提取iOS App中的png图片资源(转)

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#---
# 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"
print "-----------------------------------"
print " "
print "[+] Searching PNG files...",
dirs, pngs = getFiles(".")
print "ok"

if len(pngs) == 0:
print " "
print "[!] Alert: There are no PNG files found. Move this python file to the folder that contains the PNG files to normalize."
exit()

print " "
print " -  %d PNG files were found at this folder (and subfolders)." % len(pngs)
print " "
while True:
normalize = raw_input("[?] Do you want to normalize all images (Y/N)? ").lower()
if len(normalize) > 0 and (normalize[0] == "y" or normalize[0] == "n"):
break

normalized = 0
if normalize[0] == "y":
for  ipng in xrange(len(pngs)):
perc = (float(ipng) / len(pngs)) * 100.0
print "%.2f%% %s" % (perc, pngs[ipng])
if updatePNG(pngs[ipng]):
normalized += 1
print " "
print "[+] %d PNG files were normalized." % normalized