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VRTDataset Class Reference
Inheritance diagram for VRTDataset:

## Public Member Functions
| VRTDataset (int nXSize, int nYSize)
void | SetNeedsFlush ()
virtual void | FlushCache ()
| Flush all write cached data to disk. More...
void | SetWritable (int bWritableIn)
virtual CPLErr | CreateMaskBand (int nFlags)
| Adds a mask band to the dataset. More...
void | SetMaskBand (VRTRasterBand *poMaskBand)
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 CPLErr | SetMetadata (char **papszMD, const char *pszDomain="")
| Set metadata. More...
virtual CPLErr | SetMetadataItem (const char *pszName, const char *pszValue, const char *pszDomain="")
| Set single metadata item. More...
virtual char ** | GetMetadata (const char *pszDomain="")
| Fetch metadata. 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...
virtual CPLErr | SetGCPs (int nGCPCount, const GDAL_GCP *pasGCPList, const char *pszGCPProjection)
| Assign GCPs. More...
virtual CPLErr | AddBand (GDALDataType eType, char **papszOptions=NULL)
| Add a band to a dataset. More...
virtual char ** | GetFileList ()
| Fetch files forming dataset. More...
virtual CPLErr | IRasterIO (GDALRWFlag eRWFlag, int nXOff, int nYOff, int nXSize, int nYSize, void *pData, int nBufXSize, int nBufYSize, GDALDataType eBufType, int nBandCount, int *panBandMap, GSpacing nPixelSpace, GSpacing nLineSpace, GSpacing nBandSpace, GDALRasterIOExtraArg *psExtraArg)
virtual CPLXMLNode * | SerializeToXML (const char *pszVRTPath)
virtual CPLErr | XMLInit (CPLXMLNode *, const char *)
virtual CPLErr | IBuildOverviews (const char *, int, int *, int, int *, GDALProgressFunc, void *)
GDALDataset * | GetSingleSimpleSource ()
void | BuildVirtualOverviews ()
void | UnsetPreservedRelativeFilenames ()
Public Member Functions inherited from GDALDataset
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 * | 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 const char * | GetDriverName ()
virtual CPLErr | AdviseRead (int nXOff, int nYOff, int nXSize, int nYSize, int nBufXSize, int nBufYSize, GDALDataType eDT, int nBandCount, int *panBandList, char **papszOptions)
| Advise driver of upcoming read requests. More...
virtual GDALAsyncReader * | BeginAsyncReader (int nXOff, int nYOff, int nXSize, int nYSize, void *pBuf, int nBufXSize, int nBufYSize, GDALDataType eBufType, int nBandCount, int *panBandMap, int nPixelSpace, int nLineSpace, int nBandSpace, char **papszOptions)
| Sets up an asynchronous data request. More...
virtual void | EndAsyncReader (GDALAsyncReader *)
| End asynchronous request. More...
CPLErr | RasterIO (GDALRWFlag, int, int, int, int, void *, int, int, GDALDataType, int, int *, GSpacing, GSpacing, GSpacing, GDALRasterIOExtraArg *psExtraArg) CPL_WARN_UNUSED_RESULT
| Read/write a region of image data from multiple bands. More...
int | Reference ()
| Add one to dataset reference count. More...
int | Dereference ()
| Subtract one from dataset reference count. More...
GDALAccess | GetAccess () const
int | GetShared () const
| Returns shared flag. More...
void | MarkAsShared ()
| Mark this dataset as available for sharing.
void | MarkSuppressOnClose ()
char ** | GetOpenOptions ()
CPLErr | BuildOverviews (const char *, int, int *, int, int *, GDALProgressFunc, void *)
| Build raster overview(s) More...
void | ReportError (CPLErr eErrClass, CPLErrorNum err_no, const char *fmt,...) CPL_PRINT_FUNC_FORMAT(4
| Emits an error related to a dataset. More...
virtual char ** | GetMetadataDomainList ()
| Fetch list of metadata domains. More...
virtual int | GetLayerCount ()
| Get the number of layers in this dataset. More...
virtual OGRLayer * | GetLayer (int)
| Fetch a layer by index. More...
virtual OGRLayer * | GetLayerByName (const char *)
| Fetch a layer by name. More...
virtual OGRErr | DeleteLayer (int)
| Delete the indicated layer from the datasource. More...
virtual int | TestCapability (const char *)
| Test if capability is available. More...
virtual OGRLayer * | CreateLayer (const char *pszName, OGRSpatialReference *poSpatialRef=NULL, OGRwkbGeometryType eGType=wkbUnknown, char **papszOptions=NULL)
| This method attempts to create a new layer on the dataset with the indicated name, coordinate system, geometry type. More...
virtual OGRLayer * | CopyLayer (OGRLayer *poSrcLayer, const char *pszNewName, char **papszOptions=NULL)
| Duplicate an existing layer. More...
virtual OGRStyleTable * | GetStyleTable ()
| Returns dataset style table. More...
virtual void | SetStyleTableDirectly (OGRStyleTable *poStyleTable)
| Set dataset style table. More...
virtual void | SetStyleTable (OGRStyleTable *poStyleTable)
| Set dataset style table. More...
virtual OGRLayer * | ExecuteSQL (const char *pszStatement, OGRGeometry *poSpatialFilter, const char *pszDialect)
| Execute an SQL statement against the data store. More...
virtual void | ReleaseResultSet (OGRLayer *poResultsSet)
| Release results of ExecuteSQL(). More...
int | GetRefCount () const
| Fetch reference count. More...
int | GetSummaryRefCount () const
| Fetch reference count of datasource and all owned layers. More...
OGRErr | Release ()
| Drop a reference to this dataset, and if the reference count drops to one close (destroy) the dataset. More...
virtual OGRErr | StartTransaction (int bForce=FALSE)
| For datasources which support transactions, StartTransaction creates a `transaction. More...
virtual OGRErr | CommitTransaction ()
| For datasources which support transactions, CommitTransaction commits a transaction. More...
virtual OGRErr | RollbackTransaction ()
| For datasources which support transactions, RollbackTransaction will roll back a datasource to its state before the start of the current transaction. More...
GDALSQLParseInfo * | BuildParseInfo (swq_select *psSelectInfo, swq_select_parse_options *poSelectParseOptions)
void | DestroyParseInfo (GDALSQLParseInfo *psParseInfo)
OGRLayer * | ExecuteSQL (const char *pszStatement, OGRGeometry *poSpatialFilter, const char *pszDialect, swq_select_parse_options *poSelectParseOptions)
Public Member Functions inherited from GDALMajorObject
int | GetMOFlags () const
void | SetMOFlags (int nFlagsIn)
virtual const char * | GetDescription () const
| Fetch object description. More...
virtual void | SetDescription (const char *)
| Set object description. More...
virtual const char * | GetMetadataItem (const char *pszName, const char *pszDomain="")
| Fetch single metadata item. More...

## Static Public Member Functions
static int | Identify (GDALOpenInfo *)
static GDALDataset * | Open (GDALOpenInfo *)
static GDALDataset * | OpenXML (const char *, const char *=NULL, GDALAccess eAccess=GA_ReadOnly)
static GDALDataset * | Create (const char *pszName, int nXSize, int nYSize, int nBands, GDALDataType eType, char **papszOptions)
static CPLErr | Delete (const char *pszFilename)
Static Public Member Functions inherited from GDALDataset
static GDALDataset ** | GetOpenDatasets (int *pnDatasetCount)
| Fetch all open GDAL dataset handles. More...
static int | IsGenericSQLDialect (const char *pszDialect)

## Protected Member Functions
virtual int | CloseDependentDatasets ()
| Drop references to any other datasets referenced by this dataset. More...
Protected Member Functions inherited from GDALDataset
| GDALDataset (int bForceCachedIO)
void | RasterInitialize (int, int)
void | SetBand (int, GDALRasterBand *)
CPLErr | BlockBasedRasterIO (GDALRWFlag, int, int, int, int, void *, int, int, GDALDataType, int, int *, GSpacing, GSpacing, GSpacing, GDALRasterIOExtraArg *psExtraArg) CPL_WARN_UNUSED_RESULT
void | BlockBasedFlushCache ()
CPLErr | BandBasedRasterIO (GDALRWFlag eRWFlag, int nXOff, int nYOff, int nXSize, int nYSize, void *pData, int nBufXSize, int nBufYSize, GDALDataType eBufType, int nBandCount, int *panBandMap, GSpacing nPixelSpace, GSpacing nLineSpace, GSpacing nBandSpace, GDALRasterIOExtraArg *psExtraArg) CPL_WARN_UNUSED_RESULT
CPLErr | RasterIOResampled (GDALRWFlag eRWFlag, int nXOff, int nYOff, int nXSize, int nYSize, void *pData, int nBufXSize, int nBufYSize, GDALDataType eBufType, int nBandCount, int *panBandMap, GSpacing nPixelSpace, GSpacing nLineSpace, GSpacing nBandSpace, GDALRasterIOExtraArg *psExtraArg) CPL_WARN_UNUSED_RESULT
CPLErr | ValidateRasterIOOrAdviseReadParameters (const char *pszCallingFunc, int *pbStopProcessingOnCENone, int nXOff, int nYOff, int nXSize, int nYSize, int nBufXSize, int nBufYSize, int nBandCount, int *panBandMap)
CPLErr | TryOverviewRasterIO (GDALRWFlag eRWFlag, int nXOff, int nYOff, int nXSize, int nYSize, void *pData, int nBufXSize, int nBufYSize, GDALDataType eBufType, int nBandCount, int *panBandMap, GSpacing nPixelSpace, GSpacing nLineSpace, GSpacing nBandSpace, GDALRasterIOExtraArg *psExtraArg, int *pbTried)
int | ValidateLayerCreationOptions (const char *const *papszLCO)
int | EnterReadWrite (GDALRWFlag eRWFlag)
void | LeaveReadWrite ()
void | TemporarilyDropReadWriteLock ()
void | ReacquireReadWriteLock ()
void | DisableReadWriteMutex ()
int | AcquireMutex ()
void | ReleaseMutex ()
virtual OGRLayer * | ICreateLayer (const char *pszName, OGRSpatialReference *poSpatialRef=NULL, OGRwkbGeometryType eGType=wkbUnknown, char **papszOptions=NULL)
| This method attempts to create a new layer on the dataset with the indicated name, coordinate system, geometry type. More...
OGRErr | ProcessSQLCreateIndex (const char *)
OGRErr | ProcessSQLDropIndex (const char *)
OGRErr | ProcessSQLDropTable (const char *)
OGRErr | ProcessSQLAlterTableAddColumn (const char *)
OGRErr | ProcessSQLAlterTableDropColumn (const char *)
OGRErr | ProcessSQLAlterTableAlterColumn (const char *)
OGRErr | ProcessSQLAlterTableRenameColumn (const char *)
Protected Member Functions inherited from GDALMajorObject
char ** | BuildMetadataDomainList (char **papszList, int bCheckNonEmpty,...) CPL_NULL_TERMINATED
| Helper function for custom implementations of GetMetadataDomainList() More...

## Friends
class | VRTRasterBand

## Additional Inherited Members
Protected Attributes inherited from GDALDataset
GDALDriver * | poDriver
GDALAccess | eAccess
int | nRasterXSize
int | nRasterYSize
int | nBands
GDALRasterBand ** | papoBands
int | nOpenFlags
int | nRefCount
bool | bForceCachedIO
bool | bShared
bool | bIsInternal
bool | bSuppressOnClose
GDALDefaultOverviews | oOvManager
char ** | papszOpenOptions
OGRStyleTable * | m_poStyleTable
Protected Attributes inherited from GDALMajorObject
int | nFlags
CPLString | sDescription
GDALMultiDomainMetadata | oMDMD

## Member Function Documentation

CPLErr VRTDataset::AddBand | ( | GDALDataType | eType,
|  | char ** | papszOptions = `NULL`
| ) |  |
| virtual

Add a band to a dataset.

This method will add a new band to the dataset if the underlying format supports this action. Most formats do not.

Note that the new GDALRasterBand is not returned. It may be fetched after successful completion of the method by calling GDALDataset::GetRasterBand(GDALDataset::GetRasterCount()) as the newest band will always be the last band.

Parameters

  eType | the data type of the pixels in the new band.
  papszOptions | a list of NAME=VALUE option strings. The supported options are format specific. NULL may be passed by default.

Returns
  CE_None on success or CE_Failure on failure.

Reimplemented from GDALDataset.

Reimplemented in VRTPansharpenedDataset, and VRTWarpedDataset.

int VRTDataset::CloseDependentDatasets | ( |  | ) |
| protected virtual

Drop references to any other datasets referenced by this dataset.

This method should release any reference to other datasets (e.g. a VRT dataset to its sources), but not close the current dataset itself.

If at least, one reference to a dependent dataset has been dropped, this method should return TRUE. Otherwise it should return FALSE. (Failure to return the proper value might result in infinite loop)

This method can be called several times on a given dataset. After the first time, it should not do anything and return FALSE.

The driver implementation may choose to destroy its raster bands, so be careful not to call any method on the raster bands afterwards.

Basically the only safe action you can do after calling CloseDependentDatasets() is to call the destructor.

Note: the only legitimate caller of CloseDependentDatasets() is GDALDriverManager::~GDALDriverManager()

Returns
  TRUE if at least one reference to another dataset has been dropped.

Reimplemented from GDALDataset.

Reimplemented in VRTPansharpenedDataset, and VRTWarpedDataset.

CPLErr VRTDataset::CreateMaskBand | ( | int | nFlagsIn | ) |
| virtual

Adds a mask band to the dataset.

The default implementation of the CreateMaskBand() method is implemented based on similar rules to the .ovr handling implemented using the GDALDefaultOverviews object. A TIFF file with the extension .msk will be created with the same basename as the original file, and it will have one band. The mask images will be deflate compressed tiled images with the same block size as the original image if possible.

Note that if you got a mask band with a previous call to GetMaskBand(), it might be invalidated by CreateMaskBand(). So you have to call GetMaskBand() again.

Since
  GDAL 1.5.0

Parameters

  nFlags | ignored. GMF_PER_DATASET will be assumed.

Returns
  CE_None on success or CE_Failure on an error.

See also
  http://trac.osgeo.org/gdal/wiki/rfc15_nodatabitmask

Reimplemented from GDALDataset.

void VRTDataset::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.

The default implementation of this method just calls the FlushCache() method on each of the raster bands and the SyncToDisk() method on each of the layers. Conceptionally, calling FlushCache() on a dataset should include any work that might be accomplished by calling SyncToDisk() on layers in that dataset.

Using this method does not prevent use from calling GDALClose() to properly close a dataset and ensure that important data not addressed by FlushCache() is written in the file.

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

Reimplemented from GDALDataset.

char ** VRTDataset::GetFileList | ( | void |  | ) |
| virtual

Fetch files forming dataset.

Returns a list of files believed to be part of this dataset. If it returns an empty list of files it means there is believed to be no local file system files associated with the dataset (for instance a virtual dataset). The returned file list is owned by the caller and should be deallocated with CSLDestroy().

The returned filenames will normally be relative or absolute paths depending on the path used to originally open the dataset. The strings will be UTF-8 encoded.

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

Returns
  NULL or a NULL terminated array of file names.

Reimplemented from GDALDataset.

Reimplemented in VRTPansharpenedDataset, and VRTWarpedDataset.

int VRTDataset::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.

Reimplemented from GDALDataset.

const char * VRTDataset::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. It should not be altered, freed or expected to last for long.

Reimplemented from GDALDataset.

const GDAL_GCP * VRTDataset::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.

Reimplemented from GDALDataset.

CPLErr VRTDataset::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.

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.

Reimplemented from GDALDataset.

char ** VRTDataset::GetMetadata | ( | const char * | pszDomain = `""` | ) |
| virtual

Fetch metadata.

The returned string list is owned by the object, and may change at any time. It is formatted as a "Name=value" list with the last pointer value being NULL. Use the CPL StringList functions such as CSLFetchNameValue() to manipulate it.

Note that relatively few formats return any metadata at this time.

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

Parameters

  pszDomain | the domain of interest. Use "" or NULL for the default domain.

Returns
  NULL or a string list.

Reimplemented from GDALDataset.

const char * VRTDataset::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 OpenGIS WKT format. It should be suitable for use with the OGRSpatialReference class.

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.

See also
  http://www.gdal.org/osr_tutorial.html

Reimplemented from GDALDataset.

CPLErr VRTDataset::SetGCPs | ( | int | nGCPCount,
|  | const GDAL_GCP * | pasGCPList,
|  | const char * | pszGCPProjection
| ) |  |
| virtual

Assign GCPs.

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

This method assigns the passed set of GCPs to this dataset, as well as setting their coordinate system. Internally copies are made of the coordinate system and list of points, so the caller remains responsible for deallocating these arguments if appropriate.

Most formats do not support setting of GCPs, even formats that can handle GCPs. These formats will return CE_Failure.

Parameters

  nGCPCount | number of GCPs being assigned.
  pasGCPList | array of GCP structures being assign (nGCPCount in array).
  pszGCPProjection | the new OGC WKT coordinate system to assign for the GCP output coordinates. This parameter should be "" if no output coordinate system is known.

Returns
  CE_None on success, CE_Failure on failure (including if action is not supported for this format).

Reimplemented from GDALDataset.

CPLErr VRTDataset::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.

Reimplemented from GDALDataset.

CPLErr VRTDataset::SetMetadata | ( | char ** | papszMetadataIn,
|  | const char * | pszDomain = `""`
| ) |  |
| virtual

Set metadata.

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

Parameters

  papszMetadataIn | the metadata in name=value string list format to apply.
  pszDomain | the domain of interest. Use "" or NULL for the default domain.

Returns
  CE_None on success, CE_Failure on failure and CE_Warning if the metadata has been accepted, but is likely not maintained persistently by the underlying object between sessions.

Reimplemented from GDALMajorObject.

CPLErr VRTDataset::SetMetadataItem | ( | const char * | pszName,
|  | const char * | pszValue,
|  | const char * | pszDomain = `""`
| ) |  |
| virtual

Set single metadata item.

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

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.

Returns
  CE_None on success, or an error code on failure.

Reimplemented from GDALMajorObject.

Reimplemented in VRTWarpedDataset.

CPLErr VRTDataset::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.

Reimplemented from GDALDataset.

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

- vrtdataset.h
- vrtdataset.cpp

Generated for GDAL by 1.8.8.