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;
}
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;
}
