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Merge pull request #85 from guzba/master

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triple blend when needed
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treeform 2021-01-29 20:18:21 -08:00 committed by GitHub
commit 9a80484bc8
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 19 additions and 3 deletions
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22
src/pixie/blends.nim
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@ -57,6 +57,22 @@ proc hardLightPremultiplied(backdrop, source: uint32): uint8 {.inline.} =
proc blendAlpha(backdrop, source: uint8): uint8 {.inline.} =
source + ((backdrop.uint32 * (255 - source)) div 255).uint8
proc tripleBlend(result: var ColorRGBA, backdrop, source: ColorRGBA) =
result.a = blendAlpha(backdrop.a, source.a)
if result.a == 0:
result = rgba(0, 0, 0, 0)
else:
let
t0 = (255 - backdrop.a.uint32) * source.a.uint32
t1 = (255 - source.a.uint32) * backdrop.a.uint32
t2 = 255.uint32 * 255
r = t0 * source.r + t1 * backdrop.r + t2 * result.r
g = t0 * source.g + t1 * backdrop.g + t2 * result.g
b = t0 * source.b + t1 * backdrop.b + t2 * result.b
result.r = (r div 255 div result.a).uint8
result.g = (g div 255 div result.a).uint8
result.b = (b div 255 div result.a).uint8
proc blendNormalPremultiplied*(backdrop, source: ColorRGBA): ColorRGBA {.inline.} =
if backdrop.a == 0:
return source
@ -75,13 +91,13 @@ proc blendDarkenPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = min(backdrop.r, source.r)
result.g = min(backdrop.g, source.g)
result.b = min(backdrop.b, source.b)
result.a = blendAlpha(backdrop.a, source.a)
result.tripleBlend(backdrop, source)
proc blendMultiplyPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = ((backdrop.r.uint32 * source.r) div 255).uint8
result.g = ((backdrop.g.uint32 * source.g) div 255).uint8
result.b = ((backdrop.b.uint32 * source.b) div 255).uint8
result.a = blendAlpha(backdrop.a, source.a)
result.tripleBlend(backdrop, source)
proc blendLinearBurnPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = min(0, backdrop.r.uint32 + source.r.uint32 - 255).uint8
@ -106,7 +122,7 @@ proc blendColorBurnPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = blend(backdrop.r, source.r)
result.g = blend(backdrop.g, source.g)
result.b = blend(backdrop.b, source.b)
result.a = blendAlpha(backdrop.a, source.a)
result.tripleBlend(backdrop, source)
proc blendScreenPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = screenPremultiplied(backdrop.r, source.r)