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#!/usr/bin/env python
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
import png
import sys
import StringIO
import struct
import ctypes
# ref: http://msdn.microsoft.com/en-us/library/ms997538
class ICONDIR(ctypes.LittleEndianStructure):
_pack_ = 1
_fields_ = [("idReserved", ctypes.c_ushort),
("idType", ctypes.c_ushort),
("idCount", ctypes.c_ushort)]
class ICONDIRENTRY(ctypes.LittleEndianStructure):
_pack_ = 1
_fields_ = [("bWidth", ctypes.c_byte),
("bHeight", ctypes.c_byte),
("bColorCount", ctypes.c_byte),
("bReserved", ctypes.c_byte),
("wPlanes", ctypes.c_ushort),
("wBitCount", ctypes.c_ushort),
("dwBytesInRes", ctypes.c_ulong),
("dwImageOffset", ctypes.c_ulong)]
# R, G, B, A, so 4 columns per pixel
COLS_PP = 4
def main(infile, left, top, size, outfile):
img = png.Reader(filename=infile)
pixels = list(img.asRGBA()[2])
# Take the subarray out. This is the ugliest but probably most efficient way
# to do it
outpixels = [[0] * (size * COLS_PP) for x in xrange(size)]
for row in xrange(size):
for col in xrange(size * COLS_PP):
outpixels[row][col] = pixels[top + row][left * COLS_PP + col]
# Set up a 32bpp RGBA PNG.
writer = png.Writer(size=(size, size), bitdepth=8, alpha=True)
# Write to a memory buffer
outpng = StringIO.StringIO()
writer.write(outpng, outpixels)
outpngbuf = outpng.getvalue()
outpng.close()
# Set up an icon header
icondir = ICONDIR()
icondir.idReserved = 0
# Icons are type 1
icondir.idType = 1
icondir.idCount = 1
iconentry = ICONDIRENTRY()
iconentry.bWidth = size
iconentry.bHeight = size
# Truecolor images have color count set to 0
iconentry.bColorCount = 0
iconentry.bReserved = 0
# PNGs have 1 color plane
iconentry.wPlanes = 1
# We're RGBA, so 32 bits per pixel
iconentry.wBitCount = 32
# Length of the buffer
iconentry.dwBytesInRes = len(outpngbuf)
# The data will be right after the icondir and iconentry
iconentry.dwImageOffset = ctypes.sizeof(icondir) + ctypes.sizeof(iconentry)
# Time to write everything out
out = open(outfile, "wb")
out.write(icondir)
out.write(iconentry)
out.write(outpngbuf)
out.close()
if __name__ == "__main__":
# Convert left, top and size into integers
main(*([sys.argv[1]] + [int(val) for val in sys.argv[2:5]] + [sys.argv[5]]))