C++ VRTDataset类代码示例

CPLErr VRTRasterBand::CreateMaskBand( int nFlags )
{
    VRTDataset* poGDS = (VRTDataset *)poDS;
    
    if (poGDS->poMaskBand)
    {
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Cannot create mask band at raster band level when a dataset mask band already exists." );
        return CE_Failure;
    }
    
    if (poMaskBand != NULL)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "This VRT band has already a mask band");
        return CE_Failure;
    }
    
    if ((nFlags & GMF_PER_DATASET) != 0)
        return poGDS->CreateMaskBand(nFlags);

    SetMaskBand(new VRTSourcedRasterBand( poGDS, 0 ));

    return CE_None;
}

GDALRasterBand *VRTRasterBand::GetOverview( int iOverview )

{
    // First: overviews declared in <Overview> element
    if( !m_apoOverviews.empty() )
    {
        if( iOverview < 0
            || iOverview >= static_cast<int>( m_apoOverviews.size() ) )
            return NULL;

        if( m_apoOverviews[iOverview].poBand == NULL
            && !m_apoOverviews[iOverview].bTriedToOpen )
        {
            m_apoOverviews[iOverview].bTriedToOpen = TRUE;

            GDALDataset *poSrcDS = reinterpret_cast<GDALDataset *>(
                GDALOpenShared( m_apoOverviews[iOverview].osFilename,
                                GA_ReadOnly ) );

            if( poSrcDS == NULL )
                return NULL;

            m_apoOverviews[iOverview].poBand = poSrcDS->GetRasterBand(
                m_apoOverviews[iOverview].nBand );

            if (m_apoOverviews[iOverview].poBand == NULL)
            {
                GDALClose( (GDALDatasetH)poSrcDS );
            }
        }

        return m_apoOverviews[iOverview].poBand;
    }

    // If not found, external .ovr overviews
    GDALRasterBand* poRet = GDALRasterBand::GetOverview( iOverview );
    if( poRet )
        return poRet;

    // If not found, implicit virtual overviews
    VRTDataset* poVRTDS = reinterpret_cast<VRTDataset *>( poDS );
    poVRTDS->BuildVirtualOverviews();
    if( !poVRTDS->m_apoOverviews.empty() && poVRTDS->m_apoOverviews[0] )
    {
        if( iOverview < 0
            || iOverview >= static_cast<int>( poVRTDS->m_apoOverviews.size() ) )
            return NULL;

        return poVRTDS->m_apoOverviews[iOverview]->GetRasterBand(nBand);
    }

    return NULL;
}

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

{
    VRTDataset *poDS = NULL;
    int        iBand = 0;

    (void) papszOptions;

    if( EQUALN(pszName,"<VRTDataset",11) )
    {
        GDALDataset *poDS = OpenXML( pszName, NULL, GA_Update );
        if (poDS)
            poDS->SetDescription( "<FromXML>" );
        return poDS;
    }
    else
    {
        const char *pszSubclass = CSLFetchNameValue( papszOptions,
                                                     "SUBCLASS" );

        if( pszSubclass == NULL || EQUAL(pszSubclass,"VRTDataset") )
            poDS = new VRTDataset( nXSize, nYSize );
        else if( EQUAL(pszSubclass,"VRTWarpedDataset") )
        {
            poDS = new VRTWarpedDataset( nXSize, nYSize );
        }
        else
        {
            CPLError( CE_Failure, CPLE_AppDefined, 
                      "SUBCLASS=%s not recognised.", 
                      pszSubclass );
            return NULL;
        }
        poDS->eAccess = GA_Update;

        poDS->SetDescription( pszName );
        
        for( iBand = 0; iBand < nBands; iBand++ )
            poDS->AddBand( eType, NULL );
        
        poDS->bNeedsFlush = 1;

        poDS->oOvManager.Initialize( poDS, pszName );
        
        return poDS;
    }
}

GDALRasterBand *VRTRasterBand::GetOverview( int iOverview )

{
    // First: overviews declared in <Overview> element
    if( apoOverviews.size() > 0 )
    {
        if( iOverview < 0 || iOverview >= (int) apoOverviews.size() )
            return NULL;

        if( apoOverviews[iOverview].poBand == NULL 
            && !apoOverviews[iOverview].bTriedToOpen )
        {
            apoOverviews[iOverview].bTriedToOpen = TRUE;

            GDALDataset *poSrcDS = (GDALDataset *)
                GDALOpenShared( apoOverviews[iOverview].osFilename, GA_ReadOnly );
            
            if( poSrcDS == NULL )
                return NULL;

            apoOverviews[iOverview].poBand = poSrcDS->GetRasterBand( 
                apoOverviews[iOverview].nBand );

            if (apoOverviews[iOverview].poBand == NULL)
            {
                GDALClose( (GDALDatasetH)poSrcDS );
            }
        }

        return apoOverviews[iOverview].poBand;
    }
    
    // If not found, external .ovr overviews
    GDALRasterBand* poRet = GDALRasterBand::GetOverview( iOverview );
    if( poRet )
        return poRet;
    
    // If not found, implicit virtual overviews
    VRTDataset* poVRTDS = ((VRTDataset *)poDS);
    poVRTDS->BuildVirtualOverviews();
    if( poVRTDS->apoOverviews.size() && poVRTDS->apoOverviews[0] )
    {
        if( iOverview < 0 || iOverview >= (int) poVRTDS->apoOverviews.size() )
            return NULL;
        return poVRTDS->apoOverviews[iOverview]->GetRasterBand(nBand);
    }
    
    return NULL;
}

int VRTRasterBand::GetOverviewCount()

{
    // First: overviews declared in <Overview> element
    if( !m_apoOverviews.empty() )
        return static_cast<int>(m_apoOverviews.size());

    // If not found, external .ovr overviews
    const int nOverviewCount = GDALRasterBand::GetOverviewCount();
    if( nOverviewCount )
        return nOverviewCount;

    // If not found, implicit virtual overviews
    VRTDataset* poVRTDS = reinterpret_cast<VRTDataset *>( poDS );
    poVRTDS->BuildVirtualOverviews();
    if( !poVRTDS->m_apoOverviews.empty() && poVRTDS->m_apoOverviews[0] )
        return static_cast<int>( poVRTDS->m_apoOverviews.size() );

    return 0;
}

int VRTRasterBand::GetOverviewCount()

{
    // First: overviews declared in <Overview> element
    if( apoOverviews.size() > 0 )
        return apoOverviews.size();

    // If not found, external .ovr overviews
    int nOverviewCount = GDALRasterBand::GetOverviewCount();
    if( nOverviewCount )
        return nOverviewCount;

    // If not found, implicit virtual overviews
    VRTDataset* poVRTDS = ((VRTDataset *)poDS);
    poVRTDS->BuildVirtualOverviews();
    if( poVRTDS->apoOverviews.size() && poVRTDS->apoOverviews[0] )
        return (int)poVRTDS->apoOverviews.size();

    return 0;
}

static GDALDataset *
VRTCreateCopy( const char * pszFilename,
               GDALDataset *poSrcDS,
               int /* bStrict */,
               char ** /* papszOptions */,
               GDALProgressFunc /* pfnProgress */,
               void * /* pProgressData */ )
{
    CPLAssert( NULL != poSrcDS );

/* -------------------------------------------------------------------- */
/*      If the source dataset is a virtual dataset then just write      */
/*      it to disk as a special case to avoid extra layers of           */
/*      indirection.                                                    */
/* -------------------------------------------------------------------- */
    if( poSrcDS->GetDriver() != NULL &&
        EQUAL(poSrcDS->GetDriver()->GetDescription(),"VRT") )
    {

    /* -------------------------------------------------------------------- */
    /*      Convert tree to a single block of XML text.                     */
    /* -------------------------------------------------------------------- */
        char *pszVRTPath = CPLStrdup(CPLGetPath(pszFilename));
        reinterpret_cast<VRTDataset *>(
            poSrcDS )->UnsetPreservedRelativeFilenames();
        CPLXMLNode *psDSTree = reinterpret_cast<VRTDataset *>(
            poSrcDS )->SerializeToXML( pszVRTPath );

        char *pszXML = CPLSerializeXMLTree( psDSTree );

        CPLDestroyXMLNode( psDSTree );

        CPLFree( pszVRTPath );

    /* -------------------------------------------------------------------- */
    /*      Write to disk.                                                  */
    /* -------------------------------------------------------------------- */
        GDALDataset* pCopyDS = NULL;

        if( 0 != strlen( pszFilename ) )
        {
            VSILFILE *fpVRT = VSIFOpenL( pszFilename, "wb" );
            if( fpVRT == NULL )
            {
                CPLError(CE_Failure, CPLE_AppDefined,
                         "Cannot create %s", pszFilename);
                CPLFree( pszXML );
                return NULL;
            }

            bool bRet = VSIFWriteL( pszXML, strlen(pszXML), 1, fpVRT ) > 0;
            if( VSIFCloseL( fpVRT ) != 0 )
                bRet = false;

            if( bRet )
                pCopyDS = reinterpret_cast<GDALDataset *>(
                    GDALOpen( pszFilename, GA_Update ) );
        }
        else
        {
            /* No destination file is given, so pass serialized XML directly. */
            pCopyDS = reinterpret_cast<GDALDataset *>(
                GDALOpen( pszXML, GA_Update ) );
        }

        CPLFree( pszXML );

        return pCopyDS;
    }

/* -------------------------------------------------------------------- */
/*      Create the virtual dataset.                                     */
/* -------------------------------------------------------------------- */
    VRTDataset *poVRTDS = reinterpret_cast<VRTDataset *>(
        VRTDataset::Create( pszFilename,
                            poSrcDS->GetRasterXSize(),
                            poSrcDS->GetRasterYSize(),
                            0, GDT_Byte, NULL ) );
    if( poVRTDS == NULL )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Do we have a geotransform?                                      */
/* -------------------------------------------------------------------- */
    double adfGeoTransform[6] = { 0.0 };

    if( poSrcDS->GetGeoTransform( adfGeoTransform ) == CE_None )
    {
        poVRTDS->SetGeoTransform( adfGeoTransform );
    }

/* -------------------------------------------------------------------- */
/*      Copy projection                                                 */
/* -------------------------------------------------------------------- */
    poVRTDS->SetProjection( poSrcDS->GetProjectionRef() );

/* -------------------------------------------------------------------- */
/*      Emit dataset level metadata.                                    */
/* -------------------------------------------------------------------- */
    poVRTDS->SetMetadata( poSrcDS->GetMetadata() );
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        
        for( iBand = 0; iBand < nBandCount; iBand++ )
        {
            fprintf( fpConfig, "%d:Band ", iBand+1 );
            if( padfScaleMin != NULL )
                fprintf( fpConfig, "%g:ScaleMin %g:ScaleMax ", 
                         padfScaleMin[iBand], padfScaleMax[iBand] );

            if( papanLUTs )
            {
                int iLUT;

                for( iLUT = 0; iLUT < nLUTBins; iLUT++ )
                    fprintf( fpConfig, "%d ", papanLUTs[iBand][iLUT] );
            }
            fprintf( fpConfig, "\n" );
        }

        if( pszConfigFile )
            fclose( fpConfig );

        exit( 0 );
    }

    if (padfScaleMin == NULL || padfScaleMax == NULL)
    {
        fprintf( stderr, "-equalize or -config filename command line options must be specified.\n");
        exit(1);
    }

/* ==================================================================== */
/*      Create a virtual dataset.                                       */
/* ==================================================================== */
    VRTDataset *poVDS;
    EnhanceCBInfo *pasEInfo = (EnhanceCBInfo *) 
        CPLCalloc(nBandCount, sizeof(EnhanceCBInfo));
        
/* -------------------------------------------------------------------- */
/*      Make a virtual clone.                                           */
/* -------------------------------------------------------------------- */
    poVDS = new VRTDataset( GDALGetRasterXSize(hDataset),
                            GDALGetRasterYSize(hDataset) );

    if( GDALGetGCPCount(hDataset) == 0 )
    {
        const char *pszProjection;
        double adfGeoTransform[6];

        pszProjection = GDALGetProjectionRef( hDataset );
        if( pszProjection != NULL && strlen(pszProjection) > 0 )
            poVDS->SetProjection( pszProjection );

        if( GDALGetGeoTransform( hDataset, adfGeoTransform ) == CE_None )
            poVDS->SetGeoTransform( adfGeoTransform );
    }
    else
    {
        poVDS->SetGCPs( GDALGetGCPCount(hDataset), 
                        GDALGetGCPs(hDataset),
                        GDALGetGCPProjection( hDataset ) );
    }
    
    poVDS->SetMetadata( ((GDALDataset*)hDataset)->GetMetadata() );

    for( iBand = 0; iBand < nBandCount; iBand++ )
    {

bool gstIconManager::CopyIcon(const std::string& src_path,
                              const std::string& dst_path) {
  // file must not exist already
  if (khExists(dst_path)) {
    notify(NFY_WARN, "Icon \"%s\" already exists", dst_path.c_str());
    return false;
  }

  GDALDataset* srcDataset = static_cast<GDALDataset*>(
                        GDALOpen(src_path.c_str(), GA_ReadOnly));
  if (!srcDataset) {
    notify(NFY_WARN, "Unable to open icon %s", src_path.c_str());
    return false;
  }

  // determine the image type
  // is it rgb or palette_index type
  bool palette_type = false;
  if (srcDataset->GetRasterCount() == 1 &&
      srcDataset->GetRasterBand(1)->GetColorInterpretation() ==
      GCI_PaletteIndex) {
    palette_type = true;
  } else if (srcDataset->GetRasterCount() != 4) {
    notify(NFY_WARN, "%s: Image type not supported", src_path.c_str());
    return false;
  }

  GDALDataset* oldSrcDataset = 0;
  int target_size = 0;
  bool need_scaling = false;
  int srcXSize = srcDataset->GetRasterXSize();
  int srcYSize = srcDataset->GetRasterYSize();
  if ((srcXSize == 32) || (srcXSize == 64)) {
    target_size = srcXSize;
    if ((srcYSize != srcXSize) &&
        (srcYSize != srcXSize*2) &&
        (srcYSize != srcXSize*3)) {
      need_scaling = true;
    }
  } else if (srcXSize < 32) {
    target_size = 32;
    need_scaling = true;
  } else {
    target_size = 64;
    need_scaling = true;
  }

  if (need_scaling) {
    // create a temp output dataset to scale the src
    // icon to a square target_size*target_size. Later we'll make a stack.
    VRTDataset* tempDataset = new VRTDataset(target_size, target_size);
    int numBands = palette_type ? 1 : 4;
    for (int b = 1; b <= numBands; ++b) {
      tempDataset->AddBand(GDT_Byte, NULL);
      VRTSourcedRasterBand* tempBand =
        static_cast<VRTSourcedRasterBand*>(tempDataset->GetRasterBand(b));

      GDALRasterBand* srcBand = srcDataset->GetRasterBand(b);
      tempBand->AddSimpleSource(srcBand,
                                0, 0, srcXSize, srcYSize,
                                0, 0, target_size, target_size);
      if (palette_type) {
        tempBand->SetColorInterpretation(srcBand->GetColorInterpretation());
        tempBand->SetColorTable(srcBand->GetColorTable());
      }
    }
    oldSrcDataset = srcDataset;
    srcDataset = tempDataset;
    srcXSize = srcYSize = target_size;
  }
  assert(srcXSize == target_size);

  // From here on we assume that we have a square, a stack of 2, or a stack of
  // 3. It will be either 32 or 64 wide. The actual size is stored in srcXSize
  // and srcYSize
  bool simpleCopy = false;
  if (srcYSize == srcXSize * 3)
    simpleCopy = true;

  // create a virtual dataset to represent the desired output image
  VRTDataset* vds = new VRTDataset(target_size, target_size * 3);

  // copy all the bands from the source
  int numBands = palette_type ? 1 : 4;
  for (int b = 1; b <= numBands; ++b) {
    vds->AddBand(GDT_Byte, NULL);
    VRTSourcedRasterBand* vrtBand =
      static_cast<VRTSourcedRasterBand*>(vds->GetRasterBand(b));

    GDALRasterBand* srcBand = srcDataset->GetRasterBand(b);
    if (!simpleCopy) {
      // extract the normal icon (on bottom of input image)
      // and put it on the bottom of new image
      // NOTE: srcYSize calculation lets us hand single, square images
      // as well as two squares stacked on top of each other
      vrtBand->AddSimpleSource(
          srcBand,
          0, srcYSize-target_size, target_size, target_size,
          0, target_size*2, target_size, target_size);

//.........这里部分代码省略.........

GDALDataset *VRTDataset::OpenXML( const char *pszXML, const char *pszVRTPath,
                                  GDALAccess eAccess)

{
 /* -------------------------------------------------------------------- */
 /*      Parse the XML.                                                  */
 /* -------------------------------------------------------------------- */
    CPLXMLNode	*psTree;

    psTree = CPLParseXMLString( pszXML );

    if( psTree == NULL )
        return NULL;

    CPLXMLNode *psRoot = CPLGetXMLNode( psTree, "=VRTDataset" );
    if (psRoot == NULL)
    {
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Missing VRTDataset element." );
        CPLDestroyXMLNode( psTree );
        return NULL;
    }

    if( CPLGetXMLNode( psRoot, "rasterXSize" ) == NULL
        || CPLGetXMLNode( psRoot, "rasterYSize" ) == NULL
        || CPLGetXMLNode( psRoot, "VRTRasterBand" ) == NULL )
    {
        CPLError( CE_Failure, CPLE_AppDefined, 
                  "Missing one of rasterXSize, rasterYSize or bands on"
                  " VRTDataset." );
        CPLDestroyXMLNode( psTree );
        return NULL;
    }

/* -------------------------------------------------------------------- */
/*      Create the new virtual dataset object.                          */
/* -------------------------------------------------------------------- */
    VRTDataset *poDS;
    int nXSize = atoi(CPLGetXMLValue(psRoot,"rasterXSize","0"));
    int nYSize = atoi(CPLGetXMLValue(psRoot,"rasterYSize","0"));
    
    if ( !GDALCheckDatasetDimensions(nXSize, nYSize) )
    {
        CPLDestroyXMLNode( psTree );
        return NULL;
    }

    if( strstr(pszXML,"VRTWarpedDataset") != NULL )
        poDS = new VRTWarpedDataset( nXSize, nYSize );
    else
    {
        poDS = new VRTDataset( nXSize, nYSize );
        poDS->eAccess = eAccess;
    }

    if( poDS->XMLInit( psRoot, pszVRTPath ) != CE_None )
    {
        delete poDS;
        poDS = NULL;
    }

/* -------------------------------------------------------------------- */
/*      Try to return a regular handle on the file.                     */
/* -------------------------------------------------------------------- */
    CPLDestroyXMLNode( psTree );

    return poDS;
}

//.........这里部分代码省略.........
        CPLFree(panBandList);

        if (!bSubCall)
        {
            GDALDumpOpenDatasets(stderr);
            GDALDestroyDriverManager();
        }

        CSLDestroy(argv);
        CSLDestroy(papszCreateOptions);

        return hOutDS == NULL;
    }

/* -------------------------------------------------------------------- */
/*      Establish some parameters.                                      */
/* -------------------------------------------------------------------- */
    if (pszOXSize == NULL)
    {
        nOXSize = anSrcWin[2];
        nOYSize = anSrcWin[3];
    }
    else
    {
        nOXSize = (int) ((pszOXSize[strlen(pszOXSize) - 1] == '%'
                          ? CPLAtofM(pszOXSize) / 100 * anSrcWin[2] : atoi(pszOXSize)));
        nOYSize = (int) ((pszOYSize[strlen(pszOYSize) - 1] == '%'
                          ? CPLAtofM(pszOYSize) / 100 * anSrcWin[3] : atoi(pszOYSize)));
    }

/* ==================================================================== */
/*      Create a virtual dataset.                                       */
/* ==================================================================== */
    VRTDataset *poVDS;

/* -------------------------------------------------------------------- */
/*      Make a virtual clone.                                           */
/* -------------------------------------------------------------------- */
    poVDS = (VRTDataset*) VRTCreate(nOXSize, nOYSize);

    if (nGCPCount == 0)
    {
        if (pszOutputSRS != NULL)
        {
            poVDS->SetProjection(pszOutputSRS);
        }
        else
        {
            pszProjection = GDALGetProjectionRef(hDataset);
            if (pszProjection != NULL && strlen(pszProjection) > 0)
                poVDS->SetProjection(pszProjection);
        }
    }

    if (bGotBounds)
    {
        adfGeoTransform[0] = adfULLR[0];
        adfGeoTransform[1] = (adfULLR[2] - adfULLR[0]) / nOXSize;
        adfGeoTransform[2] = 0.0;
        adfGeoTransform[3] = adfULLR[1];
        adfGeoTransform[4] = 0.0;
        adfGeoTransform[5] = (adfULLR[3] - adfULLR[1]) / nOYSize;

        poVDS->SetGeoTransform(adfGeoTransform);
    }

bool CreateSubRaster( wxGISRasterDatasetSPtr pSrcRasterDataSet, OGREnvelope &Env, const OGRGeometry *pGeom, GDALDriver* pDriver, CPLString &szDstPath, GDALDataType eOutputType, int nBandCount, int *panBandList, double dfOutResX, double dfOutResY, bool bCopyNodata, bool bSkipSourceMetadata, char** papszOptions, ITrackCancel* pTrackCancel )
{
	GDALDataset* pDset = pSrcRasterDataSet->GetRaster();
	if(!pDset)
	{
		if(pTrackCancel)
			pTrackCancel->PutMessage(_("Get raster failed"), -1, enumGISMessageErr);
		return false;
	}

    double adfGeoTransform[6] = { 0, 0, 0, 0, 0, 0 };
	CPLErr err = pDset->GetGeoTransform(adfGeoTransform);
	if(err == CE_Fatal)
	{
		if(pTrackCancel)
			pTrackCancel->PutMessage(_("Get raster failed"), -1, enumGISMessageErr);
		return false;
	}
	if( adfGeoTransform[2] != 0.0 || adfGeoTransform[4] != 0.0 )
	{
		if(pTrackCancel)
			pTrackCancel->PutMessage(_("The geotransform is rotated. This configuration is not supported."), -1, enumGISMessageErr);
		return false;
    }
	int anSrcWin[4] = {0, 0, 0, 0};

    anSrcWin[0] = floor ((Env.MinX - adfGeoTransform[0]) / adfGeoTransform[1] + 0.001);
    anSrcWin[1] = floor ((Env.MaxY - adfGeoTransform[3]) / adfGeoTransform[5] + 0.001);
	anSrcWin[2] = ceil ((Env.MaxX - Env.MinX) / adfGeoTransform[1]);
	anSrcWin[3] = ceil ((Env.MinY - Env.MaxY) / adfGeoTransform[5]);
	if(pTrackCancel)
		pTrackCancel->PutMessage(wxString::Format(_("Computed source pixel window %d %d %d %d from geographic window."), anSrcWin[0], anSrcWin[1], anSrcWin[2], anSrcWin[3] ), -1, enumGISMessageInfo);

	if( anSrcWin[0] < 0 || anSrcWin[1] < 0 || anSrcWin[0] + anSrcWin[2] > pSrcRasterDataSet->GetWidth() || anSrcWin[1] + anSrcWin[3] > pSrcRasterDataSet->GetHeight() )
    {
		if(pTrackCancel)
			pTrackCancel->PutMessage(wxString::Format(_("Computed source pixel window falls outside raster size of %dx%d."), pSrcRasterDataSet->GetWidth(), pSrcRasterDataSet->GetHeight()), -1, enumGISMessageErr);
		return false;
    }

	int nOXSize = 0, nOYSize = 0;

    if(IsDoubleEquil(dfOutResX, -1) && IsDoubleEquil(dfOutResY, -1))
    {
        nOXSize = anSrcWin[2];
        nOYSize = anSrcWin[3];
    }
    else
    {
        nOXSize = ceil ((Env.MaxX - Env.MinX) / dfOutResX);
        nOYSize = ceil ((Env.MinY - Env.MaxY) / (adfGeoTransform[5] < 0 ? dfOutResY * -1 : dfOutResY));
    }

/* ==================================================================== */
/*      Create a virtual dataset.                                       */
/* ==================================================================== */
    VRTDataset *poVDS;
/* -------------------------------------------------------------------- */
/*      Make a virtual clone.                                           */
/* -------------------------------------------------------------------- */
    poVDS = (VRTDataset *) VRTCreate( nOXSize, nOYSize );

    if( pSrcRasterDataSet->GetSpatialReference() != NULL )
    {
		poVDS->SetProjection( pDset->GetProjectionRef() );
    }

	adfGeoTransform[0] += anSrcWin[0] * adfGeoTransform[1] + anSrcWin[1] * adfGeoTransform[2];
    adfGeoTransform[3] += anSrcWin[0] * adfGeoTransform[4] + anSrcWin[1] * adfGeoTransform[5];

    adfGeoTransform[1] *= anSrcWin[2] / (double) nOXSize;
    adfGeoTransform[2] *= anSrcWin[3] / (double) nOYSize;
    adfGeoTransform[4] *= anSrcWin[2] / (double) nOXSize;
    adfGeoTransform[5] *= anSrcWin[3] / (double) nOYSize;

    poVDS->SetGeoTransform( adfGeoTransform );

    int nGCPs = pDset->GetGCPCount();
    if( nGCPs > 0 )
    {
        GDAL_GCP *pasGCPs = GDALDuplicateGCPs( nGCPs, pDset->GetGCPs() );

        for(size_t i = 0; i < nGCPs; ++i )
        {
            pasGCPs[i].dfGCPPixel -= anSrcWin[0];
            pasGCPs[i].dfGCPLine  -= anSrcWin[1];
            pasGCPs[i].dfGCPPixel *= (nOXSize / (double) anSrcWin[2] );
            pasGCPs[i].dfGCPLine  *= (nOYSize / (double) anSrcWin[3] );
        }

        poVDS->SetGCPs( nGCPs, pasGCPs, pDset->GetGCPProjection() );
        GDALDeinitGCPs( nGCPs, pasGCPs );
        CPLFree( pasGCPs );
    }

/* -------------------------------------------------------------------- */
/*      Transfer generally applicable metadata.                         */
/* -------------------------------------------------------------------- */
    if(!bSkipSourceMetadata)
        poVDS->SetMetadata( pDset->GetMetadata() );
//.........这里部分代码省略.........