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much faster

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This commit is contained in:
Ryan Oldenburg 2020-11-21 18:19:16 -06:00
parent dbf6a481c4
commit 641b2b79fa
1 changed files with 28 additions and 15 deletions
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43
src/pixie/fileformats/png.nim
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@ -217,22 +217,35 @@ proc decodeImageData(
inc bytePos
bitPos = 0
of 2:
let special =
if transparency.len == 6:
ColorRGBA(
r: transparency[1], g: transparency[3], b: transparency[5], a: 255
)
else:
ColorRGBA()
var bytePos: int
for y in 0 ..< header.height:
for x in 0 ..< header.width:
let rgb = cast[ptr array[3, uint8]](unfiltered[bytePos].unsafeAddr)[]
var rgba = ColorRGBA(r: rgb[0], g: rgb[1], b: rgb[2], a: 255)
if transparency.len == 6:
# Need to apply transparency check, slower.
let special = [transparency[1], transparency[3], transparency[5], 255]
# While we can read an extra byte safely, do so. Much faster.
for i in 0 ..< header.height * header.width - 1:
var rgba = cast[ptr array[4, uint8]](unfiltered[i * 3].unsafeAddr)[]
rgba[3] = 255
if rgba == special:
rgba.a = 0
result[x + y * header.width] = rgba
bytePos += 3
rgba[3] = 0
result[i] = cast[ColorRGBA](rgba)
let
lastOffset = header.height * header.width - 1
rgb = cast[ptr array[3, uint8]](unfiltered[lastOffset * 3].unsafeAddr)[]
var rgba = [rgb[0], rgb[1], rgb[2], 255]
if rgba == special:
rgba[3] = 0
result[header.height * header.width - 1] = cast[ColorRGBA](rgba)
else:
# While we can read an extra byte safely, do so. Much faster.
for i in 0 ..< header.height * header.width - 1:
var rgba = cast[ptr array[4, uint8]](unfiltered[i * 3].unsafeAddr)[]
rgba[3] = 255
result[i] = cast[ColorRGBA](rgba)
let
lastOffset = header.height * header.width - 1
rgb = cast[ptr array[3, uint8]](unfiltered[lastOffset * 3].unsafeAddr)[]
result[header.height * header.width - 1] = ColorRGBA(
r: rgb[0], g: rgb[1], b: rgb[2], a: 255
)
of 3:
var bytePos, bitPos: int
for y in 0 ..< header.height: