将iPhone的png图片转换为可读png图片的Python源码

本段将iPhone的png图片转换为可读png图片的Python源码来自国外网站（代码注释里也能看到），原文地址 http://www.axelbrz.com.ar/?mod=iphone-png-images-normalizer
#---

# iPIN - iPhone PNG Images Normalizer v1.0

# Copyright (C) 2007

#

# Author:

# Axel E. Brzostowski

# http://www.axelbrz.com.ar/
# axelbrz@gmail.com

#

# References:

# http://iphone.fiveforty.net/wiki/index.php/PNG_Images
# http://www.libpng.org/pub/png/spec/1.2/PNG-Contents.html
#

# This program is free software: you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation, either version 3 of the License.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

# GNU General Public License for more details.

#

#---
from struct import *

from zlib import *

import stat

import sys

import os
def getNormalizedPNG(filename):

pngheader = "\x89PNG\r\n\x1a\n"



file = open(filename, "rb")

oldPNG = file.read()

file.close()
if oldPNG[:8] != pngheader:

return None



newPNG = oldPNG[:8]



chunkPos = len(newPNG)



# For each chunk in the PNG file

while chunkPos < len(oldPNG):



# Reading chunk

chunkLength = oldPNG[chunkPos:chunkPos+4]

chunkLength = unpack(">L", chunkLength)[0]

chunkType = oldPNG[chunkPos+4 : chunkPos+8]

chunkData = oldPNG[chunkPos+8:chunkPos+8+chunkLength]

chunkCRC = oldPNG[chunkPos+chunkLength+8:chunkPos+chunkLength+12]

chunkCRC = unpack(">L", chunkCRC)[0]

chunkPos += chunkLength + 12
# Parsing the header chunk

if chunkType == "IHDR":

width = unpack(">L", chunkData[0:4])[0]

height = unpack(">L", chunkData[4:8])[0]
# Parsing the image chunk

if chunkType == "IDAT":

try:

# Uncompressing the image chunk

bufSize = width * height * 4 + height

chunkData = decompress( chunkData, -8, bufSize)



except Exception, e:

# The PNG image is normalized

return None
# Swapping red & blue bytes for each pixel

newdata = ""

for y in xrange(height):

i = len(newdata)

newdata += chunkData[i]

for x in xrange(width):

i = len(newdata)

newdata += chunkData[i+2]

newdata += chunkData[i+1]

newdata += chunkData[i+0]

newdata += chunkData[i+3]
# Compressing the image chunk

chunkData = newdata

chunkData = compress( chunkData )

chunkLength = len( chunkData )

chunkCRC = crc32(chunkType)

chunkCRC = crc32(chunkData, chunkCRC)

chunkCRC = (chunkCRC + 0x100000000) % 0x100000000
# Removing CgBI chunk

if chunkType != "CgBI":

newPNG += pack(">L", chunkLength)

newPNG += chunkType

if chunkLength > 0:

newPNG += chunkData

newPNG += pack(">L", chunkCRC)
# Stopping the PNG file parsing

if chunkType == "IEND":

break



return newPNG
def updatePNG(filename):

data = getNormalizedPNG(filename)

if data != None:

file = open(filename, "wb")

file.write(data)

file.close()

return True

return data
def getFiles(base):

global _dirs

global _pngs

if base == ".":

_dirs = []

_pngs = []



if base in _dirs:

return
files = os.listdir(base)

for file in files:

filepath = os.path.join(base, file)

try:

st = os.lstat(filepath)

except os.error:

continue



if stat.S_ISDIR(st.st_mode):

if not filepath in _dirs:

getFiles(filepath)

_dirs.append( filepath )



elif file[-4:].lower() == ".png":

if not filepath in _pngs:

_pngs.append( filepath )



if base == ".":

return _dirs, _pngs
print "-----------------------------------"

print " iPhone PNG Images Normalizer v1.0"