commit 2a9eb581f0edfae8123018006df5cc9de1e1fd45
author Patrick Luby <guibmacdev@gmail.com> Sun May 12 14:04:30 2024 -0400
committer Patrick Luby <guibomacdev@gmail.com> Wed May 15 18:04:35 2024 +0200
tree 26214b1453b9a03664c4d93eeb3d747850f17c33
parent eee70d4e776a970a700db5379355292c480f8a02

tdf#160690 set an opaque alpha mask for non-transparent frames

Due to the switch from transparency to alpha in commit
81994cb2b8b32453a92bcb011830fcb884f22ff3, an empty alpha mask
is treated as a completely transparent bitmap. So revert all
of the previous commits for tdf#157576, tdf#157635, and tdf#157793
and create a completely opaque bitmap instead.

Note: this fix also fixes tdf#157576, tdf#157635, and tdf#157793.

Change-Id: Ic2ccad6ab94e4d43b1b66013f85955d474dc0151
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/167563
Reviewed-by: Patrick Luby <guibomacdev@gmail.com>
Tested-by: Jenkins

sd/qa/unit/PNGExportTests.cxx

diff --git a/sd/qa/unit/PNGExportTests.cxx b/sd/qa/unit/PNGExportTests.cxx
index 8c28a195..d99955a 100644
--- a/sd/qa/unit/PNGExportTests.cxx
+++ b/sd/qa/unit/PNGExportTests.cxx
@@ -536,25 +536,21 @@ CPPUNIT_TEST_FIXTURE(SdPNGExportTest, testTdf157793)
    CPPUNIT_ASSERT_EQUAL(Size(100, 100), aSize);
    Bitmap aBMP = aBMPEx.GetBitmap();
    BitmapScopedReadAccess pReadAccess(aBMP);
    int nLightGrayCount = 0;
    int nWhiteCount = 0;
    for (tools::Long nX = 1; nX < aSize.Width() - 1; ++nX)
    {
        for (tools::Long nY = 1; nY < aSize.Height() - 1; ++nY)
        {
            const Color aColor = pReadAccess->GetColor(nY, nX);
            if (aColor == 0xfefefe)
                ++nLightGrayCount;
            if (aColor == 0xffffff)
                ++nWhiteCount;
        }
    }

    // FIXME this still has some issues with skia
    if (SkiaHelper::isVCLSkiaEnabled())
        return;

    // Without the fix in place, this test would have failed with
    // - Expected greater than: 7800
    // - Actual  : 0
    CPPUNIT_ASSERT_GREATER(7800, nLightGrayCount);
    CPPUNIT_ASSERT_GREATER(7800, nWhiteCount);
}

CPPUNIT_TEST_FIXTURE(SdPNGExportTest, testTdf157635)

vcl/source/filter/igif/gifread.cxx

diff --git a/vcl/source/filter/igif/gifread.cxx b/vcl/source/filter/igif/gifread.cxx
index c3151f3..443eb05 100644
--- a/vcl/source/filter/igif/gifread.cxx
+++ b/vcl/source/filter/igif/gifread.cxx
@@ -97,7 +97,7 @@ class GIFReader : public GraphicReader
    sal_uInt8           nGCDisposalMethod;      // 'Disposal Method' (see GIF docs)
    sal_uInt8           cTransIndex1;
    sal_uInt8           cNonTransIndex1;
    bool                bEnhance;
    sal_uLong           nPaletteSize;

    void                ReadPaletteEntries( BitmapPalette* pPal, sal_uLong nCount );
    void                ClearImageExtensions();
@@ -155,7 +155,7 @@ GIFReader::GIFReader( SvStream& rStm )
    , nGCTransparentIndex ( 0 )
    , cTransIndex1 ( 0 )
    , cNonTransIndex1 ( 0 )
    , bEnhance( false )
    , nPaletteSize( 0 )
{
    maUpperName = "SVIGIF";
    aSrcBuf.resize(256);    // Memory buffer for ReadNextBlock
@@ -330,12 +330,7 @@ void GIFReader::ReadPaletteEntries( BitmapPalette* pPal, sal_uLong nCount )
            (*pPal)[ 254UL ] = COL_BLACK;
    }

    // tdf#157793 limit tdf#157635 fix to only larger palettes
    // I don't know why, but the fix for tdf#157635 causes
    // images with a palette of 16 entries to be inverted.
    // Also, fix tdf#158047 by allowing the tdf#157635 fix for
    // palettes with 64 entries.
    bEnhance = (nCount > 16);
    nPaletteSize = nCount;
}

bool GIFReader::ReadExtension()
@@ -677,16 +672,25 @@ void GIFReader::CreateNewBitmaps()
        // aBmp1 is already inverted
        aAnimationFrame.maBitmapEx = BitmapEx( aBmp8, aAlphaMask );
    }
    else if( nPaletteSize > 2 )
    {
        // tdf#160690 set an opaque alpha mask for non-transparent frames
        // Due to the switch from transparency to alpha in commit
        // 81994cb2b8b32453a92bcb011830fcb884f22ff3, an empty alpha mask
        // is treated as a completely transparent bitmap. So revert all
        // of the previous commits for tdf#157576, tdf#157635, and tdf#157793
        // and create a completely opaque bitmap instead.
        // Note: this fix also fixes tdf#157576, tdf#157635, and tdf#157793.
        AlphaMask aAlphaMask(aBmp8.GetSizePixel());
        aAnimationFrame.maBitmapEx = BitmapEx( aBmp8, aAlphaMask );
    }
    else
    {
        // tdf#157576 and tdf#157635 mask out black pixels
        // Due to the switch from transparency to alpha in commit
        // 81994cb2b8b32453a92bcb011830fcb884f22ff3, mask out black
        // pixels in bitmap.
        if (bEnhance)
            aAnimationFrame.maBitmapEx = BitmapEx( aBmp8, aBmp8 );
        else
            aAnimationFrame.maBitmapEx = BitmapEx( aBmp8 );
        // Don't apply the fix for tdf#160690 as it will cause 1 bit bitmaps
        // in Word documents like the following test document to fail to be
        // parsed correctly:
        // sw/qa/extras/tiledrendering/data/tdf159626_yellowPatternFill.docx
        aAnimationFrame.maBitmapEx = BitmapEx( aBmp8 );
    }

    aAnimationFrame.maPositionPixel = Point( nImagePosX, nImagePosY );