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This commit is contained in:
Ryan Oldenburg 2022-06-15 16:02:43 -05:00
parent 03c6ee1411
commit 6d2c681a64
1 changed files with 11 additions and 8 deletions
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19
src/pixie/fileformats/png.nim
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@ -93,9 +93,9 @@ proc decodePalette(data: pointer, len: int): seq[ColorRGB] =
copyMem(result[0].addr, data, len)
proc unfilter(
uncompressed: string, height, rowBytes, bpp: int
uncompressed: pointer, len, height, rowBytes, bpp: int
): seq[uint8] =
result.setLen(uncompressed.len - height)
result.setLen(len - height)
template uncompressedIdx(x, y: int): int =
x + y * (rowBytes + 1)
@ -103,9 +103,11 @@ proc unfilter(
template unfiteredIdx(x, y: int): int =
x + y * rowBytes
let uncompressed = cast[ptr UncheckedArray[uint8]](uncompressed)
# Unfilter the image data
for y in 0 ..< height:
let filterType = uncompressed.readUint8(uncompressedIdx(0, y))
let filterType = uncompressed[uncompressedIdx(0, y)]
case filterType:
of 0: # None
copyMem(
@ -118,7 +120,7 @@ proc unfilter(
uncompressedStartIdx = uncompressedIdx(1, y)
unfilteredStartIx = unfiteredIdx(0, y)
for x in 0 ..< rowBytes:
var value = uncompressed.readUint8(uncompressedStartIdx + x)
var value = uncompressed[uncompressedStartIdx + x]
if x - bpp >= 0:
value += result[unfilteredStartIx + x - bpp]
result[unfilteredStartIx + x] = value
@ -127,7 +129,7 @@ proc unfilter(
uncompressedStartIdx = uncompressedIdx(1, y)
unfilteredStartIx = unfiteredIdx(0, y)
for x in 0 ..< rowBytes:
var value = uncompressed.readUint8(uncompressedStartIdx + x)
var value = uncompressed[uncompressedStartIdx + x]
if y - 1 >= 0:
value += result[unfilteredStartIx + x - rowBytes]
result[unfilteredStartIx + x] = value
@ -137,7 +139,7 @@ proc unfilter(
unfilteredStartIx = unfiteredIdx(0, y)
for x in 0 ..< rowBytes:
var
value = uncompressed.readUint8(uncompressedStartIdx + x)
value = uncompressed[uncompressedStartIdx + x]
left, up: uint32
if x - bpp >= 0:
left = result[unfilteredStartIx + x - bpp]
@ -151,7 +153,7 @@ proc unfilter(
unfilteredStartIx = unfiteredIdx(0, y)
for x in 0 ..< rowBytes:
var
value = uncompressed.readUint8(uncompressedStartIdx + x)
value = uncompressed[uncompressedStartIdx + x]
left, up, upLeft: int
if x - bpp >= 0:
left = result[unfilteredStartIx + x - bpp].int
@ -220,7 +222,8 @@ proc decodeImageData(
failInvalid()
let unfiltered = unfilter(
uncompressed,
uncompressed.cstring,
uncompressed.len,
header.height,
rowBytes,
max(valuesPerPixel div valuesPerByte, 1)