diff options
| author | Michael Meeks <michael.meeks@collabora.com> | 2014-11-17 06:37:06 +0000 |
|---|---|---|
| committer | Michael Meeks <michael.meeks@collabora.com> | 2014-11-17 06:40:56 +0000 |
| commit | 18c50cefd761efe71a5e6957422ed6f153e6ba34 (patch) | |
| tree | a25fdf0e95f695b14694b64b04b57942afc47bcb /vcl/workben | |
| parent | 691402155ef119fa89d1e09d3bde1f7d063a9941 (diff) | |
vcldemo: improve my rather trivial inferred alpha maths.
Change-Id: I420628cea2272d6f5af0b13b9c32902627dcf86f
Diffstat (limited to 'vcl/workben')
| -rw-r--r-- | vcl/workben/vcldemo.cxx | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/vcl/workben/vcldemo.cxx b/vcl/workben/vcldemo.cxx index 7ccde7cab3b9..94d549247410 100644 --- a/vcl/workben/vcldemo.cxx +++ b/vcl/workben/vcldemo.cxx @@ -798,16 +798,25 @@ public: // we get the most precision from the largest delta long nInverseAlpha = std::max(nAR, std::max(nAG, nAB)); // (1-a) nInverseAlpha = CLAMP(nInverseAlpha, 0, 255); + long nAlpha = 255 - nInverseAlpha; pMaskAcc->SetPixel(y,x,BitmapColor((sal_Int8)CLAMP(nInverseAlpha,0,255))); // now recover the pixels - long n2R = aColW.GetRed() + aColB.GetRed(); - long n2G = aColW.GetGreen() + aColB.GetGreen(); - long n2B = aColW.GetBlue() + aColB.GetBlue(); + long nR = (aColW.GetRed() + aColB.GetRed() - nInverseAlpha) * 128; + long nG = (aColW.GetGreen() + aColB.GetGreen() - nInverseAlpha) * 128; + long nB = (aColW.GetBlue() + aColB.GetBlue() - nInverseAlpha) * 128; + if (nAlpha == 0) + { // doesn't matter what's behind transparency + nR = nG = nB = 0; + } + else + { + nR /= nAlpha; nG /= nAlpha; nB /= nAlpha; + } pRecAcc->SetPixel(y,x,BitmapColor( - (sal_uInt8)CLAMP((n2R+1)/2-nInverseAlpha,0,255), - (sal_uInt8)CLAMP((n2G+1)/2-nInverseAlpha,0,255), - (sal_uInt8)CLAMP((n2B+1)/2-nInverseAlpha,0,255))); + (sal_uInt8)CLAMP(nR,0,255), + (sal_uInt8)CLAMP(nG,0,255), + (sal_uInt8)CLAMP(nB,0,255))); #undef CLAMP } } |