GDALDriver C++ API

GDALDriver class

class GDALDriver : public GDALMajorObject

Format specific driver.

An instance of this class is created for each supported format, and manages information about the format.

This roughly corresponds to a file format, though some drivers may be gateways to many formats through a secondary multi-library.

Subclassed by OGRSFDriver

Public Functions

CPLErr SetMetadataItem(const char *pszName, const char *pszValue, const char *pszDomain = "")

Set single metadata item.

The C function GDALSetMetadataItem() does the same thing as this method.

Return

CE_None on success, or an error code on failure.

Parameters
  • pszName: the key for the metadata item to fetch.

  • pszValue: the value to assign to the key.

  • pszDomain: the domain to set within, use NULL for the default domain.

GDALDataset *Create(const char *pszName, int nXSize, int nYSize, int nBands, GDALDataType eType, char **papszOptions)

Create a new dataset with this driver.

What argument values are legal for particular drivers is driver specific, and there is no way to query in advance to establish legal values.

That function will try to validate the creation option list passed to the driver with the GDALValidateCreationOptions() method. This check can be disabled by defining the configuration option GDAL_VALIDATE_CREATION_OPTIONS=NO.

After you have finished working with the returned dataset, it is required to close it with GDALClose(). This does not only close the file handle, but also ensures that all the data and metadata has been written to the dataset (GDALFlushCache() is not sufficient for that purpose).

In some situations, the new dataset can be created in another process through the GDAL API Proxy mechanism.

In GDAL 2, the arguments nXSize, nYSize and nBands can be passed to 0 when creating a vector-only dataset for a compatible driver.

Equivalent of the C function GDALCreate().

Return

NULL on failure, or a new GDALDataset.

Parameters
  • pszFilename: the name of the dataset to create. UTF-8 encoded.

  • nXSize: width of created raster in pixels.

  • nYSize: height of created raster in pixels.

  • nBands: number of bands.

  • eType: type of raster.

  • papszOptions: list of driver specific control parameters. The APPEND_SUBDATASET=YES option can be specified to avoid prior destruction of existing dataset.

CPLErr Delete(const char *pszName)

Delete named dataset.

The driver will attempt to delete the named dataset in a driver specific fashion. Full featured drivers will delete all associated files, database objects, or whatever is appropriate. The default behaviour when no driver specific behaviour is provided is to attempt to delete all the files that are returned by GDALGetFileList() on the dataset handle.

It is unwise to have open dataset handles on this dataset when it is deleted.

Equivalent of the C function GDALDeleteDataset().

Return

CE_None on success, or CE_Failure if the operation fails.

Parameters
  • pszFilename: name of dataset to delete.

CPLErr Rename(const char *pszNewName, const char *pszOldName)

Rename a dataset.

Rename a dataset. This may including moving the dataset to a new directory or even a new filesystem.

It is unwise to have open dataset handles on this dataset when it is being renamed.

Equivalent of the C function GDALRenameDataset().

Return

CE_None on success, or CE_Failure if the operation fails.

Parameters
  • pszNewName: new name for the dataset.

  • pszOldName: old name for the dataset.

CPLErr CopyFiles(const char *pszNewName, const char *pszOldName)

Copy the files of a dataset.

Copy all the files associated with a dataset.

Equivalent of the C function GDALCopyDatasetFiles().

Return

CE_None on success, or CE_Failure if the operation fails.

Parameters
  • pszNewName: new name for the dataset.

  • pszOldName: old name for the dataset.

GDALDataset *CreateCopy(const char *pszFilename, GDALDataset *poSrcDS, int bStrict, char **papszOptions, GDALProgressFunc pfnProgress, void *pProgressData)

Create a copy of a dataset.

This method will attempt to create a copy of a raster dataset with the indicated filename, and in this drivers format. Band number, size, type, projection, geotransform and so forth are all to be copied from the provided template dataset.

Note that many sequential write once formats (such as JPEG and PNG) don’t implement the Create() method but do implement this CreateCopy() method. If the driver doesn’t implement CreateCopy(), but does implement Create() then the default CreateCopy() mechanism built on calling Create() will be used. So to test if CreateCopy() is available, you can test if GDAL_DCAP_CREATECOPY or GDAL_DCAP_CREATE is set in the GDAL metadata.

It is intended that CreateCopy() will often be used with a source dataset which is a virtual dataset allowing configuration of band types, and other information without actually duplicating raster data (see the VRT driver). This is what is done by the gdal_translate utility for example.

That function will try to validate the creation option list passed to the driver with the GDALValidateCreationOptions() method. This check can be disabled by defining the configuration option GDAL_VALIDATE_CREATION_OPTIONS=NO.

After you have finished working with the returned dataset, it is required to close it with GDALClose(). This does not only close the file handle, but also ensures that all the data and metadata has been written to the dataset (GDALFlushCache() is not sufficient for that purpose).

In some situations, the new dataset can be created in another process through the GDAL API Proxy mechanism.

Return

a pointer to the newly created dataset (may be read-only access).

Parameters
  • pszFilename: the name for the new dataset. UTF-8 encoded.

  • poSrcDS: the dataset being duplicated.

  • bStrict: TRUE if the copy must be strictly equivalent, or more normally FALSE indicating that the copy may adapt as needed for the output format.

  • papszOptions: additional format dependent options controlling creation of the output file. The APPEND_SUBDATASET=YES option can be specified to avoid prior destruction of existing dataset.

  • pfnProgress: a function to be used to report progress of the copy.

  • pProgressData: application data passed into progress function.

Public Static Functions

CPLErr QuietDelete(const char *pszName)

Delete dataset if found.

This is a helper method primarily used by Create() and CreateCopy() to predelete any dataset of the name soon to be created. It will attempt to delete the named dataset if one is found, otherwise it does nothing. An error is only returned if the dataset is found but the delete fails.

This is a static method and it doesn’t matter what driver instance it is invoked on. It will attempt to discover the correct driver using Identify().

Return

CE_None if the dataset does not exist, or is deleted without issues.

Parameters
  • pszName: the dataset name to try and delete.

static GDALDriverH ToHandle(GDALDriver *poDriver)

Convert a GDALDriver* to a GDALDriverH.

Since

GDAL 2.3

static GDALDriver *FromHandle(GDALDriverH hDriver)

Convert a GDALDriverH to a GDALDriver*.

Since

GDAL 2.3

GDALDriverManager class

class GDALDriverManager : public GDALMajorObject

Class for managing the registration of file format drivers.

Use GetGDALDriverManager() to fetch the global singleton instance of this class.

Public Functions

int GetDriverCount(void) const

Fetch the number of registered drivers.

This C analog to this is GDALGetDriverCount().

Return

the number of registered drivers.

GDALDriver *GetDriver(int iDriver)

Fetch driver by index.

This C analog to this is GDALGetDriver().

Return

the driver identified by the index or NULL if the index is invalid

Parameters

GDALDriver *GetDriverByName(const char *pszName)

Fetch a driver based on the short name.

The C analog is the GDALGetDriverByName() function.

Return

the identified driver, or NULL if no match is found.

Parameters
  • pszName: the short name, such as GTiff, being searched for.

int RegisterDriver(GDALDriver *poDriver)

Register a driver for use.

The C analog is GDALRegisterDriver().

Normally this method is used by format specific C callable registration entry points such as GDALRegister_GTiff() rather than being called directly by application level code.

If this driver (based on the object pointer, not short name) is already registered, then no change is made, and the index of the existing driver is returned. Otherwise the driver list is extended, and the new driver is added at the end.

Return

the index of the new installed driver.

Parameters
  • poDriver: the driver to register.

void DeregisterDriver(GDALDriver *poDriver)

Deregister the passed driver.

If the driver isn’t found no change is made.

The C analog is GDALDeregisterDriver().

Parameters
  • poDriver: the driver to deregister.

void AutoSkipDrivers()

This method unload undesirable drivers.

All drivers specified in the comma delimited list in the GDAL_SKIP environment variable) will be deregistered and destroyed. This method should normally be called after registration of standard drivers to allow the user a way of unloading undesired drivers. The GDALAllRegister() function already invokes AutoSkipDrivers() at the end, so if that functions is called, it should not be necessary to call this method from application code.

Note: space separator is also accepted for backward compatibility, but some vector formats have spaces in their names, so it is encouraged to use comma to avoid issues.

Public Static Functions

void AutoLoadDrivers()

Auto-load GDAL drivers from shared libraries.

This function will automatically load drivers from shared libraries. It searches the “driver path” for .so (or .dll) files that start with the prefix “gdal_X.so”. It then tries to load them and then tries to call a function within them called GDALRegister_X() where the ‘X’ is the same as the remainder of the shared library basename (‘X’ is case sensitive), or failing that to call GDALRegisterMe().

There are a few rules for the driver path. If the GDAL_DRIVER_PATH environment variable it set, it is taken to be a list of directories to search separated by colons on UNIX, or semi-colons on Windows. Otherwise the /usr/local/lib/gdalplugins directory, and (if known) the lib/gdalplugins subdirectory of the gdal home directory are searched on UNIX and \gdalplugins on Windows.

Auto loading can be completely disabled by setting the GDAL_DRIVER_PATH config option to “disable”.