60 lines
2.0 KiB
Python
60 lines
2.0 KiB
Python
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#!/usr/bin/python3
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import sys
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import struct
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import PIL.Image
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_, inpath, outpath = sys.argv
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image = PIL.Image.open(inpath)
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assert image.mode == "RGBA", "image mode is "+image.mode
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# We measure width and height prior to the rotation
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width, height = image.width, image.height
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image = image.transpose(PIL.Image.Transpose.ROTATE_270)
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with open(outpath, "wb") as out:
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out.write(struct.pack("=HH", width, height))
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for channel in "BGRA":
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pixelbytes = image.getchannel(channel).tobytes()
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def rlegroups():
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curpixel=None
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count=0
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litrun = b""
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for pixel in pixelbytes:
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if curpixel is None:
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curpixel = pixel
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count = 1
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elif curpixel != pixel:
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assert count > 0
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if count <= 2:
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if len(litrun)+count > 127:
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assert len(litrun) > 0
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yield litrun
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litrun = b""
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litrun += bytes([curpixel]) * count
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else:
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if litrun != b"":
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assert len(litrun) > 0
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yield litrun
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litrun = b""
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yield (curpixel, count)
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curpixel = pixel
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count = 1
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else:
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count += 1
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if litrun != b"":
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assert len(litrun) > 0
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yield litrun
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if count > 0:
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yield (curpixel, count)
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for group in rlegroups():
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if type(group) == bytes:
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out.write(struct.pack("=B", len(group)+128) + group)
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else:
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pixel, count = group
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assert count > 0
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if count >= 128:
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out.write(struct.pack("=BIB", 0, count, pixel))
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else:
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out.write(struct.pack("=BB", count, pixel))
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