CPLErr BIGGifRasterBand::IReadBlock( CPL_UNUSED int nBlockXOff,
int nBlockYOff,
void * pImage )
{
BIGGIFDataset *poGDS = (BIGGIFDataset *) poDS;
CPLAssert( nBlockXOff == 0 );
if( panInterlaceMap != NULL )
nBlockYOff = panInterlaceMap[nBlockYOff];
/* -------------------------------------------------------------------- */
/* Do we already have this line in the work dataset? */
/* -------------------------------------------------------------------- */
if( poGDS->poWorkDS != NULL && nBlockYOff <= poGDS->nLastLineRead )
{
return poGDS->poWorkDS->
RasterIO( GF_Read, 0, nBlockYOff, nBlockXSize, 1,
pImage, nBlockXSize, 1, GDT_Byte,
1, NULL, 0, 0, 0, NULL );
}
/* -------------------------------------------------------------------- */
/* Do we need to restart from the start of the image? */
/* -------------------------------------------------------------------- */
if( nBlockYOff <= poGDS->nLastLineRead )
{
if( poGDS->ReOpen() == CE_Failure )
return CE_Failure;
}
/* -------------------------------------------------------------------- */
/* Read till we get our target line. */
/* -------------------------------------------------------------------- */
CPLErr eErr = CE_None;
while( poGDS->nLastLineRead < nBlockYOff && eErr == CE_None )
{
if( DGifGetLine( poGDS->hGifFile, (GifPixelType*)pImage,
nBlockXSize ) == GIF_ERROR )
{
CPLError( CE_Failure, CPLE_AppDefined,
"Failure decoding scanline of GIF file." );
return CE_Failure;
}
poGDS->nLastLineRead++;
if( poGDS->poWorkDS != NULL )
{
eErr = poGDS->poWorkDS->RasterIO( GF_Write,
0, poGDS->nLastLineRead, nBlockXSize, 1,
pImage, nBlockXSize, 1, GDT_Byte,
1, NULL, 0, 0, 0, NULL );
}
}
return eErr;
}
GDALDataset *BIGGIFDataset::Open( GDALOpenInfo * poOpenInfo )
{
if( !Identify( poOpenInfo ) || poOpenInfo->fpL == NULL )
return NULL;
if( poOpenInfo->eAccess == GA_Update )
{
CPLError( CE_Failure, CPLE_NotSupported,
"The GIF driver does not support update access to existing"
" files.\n" );
return NULL;
}
/* -------------------------------------------------------------------- */
/* Create a corresponding GDALDataset. */
/* -------------------------------------------------------------------- */
BIGGIFDataset *poDS = new BIGGIFDataset();
poDS->fp = poOpenInfo->fpL;
poOpenInfo->fpL = NULL;
poDS->eAccess = GA_ReadOnly;
if( poDS->ReOpen() == CE_Failure )
{
delete poDS;
return NULL;
}
/* -------------------------------------------------------------------- */
/* Capture some information from the file that is of interest. */
/* -------------------------------------------------------------------- */
poDS->nRasterXSize = poDS->hGifFile->SavedImages[0].ImageDesc.Width;
poDS->nRasterYSize = poDS->hGifFile->SavedImages[0].ImageDesc.Height;
if( poDS->hGifFile->SavedImages[0].ImageDesc.ColorMap == NULL &&
poDS->hGifFile->SColorMap == NULL )
{
CPLDebug("GIF", "Skipping image without color table");
delete poDS;
return NULL;
}
/* -------------------------------------------------------------------- */
/* Create band information objects. */
/* -------------------------------------------------------------------- */
poDS->SetBand( 1,
new BIGGifRasterBand( poDS,
poDS->hGifFile->SBackGroundColor ));
/* -------------------------------------------------------------------- */
/* Check for georeferencing. */
/* -------------------------------------------------------------------- */
poDS->DetectGeoreferencing(poOpenInfo);
/* -------------------------------------------------------------------- */
/* Initialize any PAM information. */
/* -------------------------------------------------------------------- */
poDS->SetDescription( poOpenInfo->pszFilename );
poDS->TryLoadXML( poOpenInfo->GetSiblingFiles() );
/* -------------------------------------------------------------------- */
/* Support overviews. */
/* -------------------------------------------------------------------- */
poDS->oOvManager.Initialize( poDS, poOpenInfo->pszFilename,
poOpenInfo->GetSiblingFiles() );
return poDS;
}
GDALDataset *BIGGIFDataset::Open( GDALOpenInfo * poOpenInfo )
{
if( !Identify( poOpenInfo ) )
return NULL;
if( poOpenInfo->eAccess == GA_Update )
{
CPLError( CE_Failure, CPLE_NotSupported,
"The GIF driver does not support update access to existing"
" files.\n" );
return NULL;
}
/* -------------------------------------------------------------------- */
/* Open the file. */
/* -------------------------------------------------------------------- */
VSILFILE *fp;
fp = VSIFOpenL( poOpenInfo->pszFilename, "r" );
if( fp == NULL )
return NULL;
/* -------------------------------------------------------------------- */
/* Create a corresponding GDALDataset. */
/* -------------------------------------------------------------------- */
BIGGIFDataset *poDS;
poDS = new BIGGIFDataset();
poDS->fp = fp;
poDS->eAccess = GA_ReadOnly;
if( poDS->ReOpen() == CE_Failure )
{
delete poDS;
return NULL;
}
/* -------------------------------------------------------------------- */
/* Capture some information from the file that is of interest. */
/* -------------------------------------------------------------------- */
poDS->nRasterXSize = poDS->hGifFile->SavedImages[0].ImageDesc.Width;
poDS->nRasterYSize = poDS->hGifFile->SavedImages[0].ImageDesc.Height;
/* -------------------------------------------------------------------- */
/* Create band information objects. */
/* -------------------------------------------------------------------- */
poDS->SetBand( 1,
new BIGGifRasterBand( poDS,
poDS->hGifFile->SBackGroundColor ));
/* -------------------------------------------------------------------- */
/* Check for world file. */
/* -------------------------------------------------------------------- */
poDS->bGeoTransformValid =
GDALReadWorldFile( poOpenInfo->pszFilename, NULL,
poDS->adfGeoTransform )
|| GDALReadWorldFile( poOpenInfo->pszFilename, ".wld",
poDS->adfGeoTransform );
/* -------------------------------------------------------------------- */
/* Initialize any PAM information. */
/* -------------------------------------------------------------------- */
poDS->SetDescription( poOpenInfo->pszFilename );
poDS->TryLoadXML();
/* -------------------------------------------------------------------- */
/* Support overviews. */
/* -------------------------------------------------------------------- */
poDS->oOvManager.Initialize( poDS, poOpenInfo->pszFilename );
return poDS;
}
