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This commit is contained in:
Ryan Oldenburg 2021-02-25 15:13:14 -06:00
parent f139c5dc79
commit b623150b3f
1 changed files with 23 additions and 17 deletions
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40
src/pixie/images.nim
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@ -218,7 +218,7 @@ proc toPremultipliedAlpha*(image: Image) =
# When supported, SIMD convert as much as possible
let
alphaMask = mm_set1_epi32(cast[int32](0xff000000))
alphaMaskComp = mm_set1_epi32(0x00ffffff)
notAlphaMask = mm_set1_epi32(0x00ffffff)
oddMask = mm_set1_epi16(cast[int16](0xff00))
div255 = mm_set1_epi16(cast[int16](0x8081))
@ -226,31 +226,37 @@ proc toPremultipliedAlpha*(image: Image) =
var
color = mm_loadu_si128(image.data[j].addr)
alpha = mm_and_si128(color, alphaMask)
colorEven = mm_slli_epi16(color, 8)
colorOdd = mm_and_si128(color, oddMask)
alpha = mm_or_si128(alpha, mm_srli_epi32(alpha, 16))
let eqOpaque = mm_cmpeq_epi16(alpha, alphaMask)
if mm_movemask_epi8(eqOpaque) != 0xffff:
# If not all of the alpha values are 255, premultiply
var
colorEven = mm_slli_epi16(color, 8)
colorOdd = mm_and_si128(color, oddMask)
colorEven = mm_mulhi_epu16(colorEven, alpha)
colorOdd = mm_mulhi_epu16(colorOdd, alpha)
alpha = mm_or_si128(alpha, mm_srli_epi32(alpha, 16))
colorEven = mm_srli_epi16(mm_mulhi_epu16(colorEven, div255), 7)
colorOdd = mm_srli_epi16(mm_mulhi_epu16(colorOdd, div255), 7)
colorEven = mm_mulhi_epu16(colorEven, alpha)
colorOdd = mm_mulhi_epu16(colorOdd, alpha)
color = mm_or_si128(colorEven, mm_slli_epi16(colorOdd, 8))
color = mm_or_si128(
mm_and_si128(alpha, alphaMask), mm_and_si128(color, alphaMaskComp)
)
colorEven = mm_srli_epi16(mm_mulhi_epu16(colorEven, div255), 7)
colorOdd = mm_srli_epi16(mm_mulhi_epu16(colorOdd, div255), 7)
mm_storeu_si128(image.data[j].addr, color)
color = mm_or_si128(colorEven, mm_slli_epi16(colorOdd, 8))
color = mm_or_si128(
mm_and_si128(alpha, alphaMask), mm_and_si128(color, notAlphaMask)
)
mm_storeu_si128(image.data[j].addr, color)
i += 4
# Convert whatever is left
for j in i ..< image.data.len:
var c = image.data[j]
c.r = ((c.r.uint32 * c.a.uint32) div 255).uint8
c.g = ((c.g.uint32 * c.a.uint32) div 255).uint8
c.b = ((c.b.uint32 * c.a.uint32) div 255).uint8
image.data[j] = c
if c.a != 255:
c.r = ((c.r.uint32 * c.a.uint32) div 255).uint8
c.g = ((c.g.uint32 * c.a.uint32) div 255).uint8
c.b = ((c.b.uint32 * c.a.uint32) div 255).uint8
image.data[j] = c
proc toStraightAlpha*(image: Image) =
## Converts an image from premultiplied alpha to straight alpha.