text: #!/usr/bin/env python
  # Copyright (c) 2014-2017 The Crowncoin Core developers
  # Distributed under the MIT software license, see the accompanying
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  '''
  Run this script every time you change one of the png files. Using pngcrush, it will optimize the png files, remove various color profiles, remove ancillary chunks (alla) and text chunks (text).
  #pngcrush -brute -ow -rem gAMA -rem cHRM -rem iCCP -rem sRGB -rem alla -rem text
  '''
  import os
  import sys
  import subprocess
  import hashlib
  from PIL import Image
  
  def file_hash(filename):
      '''Return hash of raw file contents'''
      with open(filename, 'rb') as f:
          return hashlib.sha256(f.read()).hexdigest()
  
  def content_hash(filename):
      '''Return hash of RGBA contents of image'''
      i = Image.open(filename)
      i = i.convert('RGBA')
      data = i.tobytes()
      return hashlib.sha256(data).hexdigest()
  
  pngcrush = 'pngcrush'
  git = 'git'
  folders = ["src/qt/res/movies", "src/qt/res/icons", "share/pixmaps"]
  basePath = subprocess.check_output([git, 'rev-parse', '--show-toplevel']).rstrip('\n')
  totalSaveBytes = 0
  noHashChange = True
  
  outputArray = []
  for folder in folders:
      absFolder=os.path.join(basePath, folder)
      for file in os.listdir(absFolder):
          extension = os.path.splitext(file)[1]
          if extension.lower() == '.png':
              print("optimizing "+file+"..."),
              file_path = os.path.join(absFolder, file)
              fileMetaMap = {'file' : file, 'osize': os.path.getsize(file_path), 'sha256Old' : file_hash(file_path)}
              fileMetaMap['contentHashPre'] = content_hash(file_path)
          
              pngCrushOutput = ""
              try:
                  pngCrushOutput = subprocess.check_output(
                          [pngcrush, "-brute", "-ow", "-rem", "gAMA", "-rem", "cHRM", "-rem", "iCCP", "-rem", "sRGB", "-rem", "alla", "-rem", "text", file_path],
                          stderr=subprocess.STDOUT).rstrip('\n')
              except:
                  print "pngcrush is not installed, aborting..."
                  sys.exit(0)
          
              #verify
              if "Not a PNG file" in subprocess.check_output([pngcrush, "-n", "-v", file_path], stderr=subprocess.STDOUT):
                  print "PNG file "+file+" is corrupted after crushing, check out pngcursh version"
                  sys.exit(1)
              
              fileMetaMap['sha256New'] = file_hash(file_path)
              fileMetaMap['contentHashPost'] = content_hash(file_path)
  
              if fileMetaMap['contentHashPre'] != fileMetaMap['contentHashPost']:
                  print "Image contents of PNG file "+file+" before and after crushing don't match"
                  sys.exit(1)
  
              fileMetaMap['psize'] = os.path.getsize(file_path)
              outputArray.append(fileMetaMap)
              print("done\n"),
  
  print "summary:\n+++++++++++++++++"
  for fileDict in outputArray:
      oldHash = fileDict['sha256Old']
      newHash = fileDict['sha256New']
      totalSaveBytes += fileDict['osize'] - fileDict['psize']
      noHashChange = noHashChange and (oldHash == newHash)
      print fileDict['file']+"\n  size diff from: "+str(fileDict['osize'])+" to: "+str(fileDict['psize'])+"\n  old sha256: "+oldHash+"\n  new sha256: "+newHash+"\n"
      
  print "completed. Checksum stable: "+str(noHashChange)+". Total reduction: "+str(totalSaveBytes)+" bytes"
  