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nimPNG
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Merge pull request #2 from jangko/filter_bug 

fixed #1
This commit is contained in:
andri lim 2016-01-18 09:11:58 +07:00
parent 9b366da376 8e492e0f90
commit 42fd94a28e
1 changed files with 12 additions and 13 deletions
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nimPNG.nim
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@ -2096,7 +2096,7 @@ method writeChunk(chunk: PNGSPalette, png: PNG): bool =
chunk.writeInt16(p.alpha)
chunk.writeInt16(p.frequency)
result = true
method writeChunk(chunk: PNGHist, png: PNG): bool =
#estimate chunk.histogram.len * 2
for c in chunk.histogram:
@ -2155,7 +2155,7 @@ method writeChunk(chunk: PNGICCProfile, png: PNG): bool =
var nz = nzDeflateInit(chunk.profile)
chunk.writeString zlib_compress(nz)
result = true
proc isGreyscaleType(mode: PNGColorMode): bool =
result = mode.colorType in {LCT_GREY, LCT_GREY_ALPHA}
@ -2376,42 +2376,41 @@ proc addPaddingBits(output: var cstring, input: cstring, olinebits, ilinebits, h
for x in 0..diff-1: setBitOfReversedStream(obp, output, 0)
proc filterScanLine(output: var cstring, scanLine, prevLine: cstring, len, byteWidth: int, filterType: PNGFilter0) =
case filterType
of FLT_NONE:
for i in 0..len-1: output[i] = scanLine[i]
of FLT_SUB:
for i in 0..byteWidth-1: output[i] = scanLine[i]
for i in byteWidth..len-1:
output[i] = chr(scanLine[i].uint8 - scanLine[i - byteWidth].uint8)
output[i] = chr(scanLine[i].uint - scanLine[i - byteWidth].uint)
of FLT_UP:
if prevLine != nil:
for i in 0..len-1:
output[i] = chr(scanLine[i].uint8 - prevLine[i].uint8)
output[i] = chr(scanLine[i].uint - prevLine[i].uint)
else:
for i in 0..len-1: output[i] = scanLine[i]
of FLT_AVERAGE:
if prevLine != nil:
for i in 0..byteWidth-1:
output[i] = chr(scanLine[i].uint8 - (prevLine[i].uint8 div 2))
output[i] = chr(scanLine[i].uint - (prevLine[i].uint div 2))
for i in byteWidth..len-1:
output[i] = chr(scanLine[i].uint8 - ((scanLine[i - byteWidth].uint8 + prevLine[i].uint8) div 2))
output[i] = chr(scanLine[i].uint - ((scanLine[i - byteWidth].uint + prevLine[i].uint) div 2))
else:
for i in 0..byteWidth-1: output[i] = scanLine[i]
for i in byteWidth..len-1:
output[i] = chr(scanLine[i].uint8 - (scanLine[i - byteWidth].uint8 div 2))
output[i] = chr(scanLine[i].uint - (scanLine[i - byteWidth].uint div 2))
of FLT_PAETH:
if prevLine != nil:
#paethPredictor(0, prevLine[i], 0) is always prevLine[i]
for i in 0..byteWidth-1:
output[i] = chr(scanLine[i].uint8 - prevLine[i].uint8)
output[i] = chr(scanLine[i].uint - prevLine[i].uint)
for i in byteWidth..len-1:
output[i] = chr(scanLine[i].uint8 - paethPredictor(ord(scanLine[i - byteWidth]), ord(prevLine[i]), ord(prevLine[i - byteWidth])).uint8)
output[i] = chr(scanLine[i].uint - paethPredictor(ord(scanLine[i - byteWidth]), ord(prevLine[i]), ord(prevLine[i - byteWidth])).uint)
else:
for i in 0..byteWidth-1: output[i] = scanLine[i]
#paethPredictor(scanLine[i - byteWidth], 0, 0) is always scanLine[i - byteWidth]
for i in byteWidth..len-1:
output[i] = chr(scanLine[i].uint8 - scanLine[i - byteWidth].uint8)
output[i] = chr(scanLine[i].uint - scanLine[i - byteWidth].uint)
else:
raise PNGError("unsupported fitler type")
@ -2947,10 +2946,10 @@ proc savePNG*(fileName, input: string, colorType: PNGcolorType, bitDepth, w, h:
except:
debugEcho getCurrentExceptionMsg()
result = false
proc savePNG32*(fileName, input: string, w, h: int): bool =
result = savePNG(fileName, input, LCT_RGBA, 8, w, h)
proc savePNG24*(fileName, input: string, w, h: int): bool =
result = savePNG(fileName, input, LCT_RGB, 8, w, h)