text: #!/usr/bin/env python3
  # Copyright (c) 2014-2018 The Bitcoin Core developers
  # Copyright (c) 2010-2021 The Freicoin Developers
  #
  # This program is free software: you can redistribute it and/or modify it under
  # the terms of version 3 of the GNU Affero General Public License as published
  # by the Free Software Foundation.
  #
  # 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 Affero General Public License for more
  # details.
  #
  # You should have received a copy of the GNU Affero General Public License
  # along with this program.  If not, see <https://www.gnu.org/licenses/>.
  '''
  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  # pip3 install Pillow
  
  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'], universal_newlines=True, encoding='utf8').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 {}...".format(file), end =' ')
              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)
  
              try:
                  subprocess.call([pngcrush, "-brute", "-ow", "-rem", "gAMA", "-rem", "cHRM", "-rem", "iCCP", "-rem", "sRGB", "-rem", "alla", "-rem", "text", file_path],
                                  stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
              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, universal_newlines=True, encoding='utf8'):
                  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 {} before and after crushing don't match".format(file))
                  sys.exit(1)
  
              fileMetaMap['psize'] = os.path.getsize(file_path)
              outputArray.append(fileMetaMap)
              print("done")
  
  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")
  