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fix alpha premultiplying

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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@20194 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin
2003-04-13 14:09:00 +00:00
parent a968cb805f
commit 106c33bb1d
1 changed files with 12 additions and 8 deletions
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20
src/msw/bitmap.cpp
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@@ -1204,24 +1204,28 @@ void wxBitmap::UngetRawData(wxRawBitmapData *data)
// AlphaBlend() wants to have premultiplied source alpha but wxRawBitmap // AlphaBlend() wants to have premultiplied source alpha but wxRawBitmap
// API uses normal, not premultiplied, colours, so adjust them here now // API uses normal, not premultiplied, colours, so adjust them here now
wxRawBitmapIterator p(data); wxRawBitmapIterator p(*data);
unsigned char *pixels = data->GetPixels();
const int w = data->GetWidth(); const int w = data->GetWidth();
const int h = data->GetHeight(); const int h = data->GetHeight();
for ( int y = 0; y < h; y++ ) for ( int y = 0; y < h; y++ )
{ {
wxRawBitmapIterator rowStart = p;
for ( int x = 0; x < w; x++ ) for ( int x = 0; x < w; x++ )
{ {
const unsigned alpha = p.Alpha(); const unsigned alpha = p.Alpha();
p.Red() *= alpha;
p.Red() /= 255 p.Red() = (p.Red() * alpha) / 255;
p.Blue() *= alpha; p.Blue() = (p.Blue() * alpha) / 255;
p.Blue() /= 255 p.Green() = (p.Green() * alpha) / 255;
p.Green() *= alpha;
p.Green() /= 255 ++p;
} }
p = rowStart;
p.OffsetY(1);
} }
} }