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Added consideration of alpha channels of original colors when blending (#659)

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Bagomot 2023-05-19 17:54:02 +03:00 committed by GitHub
parent 76daac9bf1
commit 9b0e0a4bfa
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1 changed files with 10 additions and 5 deletions
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15
src/dlangui/graphics/colors.d
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@ -25,7 +25,6 @@ import std.algorithm;
import std.traits;
import std.conv;
import std.range;
import dimage.jpeg;
/// special color constant to identify value as not a color (to use default/parent value instead)
immutable uint COLOR_UNSPECIFIED = 0xFFDEADFF;
@ -191,20 +190,26 @@ uint makeRGBA(T)(T r, T g, T b, T a) pure nothrow {
/// blend two RGB pixels using alpha
uint blendARGB(uint dst, uint src, uint alpha) pure nothrow {
uint dstalpha = dst >> 24;
if (dstalpha > 0x80)
return src;
uint srca = (src >> 24) & 0xFF;
uint dsta = (dst >> 24) & 0xFF;
uint srcr = (src >> 16) & 0xFF;
uint srcg = (src >> 8) & 0xFF;
uint srcb = (src >> 0) & 0xFF;
uint dstr = (dst >> 16) & 0xFF;
uint dstg = (dst >> 8) & 0xFF;
uint dstb = (dst >> 0) & 0xFF;
uint ialpha = 255 - alpha;
uint r = ((srcr * ialpha + dstr * alpha) >> 8) & 0xFF;
uint g = ((srcg * ialpha + dstg * alpha) >> 8) & 0xFF;
uint b = ((srcb * ialpha + dstb * alpha) >> 8) & 0xFF;
return (r << 16) | (g << 8) | b;
uint a = ((srca * ialpha + dsta * alpha) >> 8) & 0xFF;
return (a << 24) | (r << 16) | (g << 8) | b;
}
//immutable int[3] COMPONENT_OFFSET_BGR = [2, 1, 0];