commit 09ad0e78129d4f85fd1b847b35409fd5440ed23c
author Caolán McNamara <caolanm@redhat.com> Mon Jul 22 15:44:12 2019 +0100
committer Caolán McNamara <caolanm@redhat.com> Tue Jul 23 11:05:59 2019 +0200
tree 404e308b97709a4b329d8f2cda16860fa41e0da1
parent 91b344b0346347ac40d2d6fa03a03e92d2e9f252

Resolves: tdf#126460 implement reading grayscale+alpha tiff format

Change-Id: I3300ae21c74f5a25c767ce643e93d2232f3b9381
Reviewed-on: https://gerrit.libreoffice.org/76123
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

filter/source/graphicfilter/itiff/itiff.cxx

diff --git a/filter/source/graphicfilter/itiff/itiff.cxx b/filter/source/graphicfilter/itiff/itiff.cxx
index 15a4fe3..31f91c1 100644
--- a/filter/source/graphicfilter/itiff/itiff.cxx
+++ b/filter/source/graphicfilter/itiff/itiff.cxx
@@ -1148,15 +1148,34 @@ bool TIFFReader::ConvertScanline(sal_Int32 nY)
        }
    }
    else if ( ( nSamplesPerPixel == 2 ) && ( nBitsPerSample == 8 ) &&
        ( nPlanarConfiguration == 1 ) && aColorMap.empty() )               // grayscale
        ( nPlanarConfiguration == 1 ) && aColorMap.empty() )               // grayscale + alpha
    {
        if ( nMaxSampleValue > nMinSampleValue )
        {
            sal_uInt32 nMinMax = ( ( 1 << 8 /*nDstBitsPerPixel*/ ) - 1 ) / ( nMaxSampleValue - nMinSampleValue );
            sal_uInt8*  pt = getMapData(0);
            for (sal_Int32 nx = 0; nx < nImageWidth; nx++, pt += 2 )
            sal_uInt8* pt = getMapData(0);

            if (nPredictor == 2)
            {
                SetPixel(nY, nx, static_cast<sal_uInt8>( (static_cast<sal_uInt32>(*pt) - nMinSampleValue) * nMinMax));
                sal_uInt8 nLastPixel = 0;
                sal_uInt8 nLastAlpha = 0;
                for (sal_Int32 nx = 0; nx < nImageWidth; nx++, pt += 2)
                {
                    nLastPixel = (nLastPixel + pt[0]) & 0xFF;
                    SetPixel(nY, nx, nLastPixel);

                    nLastAlpha = (nLastAlpha + pt[1]) & 0xFF;
                    SetPixelAlpha(nY, nx, ~nLastAlpha);
                }
            }
            else
            {
                sal_uInt32 nMinMax = ( ( 1 << 8 /*nDstBitsPerPixel*/ ) - 1 ) / ( nMaxSampleValue - nMinSampleValue );
                for (sal_Int32 nx = 0; nx < nImageWidth; nx++, pt += 2)
                {
                    SetPixel(nY, nx, static_cast<sal_uInt8>( (static_cast<sal_uInt32>(pt[0]) - nMinSampleValue) * nMinMax ));
                    sal_uInt8 nAlpha = static_cast<sal_uInt8>( (static_cast<sal_uInt32>(pt[1]) - nMinSampleValue) * nMinMax );
                    SetPixelAlpha(nY, nx, ~nAlpha);
                }
            }
        }
    }
@@ -1239,13 +1258,21 @@ void TIFFReader::ReadHeader()
bool TIFFReader::HasAlphaChannel() const
{
    /*There are undoubtedly more variants we could support, but keep it simple for now*/
    return (
             nDstBitsPerPixel == 24 &&
             nBitsPerSample == 8 &&
             nSamplesPerPixel >= 4 &&
             nPlanes == 1 &&
             nPhotometricInterpretation == 2
           );
    bool bRGBA = nDstBitsPerPixel == 24 &&
                 nBitsPerSample == 8 &&
                 nSamplesPerPixel >= 4 &&
                 nPlanes == 1 &&
                 nPhotometricInterpretation == 2;
    if (bRGBA)
        return true;

    // additionally support the format used in tdf#126460
    bool bGrayScaleAlpha = nDstBitsPerPixel == 8 &&
                           nBitsPerSample == 8 &&
                           nSamplesPerPixel == 2 &&
                           nPlanarConfiguration == 1;

    return bGrayScaleAlpha;
}

namespace
@@ -1623,7 +1650,7 @@ bool TIFFReader::ReadTIFF(SvStream & rTIFF, Graphic & rGraphic )
                        {
                            for (sal_Int32 nX = 0; nX < nImageWidth; ++nX)
                            {
                                auto p = maBitmap.data() + ((maBitmapPixelSize.Width() * nY + nX) * 3);
                                auto p = maBitmap.data() + ((maBitmapPixelSize.Width() * nY + nX) * (HasAlphaChannel() ? 4 : 3));
                                auto c = SanitizePaletteIndex(*p, mvPalette);
                                *p = c.GetRed();
                                p++;