

Since

3.8

Parameters:

  • hLayer -- Layer.

  • schema -- Schema of the field to create.

  • papszOptions -- Options (none currently). Null terminated list, or nullptr.

Returns:

true in case of success

bool OGR_L_WriteArrowBatch(OGRLayerH hLayer, const struct ArrowSchema *schema, struct ArrowArray *array, char **papszOptions)

Writes a batch of rows from an ArrowArray.

This is semantically close to calling CreateFeature() with multiple features at once.

The ArrowArray must be of type struct (format=+s), and its children generally map to a OGR attribute or geometry field (unless they are struct themselves).

Method IsArrowSchemaSupported() can be called to determine if the schema will be supported by WriteArrowBatch().

OGR fields for the corresponding children arrays must exist and be of a compatible type. For attribute fields, they should be created with CreateFieldFromArrowSchema(). For geometry fields, they should be created either implicitly at CreateLayer() type (if geom_type != wkbNone), or explicitly with CreateGeomField().

Arrays for geometry columns should be of binary or large binary type and contain WKB geometry.

Note that the passed array may be set to a released state (array->release==NULL) after this call (not by the base implementation, but in specialized ones such as Parquet or Arrow for example)

Supported options of the base implementation are:

  • FID=name. Name of the FID column in the array. If not provided, GetFIDColumn() is used to determine it. The special name OGRLayer::DEFAULT_ARROW_FID_NAME is also recognized if neither FID nor GetFIDColumn() are set. The corresponding ArrowArray must be of type int32 (i) or int64 (l). On input, values of the FID column are used to create the feature. On output, the values of the FID column may be set with the FID of the created feature (if the array is not released).

  • IF_FID_NOT_PRESERVED=NOTHING/ERROR/WARNING. Action to perform when the input FID is not preserved in the output layer. The default is NOTHING. Setting it to ERROR will cause the function to error out. Setting it to WARNING will cause the function to emit a warning but continue its processing.

  • GEOMETRY_NAME=name. Name of the geometry column. If not provided, GetGeometryColumn() is used. The special name OGRLayer::DEFAULT_ARROW_GEOMETRY_NAME is also recognized if neither GEOMETRY_NAME nor GetGeometryColumn() are set. Geometry columns are also identified if they have ARROW:extension:name=ogc.wkb as a field metadata. The corresponding ArrowArray must be of type binary (w) or large binary (W).

The following example demonstrates how to copy a layer from one format to another one (assuming it has at most a single geometry column): 

def copy_layer(src_lyr, out_filename, out_format, lcos = {}):
    stream = src_lyr.GetArrowStream()
    schema = stream.GetSchema()

    # If the source layer has a FID column and the output driver supports
    # a FID layer creation option, set it to the source FID column name.
    if src_lyr.GetFIDColumn():
        creationOptions = gdal.GetDriverByName(out_format).GetMetadataItem(
            "DS_LAYER_CREATIONOPTIONLIST"
        )
        if creationOptions and '"FID"' in creationOptions:
            lcos["FID"] = src_lyr.GetFIDColumn()

    with ogr.GetDriverByName(out_format).CreateDataSource(out_filename) as out_ds:
        if src_lyr.GetLayerDefn().GetGeomFieldCount() > 1:
            out_lyr = out_ds.CreateLayer(
                src_lyr.GetName(), geom_type=ogr.wkbNone, options=lcos
            )
            for i in range(src_lyr.GetLayerDefn().GetGeomFieldCount()):
                out_lyr.CreateGeomField(src_lyr.GetLayerDefn().GetGeomFieldDefn(i))
        else:
            out_lyr = out_ds.CreateLayer(
                src_lyr.GetName(),
                geom_type=src_lyr.GetGeomType(),
                srs=src_lyr.GetSpatialRef(),
                options=lcos,
            )

        success, error_msg = out_lyr.IsArrowSchemaSupported(schema)
        assert success, error_msg

        src_geom_field_names = [
            src_lyr.GetLayerDefn().GetGeomFieldDefn(i).GetName()
            for i in range(src_lyr.GetLayerDefn().GetGeomFieldCount())
        ]
        for i in range(schema.GetChildrenCount()):
            # GetArrowStream() may return "OGC_FID" for a unnamed source FID
            # column and "wkb_geometry" for a unnamed source geometry column.
            # Also test GetFIDColumn() and src_geom_field_names if they are
            # named.
            if (
                schema.GetChild(i).GetName()
                not in ("OGC_FID", "wkb_geometry", src_lyr.GetFIDColumn())
                and schema.GetChild(i).GetName() not in src_geom_field_names
            ):
                out_lyr.CreateFieldFromArrowSchema(schema.GetChild(i))

        write_options = []
        if src_lyr.GetFIDColumn():
            write_options.append("FID=" + src_lyr.GetFIDColumn())
        if (
            src_lyr.GetLayerDefn().GetGeomFieldCount() == 1
            and src_lyr.GetGeometryColumn()
        ):
            write_options.append("GEOMETRY_NAME=" + src_lyr.GetGeometryColumn())

        while True:
            array = stream.GetNextRecordBatch()
            if array is None:
                break
            out_lyr.WriteArrowBatch(schema, array, write_options)

This method and CreateFeature() are mutually exclusive in the same session.

This method is the same as the C++ method OGRLayer::WriteArrowBatch().

Since

3.8

Parameters:

  • hLayer -- Layer.

  • schema -- Schema of array.

  • array -- Array of type struct. It may be released (array->release==NULL) after calling this method.

  • papszOptions -- Options. Null terminated list, or nullptr.

Returns:

true in case of success

OGRErr OGR_L_SetNextByIndex(OGRLayerH, GIntBig)

Move read cursor to the nIndex'th feature in the current resultset.

This method allows positioning of a layer such that the GetNextFeature() call will read the requested feature, where nIndex is an absolute index into the current result set. So, setting it to 3 would mean the next feature read with GetNextFeature() would have been the 4th feature to have been read if sequential reading took place from the beginning of the layer, including accounting for spatial and attribute filters.

Only in rare circumstances is SetNextByIndex() efficiently implemented. In all other cases the default implementation which calls ResetReading() and then calls GetNextFeature() nIndex times is used. To determine if fast seeking is available on the current layer use the TestCapability() method with a value of OLCFastSetNextByIndex.

This method is the same as the C++ method OGRLayer::SetNextByIndex()

Parameters:

  • hLayer -- handle to the layer

  • nIndex -- the index indicating how many steps into the result set to seek.

Returns:

OGRERR_NONE on success or an error code.

OGRFeatureH OGR_L_GetFeature(OGRLayerH, GIntBig)

Fetch a feature by its identifier.

This function will attempt to read the identified feature. The nFID value cannot be OGRNullFID. Success or failure of this operation is unaffected by the spatial or attribute filters (and specialized implementations in drivers should make sure that they do not take into account spatial or attribute filters).

If this function returns a non-NULL feature, it is guaranteed that its feature id (OGR_F_GetFID()) will be the same as nFID.

Use OGR_L_TestCapability(OLCRandomRead) to establish if this layer supports efficient random access reading via OGR_L_GetFeature(); however, the call should always work if the feature exists as a fallback implementation just scans all the features in the layer looking for the desired feature.

Sequential reads (with OGR_L_GetNextFeature()) are generally considered interrupted by a OGR_L_GetFeature() call.

The returned feature should be free with OGR_F_Destroy().

This function is the same as the C++ method OGRLayer::GetFeature( ).

Parameters:

  • hLayer -- handle to the layer that owned the feature.

  • nFeatureId -- the feature id of the feature to read.

Returns:

a handle to a feature now owned by the caller, or NULL on failure.

OGRErr OGR_L_SetFeature(OGRLayerH, OGRFeatureH)

Rewrite/replace an existing feature.

This function will write a feature to the layer, based on the feature id within the OGRFeature.

Use OGR_L_TestCapability(OLCRandomWrite) to establish if this layer supports random access writing via OGR_L_SetFeature().

The way unset fields in the provided poFeature are processed is driver dependent:

  • SQL based drivers which implement SetFeature() through SQL UPDATE will skip unset fields, and thus the content of the existing feature will be preserved.

  • The shapefile driver will write a NULL value in the DBF file.

  • The GeoJSON driver will take into account unset fields to remove the corresponding JSON member.

This function is the same as the C++ method OGRLayer::SetFeature().

To set a feature, but create it if it doesn't exist see OGR_L_UpsertFeature().

See also

OGR_L_UpdateFeature(), OGR_L_CreateFeature(), OGR_L_UpsertFeature()

Parameters:

  • hLayer -- handle to the layer to write the feature.

  • hFeat -- the feature to write.

Returns:

OGRERR_NONE if the operation works, otherwise an appropriate error code (e.g OGRERR_NON_EXISTING_FEATURE if the feature does not exist).

OGRErr OGR_L_CreateFeature(OGRLayerH, OGRFeatureH)

Create and write a new feature within a layer.

The passed feature is written to the layer as a new feature, rather than overwriting an existing one. If the feature has a feature id other than OGRNullFID, then the native implementation may use that as the feature id of the new feature, but not necessarily. Upon successful return the passed feature will have been updated with the new feature id.

This function is the same as the C++ method OGRLayer::CreateFeature().

To create a feature, but set it if it exists see OGR_L_UpsertFeature().

See also

OGR_L_SetFeature(), OGR_L_UpdateFeature(), OGR_L_UpsertFeature()

Parameters:

  • hLayer -- handle to the layer to write the feature to.

  • hFeat -- the handle of the feature to write to disk.

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_DeleteFeature(OGRLayerH, GIntBig)

Delete feature from layer.

The feature with the indicated feature id is deleted from the layer if supported by the driver. Most drivers do not support feature deletion, and will return OGRERR_UNSUPPORTED_OPERATION. The OGR_L_TestCapability() function may be called with OLCDeleteFeature to check if the driver supports feature deletion.

This method is the same as the C++ method OGRLayer::DeleteFeature().

Parameters:

  • hLayer -- handle to the layer

  • nFID -- the feature id to be deleted from the layer

Returns:

OGRERR_NONE if the operation works, otherwise an appropriate error code (e.g OGRERR_NON_EXISTING_FEATURE if the feature does not exist).

OGRErr OGR_L_UpsertFeature(OGRLayerH, OGRFeatureH)

Rewrite/replace an existing feature or create a new feature within a layer.

This function will write a feature to the layer, based on the feature id within the OGRFeature. If the feature id doesn't exist a new feature will be written. Otherwise, the existing feature will be rewritten.

Use OGR_L_TestCapability(OLCUpsertFeature) to establish if this layer supports upsert writing.

This function is the same as the C++ method OGRLayer::UpsertFeature().

See also

OGR_L_SetFeature(), OGR_L_CreateFeature(), OGR_L_UpdateFeature()

Since

GDAL 3.6.0

Parameters:

  • hLayer -- handle to the layer to write the feature to.

  • hFeat -- the handle of the feature to write to disk.

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_UpdateFeature(OGRLayerH, OGRFeatureH, int nUpdatedFieldsCount, const int *panUpdatedFieldsIdx, int nUpdatedGeomFieldsCount, const int *panUpdatedGeomFieldsIdx, bool bUpdateStyleString)

Update (part of) an existing feature.

This function will update the specified attribute and geometry fields of a feature to the layer, based on the feature id within the OGRFeature.

Use OGR_L_TestCapability(OLCRandomWrite) to establish if this layer supports random access writing via UpdateFeature(). And to know if the driver supports a dedicated/efficient UpdateFeature() method, test for the OLCUpdateFeature capability.

The way unset fields in the provided poFeature are processed is driver dependent:

  • SQL based drivers which implement SetFeature() through SQL UPDATE will skip unset fields, and thus the content of the existing feature will be preserved.

  • The shapefile driver will write a NULL value in the DBF file.

  • The GeoJSON driver will take into account unset fields to remove the corresponding JSON member.

This method is the same as the C++ method OGRLayer::UpdateFeature().

To fully replace a feature, see OGR_L_SetFeature()

Note that after this call the content of hFeat might have changed, and will not* reflect the content you would get with OGR_L_GetFeature(). In particular for performance reasons, passed geometries might have been "stolen", in particular for the default implementation of UpdateFeature() which relies on GetFeature() + SetFeature().

See also

OGR_L_UpdateFeature(), OGR_L_CreateFeature(), OGR_L_UpsertFeature()

Since

GDAL 3.7

Parameters:

  • hLayer -- handle to the layer to write the feature.

  • hFeat -- the feature to update.

  • nUpdatedFieldsCount -- number of attribute fields to update. May be 0

  • panUpdatedFieldsIdx -- array of nUpdatedFieldsCount values, each between 0 and GetLayerDefn()->GetFieldCount() - 1, indicating which fields of hFeat must be updated in the layer.

  • nUpdatedGeomFieldsCount -- number of geometry fields to update. May be 0

  • panUpdatedGeomFieldsIdx -- array of nUpdatedGeomFieldsCount values, each between 0 and GetLayerDefn()->GetGeomFieldCount() - 1, indicating which geometry fields of hFeat must be updated in the layer.

  • bUpdateStyleString -- whether the feature style string in the layer should be updated with the one of hFeat.

Returns:

OGRERR_NONE if the operation works, otherwise an appropriate error code (e.g OGRERR_NON_EXISTING_FEATURE if the feature does not exist).

OGRFeatureDefnH OGR_L_GetLayerDefn(OGRLayerH)

Fetch the schema information for this layer.

The returned handle to the OGRFeatureDefn is owned by the OGRLayer, and should not be modified or freed by the application. It encapsulates the attribute schema of the features of the layer.

This function is the same as the C++ method OGRLayer::GetLayerDefn().

Parameters:

hLayer -- handle to the layer to get the schema information.

Returns:

a handle to the feature definition.

OGRSpatialReferenceH OGR_L_GetSpatialRef(OGRLayerH)

Fetch the spatial reference system for this layer.

The returned object is owned by the OGRLayer and should not be modified or freed by the application.

This function is the same as the C++ method OGRLayer::GetSpatialRef().

Parameters:

hLayer -- handle to the layer to get the spatial reference from.

Returns:

spatial reference, or NULL if there isn't one.

OGRSpatialReferenceH *OGR_L_GetSupportedSRSList(OGRLayerH hLayer, int iGeomField, int *pnCount)

Get the list of SRS supported.

The base implementation of this method will return an empty list. Some drivers (OAPIF, WFS) may return a non-empty list.

One of the SRS returned may be passed to SetActiveSRS() to change the active SRS.

Since

GDAL 3.7

Parameters:

  • hLayer -- Layer.

  • iGeomField -- Geometry field index.

  • pnCount -- [out] Number of values in returned array. Must not be null.

Returns:

list of supported SRS, to be freeds with OSRFreeSRSArray(), or nullptr

OGRErr OGR_L_SetActiveSRS(OGRLayerH hLayer, int iGeomField, OGRSpatialReferenceH hSRS)

Change the active SRS.

The passed SRS must be in the list returned by GetSupportedSRSList() (the actual pointer may be different, but should be tested as identical with OGRSpatialReference::IsSame()).

Changing the active SRS affects:

  • the SRS in which geometries of returned features are expressed,

  • the SRS in which geometries of passed features (CreateFeature(), SetFeature()) are expressed,

  • the SRS returned by GetSpatialRef() and GetGeomFieldDefn()->GetSpatialRef(),

  • the SRS used to interpret SetSpatialFilter() values.

This also resets feature reading and the spatial filter. Note however that this does not modify the storage SRS of the features of geometries. Said otherwise, this setting is volatile and has no persistent effects after dataset reopening.

Since

GDAL 3.7

Parameters:

  • hLayer -- Layer.

  • iGeomField -- Geometry field index.

  • hSRS -- SRS to use

Returns:

OGRERR_NONE in case of success, OGRERR_FAILURE if the passed SRS is not in GetSupportedSRSList().

int OGR_L_FindFieldIndex(OGRLayerH, const char*, int bExactMatch)

Find the index of field in a layer.

The returned number is the index of the field in the layers, or -1 if the field doesn't exist.

If bExactMatch is set to FALSE and the field doesn't exists in the given form the driver might apply some changes to make it match, like those it might do if the layer was created (eg. like LAUNDER in the OCI driver).

This method is the same as the C++ method OGRLayer::FindFieldIndex().

Returns:

field index, or -1 if the field doesn't exist

GIntBig OGR_L_GetFeatureCount(OGRLayerH, int)

Fetch the feature count in this layer.

Returns the number of features in the layer. For dynamic databases the count may not be exact. If bForce is FALSE, and it would be expensive to establish the feature count a value of -1 may be returned indicating that the count isn't know. If bForce is TRUE some implementations will actually scan the entire layer once to count objects.

The returned count takes the spatial filter into account.

Note that some implementations of this method may alter the read cursor of the layer.

This function is the same as the CPP OGRLayer::GetFeatureCount().

Note: since GDAL 2.0, this method returns a GIntBig (previously a int)

Parameters:

  • hLayer -- handle to the layer that owned the features.

  • bForce -- Flag indicating whether the count should be computed even if it is expensive.

Returns:

feature count, -1 if count not known.

OGRErr OGR_L_GetExtent(OGRLayerH, OGREnvelope*, int)

Fetch the extent of this layer.

Returns the extent (MBR) of the data in the layer. If bForce is FALSE, and it would be expensive to establish the extent then OGRERR_FAILURE will be returned indicating that the extent isn't know. If bForce is TRUE then some implementations will actually scan the entire layer once to compute the MBR of all the features in the layer.

Depending on the drivers, the returned extent may or may not take the spatial filter into account. So it is safer to call OGR_L_GetExtent() without setting a spatial filter.

Layers without any geometry may return OGRERR_FAILURE just indicating that no meaningful extents could be collected.

Note that some implementations of this method may alter the read cursor of the layer.

This function is the same as the C++ method OGRLayer::GetExtent().

Parameters:

  • hLayer -- handle to the layer from which to get extent.

  • psExtent -- the structure in which the extent value will be returned.

  • bForce -- Flag indicating whether the extent should be computed even if it is expensive.

Returns:

OGRERR_NONE on success, OGRERR_FAILURE if extent not known.

OGRErr OGR_L_GetExtentEx(OGRLayerH, int iGeomField, OGREnvelope *psExtent, int bForce)

Fetch the extent of this layer, on the specified geometry field.

Returns the extent (MBR) of the data in the layer. If bForce is FALSE, and it would be expensive to establish the extent then OGRERR_FAILURE will be returned indicating that the extent isn't know. If bForce is TRUE then some implementations will actually scan the entire layer once to compute the MBR of all the features in the layer.

Depending on the drivers, the returned extent may or may not take the spatial filter into account. So it is safer to call OGR_L_GetExtent() without setting a spatial filter.

Layers without any geometry may return OGRERR_FAILURE just indicating that no meaningful extents could be collected.

Note that some implementations of this method may alter the read cursor of the layer.

This function is the same as the C++ method OGRLayer::GetExtent().

Parameters:

  • hLayer -- handle to the layer from which to get extent.

  • iGeomField -- the index of the geometry field on which to compute the extent.

  • psExtent -- the structure in which the extent value will be returned.

  • bForce -- Flag indicating whether the extent should be computed even if it is expensive.

Returns:

OGRERR_NONE on success, OGRERR_FAILURE if extent not known.

OGRErr OGR_L_GetExtent3D(OGRLayerH hLayer, int iGeomField, OGREnvelope3D *psExtent3D, int bForce)

Fetch the 3D extent of this layer, on the specified geometry field.

Returns the 3D extent (MBR) of the data in the layer. If bForce is FALSE, and it would be expensive to establish the extent then OGRERR_FAILURE will be returned indicating that the extent isn't know. If bForce is TRUE then some implementations will actually scan the entire layer once to compute the MBR of all the features in the layer.

(Contrarty to GetExtent() 2D), the returned extent will always take into account the attribute and spatial filters that may be installed.

Layers without any geometry may return OGRERR_FAILURE just indicating that no meaningful extents could be collected.

For layers that have no 3D geometries, the psExtent3D->MinZ and psExtent3D->MaxZ fields will be respectively set to +Infinity and -Infinity.

Note that some implementations of this method may alter the read cursor of the layer.

This function is the same as the C++ method OGRLayer::GetExtent3D().

Since

GDAL 3.9

Parameters:

  • hLayer -- the layer to consider.

  • iGeomField -- 0-based index of the geometry field to consider.

  • psExtent3D -- the computed 3D extent of the layer.

  • bForce -- if TRUE, the extent will be computed even if all the layer features have to be fetched.

Returns:

OGRERR_NONE on success or an error code in case of failure.

int OGR_L_TestCapability(OGRLayerH, const char*)

Test if this layer supported the named capability.

The capability codes that can be tested are represented as strings, but #defined constants exists to ensure correct spelling. Specific layer types may implement class specific capabilities, but this can't generally be discovered by the caller.

  • OLCRandomRead / "RandomRead": TRUE if the GetFeature() method is implemented in an optimized way for this layer, as opposed to the default implementation using ResetReading() and GetNextFeature() to find the requested feature id.

  • OLCSequentialWrite / "SequentialWrite": TRUE if the CreateFeature() method works for this layer. Note this means that this particular layer is writable. The same OGRLayer class may return FALSE for other layer instances that are effectively read-only.

  • OLCRandomWrite / "RandomWrite": TRUE if the SetFeature() method is operational on this layer. Note this means that this particular layer is writable. The same OGRLayer class may return FALSE for other layer instances that are effectively read-only.

  • OLCUpsertFeature / "UpsertFeature": TRUE if the UpsertFeature() method is operational on this layer. Note this means that this particular layer is writable. The same OGRLayer class may return FALSE for other layer instances that are effectively read-only.

  • OLCFastSpatialFilter / "FastSpatialFilter": TRUE if this layer implements spatial filtering efficiently. Layers that effectively read all features, and test them with the OGRFeature intersection methods should return FALSE. This can be used as a clue by the application whether it should build and maintain its own spatial index for features in this layer.

  • OLCFastFeatureCount / "FastFeatureCount": TRUE if this layer can return a feature count (via OGR_L_GetFeatureCount()) efficiently, i.e. without counting the features. In some cases this will return TRUE until a spatial filter is installed after which it will return FALSE.

  • OLCFastGetExtent / "FastGetExtent": TRUE if this layer can return its data extent (via OGR_L_GetExtent()) efficiently, i.e. without scanning all the features. In some cases this will return TRUE until a spatial filter is installed after which it will return FALSE.

  • OLCFastSetNextByIndex / "FastSetNextByIndex": TRUE if this layer can perform the SetNextByIndex() call efficiently, otherwise FALSE.

  • OLCCreateField / "CreateField": TRUE if this layer can create new fields on the current layer using CreateField(), otherwise FALSE.

  • OLCCreateGeomField / "CreateGeomField": (GDAL >= 1.11) TRUE if this layer can create new geometry fields on the current layer using CreateGeomField(), otherwise FALSE.

  • OLCDeleteField / "DeleteField": TRUE if this layer can delete existing fields on the current layer using DeleteField(), otherwise FALSE.

  • OLCReorderFields / "ReorderFields": TRUE if this layer can reorder existing fields on the current layer using ReorderField() or ReorderFields(), otherwise FALSE.

  • OLCAlterFieldDefn / "AlterFieldDefn": TRUE if this layer can alter the definition of an existing field on the current layer using AlterFieldDefn(), otherwise FALSE.

  • OLCAlterGeomFieldDefn / "AlterGeomFieldDefn": TRUE if this layer can alter the definition of an existing geometry field on the current layer using AlterGeomFieldDefn(), otherwise FALSE.

  • OLCDeleteFeature / "DeleteFeature": TRUE if the DeleteFeature() method is supported on this layer, otherwise FALSE.

  • OLCStringsAsUTF8 / "StringsAsUTF8": TRUE if values of OFTString fields are assured to be in UTF-8 format. If FALSE the encoding of fields is uncertain, though it might still be UTF-8.

  • OLCTransactions / "Transactions": TRUE if the StartTransaction(), CommitTransaction() and RollbackTransaction() methods work in a meaningful way, otherwise FALSE.

  • OLCCurveGeometries / "CurveGeometries": TRUE if this layer supports writing curve geometries or may return such geometries. (GDAL 2.0).

This function is the same as the C++ method OGRLayer::TestCapability().

Parameters:

  • hLayer -- handle to the layer to get the capability from.

  • pszCap -- the name of the capability to test.

Returns:

TRUE if the layer has the requested capability, or FALSE otherwise. OGRLayers will return FALSE for any unrecognized capabilities.

OGRErr OGR_L_CreateField(OGRLayerH, OGRFieldDefnH, int)

Create a new field on a layer.

You must use this to create new fields on a real layer. Internally the OGRFeatureDefn for the layer will be updated to reflect the new field. Applications should never modify the OGRFeatureDefn used by a layer directly.

This function should not be called while there are feature objects in existence that were obtained or created with the previous layer definition.

Not all drivers support this function. You can query a layer to check if it supports it with the OLCCreateField capability. Some drivers may only support this method while there are still no features in the layer. When it is supported, the existing features of the backing file/database should be updated accordingly.

Drivers may or may not support not-null constraints. If they support creating fields with not-null constraints, this is generally before creating any feature to the layer.

This function is the same as the C++ method OGRLayer::CreateField().

Parameters:

  • hLayer -- handle to the layer to write the field definition.

  • hField -- handle of the field definition to write to disk.

  • bApproxOK -- If TRUE, the field may be created in a slightly different form depending on the limitations of the format driver.

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_CreateGeomField(OGRLayerH hLayer, OGRGeomFieldDefnH hFieldDefn, int bForce)

Create a new geometry field on a layer.

You must use this to create new geometry fields on a real layer. Internally the OGRFeatureDefn for the layer will be updated to reflect the new field. Applications should never modify the OGRFeatureDefn used by a layer directly.

This function should not be called while there are feature objects in existence that were obtained or created with the previous layer definition.

Not all drivers support this function. You can query a layer to check if it supports it with the OLCCreateField capability. Some drivers may only support this method while there are still no features in the layer. When it is supported, the existing features of the backing file/database should be updated accordingly.

Drivers may or may not support not-null constraints. If they support creating fields with not-null constraints, this is generally before creating any feature to the layer.

This function is the same as the C++ method OGRLayer::CreateField().

Since

OGR 1.11

Parameters:

  • hLayer -- handle to the layer to write the field definition.

  • hField -- handle of the geometry field definition to write to disk.

  • bApproxOK -- If TRUE, the field may be created in a slightly different form depending on the limitations of the format driver.

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_DeleteField(OGRLayerH, int iField)

Delete an existing field on a layer.

You must use this to delete existing fields on a real layer. Internally the OGRFeatureDefn for the layer will be updated to reflect the deleted field. Applications should never modify the OGRFeatureDefn used by a layer directly.

This function should not be called while there are feature objects in existence that were obtained or created with the previous layer definition.

Not all drivers support this function. You can query a layer to check if it supports it with the OLCDeleteField capability. Some drivers may only support this method while there are still no features in the layer. When it is supported, the existing features of the backing file/database should be updated accordingly.

This function is the same as the C++ method OGRLayer::DeleteField().

Since

OGR 1.9.0

Parameters:

  • hLayer -- handle to the layer.

  • iField -- index of the field to delete.

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_ReorderFields(OGRLayerH, int *panMap)

Reorder all the fields of a layer.

You must use this to reorder existing fields on a real layer. Internally the OGRFeatureDefn for the layer will be updated to reflect the reordering of the fields. Applications should never modify the OGRFeatureDefn used by a layer directly.

This function should not be called while there are feature objects in existence that were obtained or created with the previous layer definition.

panMap is such that,for each field definition at position i after reordering, its position before reordering was panMap[i].

For example, let suppose the fields were "0","1","2","3","4" initially. ReorderFields([0,2,3,1,4]) will reorder them as "0","2","3","1","4".

Not all drivers support this function. You can query a layer to check if it supports it with the OLCReorderFields capability. Some drivers may only support this method while there are still no features in the layer. When it is supported, the existing features of the backing file/database should be updated accordingly.

This function is the same as the C++ method OGRLayer::ReorderFields().

Since

OGR 1.9.0

Parameters:
Returns:

OGRERR_NONE on success.

OGRErr OGR_L_ReorderField(OGRLayerH, int iOldFieldPos, int iNewFieldPos)

Reorder an existing field on a layer.

This function is a convenience wrapper of OGR_L_ReorderFields() dedicated to move a single field.

You must use this to reorder existing fields on a real layer. Internally the OGRFeatureDefn for the layer will be updated to reflect the reordering of the fields. Applications should never modify the OGRFeatureDefn used by a layer directly.

This function should not be called while there are feature objects in existence that were obtained or created with the previous layer definition.

The field definition that was at initial position iOldFieldPos will be moved at position iNewFieldPos, and elements between will be shuffled accordingly.

For example, let suppose the fields were "0","1","2","3","4" initially. ReorderField(1, 3) will reorder them as "0","2","3","1","4".

Not all drivers support this function. You can query a layer to check if it supports it with the OLCReorderFields capability. Some drivers may only support this method while there are still no features in the layer. When it is supported, the existing features of the backing file/database should be updated accordingly.

This function is the same as the C++ method OGRLayer::ReorderField().

Since

OGR 1.9.0

Parameters:

  • hLayer -- handle to the layer.

  • iOldFieldPos -- previous position of the field to move. Must be in the range [0,GetFieldCount()-1].

  • iNewFieldPos -- new position of the field to move. Must be in the range [0,GetFieldCount()-1].

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_AlterFieldDefn(OGRLayerH, int iField, OGRFieldDefnH hNewFieldDefn, int nFlags)

Alter the definition of an existing field on a layer.

You must use this to alter the definition of an existing field of a real layer. Internally the OGRFeatureDefn for the layer will be updated to reflect the altered field. Applications should never modify the OGRFeatureDefn used by a layer directly.

This function should not be called while there are feature objects in existence that were obtained or created with the previous layer definition.

Not all drivers support this function. You can query a layer to check if it supports it with the OLCAlterFieldDefn capability. Some drivers may only support this method while there are still no features in the layer. When it is supported, the existing features of the backing file/database should be updated accordingly. Some drivers might also not support all update flags.

This function is the same as the C++ method OGRLayer::AlterFieldDefn().

Since

OGR 1.9.0

Parameters:

  • hLayer -- handle to the layer.

  • iField -- index of the field whose definition must be altered.

  • hNewFieldDefn -- new field definition

  • nFlags -- combination of ALTER_NAME_FLAG, ALTER_TYPE_FLAG, ALTER_WIDTH_PRECISION_FLAG, ALTER_NULLABLE_FLAG and ALTER_DEFAULT_FLAG to indicate which of the name and/or type and/or width and precision fields and/or nullability from the new field definition must be taken into account.

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_AlterGeomFieldDefn(OGRLayerH, int iField, OGRGeomFieldDefnH hNewGeomFieldDefn, int nFlags)

Alter the definition of an existing geometry field on a layer.

You must use this to alter the definition of an existing geometry field of a real layer. Internally the OGRFeatureDefn for the layer will be updated to reflect the altered field. Applications should never modify the OGRFeatureDefn used by a layer directly.

Note that altering the SRS does not cause coordinate reprojection to occur: this is simply a modification of the layer metadata (correcting a wrong SRS definition). No modification to existing geometries will ever be performed, so this method cannot be used to e.g. promote single part geometries to their multipart equivalents.

This function should not be called while there are feature objects in existence that were obtained or created with the previous layer definition.

Not all drivers support this function. You can query a layer to check if it supports it with the OLCAlterGeomFieldDefn capability. Some drivers might not support all update flags. The GDAL_DMD_ALTER_GEOM_FIELD_DEFN_FLAGS driver metadata item can be queried to examine which flags may be supported by a driver.

This function is the same as the C++ method OGRLayer::AlterFieldDefn().

Since

OGR 3.6.0

Parameters:

  • hLayer -- handle to the layer.

  • iGeomField -- index of the field whose definition must be altered.

  • hNewGeomFieldDefn -- new field definition

  • nFlags -- combination of ALTER_GEOM_FIELD_DEFN_NAME_FLAG, ALTER_GEOM_FIELD_DEFN_TYPE_FLAG, ALTER_GEOM_FIELD_DEFN_NULLABLE_FLAG, ALTER_GEOM_FIELD_DEFN_SRS_FLAG, ALTER_GEOM_FIELD_DEFN_SRS_COORD_EPOCH_FLAG to indicate which of the name and/or type and/or nullability and/or SRS and/or coordinate epoch from the new field definition must be taken into account. Or ALTER_GEOM_FIELD_DEFN_ALL_FLAG to update all members.

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_StartTransaction(OGRLayerH)

For datasources which support transactions, StartTransaction creates a transaction.

If starting the transaction fails, will return OGRERR_FAILURE. Datasources which do not support transactions will always return OGRERR_NONE.

Note: as of GDAL 2.0, use of this API is discouraged when the dataset offers dataset level transaction with GDALDataset::StartTransaction(). The reason is that most drivers can only offer transactions at dataset level, and not layer level. Very few drivers really support transactions at layer scope.

This function is the same as the C++ method OGRLayer::StartTransaction().

Parameters:

hLayer -- handle to the layer

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_CommitTransaction(OGRLayerH)

For datasources which support transactions, CommitTransaction commits a transaction.

If no transaction is active, or the commit fails, will return OGRERR_FAILURE. Datasources which do not support transactions will always return OGRERR_NONE.

This function is the same as the C++ method OGRLayer::CommitTransaction().

Parameters:

hLayer -- handle to the layer

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_RollbackTransaction(OGRLayerH)

For datasources which support transactions, RollbackTransaction will roll back a datasource to its state before the start of the current transaction.

If no transaction is active, or the rollback fails, will return OGRERR_FAILURE. Datasources which do not support transactions will always return OGRERR_NONE.

This function is the same as the C++ method OGRLayer::RollbackTransaction().

Parameters:

hLayer -- handle to the layer

Returns:

OGRERR_NONE on success.

OGRErr OGR_L_Rename(OGRLayerH hLayer, const char *pszNewName)

Rename layer.

This operation is implemented only by layers that expose the OLCRename capability, and drivers that expose the GDAL_DCAP_RENAME_LAYERS capability

This operation will fail if a layer with the new name already exists.

On success, GetDescription() and GetLayerDefn()->GetName() will return pszNewName.

Renaming the layer may interrupt current feature iteration.

Since

GDAL 3.5

Parameters:

  • hLayer -- Layer to rename.

  • pszNewName -- New layer name. Must not be NULL.

Returns:

OGRERR_NONE in case of success

OGRErr OGR_L_SyncToDisk(OGRLayerH)

Flush pending changes to disk.

This call is intended to force the layer to flush any pending writes to disk, and leave the disk file in a consistent state. It would not normally have any effect on read-only datasources.

Some layers do not implement this method, and will still return OGRERR_NONE. The default implementation just returns OGRERR_NONE. An error is only returned if an error occurs while attempting to flush to disk.

In any event, you should always close any opened datasource with OGR_DS_Destroy() that will ensure all data is correctly flushed.

This method is the same as the C++ method OGRLayer::SyncToDisk()

Parameters:

hLayer -- handle to the layer

Returns:

OGRERR_NONE if no error occurs (even if nothing is done) or an error code.

const char *OGR_L_GetFIDColumn(OGRLayerH)

This method returns the name of the underlying database column being used as the FID column, or "" if not supported.

This method is the same as the C++ method OGRLayer::GetFIDColumn()

Parameters:

hLayer -- handle to the layer

Returns:

fid column name.

const char *OGR_L_GetGeometryColumn(OGRLayerH)

This method returns the name of the underlying database column being used as the geometry column, or "" if not supported.

For layers with multiple geometry fields, this method only returns the geometry type of the first geometry column. For other columns, use OGR_GFld_GetNameRef(OGR_FD_GetGeomFieldDefn(OGR_L_GetLayerDefn(hLayer), i)).

This method is the same as the C++ method OGRLayer::GetGeometryColumn()

Parameters:

hLayer -- handle to the layer

Returns:

geometry column name.

OGRStyleTableH OGR_L_GetStyleTable(OGRLayerH)

Get style table.

void OGR_L_SetStyleTableDirectly(OGRLayerH, OGRStyleTableH)

Set style table (and take ownership)

void OGR_L_SetStyleTable(OGRLayerH, OGRStyleTableH)

Set style table.

OGRErr OGR_L_SetIgnoredFields(OGRLayerH, const char**)

Set which fields can be omitted when retrieving features from the layer.

If the driver supports this functionality (testable using OLCIgnoreFields capability), it will not fetch the specified fields in subsequent calls to GetFeature() / GetNextFeature() and thus save some processing time and/or bandwidth.

Besides field names of the layers, the following special fields can be passed: "OGR_GEOMETRY" to ignore geometry and "OGR_STYLE" to ignore layer style.

By default, no fields are ignored.

Note that fields that are used in an attribute filter should generally not be set as ignored fields, as most drivers (such as those relying on the OGR SQL engine) will be unable to correctly evaluate the attribute filter.

This method is the same as the C++ method OGRLayer::SetIgnoredFields()

Parameters:

  • hLayer -- handle to the layer

  • papszFields -- an array of field names terminated by NULL item. If NULL is passed, the ignored list is cleared.

Returns:

OGRERR_NONE if all field names have been resolved (even if the driver does not support this method)

OGRErr OGR_L_Intersection(OGRLayerH, OGRLayerH, OGRLayerH, char**, GDALProgressFunc, void*)

Intersection of two layers.

The result layer contains features whose geometries represent areas that are common between features in the input layer and in the method layer. The features in the result layer have attributes from both input and method layers. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in the input and method layers.

The recognized list of options is :

  • SKIP_FAILURES=YES/NO. Set it to YES to go on, even when a feature could not be inserted or a GEOS call failed.

  • PROMOTE_TO_MULTI=YES/NO. Set it to YES to convert Polygons into MultiPolygons, or LineStrings to MultiLineStrings.

  • INPUT_PREFIX=string. Set a prefix for the field names that will be created from the fields of the input layer.

  • METHOD_PREFIX=string. Set a prefix for the field names that will be created from the fields of the method layer.

  • USE_PREPARED_GEOMETRIES=YES/NO. Set to NO to not use prepared geometries to pretest intersection of features of method layer with features of this layer.

  • PRETEST_CONTAINMENT=YES/NO. Set to YES to pretest the containment of features of method layer within the features of this layer. This will speed up the method significantly in some cases. Requires that the prepared geometries are in effect.

  • KEEP_LOWER_DIMENSION_GEOMETRIES=YES/NO. Set to NO to skip result features with lower dimension geometry that would otherwise be added to the result layer. The default is to add but only if the result layer has an unknown geometry type.

This function is the same as the C++ method OGRLayer::Intersection().

Since

OGR 1.10

Note

If the schema of the result is set by user and contains fields that have the same name as a field in input and in method layer, then the attribute in the result feature will get the value from the feature of the method layer.

Note

For best performance use the minimum amount of features in the method layer and copy it into a memory layer.

Note

This method relies on GEOS support. Do not use unless the GEOS support is compiled in.

Note

The first geometry field is always used.

Parameters:

  • pLayerInput -- the input layer. Should not be NULL.

  • pLayerMethod -- the method layer. Should not be NULL.

  • pLayerResult -- the layer where the features resulting from the operation are inserted. Should not be NULL. See above the note about the schema.

  • papszOptions -- NULL terminated list of options (may be NULL).

  • pfnProgress -- a GDALProgressFunc() compatible callback function for reporting progress or NULL.

  • pProgressArg -- argument to be passed to pfnProgress. May be NULL.

Returns:

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

OGRErr OGR_L_Union(OGRLayerH, OGRLayerH, OGRLayerH, char**, GDALProgressFunc, void*)

Union of two layers.

The result layer contains features whose geometries represent areas that are in either in the input layer, in the method layer, or in both. The features in the result layer have attributes from both input and method layers. For features which represent areas that are only in the input or in the method layer the respective attributes have undefined values. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in the input and method layers.

The recognized list of options is :

  • SKIP_FAILURES=YES/NO. Set it to YES to go on, even when a feature could not be inserted or a GEOS call failed.

  • PROMOTE_TO_MULTI=YES/NO. Set it to YES to convert Polygons into MultiPolygons, or LineStrings to MultiLineStrings.

  • INPUT_PREFIX=string. Set a prefix for the field names that will be created from the fields of the input layer.

  • METHOD_PREFIX=string. Set a prefix for the field names that will be created from the fields of the method layer.

  • USE_PREPARED_GEOMETRIES=YES/NO. Set to NO to not use prepared geometries to pretest intersection of features of method layer with features of this layer.

  • KEEP_LOWER_DIMENSION_GEOMETRIES=YES/NO. Set to NO to skip result features with lower dimension geometry that would otherwise be added to the result layer. The default is to add but only if the result layer has an unknown geometry type.

This function is the same as the C++ method OGRLayer::Union().

Since

OGR 1.10

Note

If the schema of the result is set by user and contains fields that have the same name as a field in input and in method layer, then the attribute in the result feature will get the value from the feature of the method layer (even if it is undefined).

Note

For best performance use the minimum amount of features in the method layer and copy it into a memory layer.

Note

This method relies on GEOS support. Do not use unless the GEOS support is compiled in.

Note

The first geometry field is always used.

Parameters:

  • pLayerInput -- the input layer. Should not be NULL.

  • pLayerMethod -- the method layer. Should not be NULL.

  • pLayerResult -- the layer where the features resulting from the operation are inserted. Should not be NULL. See above the note about the schema.

  • papszOptions -- NULL terminated list of options (may be NULL).

  • pfnProgress -- a GDALProgressFunc() compatible callback function for reporting progress or NULL.

  • pProgressArg -- argument to be passed to pfnProgress. May be NULL.

Returns:

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

OGRErr OGR_L_SymDifference(OGRLayerH, OGRLayerH, OGRLayerH, char**, GDALProgressFunc, void*)

Symmetrical difference of two layers.

The result layer contains features whose geometries represent areas that are in either in the input layer or in the method layer but not in both. The features in the result layer have attributes from both input and method layers. For features which represent areas that are only in the input or in the method layer the respective attributes have undefined values. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in the input and method layers.

The recognized list of options is :

  • SKIP_FAILURES=YES/NO. Set it to YES to go on, even when a feature could not be inserted or a GEOS call failed.

  • PROMOTE_TO_MULTI=YES/NO. Set it to YES to convert Polygons into MultiPolygons, or LineStrings to MultiLineStrings.

  • INPUT_PREFIX=string. Set a prefix for the field names that will be created from the fields of the input layer.

  • METHOD_PREFIX=string. Set a prefix for the field names that will be created from the fields of the method layer.

This function is the same as the C++ method OGRLayer::SymDifference().

Since

OGR 1.10

Note

If the schema of the result is set by user and contains fields that have the same name as a field in input and in method layer, then the attribute in the result feature will get the value from the feature of the method layer (even if it is undefined).

Note

For best performance use the minimum amount of features in the method layer and copy it into a memory layer.

Note

This method relies on GEOS support. Do not use unless the GEOS support is compiled in.

Note

The first geometry field is always used.

Parameters:

  • pLayerInput -- the input layer. Should not be NULL.

  • pLayerMethod -- the method layer. Should not be NULL.

  • pLayerResult -- the layer where the features resulting from the operation are inserted. Should not be NULL. See above the note about the schema.

  • papszOptions -- NULL terminated list of options (may be NULL).

  • pfnProgress -- a GDALProgressFunc() compatible callback function for reporting progress or NULL.

  • pProgressArg -- argument to be passed to pfnProgress. May be NULL.

Returns:

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

OGRErr OGR_L_Identity(OGRLayerH, OGRLayerH, OGRLayerH, char**, GDALProgressFunc, void*)

Identify the features of this layer with the ones from the identity layer.

The result layer contains features whose geometries represent areas that are in the input layer. The features in the result layer have attributes from both input and method layers. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in input and method layers.

The recognized list of options is :

  • SKIP_FAILURES=YES/NO. Set it to YES to go on, even when a feature could not be inserted or a GEOS call failed.

  • PROMOTE_TO_MULTI=YES/NO. Set it to YES to convert Polygons into MultiPolygons, or LineStrings to MultiLineStrings.

  • INPUT_PREFIX=string. Set a prefix for the field names that will be created from the fields of the input layer.

  • METHOD_PREFIX=string. Set a prefix for the field names that will be created from the fields of the method layer.

  • USE_PREPARED_GEOMETRIES=YES/NO. Set to NO to not use prepared geometries to pretest intersection of features of method layer with features of this layer.

  • KEEP_LOWER_DIMENSION_GEOMETRIES=YES/NO. Set to NO to skip result features with lower dimension geometry that would otherwise be added to the result layer. The default is to add but only if the result layer has an unknown geometry type.

This function is the same as the C++ method OGRLayer::Identity().

Since

OGR 1.10

Note

If the schema of the result is set by user and contains fields that have the same name as a field in input and in method layer, then the attribute in the result feature will get the value from the feature of the method layer (even if it is undefined).

Note

For best performance use the minimum amount of features in the method layer and copy it into a memory layer.

Note

This method relies on GEOS support. Do not use unless the GEOS support is compiled in.

Note

The first geometry field is always used.

Parameters:

  • pLayerInput -- the input layer. Should not be NULL.

  • pLayerMethod -- the method layer. Should not be NULL.

  • pLayerResult -- the layer where the features resulting from the operation are inserted. Should not be NULL. See above the note about the schema.

  • papszOptions -- NULL terminated list of options (may be NULL).

  • pfnProgress -- a GDALProgressFunc() compatible callback function for reporting progress or NULL.

  • pProgressArg -- argument to be passed to pfnProgress. May be NULL.

Returns:

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

OGRErr OGR_L_Update(OGRLayerH, OGRLayerH, OGRLayerH, char**, GDALProgressFunc, void*)

Update this layer with features from the update layer.

The result layer contains features whose geometries represent areas that are either in the input layer or in the method layer. The features in the result layer have areas of the features of the method layer or those ares of the features of the input layer that are not covered by the method layer. The features of the result layer get their attributes from the input layer. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in the input layer.

The recognized list of options is :

  • SKIP_FAILURES=YES/NO. Set it to YES to go on, even when a feature could not be inserted or a GEOS call failed.

  • PROMOTE_TO_MULTI=YES/NO. Set it to YES to convert Polygons into MultiPolygons, or LineStrings to MultiLineStrings.

  • INPUT_PREFIX=string. Set a prefix for the field names that will be created from the fields of the input layer.

  • METHOD_PREFIX=string. Set a prefix for the field names that will be created from the fields of the method layer.

This function is the same as the C++ method OGRLayer::Update().

Since

OGR 1.10

Note

If the schema of the result is set by user and contains fields that have the same name as a field in the method layer, then the attribute in the result feature the originates from the method layer will get the value from the feature of the method layer.

Note

For best performance use the minimum amount of features in the method layer and copy it into a memory layer.

Note

This method relies on GEOS support. Do not use unless the GEOS support is compiled in.

Note

The first geometry field is always used.

Parameters:

  • pLayerInput -- the input layer. Should not be NULL.

  • pLayerMethod -- the method layer. Should not be NULL.

  • pLayerResult -- the layer where the features resulting from the operation are inserted. Should not be NULL. See above the note about the schema.

  • papszOptions -- NULL terminated list of options (may be NULL).

  • pfnProgress -- a GDALProgressFunc() compatible callback function for reporting progress or NULL.

  • pProgressArg -- argument to be passed to pfnProgress. May be NULL.

Returns:

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

OGRErr OGR_L_Clip(OGRLayerH, OGRLayerH, OGRLayerH, char**, GDALProgressFunc, void*)

Clip off areas that are not covered by the method layer.

The result layer contains features whose geometries represent areas that are in the input layer and in the method layer. The features in the result layer have the (possibly clipped) areas of features in the input layer and the attributes from the same features. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in the input layer.

The recognized list of options is :

  • SKIP_FAILURES=YES/NO. Set it to YES to go on, even when a feature could not be inserted or a GEOS call failed.

  • PROMOTE_TO_MULTI=YES/NO. Set it to YES to convert Polygons into MultiPolygons, or LineStrings to MultiLineStrings.

  • INPUT_PREFIX=string. Set a prefix for the field names that will be created from the fields of the input layer.

  • METHOD_PREFIX=string. Set a prefix for the field names that will be created from the fields of the method layer.

This function is the same as the C++ method OGRLayer::Clip().

Since

OGR 1.10

Note

For best performance use the minimum amount of features in the method layer and copy it into a memory layer.

Note

This method relies on GEOS support. Do not use unless the GEOS support is compiled in.

Note

The first geometry field is always used.

Parameters:

  • pLayerInput -- the input layer. Should not be NULL.

  • pLayerMethod -- the method layer. Should not be NULL.

  • pLayerResult -- the layer where the features resulting from the operation are inserted. Should not be NULL. See above the note about the schema.

  • papszOptions -- NULL terminated list of options (may be NULL).

  • pfnProgress -- a GDALProgressFunc() compatible callback function for reporting progress or NULL.

  • pProgressArg -- argument to be passed to pfnProgress. May be NULL.

Returns:

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

OGRErr OGR_L_Erase(OGRLayerH, OGRLayerH, OGRLayerH, char**, GDALProgressFunc, void*)

Remove areas that are covered by the method layer.

The result layer contains features whose geometries represent areas that are in the input layer but not in the method layer. The features in the result layer have attributes from the input layer. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in the input layer.

The recognized list of options is :

  • SKIP_FAILURES=YES/NO. Set it to YES to go on, even when a feature could not be inserted or a GEOS call failed.

  • PROMOTE_TO_MULTI=YES/NO. Set it to YES to convert Polygons into MultiPolygons, or LineStrings to MultiLineStrings.

  • INPUT_PREFIX=string. Set a prefix for the field names that will be created from the fields of the input layer.

  • METHOD_PREFIX=string. Set a prefix for the field names that will be created from the fields of the method layer.

This function is the same as the C++ method OGRLayer::Erase().

Since

OGR 1.10

Note

For best performance use the minimum amount of features in the method layer and copy it into a memory layer.

Note

This method relies on GEOS support. Do not use unless the GEOS support is compiled in.

Note

The first geometry field is always used.

Parameters:

  • pLayerInput -- the input layer. Should not be NULL.

  • pLayerMethod -- the method layer. Should not be NULL.

  • pLayerResult -- the layer where the features resulting from the operation are inserted. Should not be NULL. See above the note about the schema.

  • papszOptions -- NULL terminated list of options (may be NULL).

  • pfnProgress -- a GDALProgressFunc() compatible callback function for reporting progress or NULL.

  • pProgressArg -- argument to be passed to pfnProgress. May be NULL.

Returns:

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

void OGR_DS_Destroy(OGRDataSourceH)

Closes opened datasource and releases allocated resources.

This method is the same as the C++ method OGRDataSource::DestroyDataSource().

Deprecated:

Use GDALClose() in GDAL 2.0

Parameters:

hDS -- handle to allocated datasource object.

const char *OGR_DS_GetName(OGRDataSourceH)

Returns the name of the data source.

This string should be sufficient to open the data source if passed to the same OGRSFDriver that this data source was opened with, but it need not be exactly the same string that was used to open the data source. Normally this is a filename.

Deprecated:

Use GDALGetDescription() in GDAL 2.0

Parameters:

hDS -- handle to the data source to get the name from.

Returns:

pointer to an internal name string which should not be modified or freed by the caller.

int OGR_DS_GetLayerCount(OGRDataSourceH)

Get the number of layers in this data source.

Deprecated:

Use GDALDatasetGetLayerCount() in GDAL 2.0

Parameters:

hDS -- handle to the data source from which to get the number of layers.

Returns:

layer count.

OGRLayerH OGR_DS_GetLayer(OGRDataSourceH, int)

Fetch a layer by index.

The returned layer remains owned by the OGRDataSource and should not be deleted by the application.

Deprecated:

Use GDALDatasetGetLayer() in GDAL 2.0

Parameters:

  • hDS -- handle to the data source from which to get the layer.

  • iLayer -- a layer number between 0 and OGR_DS_GetLayerCount()-1.

Returns:

a handle to the layer, or NULL if iLayer is out of range or an error occurs.

OGRLayerH OGR_DS_GetLayerByName(OGRDataSourceH, const char*)

Fetch a layer by name.

The returned layer remains owned by the OGRDataSource and should not be deleted by the application.

Deprecated:

Use GDALDatasetGetLayerByName() in GDAL 2.0

Parameters:

  • hDS -- handle to the data source from which to get the layer.

  • pszLayerName -- Layer the layer name of the layer to fetch.

Returns:

a handle to the layer, or NULL if the layer is not found or an error occurs.

OGRErr OGR_DS_DeleteLayer(OGRDataSourceH, int)

Delete the indicated layer from the datasource.

If this method is supported the ODsCDeleteLayer capability will test TRUE on the OGRDataSource.

Deprecated:

Use GDALDatasetDeleteLayer() in GDAL 2.0

Parameters:

  • hDS -- handle to the datasource

  • iLayer -- the index of the layer to delete.

Returns:

OGRERR_NONE on success, or OGRERR_UNSUPPORTED_OPERATION if deleting layers is not supported for this datasource.

OGRSFDriverH OGR_DS_GetDriver(OGRDataSourceH)

Returns the driver that the dataset was opened with.

NOTE: Starting with GDAL 2.0, it is NOT safe to cast the returned handle to OGRSFDriver*. If a C++ object is needed, the handle should be cast to GDALDriver*.

Deprecated:

Use GDALGetDatasetDriver() in GDAL 2.0

Parameters:

hDS -- handle to the datasource

Returns:

NULL if driver info is not available, or pointer to a driver owned by the OGRSFDriverManager.

OGRLayerH OGR_DS_CreateLayer(OGRDataSourceH, const char*, OGRSpatialReferenceH, OGRwkbGeometryType, char**)

This function attempts to create a new layer on the data source with the indicated name, coordinate system, geometry type.

The papszOptions argument can be used to control driver specific creation options. These options are normally documented in the format specific documentation.

Deprecated:

Use GDALDatasetCreateLayer() in GDAL 2.0

Example:

#include "ogrsf_frmts.h"
#include "cpl_string.h"

...

        OGRLayerH *hLayer;
        char     **papszOptions;

        if( OGR_DS_TestCapability( hDS, ODsCCreateLayer ) )
        {
            ...
        }

        papszOptions = CSLSetNameValue( papszOptions, "DIM", "2" );
        hLayer = OGR_DS_CreateLayer( hDS, "NewLayer", NULL, wkbUnknown,
                                     papszOptions );
        CSLDestroy( papszOptions );

        if( hLayer == NULL )
        {
            ...
        }
Parameters:

  • hDS -- The dataset handle.

  • pszName -- the name for the new layer. This should ideally not match any existing layer on the datasource.

  • hSpatialRef -- handle to the coordinate system to use for the new layer, or NULL if no coordinate system is available. The driver might only increase the reference counter of the object to take ownership, and not make a full copy, so do not use OSRDestroySpatialReference(), but OSRRelease() instead when you are done with the object.

  • eType -- the geometry type for the layer. Use wkbUnknown if there are no constraints on the types geometry to be written.

  • papszOptions -- a StringList of name=value options. Options are driver specific, and driver information can be found at the following url: http://www.gdal.org/ogr_formats.html

Returns:

NULL is returned on failure, or a new OGRLayer handle on success.

OGRLayerH OGR_DS_CopyLayer(OGRDataSourceH, OGRLayerH, const char*, char**)

Duplicate an existing layer.

This function creates a new layer, duplicate the field definitions of the source layer and then duplicate each features of the source layer. The papszOptions argument can be used to control driver specific creation options. These options are normally documented in the format specific documentation. The source layer may come from another dataset.

Deprecated:

Use GDALDatasetCopyLayer() in GDAL 2.0

Parameters:

  • hDS -- handle to the data source where to create the new layer

  • hSrcLayer -- handle to the source layer.

  • pszNewName -- the name of the layer to create.

  • papszOptions -- a StringList of name=value options. Options are driver specific.

Returns:

a handle to the layer, or NULL if an error occurs.

int OGR_DS_TestCapability(OGRDataSourceH, const char*)

Test if capability is available.

One of the following data source capability names can be passed into this function, and a TRUE or FALSE value will be returned indicating whether or not the capability is available for this object.

  • ODsCCreateLayer: True if this datasource can create new layers.

  • ODsCDeleteLayer: True if this datasource can delete existing layers.

  • ODsCCreateGeomFieldAfterCreateLayer: True if the layers of this datasource support CreateGeomField() just after layer creation.

  • ODsCCurveGeometries: True if this datasource supports writing curve geometries. (GDAL 2.0). In that case, OLCCurveGeometries must also be declared in layers of that dataset.

The #define macro forms of the capability names should be used in preference to the strings themselves to avoid misspelling.

Deprecated:

Use GDALDatasetTestCapability() in GDAL 2.0

Parameters:

  • hDS -- handle to the data source against which to test the capability.

  • pszCapability -- the capability to test.

Returns:

TRUE if capability available otherwise FALSE.

OGRLayerH OGR_DS_ExecuteSQL(OGRDataSourceH, const char*, OGRGeometryH, const char*)

Execute an SQL statement against the data store.

The result of an SQL query is either NULL for statements that are in error, or that have no results set, or an OGRLayer handle representing a results set from the query. Note that this OGRLayer is in addition to the layers in the data store and must be destroyed with OGR_DS_ReleaseResultSet() before the data source is closed (destroyed).

For more information on the SQL dialect supported internally by OGR review the OGR SQL document. Some drivers (i.e. Oracle and PostGIS) pass the SQL directly through to the underlying RDBMS.

The SQLITE dialect can also be used.

Deprecated:

Use GDALDatasetExecuteSQL() in GDAL 2.0

Parameters:

  • hDS -- handle to the data source on which the SQL query is executed.

  • pszStatement -- the SQL statement to execute.

  • hSpatialFilter -- handle to a geometry which represents a spatial filter. Can be NULL.

  • pszDialect -- allows control of the statement dialect. If set to NULL, the OGR SQL engine will be used, except for RDBMS drivers that will use their dedicated SQL engine, unless OGRSQL is explicitly passed as the dialect. The SQLITE dialect can also be used.

Returns:

a handle to a OGRLayer containing the results of the query. Deallocate with OGR_DS_ReleaseResultSet().

void OGR_DS_ReleaseResultSet(OGRDataSourceH, OGRLayerH)

Release results of OGR_DS_ExecuteSQL().

This function should only be used to deallocate OGRLayers resulting from an OGR_DS_ExecuteSQL() call on the same OGRDataSource. Failure to deallocate a results set before destroying the OGRDataSource may cause errors.

Deprecated:

Use GDALDatasetReleaseResultSet() in GDAL 2.0

Parameters:

  • hDS -- a handle to the data source on which was executed an SQL query.

  • hLayer -- handle to the result of a previous OGR_DS_ExecuteSQL() call.

OGRErr OGR_DS_SyncToDisk(OGRDataSourceH)

Flush pending changes to disk.

See GDALDataset::FlushCache()

OGRStyleTableH OGR_DS_GetStyleTable(OGRDataSourceH)

Get style table.

void OGR_DS_SetStyleTableDirectly(OGRDataSourceH, OGRStyleTableH)

Set style table (and take ownership)

void OGR_DS_SetStyleTable(OGRDataSourceH, OGRStyleTableH)

Set style table.

const char *OGR_Dr_GetName(OGRSFDriverH)

Fetch name of driver (file format).

This name should be relatively short (10-40 characters), and should reflect the underlying file format. For instance "ESRI Shapefile".

This function is the same as the C++ method OGRSFDriver::GetName().

Parameters:

hDriver -- handle to the driver to get the name from.

Returns:

driver name. This is an internal string and should not be modified or freed.

OGRDataSourceH OGR_Dr_Open(OGRSFDriverH, const char*, int)

Attempt to open file with this driver.

NOTE: Starting with GDAL 2.0, it is NOT safe to cast the returned handle to OGRDataSource*. If a C++ object is needed, the handle should be cast to GDALDataset*. Similarly, the returned OGRSFDriverH handle should be cast to GDALDriver*, and NOT* OGRSFDriver*.

Deprecated:

Use GDALOpenEx() in GDAL 2.0

Parameters:

  • hDriver -- handle to the driver that is used to open file.

  • pszName -- the name of the file, or data source to try and open.

  • bUpdate -- TRUE if update access is required, otherwise FALSE (the default).

Returns:

NULL on error or if the pass name is not supported by this driver, otherwise a handle to a GDALDataset. This GDALDataset should be closed by deleting the object when it is no longer needed.

int OGR_Dr_TestCapability(OGRSFDriverH, const char*)

Test if capability is available.

One of the following data source capability names can be passed into this function, and a TRUE or FALSE value will be returned indicating whether or not the capability is available for this object.

  • ODrCCreateDataSource: True if this driver can support creating data sources.

  • ODrCDeleteDataSource: True if this driver supports deleting data sources.

The #define macro forms of the capability names should be used in preference to the strings themselves to avoid misspelling.

Deprecated:

Use GDALGetMetadataItem(hDriver, GDAL_DCAP_CREATE) in GDAL 2.0

Parameters:

  • hDriver -- handle to the driver to test the capability against.

  • pszCap -- the capability to test.

Returns:

TRUE if capability available otherwise FALSE.

OGRDataSourceH OGR_Dr_CreateDataSource(OGRSFDriverH, const char*, char**)

This function attempts to create a new data source based on the passed driver.

The papszOptions argument can be used to control driver specific creation options. These options are normally documented in the format specific documentation.

It is important to call OGR_DS_Destroy() when the datasource is no longer used to ensure that all data has been properly flushed to disk.

Deprecated:

Use GDALCreate() in GDAL 2.0

Parameters:

  • hDriver -- handle to the driver on which data source creation is based.

  • pszName -- the name for the new data source. UTF-8 encoded.

  • papszOptions -- a StringList of name=value options. Options are driver specific, and driver information can be found at the following url: http://www.gdal.org/ogr_formats.html

Returns:

NULL is returned on failure, or a new OGRDataSource handle on success.

OGRDataSourceH OGR_Dr_CopyDataSource(OGRSFDriverH, OGRDataSourceH, const char*, char**)

This function creates a new datasource by copying all the layers from the source datasource.

It is important to call OGR_DS_Destroy() when the datasource is no longer used to ensure that all data has been properly flushed to disk.

Deprecated:

Use GDALCreateCopy() in GDAL 2.0

Parameters:

  • hDriver -- handle to the driver on which data source creation is based.

  • hSrcDS -- source datasource

  • pszNewName -- the name for the new data source.

  • papszOptions -- a StringList of name=value options. Options are driver specific, and driver information can be found at the following url: http://www.gdal.org/ogr_formats.html

Returns:

NULL is returned on failure, or a new OGRDataSource handle on success.

OGRErr OGR_Dr_DeleteDataSource(OGRSFDriverH, const char*)

Delete a datasource.

Delete (from the disk, in the database, ...) the named datasource. Normally it would be safest if the datasource was not open at the time.

Whether this is a supported operation on this driver case be tested using TestCapability() on ODrCDeleteDataSource.

Deprecated:

Use GDALDeleteDataset() in GDAL 2

Parameters:

  • hDriver -- handle to the driver on which data source deletion is based.

  • pszDataSource -- the name of the datasource to delete.

Returns:

OGRERR_NONE on success, and OGRERR_UNSUPPORTED_OPERATION if this is not supported by this driver.

OGRDataSourceH OGROpen(const char*, int, OGRSFDriverH*)

Open a file / data source with one of the registered drivers.

This function loops through all the drivers registered with the driver manager trying each until one succeeds with the given data source.

If this function fails, CPLGetLastErrorMsg() can be used to check if there is an error message explaining why.

For drivers supporting the VSI virtual file API, it is possible to open a file in a .zip archive (see VSIInstallZipFileHandler()), in a .tar/.tar.gz/.tgz archive (see VSIInstallTarFileHandler()) or on a HTTP / FTP server (see VSIInstallCurlFileHandler())

NOTE: Starting with GDAL 2.0, it is NOT safe to cast the returned handle to OGRDataSource*. If a C++ object is needed, the handle should be cast to GDALDataset*. Similarly, the returned OGRSFDriverH handle should be cast to GDALDriver*, and NOT* OGRSFDriver*.

Deprecated:

Use GDALOpenEx() in GDAL 2.0

Example:

Parameters:

  • pszName -- the name of the file, or data source to open.

  • bUpdate -- FALSE for read-only access (the default) or TRUE for read-write access.

  • pahDriverList -- if non-NULL, this argument will be updated with a pointer to the driver which was used to open the data source.

Returns:

NULL on error or if the pass name is not supported by this driver, otherwise a handle to a GDALDataset. This GDALDataset should be closed by deleting the object when it is no longer needed.

OGRDataSourceH OGROpenShared(const char*, int, OGRSFDriverH*)

Open a file / data source with one of the registered drivers if not already opened, or increment reference count of already opened data source previously opened with OGROpenShared()

This function loops through all the drivers registered with the driver manager trying each until one succeeds with the given data source.

If this function fails, CPLGetLastErrorMsg() can be used to check if there is an error message explaining why.

NOTE: Starting with GDAL 2.0, it is NOT safe to cast the returned handle to OGRDataSource*. If a C++ object is needed, the handle should be cast to GDALDataset*. Similarly, the returned OGRSFDriverH handle should be cast to GDALDriver*, and NOT* OGRSFDriver*.

Deprecated:

Use GDALOpenEx() in GDAL 2.0

Example:

Parameters:

  • pszName -- the name of the file, or data source to open.

  • bUpdate -- FALSE for read-only access (the default) or TRUE for read-write access.

  • pahDriverList -- if non-NULL, this argument will be updated with a pointer to the driver which was used to open the data source.

Returns:

NULL on error or if the pass name is not supported by this driver, otherwise a handle to a GDALDataset. This GDALDataset should be closed by deleting the object when it is no longer needed.

OGRErr OGRReleaseDataSource(OGRDataSourceH)

Drop a reference to this datasource, and if the reference count drops to zero close (destroy) the datasource.

Internally this actually calls the OGRSFDriverRegistrar::ReleaseDataSource() method. This method is essentially a convenient alias.

Deprecated:

Use GDALClose() in GDAL 2.0

Parameters:

hDS -- handle to the data source to release

Returns:

OGRERR_NONE on success or an error code.

int OGRGetDriverCount(void)

Fetch the number of registered drivers.

Deprecated:

Use GDALGetDriverCount() in GDAL 2.0

Returns:

the drivers count.

OGRSFDriverH OGRGetDriver(int)

Fetch the indicated driver.

NOTE: Starting with GDAL 2.0, it is NOT safe to cast the returned handle to OGRSFDriver*. If a C++ object is needed, the handle should be cast to GDALDriver*.

Deprecated:

Use GDALGetDriver() in GDAL 2.0

Parameters:

iDriver -- the driver index, from 0 to GetDriverCount()-1.

Returns:

handle to the driver, or NULL if iDriver is out of range.

OGRSFDriverH OGRGetDriverByName(const char*)

Fetch the indicated driver.

NOTE: Starting with GDAL 2.0, it is NOT safe to cast the returned handle to OGRSFDriver*. If a C++ object is needed, the handle should be cast to GDALDriver*.

Deprecated:

Use GDALGetDriverByName() in GDAL 2.0

Parameters:

pszName -- the driver name

Returns:

the driver, or NULL if no driver with that name is found

void OGRRegisterAll(void)

Register all drivers.

Deprecated:

Use GDALAllRegister() in GDAL 2.0

void OGRCleanupAll(void)

Clean-up all drivers (including raster ones starting with GDAL 2.0.

See GDALDestroyDriverManager()

OGRStyleMgrH OGR_SM_Create(OGRStyleTableH hStyleTable)

OGRStyleMgr factory.

This function is the same as the C++ method OGRStyleMgr::OGRStyleMgr().

Parameters:

hStyleTable -- pointer to OGRStyleTable or NULL if not working with a style table.

Returns:

a handle to the new style manager object.

void OGR_SM_Destroy(OGRStyleMgrH hSM)

Destroy Style Manager.

This function is the same as the C++ method OGRStyleMgr::~OGRStyleMgr().

Parameters:

hSM -- handle to the style manager to destroy.

const char *OGR_SM_InitFromFeature(OGRStyleMgrH hSM, OGRFeatureH hFeat)

Initialize style manager from the style string of a feature.

This function is the same as the C++ method OGRStyleMgr::InitFromFeature().

Parameters:

  • hSM -- handle to the style manager.

  • hFeat -- handle to the new feature from which to read the style.

Returns:

a reference to the style string read from the feature, or NULL in case of error.

int OGR_SM_InitStyleString(OGRStyleMgrH hSM, const char *pszStyleString)

Initialize style manager from the style string.

Style string can be an expanded style string (e.g. "PEN(c:#FF0000,w:5px)"), or (starting with GDAL 3.5.1), a reference to a style name starting with @ (e.g. "@my_style") registered in the associated style table.

This function is the same as the C++ method OGRStyleMgr::InitStyleString().

Parameters:

  • hSM -- handle to the style manager.

  • pszStyleString -- the style string to use (can be NULL).

Returns:

TRUE on success, FALSE on errors.

int OGR_SM_GetPartCount(OGRStyleMgrH hSM, const char *pszStyleString)

Get the number of parts in a style.

This function is the same as the C++ method OGRStyleMgr::GetPartCount().

Parameters:

  • hSM -- handle to the style manager.

  • pszStyleString -- (optional) the style string on which to operate. If NULL then the current style string stored in the style manager is used.

Returns:

the number of parts (style tools) in the style.

OGRStyleToolH OGR_SM_GetPart(OGRStyleMgrH hSM, int nPartId, const char *pszStyleString)

Fetch a part (style tool) from the current style.

This function is the same as the C++ method OGRStyleMgr::GetPart().

This function instantiates a new object that should be freed with OGR_ST_Destroy().

Parameters:

  • hSM -- handle to the style manager.

  • nPartId -- the part number (0-based index).

  • pszStyleString -- (optional) the style string on which to operate. If NULL then the current style string stored in the style manager is used.

Returns:

OGRStyleToolH of the requested part (style tools) or NULL on error.

int OGR_SM_AddPart(OGRStyleMgrH hSM, OGRStyleToolH hST)

Add a part (style tool) to the current style.

This function is the same as the C++ method OGRStyleMgr::AddPart().

Parameters:

  • hSM -- handle to the style manager.

  • hST -- the style tool defining the part to add.

Returns:

TRUE on success, FALSE on errors.

int OGR_SM_AddStyle(OGRStyleMgrH hSM, const char *pszStyleName, const char *pszStyleString)

Add a style to the current style table.

This function is the same as the C++ method OGRStyleMgr::AddStyle().

Parameters:

  • hSM -- handle to the style manager.

  • pszStyleName -- the name of the style to add.

  • pszStyleString -- the style string to use, or NULL to use the style stored in the manager.

Returns:

TRUE on success, FALSE on errors.

OGRStyleToolH OGR_ST_Create(OGRSTClassId eClassId)

OGRStyleTool factory.

This function is a constructor for OGRStyleTool derived classes.

Parameters:

eClassId -- subclass of style tool to create. One of OGRSTCPen (1), OGRSTCBrush (2), OGRSTCSymbol (3) or OGRSTCLabel (4).

Returns:

a handle to the new style tool object or NULL if the creation failed.

void OGR_ST_Destroy(OGRStyleToolH hST)

Destroy Style Tool.

Parameters:

hST -- handle to the style tool to destroy.

OGRSTClassId OGR_ST_GetType(OGRStyleToolH hST)

Determine type of Style Tool.

Parameters:

hST -- handle to the style tool.

Returns:

the style tool type, one of OGRSTCPen (1), OGRSTCBrush (2), OGRSTCSymbol (3) or OGRSTCLabel (4). Returns OGRSTCNone (0) if the OGRStyleToolH is invalid.

OGRSTUnitId OGR_ST_GetUnit(OGRStyleToolH hST)

Get Style Tool units.

Parameters:

hST -- handle to the style tool.

Returns:

the style tool units.

void OGR_ST_SetUnit(OGRStyleToolH hST, OGRSTUnitId eUnit, double dfGroundPaperScale)

Set Style Tool units.

This function is the same as OGRStyleTool::SetUnit()

Parameters:

  • hST -- handle to the style tool.

  • eUnit -- the new unit.

  • dfGroundPaperScale -- ground to paper scale factor.

const char *OGR_ST_GetParamStr(OGRStyleToolH hST, int eParam, int *bValueIsNull)

Get Style Tool parameter value as string.

Maps to the OGRStyleTool subclasses' GetParamStr() methods.

Parameters:

  • hST -- handle to the style tool.

  • eParam -- the parameter id from the enumeration corresponding to the type of this style tool (one of the OGRSTPenParam, OGRSTBrushParam, OGRSTSymbolParam or OGRSTLabelParam enumerations)

  • bValueIsNull -- pointer to an integer that will be set to TRUE or FALSE to indicate whether the parameter value is NULL.

Returns:

the parameter value as string and sets bValueIsNull.

int OGR_ST_GetParamNum(OGRStyleToolH hST, int eParam, int *bValueIsNull)

Get Style Tool parameter value as an integer.

Maps to the OGRStyleTool subclasses' GetParamNum() methods.

Parameters:

  • hST -- handle to the style tool.

  • eParam -- the parameter id from the enumeration corresponding to the type of this style tool (one of the OGRSTPenParam, OGRSTBrushParam, OGRSTSymbolParam or OGRSTLabelParam enumerations)

  • bValueIsNull -- pointer to an integer that will be set to TRUE or FALSE to indicate whether the parameter value is NULL.

Returns:

the parameter value as integer and sets bValueIsNull.

double OGR_ST_GetParamDbl(OGRStyleToolH hST, int eParam, int *bValueIsNull)

Get Style Tool parameter value as a double.

Maps to the OGRStyleTool subclasses' GetParamDbl() methods.

Parameters:

  • hST -- handle to the style tool.

  • eParam -- the parameter id from the enumeration corresponding to the type of this style tool (one of the OGRSTPenParam, OGRSTBrushParam, OGRSTSymbolParam or OGRSTLabelParam enumerations)

  • bValueIsNull -- pointer to an integer that will be set to TRUE or FALSE to indicate whether the parameter value is NULL.

Returns:

the parameter value as double and sets bValueIsNull.

void OGR_ST_SetParamStr(OGRStyleToolH hST, int eParam, const char *pszValue)

Set Style Tool parameter value from a string.

Maps to the OGRStyleTool subclasses' SetParamStr() methods.

Parameters:

  • hST -- handle to the style tool.

  • eParam -- the parameter id from the enumeration corresponding to the type of this style tool (one of the OGRSTPenParam, OGRSTBrushParam, OGRSTSymbolParam or OGRSTLabelParam enumerations)

  • pszValue -- the new parameter value

void OGR_ST_SetParamNum(OGRStyleToolH hST, int eParam, int nValue)

Set Style Tool parameter value from an integer.

Maps to the OGRStyleTool subclasses' SetParamNum() methods.

Parameters:

  • hST -- handle to the style tool.

  • eParam -- the parameter id from the enumeration corresponding to the type of this style tool (one of the OGRSTPenParam, OGRSTBrushParam, OGRSTSymbolParam or OGRSTLabelParam enumerations)

  • nValue -- the new parameter value

void OGR_ST_SetParamDbl(OGRStyleToolH hST, int eParam, double dfValue)

Set Style Tool parameter value from a double.

Maps to the OGRStyleTool subclasses' SetParamDbl() methods.

Parameters:

  • hST -- handle to the style tool.

  • eParam -- the parameter id from the enumeration corresponding to the type of this style tool (one of the OGRSTPenParam, OGRSTBrushParam, OGRSTSymbolParam or OGRSTLabelParam enumerations)

  • dfValue -- the new parameter value

const char *OGR_ST_GetStyleString(OGRStyleToolH hST)

Get the style string for this Style Tool.

Maps to the OGRStyleTool subclasses' GetStyleString() methods.

Parameters:

hST -- handle to the style tool.

Returns:

the style string for this style tool or "" if the hST is invalid.

int OGR_ST_GetRGBFromString(OGRStyleToolH hST, const char *pszColor, int *pnRed, int *pnGreen, int *pnBlue, int *pnAlpha)

Return the r,g,b,a components of a color encoded in #RRGGBB[AA] format.

Maps to OGRStyleTool::GetRGBFromString().

Parameters:

  • hST -- handle to the style tool.

  • pszColor -- the color to parse

  • pnRed -- pointer to an int in which the red value will be returned

  • pnGreen -- pointer to an int in which the green value will be returned

  • pnBlue -- pointer to an int in which the blue value will be returned

  • pnAlpha -- pointer to an int in which the (optional) alpha value will be returned

Returns:

TRUE if the color could be successfully parsed, or FALSE in case of errors.

OGRStyleTableH OGR_STBL_Create(void)

OGRStyleTable factory.

This function is the same as the C++ method OGRStyleTable::OGRStyleTable().

Returns:

a handle to the new style table object.

void OGR_STBL_Destroy(OGRStyleTableH hSTBL)

Destroy Style Table.

Parameters:

hSTBL -- handle to the style table to destroy.

int OGR_STBL_AddStyle(OGRStyleTableH hStyleTable, const char *pszName, const char *pszStyleString)

Add a new style in the table.

No comparison will be done on the Style string, only on the name. This function is the same as the C++ method OGRStyleTable::AddStyle().

Parameters:

  • hStyleTable -- handle to the style table.

  • pszName -- the name the style to add.

  • pszStyleString -- the style string to add.

Returns:

TRUE on success, FALSE on error

int OGR_STBL_SaveStyleTable(OGRStyleTableH hStyleTable, const char *pszFilename)

Save a style table to a file.

This function is the same as the C++ method OGRStyleTable::SaveStyleTable().

Parameters:

  • hStyleTable -- handle to the style table.

  • pszFilename -- the name of the file to save to.

Returns:

TRUE on success, FALSE on error

int OGR_STBL_LoadStyleTable(OGRStyleTableH hStyleTable, const char *pszFilename)

Load a style table from a file.

This function is the same as the C++ method OGRStyleTable::LoadStyleTable().

Parameters:

  • hStyleTable -- handle to the style table.

  • pszFilename -- the name of the file to load from.

Returns:

TRUE on success, FALSE on error

const char *OGR_STBL_Find(OGRStyleTableH hStyleTable, const char *pszName)

Get a style string by name.

This function is the same as the C++ method OGRStyleTable::Find().

Parameters:

  • hStyleTable -- handle to the style table.

  • pszName -- the name of the style string to find.

Returns:

the style string matching the name or NULL if not found or error.

void OGR_STBL_ResetStyleStringReading(OGRStyleTableH hStyleTable)

Reset the next style pointer to 0.

This function is the same as the C++ method OGRStyleTable::ResetStyleStringReading().

Parameters:

hStyleTable -- handle to the style table.

const char *OGR_STBL_GetNextStyle(OGRStyleTableH hStyleTable)

Get the next style string from the table.

This function is the same as the C++ method OGRStyleTable::GetNextStyle().

Parameters:

hStyleTable -- handle to the style table.

Returns:

the next style string or NULL on error.

const char *OGR_STBL_GetLastStyleName(OGRStyleTableH hStyleTable)

Get the style name of the last style string fetched with OGR_STBL_GetNextStyle.

This function is the same as the C++ method OGRStyleTable::GetStyleName().

Parameters:

hStyleTable -- handle to the style table.

Returns:

the Name of the last style string or NULL on error.

struct OGRGeometryTypeCounter
#include <ogr_api.h>

Result item of OGR_L_GetGeometryTypes.

Public Members

OGRwkbGeometryType eGeomType

Geometry type.

int64_t nCount

Number of geometries of type eGeomType.