Error when applying PixelFuntion to a VRTDerivedRasterBand

[bugbuster]

I have tried to apply a PixelFunction to a VRTDerivedRasterBand with no succes. My environment :

• windows 8 64 bits
• VisualC++ 2010

To illustrate the problem, I slightly modified gdal_translate.cpp code :

• add a GDALDerivedPixelFunc function (called SnafuFunc()), based on the great plugin developped by Antonio (see ​https://github.com/avalentino/gdal-pixfun-plugin)
• register the function along with plugins

      GDALAddDerivedBandPixelFunc("MySnafuFunc", SnafuFunc);
      GDALAllRegister()
  

In every call to SnafuFunc(), I print several Input/output parameters. I noticed that I always get :

• nSources = 0
• papoSources = 0x000 (which is consistent with nSources being null)

The data I have used for this test are :

• original image : TIF gray scale 8-bit depth
• VRT image :

  <VRTDataset rasterXSize="512" rasterYSize="512"  >
    <VRTRasterBand dataType="Byte" band="1" subClass="VRTDerivedRasterBand">
      <Description>SnafuFunc</Description>
      <PixelFunctionType>MySnafuFunc</PixelFunctionType>
      <SourceTransferType>Byte</SourceTransferType>
      <SimpleSource>
        <SourceFilename relativeToVRT="1">fubar_ori.tif</SourceFilename>
        <SourceBand>1</SourceBand>
        <SourceProperties RasterXSize="512" RasterYSize="512" DataType="Byte" />
        <SrcRect xOff="0" yOff="0" xSize="512" ySize="512"/>
        <DstRect xOff="0" yOff="0" xSize="512" ySize="512"/>
      </SimpleSource>
    </VRTRasterBand>
  </VRTDataset>
  

Why do I always get nSources = 0 in every call to SnafuFunc() ? Every call to SnafuFunc() exit with a CE_Failure status. Am I doing something wrong ?

Thanks for your help

[bugbuster]

original TIF image

[bugbuster]

gdal_translate.cpp source code, with modification for SnafuFunc()

[Even Rouault]

In 34728:

VRT: make CheckCompatibleForDatasetIO() return FALSE on VRTDerivedRasterBands (fixes #6599)

[Even Rouault]

In 34729:

Test fixes #6599

[Even Rouault]

In 34730:

VRT: make CheckCompatibleForDatasetIO() return FALSE on VRTDerivedRasterBands (fixes #6599)

[Even Rouault]

In 34731:

VRT: make CheckCompatibleForDatasetIO() return FALSE on VRTDerivedRasterBands (fixes #6599)

[Even Rouault]

In 34732:

VRT: make CheckCompatibleForDatasetIO() return FALSE on VRTDerivedRasterBands (fixes #6599)

[Even Rouault]

A workaround can be to modify the VRT and replace <SimpleSource> by <ComplexSource>.