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faster minifyBy2

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This commit is contained in:
Ryan Oldenburg 2021-02-07 20:52:33 -06:00
parent 6df03ed1d1
commit de1b1b95ca
1 changed files with 20 additions and 6 deletions

26
src/pixie/images.nim
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@ -180,12 +180,26 @@ proc minifyBy2*(image: Image, power = 1): Image =
result = newImage(image.width div 2, image.height div 2)
for y in 0 ..< result.height:
for x in 0 ..< result.width:
var color =
image.getRgbaUnsafe(x * 2 + 0, y * 2 + 0).color / 4.0 +
image.getRgbaUnsafe(x * 2 + 1, y * 2 + 0).color / 4.0 +
image.getRgbaUnsafe(x * 2 + 1, y * 2 + 1).color / 4.0 +
image.getRgbaUnsafe(x * 2 + 0, y * 2 + 1).color / 4.0
result.setRgbaUnsafe(x, y, color.rgba)
let
a = image.getRgbaUnsafe(x * 2 + 0, y * 2 + 0)
b = image.getRgbaUnsafe(x * 2 + 1, y * 2 + 0)
c = image.getRgbaUnsafe(x * 2 + 1, y * 2 + 1)
d = image.getRgbaUnsafe(x * 2 + 0, y * 2 + 1)
var values: array[4, uint32]
values[0] = a.r.uint32 + b.r + c.r + d.r
values[1] = a.g.uint32 + b.g + c.g + d.g
values[2] = a.b.uint32 + b.b + c.b + d.b
values[3] = a.a.uint32 + b.a + c.a + d.a
let color = rgba(
(values[0] div 4).uint8,
(values[1] div 4).uint8,
(values[2] div 4).uint8,
(values[3] div 4).uint8
)
result.setRgbaUnsafe(x, y, color)
proc magnifyBy2*(image: Image, power = 1): Image =
## Scales image image up by 2 ^ power.