ogr_api.h: Vector C API

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_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 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 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

OGRErr OGR_G_CreateFromWkb(const void *pabyData, OGRSpatialReferenceH hSRS, OGRGeometryH *phGeometry, int nBytes)

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.

Return

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

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.

OGRErr OGR_G_CreateFromWkt(char **ppszData, OGRSpatialReferenceH hSRS, OGRGeometryH *phGeometry)

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.

Return

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

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.

OGRErr OGR_G_CreateFromFgf(const void *pabyData, OGRSpatialReferenceH hSRS, OGRGeometryH *phGeometry, int nBytes, int *pnBytesConsumed)

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

See OGRGeometryFactory::createFromFgf()

void OGR_G_DestroyGeometry(OGRGeometryH hGeom)

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 eGeometryType)

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.

Return

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

Parameters
  • eGeometryType: the type code of the geometry to be created.

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

CPLSetConfigOption()

Return

OGRLineString geometry representing an approximation of the arc.

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.

OGRGeometryH OGR_G_ForceToPolygon(OGRGeometryH hGeom)

Convert to polygon.

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

Return

the converted geometry (ownership to caller).

Since

GDAL/OGR 1.8.0

Parameters
  • hGeom: handle to the geometry to convert (ownership surrendered).

OGRGeometryH OGR_G_ForceToLineString(OGRGeometryH hGeom)

Convert to line string.

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

Return

the converted geometry (ownership to caller).

Since

GDAL/OGR 1.10.0

Parameters
  • hGeom: handle to the geometry to convert (ownership surrendered).

OGRGeometryH OGR_G_ForceToMultiPolygon(OGRGeometryH hGeom)

Convert to multipolygon.

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

Return

the converted geometry (ownership to caller).

Since

GDAL/OGR 1.8.0

Parameters
  • hGeom: handle to the geometry to convert (ownership surrendered).

OGRGeometryH OGR_G_ForceToMultiPoint(OGRGeometryH hGeom)

Convert to multipoint.

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

Return

the converted geometry (ownership to caller).

Since

GDAL/OGR 1.8.0

Parameters
  • hGeom: handle to the geometry to convert (ownership surrendered).

OGRGeometryH OGR_G_ForceToMultiLineString(OGRGeometryH hGeom)

Convert to multilinestring.

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

Return

the converted geometry (ownership to caller).

Since

GDAL/OGR 1.8.0

Parameters
  • hGeom: handle to the geometry to convert (ownership surrendered).

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().

Return

new geometry.

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.

int OGR_G_GetDimension(OGRGeometryH hGeom)

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().

Return

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

Parameters
  • hGeom: handle on the geometry to get the dimension from.

int OGR_G_GetCoordinateDimension(OGRGeometryH hGeom)

Get the dimension of the coordinates in this geometry.

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

Parameters
  • hGeom: handle on the geometry to get the dimension of the coordinates from.

Return

this will return 2 or 3.

int OGR_G_CoordinateDimension(OGRGeometryH hGeom)

Get the dimension of the coordinates in this geometry.

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

Return

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

Since

GDAL 2.1

Parameters
  • hGeom: handle on the geometry to get the dimension of the coordinates from.

void OGR_G_SetCoordinateDimension(OGRGeometryH hGeom, int nNewDimension)

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.

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 hGeom)

See whether this geometry has Z coordinates.

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

Return

TRUE if the geometry has Z coordinates.

Since

GDAL 2.1

Parameters
  • hGeom: handle on the geometry to check whether it has Z coordinates.

int OGR_G_IsMeasured(OGRGeometryH hGeom)

See whether this geometry is measured.

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

Return

TRUE if the geometry has M coordinates.

Since

GDAL 2.1

Parameters
  • hGeom: handle on the geometry to check whether it is measured.

void OGR_G_Set3D(OGRGeometryH hGeom, int bIs3D)

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 hGeom, int bIsMeasured)

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 hGeom)

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().

Return

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

Parameters
  • hGeom: handle on the geometry to clone from.

void OGR_G_GetEnvelope(OGRGeometryH hGeom, OGREnvelope *psEnvelope)

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 hGeom, OGREnvelope3D *psEnvelope)

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 hGeom, const void *pabyData, int nSize)

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().

Return

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

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.

OGRErr OGR_G_ExportToWkb(OGRGeometryH hGeom, OGRwkbByteOrder eOrder, unsigned char *pabyDstBuffer)

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.

Return

Currently OGRERR_NONE is always returned.

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.

OGRErr OGR_G_ExportToIsoWkb(OGRGeometryH hGeom, OGRwkbByteOrder eOrder, unsigned char *pabyDstBuffer)

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.

Return

Currently OGRERR_NONE is always returned.

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.

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().

Return

size of binary representation in bytes.

Parameters
  • hGeom: handle on the geometry to get the binary size from.

OGRErr OGR_G_ImportFromWkt(OGRGeometryH hGeom, char **ppszSrcText)

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().

Return

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

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.

OGRErr OGR_G_ExportToWkt(OGRGeometryH hGeom, char **ppszSrcText)

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().

Return

Currently OGRERR_NONE is always returned.

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().

OGRErr OGR_G_ExportToIsoWkt(OGRGeometryH hGeom, char **ppszSrcText)

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).

Return

Currently OGRERR_NONE is always returned.

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().

OGRwkbGeometryType OGR_G_GetGeometryType(OGRGeometryH hGeom)

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().

Return

the geometry type code.

Parameters
  • hGeom: handle on the geometry to get type from.

const char *OGR_G_GetGeometryName(OGRGeometryH hGeom)

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().

Return

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

Parameters
  • hGeom: handle on the geometry to get name from.

void OGR_G_DumpReadable(OGRGeometryH hGeom, FILE *fp, const char *pszPrefix)

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 hGeom)

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 hGeom)

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 *pszGML)

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.

(OGR >= 1.8.0) 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 stroked to linestring, by using a 4 degrees step, 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.

Return

a geometry on success, or NULL on error.

Parameters
  • pszGML: The GML fragment for the geometry.

char *OGR_G_ExportToGML(OGRGeometryH hGeometry)

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().

Return

A GML fragment or NULL in case of error.

Parameters
  • hGeometry: handle to the geometry.

char *OGR_G_ExportToGMLEx(OGRGeometryH hGeometry, 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

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().

Return

A GML fragment or NULL in case of error.

Since

OGR 1.8.0

Parameters
  • hGeometry: handle to the geometry.

  • papszOptions: NULL-terminated list of options.

OGRGeometryH OGR_G_CreateFromGMLTree(const CPLXMLNode *)

Create geometry from GML.

CPLXMLNode *OGR_G_ExportToGMLTree(OGRGeometryH hGeometry)

Convert a geometry into GML format.

CPLXMLNode *OGR_G_ExportEnvelopeToGMLTree(OGRGeometryH hGeometry)

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

char *OGR_G_ExportToKML(OGRGeometryH hGeometry, 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().

Return

A KML fragment or NULL in case of error.

Parameters
  • hGeometry: handle to the geometry.

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

char *OGR_G_ExportToJson(OGRGeometryH hGeometry)

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().

Return

A GeoJSON fragment or NULL in case of error.

Parameters
  • hGeometry: handle to the geometry.

char *OGR_G_ExportToJsonEx(OGRGeometryH hGeometry, 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.

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

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().

Return

A GeoJSON fragment or NULL in case of error.

Since

OGR 1.9.0

Parameters
  • hGeometry: handle to the geometry.

  • papszOptions: a null terminated list of options.

OGRGeometryH OGR_G_CreateGeometryFromJson(const char *)

Create a OGR geometry from a GeoJSON geometry object.

void OGR_G_AssignSpatialReference(OGRGeometryH hGeom, OGRSpatialReferenceH hSRS)

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 hGeom)

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().

Return

a reference to the spatial reference geometry.

Parameters
  • hGeom: handle on the geometry to get spatial reference from.

OGRErr OGR_G_Transform(OGRGeometryH hGeom, OGRCoordinateTransformationH hTransform)

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

Return

OGRERR_NONE on success or an error code.

Parameters
  • hGeom: handle on the geometry to apply the transform to.

  • hTransform: handle on the transformation to apply.

OGRErr OGR_G_TransformTo(OGRGeometryH hGeom, OGRSpatialReferenceH hSRS)

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.

Return

OGRERR_NONE on success, or an error code.

Parameters
  • hGeom: handle on the geometry to apply the transform to.

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

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.

Return

the simplified geometry or NULL if an error occurs.

Since

OGR 1.8.0

Parameters
  • hThis: the geometry.

  • dTolerance: the distance tolerance for the simplification.

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.

Return

the simplified geometry or NULL if an error occurs.

Since

OGR 1.9.0

Parameters
  • hThis: the geometry.

  • dTolerance: the distance tolerance for the simplification.

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.

Return

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

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.

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 hGeom, OGRGeometryH hOtherGeom)

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.

Return

TRUE if the geometries intersect, otherwise FALSE.

Parameters
  • hGeom: handle on the first geometry.

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

int OGR_G_Equals(OGRGeometryH hGeom, OGRGeometryH hOther)

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.

Return

TRUE if equivalent or FALSE otherwise.

Parameters
  • hGeom: handle on the first geometry.

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

int OGR_G_Disjoint(OGRGeometryH hThis, OGRGeometryH hOther)

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.

Return

TRUE if they are disjoint, otherwise FALSE.

Parameters
  • hThis: the geometry to compare.

  • hOther: the other geometry to compare.

int OGR_G_Touches(OGRGeometryH hThis, OGRGeometryH hOther)

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.

Return

TRUE if they are touching, otherwise FALSE.

Parameters
  • hThis: the geometry to compare.

  • hOther: the other geometry to compare.

int OGR_G_Crosses(OGRGeometryH hThis, OGRGeometryH hOther)

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.

Return

TRUE if they are crossing, otherwise FALSE.

Parameters
  • hThis: the geometry to compare.

  • hOther: the other geometry to compare.

int OGR_G_Within(OGRGeometryH hThis, OGRGeometryH hOther)

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.

Return

TRUE if hThis is within hOther, otherwise FALSE.

Parameters
  • hThis: the geometry to compare.

  • hOther: the other geometry to compare.

int OGR_G_Contains(OGRGeometryH hThis, OGRGeometryH hOther)

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.

Return

TRUE if hThis contains hOther geometry, otherwise FALSE.

Parameters
  • hThis: the geometry to compare.

  • hOther: the other geometry to compare.

int OGR_G_Overlaps(OGRGeometryH hThis, OGRGeometryH hOther)

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.

Return

TRUE if they are overlapping, otherwise FALSE.

Parameters
  • hThis: the geometry to compare.

  • hOther: the other geometry to compare.

OGRGeometryH OGR_G_Boundary(OGRGeometryH hTarget)

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.

Return

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

Since

OGR 1.8.0

Parameters
  • hTarget: The Geometry to calculate the boundary of.

OGRGeometryH OGR_G_ConvexHull(OGRGeometryH hTarget)

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.

Return

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

Parameters
  • hTarget: The Geometry to calculate the convex hull of.

OGRGeometryH OGR_G_Buffer(OGRGeometryH hTarget, double dfDist, int nQuadSegs)

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.

Return

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

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.

OGRGeometryH OGR_G_Intersection(OGRGeometryH hThis, OGRGeometryH hOther)

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.

Return

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

Parameters
  • hThis: the geometry.

  • hOther: the other geometry.

OGRGeometryH OGR_G_Union(OGRGeometryH hThis, OGRGeometryH hOther)

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.

Return

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

Parameters
  • hThis: the geometry.

  • hOther: the other geometry.

OGRGeometryH OGR_G_UnionCascaded(OGRGeometryH hThis)

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.

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.

Return

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

Parameters
  • hThis: the geometry.

OGRGeometryH OGR_G_PointOnSurface(OGRGeometryH hGeom)

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.

Return

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

Since

OGR 1.10

Parameters
  • hGeom: the geometry to operate on.

OGRGeometryH OGR_G_Difference(OGRGeometryH hThis, OGRGeometryH hOther)

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.

Return

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

Parameters
  • hThis: the geometry.

  • hOther: the other geometry.

OGRGeometryH OGR_G_SymDifference(OGRGeometryH hThis, OGRGeometryH hOther)

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.

Return

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

Since

OGR 1.8.0

Parameters
  • hThis: the geometry.

  • hOther: the other geometry.

double OGR_G_Distance(OGRGeometryH hFirst, OGRGeometryH hOther)

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.

Return

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

Parameters
  • hFirst: the first geometry to compare against.

  • hOther: the other geometry to compare against.

double OGR_G_Distance3D(OGRGeometryH hFirst, OGRGeometryH hOther)

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().

Return

distance between the two geometries

Since

GDAL 2.2

Return

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

Parameters
  • hFirst: the first geometry to compare against.

  • hOther: the other geometry to compare against.

double OGR_G_Length(OGRGeometryH hGeom)

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.

Return

the length or 0.0 for unsupported geometry types.

Since

OGR 1.8.0

Parameters
  • hGeom: the geometry to operate on.

double OGR_G_Area(OGRGeometryH hGeom)

Compute geometry area.

Computes the area for an OGRLinearRing, OGRPolygon or OGRMultiPolygon. Undefined for all other geometry types (returns zero).

This function utilizes the C++ get_Area() methods such as OGRPolygon::get_Area().

Return

the area or 0.0 for unsupported geometry types.

Since

OGR 1.8.0

Parameters
  • hGeom: the geometry to operate on.

int OGR_G_Centroid(OGRGeometryH hGeom, OGRGeometryH hCentroidPoint)

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.

Return

OGRERR_NONE on success or OGRERR_FAILURE on error.

OGRGeometryH OGR_G_Value(OGRGeometryH hGeom, 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().

Return

a point or NULL.

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.

void OGR_G_Empty(OGRGeometryH hGeom)

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 hGeom)

Test if the geometry is empty.

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

Return

TRUE if the geometry has no points, otherwise FALSE.

Parameters
  • hGeom: The Geometry to test.

int OGR_G_IsValid(OGRGeometryH hGeom)

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.

Return

TRUE if the geometry has no points, otherwise FALSE.

Parameters
  • hGeom: The Geometry to test.

OGRGeometryH OGR_G_MakeValid(OGRGeometryH hGeom)

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

Return

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

Since

GDAL 3.0

Parameters
  • hGeom: The Geometry to make valid.

int OGR_G_IsSimple(OGRGeometryH hGeom)

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.

Return

TRUE if object is simple, otherwise FALSE.

Parameters
  • hGeom: The Geometry to test.

int OGR_G_IsRing(OGRGeometryH hGeom)

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.

Return

TRUE if the geometry has no points, otherwise FALSE.

Parameters
  • hGeom: The Geometry to test.

OGRGeometryH OGR_G_Polygonize(OGRGeometryH hTarget)

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.

Return

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

Since

OGR 1.9.0

Parameters
  • hTarget: The Geometry to be polygonized.

int OGR_G_GetPointCount(OGRGeometryH hGeom)

Fetch number of points from a geometry.

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

Return

the number of points.

Parameters
  • hGeom: handle to the geometry from which to get 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.

Return

the number of points

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.

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.

Return

the number of points

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.

double OGR_G_GetX(OGRGeometryH hGeom, int i)

Fetch the x coordinate of a point from a geometry.

Return

the X coordinate of this point.

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

  • i: point to get the x coordinate.

double OGR_G_GetY(OGRGeometryH hGeom, int i)

Fetch the x coordinate of a point from a geometry.

Return

the Y coordinate of this point.

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

  • i: point to get the Y coordinate.

double OGR_G_GetZ(OGRGeometryH hGeom, int i)

Fetch the z coordinate of a point from a geometry.

Return

the Z coordinate of this point.

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

  • i: point to get the Z coordinate.

double OGR_G_GetM(OGRGeometryH hGeom, int i)

Fetch the m coordinate of a point from a geometry.

Return

the M coordinate of this point.

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

  • i: point to get the M coordinate.

void OGR_G_GetPoint(OGRGeometryH hGeom, int iPoint, double *pdfX, double *pdfY, double *pdfZ)

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 hGeom, int iPoint, double *pdfX, double *pdfY, double *pdfZ, double *pdfM)

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 hGeom, int iPoint, double dfX, double dfY, double dfZ)

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 hGeom, int iPoint, double dfX, double dfY)

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 hGeom, int iPoint, double dfX, double dfY, double dfM)

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 hGeom, int iPoint, double dfX, double dfY, double dfZ, double dfM)

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 hGeom, double dfX, double dfY, double dfZ)

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 hGeom, double dfX, double dfY)

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 hGeom, double dfX, double dfY, double dfM)

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 hGeom, double dfX, double dfY, double dfZ, double dfM)

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 hGeom)

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).

Return

the number of elements.

Parameters
  • hGeom: single geometry or geometry container from which to get the number of elements.

OGRGeometryH OGR_G_GetGeometryRef(OGRGeometryH hGeom, int iSubGeom)

Fetch geometry from a geometry container.

This function returns an 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.

Return

handle to the requested geometry.

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.

OGRErr OGR_G_AddGeometry(OGRGeometryH hGeom, OGRGeometryH hNewSubGeom)

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.

Return

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

Parameters
  • hGeom: existing geometry container.

  • hNewSubGeom: geometry to add to the container.

OGRErr OGR_G_AddGeometryDirectly(OGRGeometryH hGeom, OGRGeometryH hNewSubGeom)

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.

Return

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

Parameters
  • hGeom: existing geometry.

  • hNewSubGeom: geometry to add to the existing geometry.

OGRErr OGR_G_RemoveGeometry(OGRGeometryH hGeom, int iGeom, int bDelete)

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.

Return

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

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.

int OGR_G_HasCurveGeometry(OGRGeometryH hGeom, 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().

Return

TRUE if this geometry is or has curve geometry.

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.

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().

Return

a new geometry.

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.

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().

Return

a new geometry.

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.

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

Build a ring from a bunch of arcs.

Return

an handle to the new geometry, a polygon.

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.

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 behaviour 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).

Since

GDAL 2.0

See

OGRSetNonLinearGeometriesEnabledFlag()

OGRFieldDefnH OGR_Fld_Create(const char *pszName, OGRFieldType eType)

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().

Return

handle to the new field definition.

Parameters
  • pszName: the name of the new field definition.

  • eType: the type of the new field definition.

void OGR_Fld_Destroy(OGRFieldDefnH hDefn)

Destroy a field definition.

Parameters
  • hDefn: handle to the field definition to destroy.

void OGR_Fld_SetName(OGRFieldDefnH hDefn, const char *pszName)

Reset the name of this field.

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

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 hDefn)

Fetch name of this field.

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

Return

the name of the field definition.

Parameters
  • hDefn: handle to the field definition.

OGRFieldType OGR_Fld_GetType(OGRFieldDefnH hDefn)

Fetch type of this field.

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

Return

field type.

Parameters
  • hDefn: handle to the field definition to get type from.

void OGR_Fld_SetType(OGRFieldDefnH hDefn, OGRFieldType eType)

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().

Parameters
  • hDefn: handle to the field definition to set type to.

  • eType: the new field type.

OGRFieldSubType OGR_Fld_GetSubType(OGRFieldDefnH hDefn)

Fetch subtype of this field.

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

Return

field subtype.

Since

GDAL 2.0

Parameters
  • hDefn: handle to the field definition to get subtype from.

void OGR_Fld_SetSubType(OGRFieldDefnH hDefn, OGRFieldSubType eSubType)

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().

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 hDefn)

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.

Return

the justification.

Parameters
  • hDefn: handle to the field definition to get justification from.

void OGR_Fld_SetJustify(OGRFieldDefnH hDefn, OGRJustification eJustify)

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 hDefn)

Get the formatting width for this field.

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

Return

the width, zero means no specified width.

Parameters
  • hDefn: handle to the field definition to get width from.

void OGR_Fld_SetWidth(OGRFieldDefnH hDefn, int nNewWidth)

Set the formatting width for this field in characters.

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

Parameters
  • hDefn: handle to the field definition to set width to.

  • nNewWidth: the new width.

int OGR_Fld_GetPrecision(OGRFieldDefnH hDefn)

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().

Return

the precision.

Parameters
  • hDefn: handle to the field definition to get precision from.

void OGR_Fld_SetPrecision(OGRFieldDefnH hDefn, int nPrecision)

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().

Parameters
  • hDefn: handle to the field definition to set precision to.

  • nPrecision: the new precision.

void OGR_Fld_Set(OGRFieldDefnH hDefn, const char *pszNameIn, OGRFieldType eTypeIn, int nWidthIn, int nPrecisionIn, OGRJustification eJustifyIn)

Set defining parameters for a field in one call.

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

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().

Return

ignore state

Parameters
  • hDefn: handle to the field definition

void OGR_Fld_SetIgnored(OGRFieldDefnH hDefn, int ignore)

Set whether this field should be omitted when fetching features.

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

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().

Return

TRUE if the field is authorized to be null.

Since

GDAL 2.0

Parameters
  • hDefn: handle to the field definition

void OGR_Fld_SetNullable(OGRFieldDefnH hDefn, int bNullableIn)

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 advertize the GDAL_DCAP_NOTNULL_FIELDS driver metadata item.

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

Since

GDAL 2.0

Parameters
  • hDefn: handle to the field definition

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

const char *OGR_Fld_GetDefault(OGRFieldDefnH hDefn)

Get default field value.

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

Return

default field value or NULL.

Since

GDAL 2.0

Parameters
  • hDefn: handle to the field definition.

void OGR_Fld_SetDefault(OGRFieldDefnH hDefn, const char *pszDefault)

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 advertize the GDAL_DCAP_DEFAULT_FIELDS driver metadata item.

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

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().

Return

TRUE if the default value is driver specific.

Since

GDAL 2.0

Parameters
  • hDefn: handle to the field definition

const char *OGR_GetFieldTypeName(OGRFieldType eType)

Fetch human readable name for a field type.

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

Return

the name.

Parameters
  • eType: the field type to get name for.

const char *OGR_GetFieldSubTypeName(OGRFieldSubType eSubType)

Fetch human readable name for a field subtype.

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

Return

the name.

Since

GDAL 2.0

Parameters
  • eSubType: the field subtype to get name for.

int OGR_AreTypeSubTypeCompatible(OGRFieldType eType, OGRFieldSubType eSubType)

Return if type and subtype are compatible.

Return

TRUE if type and subtype are compatible

Since

GDAL 2.0

Parameters
  • eType: the field type.

  • eSubType: the field subtype.

OGRGeomFieldDefnH OGR_GFld_Create(const char *pszName, OGRwkbGeometryType eType)

Create a new field geometry definition.

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

Return

handle to the new field definition.

Since

GDAL 1.11

Parameters
  • pszName: the name of the new field definition.

  • eType: the type of the new field definition.

void OGR_GFld_Destroy(OGRGeomFieldDefnH hDefn)

Destroy a geometry field definition.

Since

GDAL 1.11

Parameters
  • hDefn: handle to the geometry field definition to destroy.

void OGR_GFld_SetName(OGRGeomFieldDefnH hDefn, const char *pszName)

Reset the name of this field.

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

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 hDefn)

Fetch name of this field.

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

Return

the name of the geometry field definition.

Since

GDAL 1.11

Parameters
  • hDefn: handle to the geometry field definition.

OGRwkbGeometryType OGR_GFld_GetType(OGRGeomFieldDefnH hDefn)

Fetch geometry type of this field.

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

Return

field geometry type.

Since

GDAL 1.11

Parameters
  • hDefn: handle to the geometry field definition to get type from.

void OGR_GFld_SetType(OGRGeomFieldDefnH hDefn, OGRwkbGeometryType eType)

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().

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 hDefn)

Fetch spatial reference system of this field.

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

Return

field spatial reference system.

Since

GDAL 1.11

Parameters
  • hDefn: handle to the geometry field definition

void OGR_GFld_SetSpatialRef(OGRGeomFieldDefnH hDefn, 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).

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().

Return

TRUE if the field is authorized to be null.

Since

GDAL 2.0

Parameters
  • hDefn: handle to the field definition

void OGR_GFld_SetNullable(OGRGeomFieldDefnH hDefn, int bNullableIn)

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 advertize 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().

Return

ignore state

Since

GDAL 1.11

Parameters
  • hDefn: handle to the geometry field definition

void OGR_GFld_SetIgnored(OGRGeomFieldDefnH hDefn, int ignore)

Set whether this field should be omitted when fetching features.

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

Since

GDAL 1.11

Parameters
  • hDefn: handle to the geometry field definition

  • ignore: ignore state

OGRFeatureDefnH OGR_FD_Create(const char *pszName)

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().

Return

handle to the newly created feature definition.

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

void OGR_FD_Destroy(OGRFeatureDefnH hDefn)

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 hDefn)

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 hDefn)

Get name of the OGRFeatureDefn passed as an argument.

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

Return

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

Parameters
  • hDefn: handle to the feature definition to get the name from.

int OGR_FD_GetFieldCount(OGRFeatureDefnH hDefn)

Fetch number of fields on the passed feature definition.

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

Return

count of fields.

Parameters
  • hDefn: handle to the feature definition to get the fields count from.

OGRFieldDefnH OGR_FD_GetFieldDefn(OGRFeatureDefnH hDefn, int iField)

Fetch field definition of the passed feature definition.

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

Return

an handle to an internal field definition object or NULL if invalid index. This object should not be modified or freed by the application.

Parameters
  • hDefn: handle to the feature definition to get the field definition from.

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

int OGR_FD_GetFieldIndex(OGRFeatureDefnH hDefn, const char *pszFieldName)

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.

Return

the field index, or -1 if no match found.

Parameters
  • hDefn: handle to the feature definition to get field index from.

  • pszFieldName: the field name to search for.

void OGR_FD_AddFieldDefn(OGRFeatureDefnH hDefn, OGRFieldDefnH hNewField)

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().

Return

OGRERR_NONE in case of success.

Since

OGR 1.9.0

Parameters
  • hDefn: handle to the feature definition.

  • iField: the index of the field definition.

OGRErr OGR_FD_ReorderFieldDefns(OGRFeatureDefnH hDefn, 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().

Return

OGRERR_NONE in case of success.

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].

OGRwkbGeometryType OGR_FD_GetGeomType(OGRFeatureDefnH hDefn)

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().

Return

the base type for all geometry related to this definition.

Parameters
  • hDefn: handle to the feature definition to get the geometry type from.

void OGR_FD_SetGeomType(OGRFeatureDefnH hDefn, OGRwkbGeometryType eType)

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 hDefn)

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().

Return

ignore state

Parameters
  • hDefn: handle to the feature definition on witch OGRFeature are based on.

void OGR_FD_SetGeometryIgnored(OGRFeatureDefnH hDefn, int bIgnore)

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 hDefn)

Determine whether the style can be omitted when fetching features.

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

Return

ignore state

Parameters
  • hDefn: handle to the feature definition on which OGRFeature are based on.

void OGR_FD_SetStyleIgnored(OGRFeatureDefnH hDefn, int bIgnore)

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 hDefn)

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().

Return

the updated reference count.

Parameters
  • hDefn: handle to the feature definition on witch OGRFeature are based on.

int OGR_FD_Dereference(OGRFeatureDefnH hDefn)

Decrements the reference count by one.

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

Return

the updated reference count.

Parameters
  • hDefn: handle to the feature definition on witch OGRFeature are based on.

int OGR_FD_GetReferenceCount(OGRFeatureDefnH hDefn)

Fetch current reference count.

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

Return

the current reference count.

Parameters
  • hDefn: handle to the feature definition on witch OGRFeature are based on.

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().

Return

count of geometry fields.

Since

GDAL 1.11

Parameters
  • hDefn: handle to the feature definition to get the fields count from.

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().

Return

an handle to an internal field definition object or NULL if invalid index. This object should not be modified or freed by the application.

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.

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.

Return

the geometry field index, or -1 if no match found.

Parameters
  • hDefn: handle to the feature definition to get field index from.

  • pszGeomFieldName: the geometry field name to search for.

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().

Return

OGRERR_NONE in case of success.

Since

GDAL 1.11

Parameters
  • hDefn: handle to the feature definition.

  • iGeomField: the index of the geometry field definition.

int OGR_FD_IsSame(OGRFeatureDefnH hFDefn, OGRFeatureDefnH hOtherFDefn)

Test if the feature definition is identical to the other one.

Return

TRUE 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.

OGRFeatureH OGR_F_Create(OGRFeatureDefnH hDefn)

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().

Return

an 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.

Parameters
  • hDefn: handle to the feature class (layer) definition to which the feature will adhere.

void OGR_F_Destroy(OGRFeatureH hFeat)

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 hFeat)

Fetch feature definition.

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

Return

an handle to the feature definition object on which feature depends.

Parameters
  • hFeat: handle to the feature to get the feature definition from.

OGRErr OGR_F_SetGeometryDirectly(OGRFeatureH hFeat, OGRGeometryH hGeom)

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.

Return

OGRERR_NONE if successful, or OGR_UNSUPPORTED_GEOMETRY_TYPE if the geometry type is illegal for the OGRFeatureDefn (checking not yet implemented).

Parameters
  • hFeat: handle to the feature on which to apply the geometry.

  • hGeom: handle to the new geometry to apply to feature.

OGRErr OGR_F_SetGeometry(OGRFeatureH hFeat, OGRGeometryH hGeom)

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.

Return

OGRERR_NONE if successful, or OGR_UNSUPPORTED_GEOMETRY_TYPE if the geometry type is illegal for the OGRFeatureDefn (checking not yet implemented).

Parameters
  • hFeat: handle to the feature on which new geometry is applied to.

  • hGeom: handle to the new geometry to apply to feature.

OGRGeometryH OGR_F_GetGeometryRef(OGRFeatureH hFeat)

Fetch an 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())

Return

an handle to internal feature geometry. This object should not be modified.

Parameters
  • hFeat: handle to the feature to get geometry from.

OGRGeometryH OGR_F_StealGeometry(OGRFeatureH hFeat)

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.

Return

the pointer to the geometry.

OGRFeatureH OGR_F_Clone(OGRFeatureH hFeat)

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().

Return

an handle to the new feature, exactly matching this feature.

Parameters
  • hFeat: handle to the feature to clone.

int OGR_F_Equal(OGRFeatureH hFeat, OGRFeatureH hOtherFeat)

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().

Return

TRUE if they are equal, otherwise FALSE.

Parameters
  • hFeat: handle to one of the feature.

  • hOtherFeat: handle to the other feature to test this one against.

int OGR_F_GetFieldCount(OGRFeatureH hFeat)

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().

Return

count of fields.

Parameters
  • hFeat: handle to the feature to get the fields count from.

OGRFieldDefnH OGR_F_GetFieldDefnRef(OGRFeatureH hFeat, int i)

Fetch definition for this field.

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

Return

an handle to the field definition (from the OGRFeatureDefn). This is an internal reference, and should not be deleted or modified.

Parameters
  • hFeat: handle to the feature on which the field is found.

  • i: the field to fetch, from 0 to GetFieldCount()-1.

int OGR_F_GetFieldIndex(OGRFeatureH hFeat, const char *pszName)

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().

Return

the field index, or -1 if no matching field is found.

Parameters
  • hFeat: handle to the feature on which the field is found.

  • pszName: the name of the field to search for.

int OGR_F_IsFieldSet(OGRFeatureH hFeat, int iField)

Test if a field has ever been assigned a value or not.

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

Return

TRUE if the field has been set, otherwise false.

Parameters
  • hFeat: handle to the feature on which the field is.

  • iField: the field to test.

void OGR_F_UnsetField(OGRFeatureH hFeat, int iField)

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 hFeat, int iField)

Test if a field is null.

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

Return

TRUE if the field is null, otherwise false.

Since

GDAL 2.2

Parameters
  • hFeat: handle to the feature on which the field is.

  • iField: the field to test.

int OGR_F_IsFieldSetAndNotNull(OGRFeatureH hFeat, int iField)

Test if a field is set and not null.

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

Return

TRUE if the field is set and not null, otherwise false.

Since

GDAL 2.2

Parameters
  • hFeat: handle to the feature on which the field is.

  • iField: the field to test.

void OGR_F_SetFieldNull(OGRFeatureH hFeat, int iField)

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 hFeat, int iField)

Fetch an handle to the internal field value given the index.

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

Return

the returned handle is to an internal data structure, and should not be freed, or modified.

Parameters
  • hFeat: handle to the feature on which field is found.

  • iField: the field to fetch, from 0 to GetFieldCount()-1.

int OGR_RawField_IsUnset(const OGRField *puField)

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 *puField)

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 *puField)

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 *puField)

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 hFeat, int iField)

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().

Return

the field value.

Parameters
  • hFeat: handle to the feature that owned the field.

  • iField: the field to fetch, from 0 to GetFieldCount()-1.

GIntBig OGR_F_GetFieldAsInteger64(OGRFeatureH hFeat, int iField)

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().

Return

the field value.

Since

GDAL 2.0

Parameters
  • hFeat: handle to the feature that owned the field.

  • iField: the field to fetch, from 0 to GetFieldCount()-1.

double OGR_F_GetFieldAsDouble(OGRFeatureH hFeat, int iField)

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().

Return

the field value.

Parameters
  • hFeat: handle to the feature that owned the field.

  • iField: the field to fetch, from 0 to GetFieldCount()-1.

const char *OGR_F_GetFieldAsString(OGRFeatureH hFeat, int iField)

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().

Return

the field value. This string is internal, and should not be modified, or freed. Its lifetime may be very brief.

Parameters
  • hFeat: handle to the feature that owned the field.

  • iField: the field to fetch, from 0 to GetFieldCount()-1.

const int *OGR_F_GetFieldAsIntegerList(OGRFeatureH hFeat, int iField, int *pnCount)

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().

Return

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.

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.

const GIntBig *OGR_F_GetFieldAsInteger64List(OGRFeatureH hFeat, int iField, int *pnCount)

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().

Return

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.

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.

const double *OGR_F_GetFieldAsDoubleList(OGRFeatureH hFeat, int iField, int *pnCount)

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().

Return

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.

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.

char **OGR_F_GetFieldAsStringList(OGRFeatureH hFeat, int iField)

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().

Return

the field value. This list is internal, and should not be modified, or freed. Its lifetime may be very brief.

Parameters
  • hFeat: handle to the feature that owned the field.

  • iField: the field to fetch, from 0 to GetFieldCount()-1.

GByte *OGR_F_GetFieldAsBinary(OGRFeatureH hFeat, int iField, int *pnBytes)

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().

Return

the field value. This list is internal, and should not be modified, or freed. Its lifetime may be very brief.

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.

int OGR_F_GetFieldAsDateTime(OGRFeatureH hFeat, int iField, int *pnYear, int *pnMonth, int *pnDay, int *pnHour, int *pnMinute, int *pnSecond, 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().

Return

TRUE on success or FALSE on failure.

See

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)

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().

Return

TRUE on success or FALSE on failure.

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)

void OGR_F_SetFieldInteger(OGRFeatureH hFeat, int iField, int nValue)

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 hFeat, int iField, GIntBig nValue)

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().

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.

Since

GDAL 2.0

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 hFeat, int iField, double dfValue)

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 hFeat, int iField, const char *pszValue)

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 hFeat, int iField, int nCount, const int *panValues)

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 hFeat, int iField, int nCount, const GIntBig *panValues)

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().

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.

Since

GDAL 2.0

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 hFeat, int iField, int nCount, const double *padfValues)

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 hFeat, int iField, CSLConstList papszValues)

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 hFeat, int iField, OGRField *psValue)

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 hFeat, int iField, int nBytes, const void *pabyData)

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 hFeat, int iField, int nYear, int nMonth, int nDay, int nHour, int nMinute, int nSecond, int nTZFlag)

Set field to datetime.

This method currently only has an effect for OFTDate, OFTTime and OFTDateTime fields.

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.

See

Use OGR_F_SetFieldDateTimeEx() for second with millisecond accuracy.

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 hFeat, int iField, int nYear, int nMonth, int nDay, int nHour, int nMinute, float fSecond, int nTZFlag)

Set field to datetime.

This method currently only has an effect for OFTDate, OFTTime and OFTDateTime fields.

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.

Since

GDAL 2.0

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().

Return

count of geometry fields.

Since

GDAL 1.11

Parameters
  • hFeat: handle to the feature to get the geometry fields count from.

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().

Return

an handle to the field definition (from the OGRFeatureDefn). This is an internal reference, and should not be deleted or modified.

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.

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().

Return

the geometry field index, or -1 if no matching geometry field is found.

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.

OGRGeometryH OGR_F_GetGeomFieldRef(OGRFeatureH hFeat, int iField)

Fetch an handle to feature geometry.

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

Return

an handle to internal feature geometry. This object should not be modified.

Since

GDAL 1.11

Parameters
  • hFeat: handle to the feature to get geometry from.

  • iField: geometry field to get.

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.

Return

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).

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.

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().

Return

OGRERR_NONE if successful, or OGR_UNSUPPORTED_GEOMETRY_TYPE if the geometry type is illegal for the OGRFeatureDefn (checking not yet implemented).

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.

GIntBig OGR_F_GetFID(OGRFeatureH hFeat)

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)

Return

feature id or OGRNullFID if none has been assigned.

Parameters
  • hFeat: handle to the feature from which to get the feature identifier.

OGRErr OGR_F_SetFID(OGRFeatureH hFeat, GIntBig nFID)

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().

Return

On success OGRERR_NONE, or on failure some other value.

Parameters
  • hFeat: handle to the feature to set the feature id to.

  • nFID: the new feature identifier value to assign.

void OGR_F_DumpReadable(OGRFeatureH hFeat, FILE *fpOut)

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.

OGRErr OGR_F_SetFrom(OGRFeatureH hFeat, OGRFeatureH hOtherFeat, int bForgiving)

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().

Return

OGRERR_NONE if the operation succeeds, even if some values are not transferred, otherwise an error code.

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.

OGRErr OGR_F_SetFromWithMap(OGRFeatureH hFeat, OGRFeatureH hOtherFeat, int bForgiving, const int *panMap)

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().

Return

OGRERR_NONE if the operation succeeds, even if some values are not transferred, otherwise an error code.

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.

const char *OGR_F_GetStyleString(OGRFeatureH hFeat)

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().

Return

a reference to a representation in string format, or NULL if there isn’t one.

Parameters
  • hFeat: handle to the feature to get the style from.

void OGR_F_SetStyleString(OGRFeatureH hFeat, const char *pszStyle)

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 hFeat, char *pszStyle)

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 hFeat)

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().

Return

a string with the native data, or NULL if there is none.

Since

GDAL 2.1

See

https://trac.osgeo.org/gdal/wiki/rfc60_improved_roundtripping_in_ogr

Parameters
  • hFeat: handle to the feature.

void OGR_F_SetNativeData(OGRFeatureH hFeat, const char *pszNativeData)

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().

Since

GDAL 2.1

See

https://trac.osgeo.org/gdal/wiki/rfc60_improved_roundtripping_in_ogr

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 hFeat)

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().

Return

a string with the native media type, or NULL if there is none.

Since

GDAL 2.1

See

https://trac.osgeo.org/gdal/wiki/rfc60_improved_roundtripping_in_ogr

Parameters
  • hFeat: handle to the feature.

void OGR_F_SetNativeMediaType(OGRFeatureH hFeat, const char *pszNativeMediaType)

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().

Since

GDAL 2.1

See

https://trac.osgeo.org/gdal/wiki/rfc60_improved_roundtripping_in_ogr

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 hFeat, 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().

Return

TRUE if all enabled validation tests pass.

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

const char *OGR_L_GetName(OGRLayerH hLayer)

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().

Return

the layer name (must not been freed)

Since

OGR 1.8.0

Parameters
  • hLayer: handle to the layer.

OGRwkbGeometryType OGR_L_GetGeomType(OGRLayerH hLayer)

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().

Return

the geometry type

Since

OGR 1.8.0

Parameters
  • hLayer: handle to the layer.

OGRGeometryH OGR_L_GetSpatialFilter(OGRLayerH hLayer)

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().

Return

an handle to the spatial filter geometry.

Parameters
  • hLayer: handle to the layer to get the spatial filter from.

void OGR_L_SetSpatialFilter(OGRLayerH hLayer, 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 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 hLayer, 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 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 hLayer, 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 hLayer, 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 hLayer, const char *pszQuery)

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 a restricted form of SQL WHERE clause as defined “eq_format=restricted_where” about half way through this document:

http://ogdi.sourceforge.net/prop/6.2.CapabilitiesMetadata.html

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().

Return

OGRERR_NONE if successfully installed, or an error code if the query expression is in error, or some other failure occurs.

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.

void OGR_L_ResetReading(OGRLayerH hLayer)

Reset feature reading to start on the first feature.

This affects GetNextFeature().

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 hLayer)

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.

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().

Return

an handle to a feature, or NULL if no more features are available.

Parameters
  • hLayer: handle to the layer from which feature are read.

OGRErr OGR_L_SetNextByIndex(OGRLayerH hLayer, GIntBig nIndex)

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()

Return

OGRERR_NONE on success or an error code.

Parameters
  • hLayer: handle to the layer

  • nIndex: the index indicating how many steps into the result set to seek.

OGRFeatureH OGR_L_GetFeature(OGRLayerH hLayer, GIntBig nFeatureId)

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( ).

Return

an handle to a feature now owned by the caller, or NULL on failure.

Parameters
  • hLayer: handle to the layer that owned the feature.

  • nFeatureId: the feature id of the feature to read.

OGRErr OGR_L_SetFeature(OGRLayerH hLayer, OGRFeatureH hFeat)

Rewrite 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().

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

Return

OGRERR_NONE if the operation works, otherwise an appropriate error code (e.g OGRERR_NON_EXISTING_FEATURE if the feature does not exist).

Parameters
  • hLayer: handle to the layer to write the feature.

  • hFeat: the feature to write.

OGRErr OGR_L_CreateFeature(OGRLayerH hLayer, OGRFeatureH hFeat)

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().

Return

OGRERR_NONE on success.

Parameters
  • hLayer: handle to the layer to write the feature to.

  • hFeat: the handle of the feature to write to disk.

OGRErr OGR_L_DeleteFeature(OGRLayerH hLayer, GIntBig nFID)

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().

Return

OGRERR_NONE if the operation works, otherwise an appropriate error code (e.g OGRERR_NON_EXISTING_FEATURE if the feature does not exist).

Parameters
  • hLayer: handle to the layer

  • nFID: the feature id to be deleted from the layer

OGRFeatureDefnH OGR_L_GetLayerDefn(OGRLayerH hLayer)

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().

Return

an handle to the feature definition.

Parameters
  • hLayer: handle to the layer to get the schema information.

OGRSpatialReferenceH OGR_L_GetSpatialRef(OGRLayerH hLayer)

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().

Return

spatial reference, or NULL if there isn’t one.

Parameters
  • hLayer: handle to the layer to get the spatial reference from.

int OGR_L_FindFieldIndex(OGRLayerH hLayer, 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().

Return

field index, or -1 if the field doesn’t exist

GIntBig OGR_L_GetFeatureCount(OGRLayerH hLayer, int bForce)

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)

Return

feature count, -1 if count not known.

Parameters
  • hLayer: handle to the layer that owned the features.

  • bForce: Flag indicating whether the count should be computed even if it is expensive.

OGRErr OGR_L_GetExtent(OGRLayerH hLayer, OGREnvelope *psExtent, int bForce)

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().

Return

OGRERR_NONE on success, OGRERR_FAILURE if extent not known.

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.

OGRErr OGR_L_GetExtentEx(OGRLayerH hLayer, 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().

Return

OGRERR_NONE on success, OGRERR_FAILURE if extent not known.

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.

int OGR_L_TestCapability(OGRLayerH hLayer, const char *pszCap)

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 returned 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 returned 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.

  • 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().

Return

TRUE if the layer has the requested capability, or FALSE otherwise. OGRLayers will return FALSE for any unrecognized capabilities.

Parameters
  • hLayer: handle to the layer to get the capability from.

  • pszCap: the name of the capability to test.

OGRErr OGR_L_CreateField(OGRLayerH hLayer, OGRFieldDefnH hField, int bApproxOK)

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().

Return

OGRERR_NONE on success.

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.

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().

Return

OGRERR_NONE on success.

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.

OGRErr OGR_L_DeleteField(OGRLayerH hLayer, 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().

Return

OGRERR_NONE on success.

Since

OGR 1.9.0

Parameters
  • hLayer: handle to the layer.

  • iField: index of the field to delete.

OGRErr OGR_L_ReorderFields(OGRLayerH hLayer, 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().

Return

OGRERR_NONE on success.

Since

OGR 1.9.0

Parameters

OGRErr OGR_L_ReorderField(OGRLayerH hLayer, 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().

Return

OGRERR_NONE on success.

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].

OGRErr OGR_L_AlterFieldDefn(OGRLayerH hLayer, 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().

Return

OGRERR_NONE on success.

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.

OGRErr OGR_L_StartTransaction(OGRLayerH hLayer)

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().

Return

OGRERR_NONE on success.

Parameters
  • hLayer: handle to the layer

OGRErr OGR_L_CommitTransaction(OGRLayerH hLayer)

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().

Return

OGRERR_NONE on success.

Parameters
  • hLayer: handle to the layer

OGRErr OGR_L_RollbackTransaction(OGRLayerH hLayer)

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().

Return

OGRERR_NONE on success.

Parameters
  • hLayer: handle to the layer

OGRErr OGR_L_SyncToDisk(OGRLayerH hLayer)

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()

Return

OGRERR_NONE if no error occurs (even if nothing is done) or an error code.

Parameters
  • hLayer: handle to the layer

const char *OGR_L_GetFIDColumn(OGRLayerH hLayer)

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()

Return

fid column name.

Parameters
  • hLayer: handle to the layer

const char *OGR_L_GetGeometryColumn(OGRLayerH hLayer)

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()

Return

geometry column name.

Parameters
  • hLayer: handle to the layer

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 **papszFields)

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.

This method is the same as the C++ method OGRLayer::SetIgnoredFields()

Return

OGRERR_NONE if all field names have been resolved (even if the driver does not support this method)

Parameters
  • papszFields: an array of field names terminated by NULL item. If NULL is passed, the ignored list is cleared.

OGRErr OGR_L_Intersection(OGRLayerH pLayerInput, OGRLayerH pLayerMethod, OGRLayerH pLayerResult, char **papszOptions, GDALProgressFunc pfnProgress, void *pProgressArg)

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.

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.

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

Return

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

Note

The first geometry field is always used.

Since

OGR 1.10

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.

OGRErr OGR_L_Union(OGRLayerH pLayerInput, OGRLayerH pLayerMethod, OGRLayerH pLayerResult, char **papszOptions, GDALProgressFunc pfnProgress, void *pProgressArg)

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.

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.

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

Return

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

Note

The first geometry field is always used.

Since

OGR 1.10

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.

OGRErr OGR_L_SymDifference(OGRLayerH pLayerInput, OGRLayerH pLayerMethod, OGRLayerH pLayerResult, char **papszOptions, GDALProgressFunc pfnProgress, void *pProgressArg)

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.

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.

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

Return

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

Note

The first geometry field is always used.

Since

OGR 1.10

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.

OGRErr OGR_L_Identity(OGRLayerH pLayerInput, OGRLayerH pLayerMethod, OGRLayerH pLayerResult, char **papszOptions, GDALProgressFunc pfnProgress, void *pProgressArg)

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.

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.

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

Return

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

Note

The first geometry field is always used.

Since

OGR 1.10

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.

OGRErr OGR_L_Update(OGRLayerH pLayerInput, OGRLayerH pLayerMethod, OGRLayerH pLayerResult, char **papszOptions, GDALProgressFunc pfnProgress, void *pProgressArg)

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.

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.

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

Return

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

Note

The first geometry field is always used.

Since

OGR 1.10

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.

OGRErr OGR_L_Clip(OGRLayerH pLayerInput, OGRLayerH pLayerMethod, OGRLayerH pLayerResult, char **papszOptions, GDALProgressFunc pfnProgress, void *pProgressArg)

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.

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.

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

Return

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

Note

The first geometry field is always used.

Since

OGR 1.10

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.

OGRErr OGR_L_Erase(OGRLayerH pLayerInput, OGRLayerH pLayerMethod, OGRLayerH pLayerResult, char **papszOptions, GDALProgressFunc pfnProgress, void *pProgressArg)

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.

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.

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

Return

an error code if there was an error or the execution was interrupted, OGRERR_NONE otherwise.

Note

The first geometry field is always used.

Since

OGR 1.10

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.

void OGR_DS_Destroy(OGRDataSourceH hDataSource)

Closes opened datasource and releases allocated resources.

This method is the same as the C++ method OGRDataSource::DestroyDataSource().

Parameters
  • hDataSource: handle to allocated datasource object.

const char *OGR_DS_GetName(OGRDataSourceH hDS)

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.

Return

pointer to an internal name string which should not be modified or freed by the caller.

Parameters
  • hDS: handle to the data source to get the name from.

int OGR_DS_GetLayerCount(OGRDataSourceH hDS)

Get the number of layers in this data source.

Return

layer count.

Parameters
  • hDS: handle to the data source from which to get the number of layers.

OGRLayerH OGR_DS_GetLayer(OGRDataSourceH hDS, int iLayer)

Fetch a layer by index.

The returned layer remains owned by the OGRDataSource and should not be deleted by the application.

Return

an handle to the layer, or NULL if iLayer is out of range or an error occurs.

Parameters
  • hDS: handle to the data source from which to get the layer.

  • iLayer: a layer number between 0 and OGR_DS_GetLayerCount()-1.

OGRLayerH OGR_DS_GetLayerByName(OGRDataSourceH hDS, const char *pszLayerName)

Fetch a layer by name.

The returned layer remains owned by the OGRDataSource and should not be deleted by the application.

Return

an handle to the layer, or NULL if the layer is not found or an error occurs.

Parameters
  • hDS: handle to the data source from which to get the layer.

  • pszLayerName: Layer the layer name of the layer to fetch.

OGRErr OGR_DS_DeleteLayer(OGRDataSourceH hDS, int iLayer)

Delete the indicated layer from the datasource.

If this method is supported the ODsCDeleteLayer capability will test TRUE on the OGRDataSource.

Return

OGRERR_NONE on success, or OGRERR_UNSUPPORTED_OPERATION if deleting layers is not supported for this datasource.

Parameters
  • hDS: handle to the datasource

  • iLayer: the index of the layer to delete.

OGRSFDriverH OGR_DS_GetDriver(OGRDataSourceH hDS)

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*.

Return

NULL if driver info is not available, or pointer to a driver owned by the OGRSFDriverManager.

Parameters
  • hDS: handle to the datasource

OGRLayerH OGR_DS_CreateLayer(OGRDataSourceH hDS, const char *pszName, OGRSpatialReferenceH hSpatialRef, OGRwkbGeometryType eType, char **papszOptions)

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.

Example:

Return

NULL is returned on failure, or a new OGRLayer handle on success.

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

#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 )
        {
            ...
        }

OGRLayerH OGR_DS_CopyLayer(OGRDataSourceH hDS, OGRLayerH hSrcLayer, const char *pszNewName, char **papszOptions)

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.

Return

an handle to the layer, or NULL if an error occurs.

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.

int OGR_DS_TestCapability(OGRDataSourceH hDS, const char *pszCapability)

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.

Return

TRUE if capability available otherwise FALSE.

Parameters
  • hDS: handle to the data source against which to test the capability.

  • pszCapability: the capability to test.

OGRLayerH OGR_DS_ExecuteSQL(OGRDataSourceH hDS, const char *pszSQLCommand, OGRGeometryH hSpatialFilter, const char *pszDialect)

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.

Starting with OGR 1.10, the SQLITE dialect can also be used.

Return

an handle to a OGRLayer containing the results of the query. Deallocate with OGR_DS_ReleaseResultSet().

Parameters
  • hDS: handle to the data source on which the SQL query is executed.

  • pszSQLCommand: 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. Starting with OGR 1.10, the SQLITE dialect can also be used.

void OGR_DS_ReleaseResultSet(OGRDataSourceH hDS, OGRLayerH hLayer)

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.

Parameters
  • hDS: an 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 hDriver)

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().

Return

driver name. This is an internal string and should not be modified or freed.

Parameters
  • hDriver: handle to the driver to get the name from.

OGRDataSourceH OGR_Dr_Open(OGRSFDriverH hDriver, const char *pszName, int bUpdate)

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*.

Return

NULL on error or if the pass name is not supported by this driver, otherwise an handle to a GDALDataset. This GDALDataset should be closed by deleting the object when it is no longer needed.

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).

int OGR_Dr_TestCapability(OGRSFDriverH hDriver, const char *pszCap)

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.

Return

TRUE if capability available otherwise FALSE.

Parameters
  • hDriver: handle to the driver to test the capability against.

  • pszCap: the capability to test.

OGRDataSourceH OGR_Dr_CreateDataSource(OGRSFDriverH hDriver, const char *pszName, char **papszOptions)

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.

Return

NULL is returned on failure, or a new OGRDataSource handle on success.

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

OGRDataSourceH OGR_Dr_CopyDataSource(OGRSFDriverH hDriver, OGRDataSourceH hSrcDS, const char *pszNewName, char **papszOptions)

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.

Return

NULL is returned on failure, or a new OGRDataSource handle on success.

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

OGRErr OGR_Dr_DeleteDataSource(OGRSFDriverH hDriver, const char *pszDataSource)

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.

Return

OGRERR_NONE on success, and OGRERR_UNSUPPORTED_OPERATION if this is not supported by this driver.

Parameters
  • hDriver: handle to the driver on which data source deletion is based.

  • pszDataSource: the name of the datasource to delete.

OGRDataSourceH OGROpen(const char *pszName, int bUpdate, OGRSFDriverH *pahDriverList)

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*.

Example:

Return

NULL on error or if the pass name is not supported by this driver, otherwise an handle to a GDALDataset. This GDALDataset should be closed by deleting the object when it is no longer needed.

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.

OGRDataSourceH OGROpenShared(const char *pszName, int bUpdate, OGRSFDriverH *pahDriverList)

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*.

Example:

Return

NULL on error or if the pass name is not supported by this driver, otherwise an handle to a GDALDataset. This GDALDataset should be closed by deleting the object when it is no longer needed.

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.

OGRErr OGRReleaseDataSource(OGRDataSourceH hDS)

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.

Return

OGRERR_NONE on success or an error code.

Parameters
  • hDS: handle to the data source to release

int OGRGetDriverCount(void)

Fetch the number of registered drivers.

Return

the drivers count.

OGRSFDriverH OGRGetDriver(int iDriver)

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*.

Return

handle to the driver, or NULL if iDriver is out of range.

Parameters
  • iDriver: the driver index, from 0 to GetDriverCount()-1.

OGRSFDriverH OGRGetDriverByName(const char *pszName)

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*.

Return

the driver, or NULL if no driver with that name is found

Parameters
  • pszName: the driver name

int OGRRegisterAll(void)

Register all drivers.

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().

Return

an handle to the new style manager object.

Parameters
  • hStyleTable: pointer to OGRStyleTable or NULL if not working with a style table.

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().

Return

a reference to the style string read from the feature, or NULL in case of error.

Parameters
  • hSM: handle to the style manager.

  • hFeat: handle to the new feature from which to read the style.

int OGR_SM_InitStyleString(OGRStyleMgrH hSM, const char *pszStyleString)

Initialize style manager from the style string.

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

Return

TRUE on success, FALSE on errors.

Parameters
  • hSM: handle to the style manager.

  • pszStyleString: the style string to use (can be NULL).

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().

Return

the number of parts (style tools) in the style.

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.

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().

Return

OGRStyleToolH of the requested part (style tools) or NULL on error.

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.

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().

Return

TRUE on success, FALSE on errors.

Parameters
  • hSM: handle to the style manager.

  • hST: the style tool defining the part to add.

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().

Return

TRUE on success, FALSE on errors.

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.

OGRStyleToolH OGR_ST_Create(OGRSTClassId eClassId)

OGRStyleTool factory.

This function is a constructor for OGRStyleTool derived classes.

Return

an handle to the new style tool object or NULL if the creation failed.

Parameters
  • eClassId: subclass of style tool to create. One of OGRSTCPen (1), OGRSTCBrush (2), OGRSTCSymbol (3) or OGRSTCLabel (4).

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.

Return

the style tool type, one of OGRSTCPen (1), OGRSTCBrush (2), OGRSTCSymbol (3) or OGRSTCLabel (4). Returns OGRSTCNone (0) if the OGRStyleToolH is invalid.

Parameters
  • hST: handle to the style tool.

OGRSTUnitId OGR_ST_GetUnit(OGRStyleToolH hST)

Get Style Tool units.

Return

the style tool units.

Parameters
  • hST: handle to the style tool.

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.

Return

the parameter value as string and sets bValueIsNull.

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.

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.

Return

the parameter value as integer and sets bValueIsNull.

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.

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.

Return

the parameter value as double and sets bValueIsNull.

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.

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.

Return

the style string for this style tool or “” if the hST is invalid.

Parameters
  • hST: handle to the style tool.

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().

Return

TRUE if the color could be successfully parsed, or FALSE in case of errors.

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

OGRStyleTableH OGR_STBL_Create(void)

OGRStyleTable factory.

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

Return

an 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().

Return

TRUE on success, FALSE on error

Parameters
  • hStyleTable: handle to the style table.

  • pszName: the name the style to add.

  • pszStyleString: the style string to add.

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().

Return

TRUE on success, FALSE on error

Parameters
  • hStyleTable: handle to the style table.

  • pszFilename: the name of the file to save to.

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().

Return

TRUE on success, FALSE on error

Parameters
  • hStyleTable: handle to the style table.

  • pszFilename: the name of the file to load from.

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().

Return

the style string matching the name or NULL if not found or error.

Parameters
  • hStyleTable: handle to the style table.

  • pszName: the name of the style string to find.

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().

Return

the next style string or NULL on error.

Parameters
  • hStyleTable: handle to the style table.

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().

Return

the Name of the last style string or NULL on error.

Parameters
  • hStyleTable: handle to the style table.