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explicit names instead of alphy shorthand

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This commit is contained in:
Ryan Oldenburg 2021-01-24 18:40:26 -06:00
parent 45fe8bd9ea
commit 9e834ce8e4
3 changed files with 13 additions and 13 deletions
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8
src/pixie/common.nim
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@ -16,14 +16,14 @@ proc lerp*(a, b: ColorRGBA, t: float32): ColorRGBA {.inline.} =
result.b = ((a.b.uint32 * (255 - x) + b.b.uint32 * x) div 255).uint8
result.a = ((a.a.uint32 * (255 - x) + b.a.uint32 * x) div 255).uint8
proc premultiplyAlpha*(c: ColorRGBA): ColorRGBA {.inline.} =
proc toPremultipliedAlpha*(c: ColorRGBA): ColorRGBA {.inline.} =
## Converts a color to premultiplied alpha from straight alpha.
result.r = ((c.r.uint16 * c.a.uint16) div 255).uint8
result.g = ((c.g.uint16 * c.a.uint16) div 255).uint8
result.b = ((c.b.uint16 * c.a.uint16) div 255).uint8
result.a = c.a
proc straightenAlpha*(c: ColorRGBA): ColorRGBA {.inline.} =
proc toStraightAlpha*(c: ColorRGBA): ColorRGBA {.inline.} =
## Converts a color to from premultiplied alpha to straight alpha.
result = c
if result.a != 0 and result.a != 255:
@ -38,14 +38,14 @@ func lerp*(a, b: Color, v: float32): Color {.inline.} =
result.b = lerp(a.b, b.b, v)
result.a = lerp(a.a, b.a, v)
proc toAlphy*(c: Color): Color {.inline.} =
proc toPremultipliedAlpha*(c: Color): Color {.inline.} =
## Converts a color to premultiplied alpha from straight.
result.r = c.r * c.a
result.g = c.g * c.a
result.b = c.b * c.a
result.a = c.a
proc fromAlphy*(c: Color): Color {.inline.} =
proc toStraightAlpha*(c: Color): Color {.inline.} =
## Converts a color to from premultiplied alpha to straight.
if c.a == 0:
return

14
src/pixie/images.nim
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@ -175,7 +175,7 @@ proc magnifyBy2*(image: Image): Image =
when defined(release):
{.pop.}
proc toAlphy*(image: Image) =
proc toPremultipliedAlpha*(image: Image) =
## Converts an image to premultiplied alpha from straight.
var i: int
when defined(amd64) and not defined(pixieNoSimd):
@ -217,7 +217,7 @@ proc toAlphy*(image: Image) =
c.b = ((c.b.uint32 * c.a.uint32) div 255).uint8
image.data[j] = c
proc fromAlphy*(image: Image) =
proc toStraightAlpha*(image: Image) =
## Converts an image from premultiplied alpha to straight alpha.
## This is expensive for large images.
for c in image.data.mitems:
@ -256,16 +256,16 @@ proc getRgbaSmooth*(image: Image, x, y: float32): ColorRGBA {.inline.} =
minY = y.floor.int
difY = y - y.floor
vX0Y0 = image[minX, minY].premultiplyAlpha()
vX1Y0 = image[minX + 1, minY].premultiplyAlpha()
vX0Y1 = image[minX, minY + 1].premultiplyAlpha()
vX1Y1 = image[minX + 1, minY + 1].premultiplyAlpha()
vX0Y0 = image[minX, minY].toPremultipliedAlpha()
vX1Y0 = image[minX + 1, minY].toPremultipliedAlpha()
vX0Y1 = image[minX, minY + 1].toPremultipliedAlpha()
vX1Y1 = image[minX + 1, minY + 1].toPremultipliedAlpha()
bottomMix = lerp(vX0Y0, vX1Y0, difX)
topMix = lerp(vX0Y1, vX1Y1, difX)
finalMix = lerp(bottomMix, topMix, difY)
finalMix.straightenAlpha()
finalMix.toStraightAlpha()
proc resize*(srcImage: Image, width, height: int): Image =
result = newImage(width, height)

4
tests/test_images.nim
View file

@ -19,13 +19,13 @@ block:
block:
let image = newImage(10, 10)
image.fill(rgba(255, 0, 0, 128))
image.toAlphy()
image.toPremultipliedAlpha()
doAssert image[9, 9] == rgba(128, 0, 0, 128)
block:
let image = newImage(10, 10)
image.fill(rgba(128, 0, 0, 128))
image.fromAlphy()
image.toStraightAlpha()
doAssert image[9, 9] == rgba(254, 0, 0, 128)
block: