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# GDALDataset Class Reference

A dataset encapsulating one or more raster bands. More...

`#include <gdal_priv.h>`

Inheritance diagram for GDALDataset:

List of all members.

## Public Methods
|  | virtual | ~GDALDataset ()
|  |  | Destroy an open GDALDataset. More...

|  | int | GetRasterXSize ( void )
|  |  | Fetch raster width in pixels. More...

|  | int | GetRasterYSize ( void )
|  |  | Fetch raster height in pixels. More...

|  | int | GetRasterCount ( void )
|  |  | Fetch the number of raster bands on this dataset. More...

|  | GDALRasterBand* | GetRasterBand ( int )
|  |  | Fetch a band object for a dataset. More...

|  | virtual void | FlushCache (void)
|  |  | Flush all write cached data to disk. More...

|  | virtual const char* | GetProjectionRef (void)
|  |  | Fetch the projection definition string for this dataset. More...

|  | virtual CPLErr | SetProjection ( const char * )
|  |  | Set the projection reference string for this dataset. More...

|  | virtual CPLErr | GetGeoTransform ( double * )
|  |  | Fetch the affine transformation coefficients. More...

|  | virtual CPLErr | SetGeoTransform ( double * )
|  |  | Set the affine transformation coefficients. More...

|  | virtual void* | GetInternalHandle ( const char * )
|  |  | Fetch a format specific internally meaningful handle. More...

|  | virtual GDALDriver* | GetDriver (void)
|  |  | Fetch the driver to which this dataset relates. More...

|  | virtual int | GetGCPCount ()
|  |  | Get number of GCPs. More...

|  | virtual const char* | GetGCPProjection ()
|  |  | Get output projection for GCPs. More...

|  | virtual const GDAL_GCP* | GetGCPs ()
|  |  | Fetch GCPs. More...

|  | int | Reference ()
|  |  | Add one to dataset reference count. More...

|  | int | Dereference ()
|  |  | Subtract one from dataset reference count. More...

|  | GDALAccess | GetAccess ()
|  | CPLErr | BuildOverviews ( const char *, int, int *, int, int *, GDALProgressFunc, void * )
|  |  | Build raster overview(s). More...

## Protected Methods
|  |  | GDALDataset (void)
|  | void | RasterInitialize ( int, int )
|  | void | SetBand ( int, GDALRasterBand * )
|  | virtual CPLErr | IBuildOverviews ( const char *, int, int *, int, int *, GDALProgressFunc, void * )
## Protected Attributes
|  | GDALDriver* | poDriver
|  | GDALAccess | eAccess
|  | int | nRasterXSize
|  | int | nRasterYSize
|  | int | nBands
|  | GDALRasterBand** | papoBands
|  | int | nRefCount
|  | GDALDefaultOverviews | oOvManager
## Friends
|  | GDALDatasetH | GDALOpen ( const char *, GDALAccess)
|  |  | Open a raster file as a GDALDataset. More...

|  | class | GDALRasterBand

## Detailed Description

A dataset encapsulating one or more raster bands.

Use GDALOpen to create a GDALDataset for a named file.

## Constructor & Destructor Documentation

GDALDataset::~GDALDataset ()`[virtual]`

Destroy an open GDALDataset.

This is the accepted method of closing a GDAL dataset and deallocating all resources associated with it.

Equivelent of the C callable GDALClose().

## Member Function Documentation

CPLErr GDALDataset::BuildOverviews (const char * pszResampling, int nOverviews, int * panOverviewList, int nBands, int * panBandList, GDALProgressFunc, void * pProgressData)

Build raster overview(s).

If the operation is unsupported for the indicated dataset, then CE_Failure is returned, and CPLGetLastError() will return CPLE_NonSupported.

Parameters:

  pszResampling | one of "NEAREST", "AVERAGE" or "MODE" controlling the downsampling method applied.
  nOverviews | number of overviews to build.
  panOverviewList | the list of overview decimation factors to build.
  nBand | number of bands to build overviews for in panBandList. Build for all bands if this is 0.
  panBandList | list of band numbers.
  pfnProgress | a function to call to report progress, or NULL.
  pProgressData | application data to pass to the progress function.

Returns:
  CE_None on success or CE_Failure if the operation doesn't work.

int GDALDataset::Dereference ()

Subtract one from dataset reference count.

The reference is one after instantiation. Generally when the reference count has dropped to zero the dataset may be safely deleted (closed).

This method is the same as the C GDALDereferenceDataset() function.

Returns:
  the post-decrement reference count.

void GDALDataset::FlushCache (void)`[virtual]`

Flush all write cached data to disk.

Any raster (or other GDAL) data written via GDAL calls, but buffered internally will be written to disk.

GDALDriver * GDALDataset::GetDriver (void)`[virtual]`

Fetch the driver to which this dataset relates.

This method is the same as the C GDALGetDatasetDriver() function.

Returns:
  the driver on which the dataset was created with GDALOpen or GDALCreate().

int GDALDataset::GetGCPCount ()`[virtual]`

Get number of GCPs.

This method is the same as the C function GDALGetGCPCount().

Returns:
  number of GCPs for this dataset. Zero if there are none.

const char * GDALDataset::GetGCPProjection ()`[virtual]`

Get output projection for GCPs.

This method is the same as the C function GDALGetGCPProjection().

The projection string follows the normal rules from GetProjectionRef().

Returns:
  internal projection string or "" if there are no GCPs.

const GDAL_GCP * GDALDataset::GetGCPs ()`[virtual]`

Fetch GCPs.

This method is the same as the C function GDALGetGCPs().

Returns:
  pointer to internal GCP structure list. It should not be modified, and may change on the next GDAL call.

CPLErr GDALDataset::GetGeoTransform (double * padfTransform)`[virtual]`

Fetch the affine transformation coefficients.

Fetches the coefficients for transforming between pixel/line (P,L) raster space, and projection coordinates (Xp,Yp) space.

Xp = padfTransform[0] + P*padfTransform[1] + L*padfTransform[2]; Yp = padfTransform[3] + P*padfTransform[4] + L*padfTransform[5];

In a north up image, padfTransform[1] is the pixel width, and padfTransform[5] is the pixel height. The upper left corner of the upper left pixel is at position (padfTransform[0],padfTransform[3]).

The default transform is (0,1,0,0,0,1) and should be returned even when a CE_Failure error is returned, such as for formats that don't support transformation to projection coordinates.

NOTE: GetGeoTransform() isn't expressive enough to handle the variety of OGC Grid Coverages pixel/line to projection transformation schemes. Eventually this method will be depreciated in favour of a more general scheme.

This method does the same thing as the C GDALGetGeoTransform() function.

Parameters:

  padfTransform | an existing six double buffer into which the transformation will be placed.

Returns:
  CE_None on success, or CE_Failure if no transform can be fetched.

void * GDALDataset::GetInternalHandle (const char *)`[virtual]`

Fetch a format specific internally meaningful handle.

This method is the same as the C GDALGetInternalHandle() method.

Parameters:

  pszHandleName | the handle name desired. The meaningful names will be specific to the file format.

Returns:
  the desired handle value, or NULL if not recognised/supported.

const char * GDALDataset::GetProjectionRef (void)`[virtual]`

Fetch the projection definition string for this dataset.

Same as the C function GDALGetProjectionRef().

The returned string defines the projection coordinate system of the image in either PROJ.4 format or OpenGIS WKT format. It should be suitable for use with the GDALProjDef object to reproject positions.

When a projection definition is not available an empty (but not NULL) string is returned.

Returns:
  a pointer to an internal projection reference string. It should not be altered, freed or expected to last for long.

GDALRasterBand * GDALDataset::GetRasterBand (int nBandId)

Fetch a band object for a dataset.

Equivelent of the C function GDALGetRasterBand().

Parameters:

  nBandId | the index number of the band to fetch, from 1 to GetRasterCount().

Returns:
  the height in pixels of raster bands in this GDALDataset.

int GDALDataset::GetRasterCount (void)

Fetch the number of raster bands on this dataset.

Same as the C function GDALGetRasterCount().

Returns:
  the number of raster bands.

int GDALDataset::GetRasterXSize (void)

Fetch raster width in pixels.

Equivelent of the C function GDALGetRasterXSize().

Returns:
  the width in pixels of raster bands in this GDALDataset.

int GDALDataset::GetRasterYSize (void)

Fetch raster height in pixels.

Equivelent of the C function GDALGetRasterYSize().

Returns:
  the height in pixels of raster bands in this GDALDataset.

int GDALDataset::Reference ()

Add one to dataset reference count.

The reference is one after instantiation.

This method is the same as the C GDALReferenceDataset() function.

Returns:
  the post-increment reference count.

CPLErr GDALDataset::SetGeoTransform (double *)`[virtual]`

Set the affine transformation coefficients.

See GetGeoTransform() for details on the meaning of the padfTransform coefficients.

This method does the same thing as the C GDALSetGeoTransform() function.

Parameters:

  padfTransform | a six double buffer containing the transformation coefficients to be written with the dataset.

Returns:
  CE_None on success, or CE_Failure if this transform cannot be written.

CPLErr GDALDataset::SetProjection (const char *)`[virtual]`

Set the projection reference string for this dataset.

The string should be in OGC WKT or PROJ.4 format. An error may occur because of incorrectly specified projection strings, because the dataset is not writable, or because the dataset does not support the indicated projection. Many formats do not support writing projections.

This method is the same as the C GDALSetProjection() function.

Parameters:

  pszProjection | projection reference string.

Returns:
  CE_Failure if an error occurs, otherwise CE_None.

## Friends And Related Function Documentation

GDALDatasetH GDALOpen (const char * pszFilename, GDALAccess eAccess)`[friend]`

Open a raster file as a GDALDataset.

Parameters:

  pszFilename | the name of the file to access. In the case of exotic drivers this may not refer to a physical file, but instead contain information for the driver on how to access a dataset.

Parameters:

  eAccess | the desired access, either GA_Update or GA_ReadOnly. Many drivers support only read only access.

Returns:
  A GDALDatasetH handle or NULL on failure. For C++ applications this handle can be cast to a GDALDataset *.

The documentation for this class was generated from the following files:

- gdal_priv.h
- gdaldataset.cpp