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#!/usr/bin/env python
# $URL: http://pypng.googlecode.com/svn/trunk/code/pipcat $
# $Rev: 77 $
# http://www.python.org/doc/2.4.4/lib/module-itertools.html
import itertools
import sys
import png
def cat(out, l):
"""Concatenate the list of images. All input images must be same
height and have the same number of channels. They are concatenated
left-to-right. `out` is the (open file) destination for the
output image. `l` should be a list of open files (the input
image files).
"""
l = map(lambda f: png.Reader(file=f), l)
# Ewgh, side effects.
map(lambda r: r.preamble(), l)
# The reference height; from the first image.
height = l[0].height
# The total target width
width = 0
for i,r in enumerate(l):
if r.height != height:
raise Error('Image %d, height %d, does not match %d.' %
(i, r.height, height))
width += r.width
pixel,info = zip(*map(lambda r: r.asDirect()[2:4], l))
tinfo = dict(info[0])
del tinfo['size']
w = png.Writer(width, height, **tinfo)
def itercat():
for row in itertools.izip(*pixel):
yield itertools.chain(*row)
w.write(out, itercat())
def main(argv):
return cat(sys.stdout, map(lambda n: open(n, 'rb'), argv[1:]))
if __name__ == '__main__':
main(sys.argv)
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