vcl/qa/cppunit/png/PngFilterTest.cxx | 53 +++++++++++++++++++++++++++++++
vcl/source/filter/png/PngImageWriter.cxx | 35 +++++++++++++++-----
2 files changed, 79 insertions(+), 9 deletions(-)
New commits:
commit c010b8cc712d1336ed79fb220764f1a850dc22e5
Author: Sarper Akdemir <sarper.akde...@collabora.com>
AuthorDate: Wed Jan 25 15:36:59 2023 +0300
Commit: Tomaž Vajngerl <qui...@gmail.com>
CommitDate: Sun Mar 5 10:55:44 2023 +0000
tdf#153180: PngImageWriter add support for gray alpha colortype
8 bit grayscale images can have alpha accompanying it, and
PNG supports 2 channel gray-alpha images.
libpng supports this with the use of colortype
PNG_COLOR_TYPE_GRAY_ALPHA.
This patch adds support for writing GRAY_ALPHA colorType PNG
images.
This is done by expanding what was in place for
ScanlineFormat::N24BitTcRgb with alpha PNG_COLOR_TYPE_RGBA.
Change-Id: I80d462d784f91529eb9371c6bdb029c78f32f81e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/146138
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <qui...@gmail.com>
diff --git a/vcl/qa/cppunit/png/PngFilterTest.cxx
b/vcl/qa/cppunit/png/PngFilterTest.cxx
index dae007eb7898..fc3963c356e8 100644
--- a/vcl/qa/cppunit/png/PngFilterTest.cxx
+++ b/vcl/qa/cppunit/png/PngFilterTest.cxx
@@ -26,6 +26,7 @@
#include <vcl/filter/PngImageReader.hxx>
#include <vcl/filter/PngImageWriter.hxx>
#include <vcl/BitmapReadAccess.hxx>
+#include <vcl/BitmapMonochromeFilter.hxx>
#include <bitmap/BitmapWriteAccess.hxx>
#include <vcl/alpha.hxx>
#include <vcl/graphicfilter.hxx>
@@ -176,6 +177,7 @@ public:
void testPngRoundtrip24_8();
void testPngRoundtrip32();
void testPngWrite8BitRGBPalette();
+ void testTdf153180MonochromeFilterPngExport();
void testDump();
CPPUNIT_TEST_SUITE(PngFilterTest);
@@ -188,6 +190,7 @@ public:
CPPUNIT_TEST(testPngRoundtrip32);
CPPUNIT_TEST(testPngWrite8BitRGBPalette);
CPPUNIT_TEST(testDump);
+ CPPUNIT_TEST(testTdf153180MonochromeFilterPngExport);
CPPUNIT_TEST_SUITE_END();
};
@@ -1958,6 +1961,56 @@ void PngFilterTest::testPngWrite8BitRGBPalette()
}
}
+void PngFilterTest::testTdf153180MonochromeFilterPngExport()
+{
+ GraphicFilter& rFilter = GraphicFilter::GetGraphicFilter();
+
+ Graphic aGraphicOriginal;
+ {
+ // 3 * 16 bits rgb color alpha, no background chunk
+ const OUString aURL(getFullUrl(u"bgan6a16.png"));
+ SvFileStream aFileStream(aURL, StreamMode::READ);
+ ErrCode aResult = rFilter.ImportGraphic(aGraphicOriginal, aURL,
aFileStream);
+ CPPUNIT_ASSERT_EQUAL(ERRCODE_NONE, aResult);
+ CPPUNIT_ASSERT(aGraphicOriginal.IsAlpha());
+ }
+
+ // Apply the monochrome filter to the graphic but keep the alpha.
+ BitmapEx aBitmapEx(aGraphicOriginal.GetBitmapEx());
+ AlphaMask aAlphaMask(aBitmapEx.GetAlphaMask());
+
+ BitmapEx aTmpBmpEx(aBitmapEx.GetBitmap());
+ BitmapFilter::Filter(aTmpBmpEx, BitmapMonochromeFilter{ sal_uInt8{ 127 }
});
+
+ Graphic aGraphicAfterFilter{ BitmapEx(aTmpBmpEx.GetBitmap(), aAlphaMask) };
+ CPPUNIT_ASSERT(aGraphicAfterFilter.IsAlpha());
+
+ // export the resulting graphic
+ utl::TempFileNamed aTempFile(u"testPngExportTdf153180", true, u".png");
+ if (!bKeepTemp)
+ aTempFile.EnableKillingFile();
+ {
+ SvStream& rStream = *aTempFile.GetStream(StreamMode::WRITE);
+ vcl::PngImageWriter aPngWriter(rStream);
+ bool bWriteSuccess =
aPngWriter.write(aGraphicAfterFilter.GetBitmapEx());
+ CPPUNIT_ASSERT_EQUAL(true, bWriteSuccess);
+ aTempFile.CloseStream();
+ }
+ {
+ SvStream& rStream = *aTempFile.GetStream(StreamMode::READ);
+ rStream.Seek(0);
+ // Import the png and check that it still has alpha
+ Graphic aGraphic;
+ ErrCode aResult = rFilter.ImportGraphic(aGraphic, aTempFile.GetURL(),
rStream);
+ CPPUNIT_ASSERT_EQUAL(ERRCODE_NONE, aResult);
+
+ // Without the accompanying patch would fail with:
+ // assertion failed
+ // -Expression : aGraphic.IsAlpha()
+ CPPUNIT_ASSERT(aGraphic.IsAlpha());
+ }
+}
+
void PngFilterTest::testDump()
{
utl::TempFileNamed aTempFile;
diff --git a/vcl/source/filter/png/PngImageWriter.cxx
b/vcl/source/filter/png/PngImageWriter.cxx
index 35ccefaec2c7..914302223d6a 100644
--- a/vcl/source/filter/png/PngImageWriter.cxx
+++ b/vcl/source/filter/png/PngImageWriter.cxx
@@ -15,15 +15,25 @@
namespace
{
-void combineScanlineChannels(Scanline pRGBScanline, Scanline pAlphaScanline,
+void combineScanlineChannels(Scanline pColorScanline, Scanline pAlphaScanline,
std::vector<std::remove_pointer_t<Scanline>>&
pResult,
- sal_uInt32 nBitmapWidth)
+ sal_uInt32 nBitmapWidth, int colorType)
{
+ if (colorType == PNG_COLOR_TYPE_GRAY_ALPHA)
+ {
+ for (sal_uInt32 i = 0; i < nBitmapWidth; ++i)
+ {
+ pResult[i * 2] = *pColorScanline++; // Gray
+ pResult[i * 2 + 1] = *pAlphaScanline++; // A
+ }
+ return;
+ }
+
for (sal_uInt32 i = 0; i < nBitmapWidth; ++i)
{
- pResult[i * 4] = *pRGBScanline++; // R
- pResult[i * 4 + 1] = *pRGBScanline++; // G
- pResult[i * 4 + 2] = *pRGBScanline++; // B
+ pResult[i * 4] = *pColorScanline++; // R
+ pResult[i * 4 + 1] = *pColorScanline++; // G
+ pResult[i * 4 + 2] = *pColorScanline++; // B
pResult[i * 4 + 3] = *pAlphaScanline++; // A
}
}
@@ -130,7 +140,14 @@ static bool pngWrite(SvStream& rStream, const BitmapEx&
rBitmapEx, int nCompress
if (!aBitmap.HasGreyPalette8Bit())
colorType = PNG_COLOR_TYPE_PALETTE;
else
+ {
colorType = PNG_COLOR_TYPE_GRAY;
+ if (pAlphaAccess)
+ {
+ colorType = PNG_COLOR_TYPE_GRAY_ALPHA;
+ bCombineChannels = true;
+ }
+ }
bitDepth = 8;
break;
}
@@ -222,14 +239,14 @@ static bool pngWrite(SvStream& rStream, const BitmapEx&
rBitmapEx, int nCompress
if (bCombineChannels)
{
auto nBitmapWidth = pAccess->Width();
- // Allocate enough size to fit all 4 channels
- aCombinedChannels.resize(nBitmapWidth * 4);
+ // Allocate enough size to fit all channels
+ aCombinedChannels.resize(nBitmapWidth *
png_get_channels(pPng, pInfo));
Scanline pAlphaPointer = pAlphaAccess->GetScanline(y);
if (!pSourcePointer || !pAlphaPointer)
return false;
- // Combine RGB and alpha channels
+ // Combine color and alpha channels
combineScanlineChannels(pSourcePointer, pAlphaPointer,
aCombinedChannels,
- nBitmapWidth);
+ nBitmapWidth, colorType);
pFinalPointer = aCombinedChannels.data();
// Invert alpha channel (255 - a)
png_set_invert_alpha(pPng);
