Added script optimize-ico-files.

tools/resources/optimize-ico-files.py

Index: tools/resources/optimize-ico-files.py
diff --git a/tools/resources/optimize-ico-files.py b/tools/resources/optimize-ico-files.py
new file mode 100755
index 0000000000000000000000000000000000000000..fcd9f5368fdffce45d01d6dac73a61ab16d6db6f
--- /dev/null
+++ b/tools/resources/optimize-ico-files.py
@@ -0,0 +1,183 @@
+#!/usr/bin/env python
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Windows ICO file crusher.
+
+Optimizes the PNG images within a Windows ICO icon file. This extracts all of
+the sub-images within the file, runs any PNG-formatted images through
+optimize-png-files.sh, then packs them back into an ICO file.
+
+NOTE: ICO files can contain both raw uncompressed BMP files and PNG files. This
+script does not touch the BMP files, which means if you have a huge uncompressed
+image, it will not get smaller. 256x256 icons should be PNG-formatted first.
+(Smaller icons should be BMPs for compatibility with Windows XP.)
+"""
+
+import argparse
+import logging
+import os
+import StringIO
+import struct
+import subprocess
+import sys
+import tempfile
+
+OPTIMIZE_PNG_FILES = 'tools/resources/optimize-png-files.sh'
+
+logging.basicConfig(level=logging.INFO, format='%(levelname)s: %(message)s')
+
+class InvalidFile(Exception):
+  """Represents an invalid ICO file."""
+
+def IsPng(png_data):
+  """Determines whether a sequence of bytes is a PNG."""
+  return png_data.startswith('\x89PNG\r\n\x1a\n')
+
+def OptimizePngFile(temp_dir, png_filename, optimization_level=None):
+  """Optimize a PNG file.
+
+  Args:
+    temp_dir: The directory containing the PNG file. Must be the only file in
+      the directory.
+    png_filename: The full path to the PNG file to optimize.
+
+  Returns:
+    The raw bytes of a PNG file, an optimized version of the input.
+  """
+  logging.debug('Crushing PNG image...')
+  args = [OPTIMIZE_PNG_FILES]
+  if optimization_level is not None:
+    args.append('-o%d' % optimization_level)
+  args.append(temp_dir)
+  result = subprocess.call(args, stdout=sys.stderr)
+  if result != 0:
+    logging.warning('Warning: optimize-png-files failed (%d)', result)
+  else:
+    logging.debug('optimize-png-files succeeded')
+
+  with open(png_filename, 'rb') as png_file:
+    return png_file.read()
+
+def OptimizePng(png_data, optimization_level=None):
+  """Optimize a PNG.
+
+  Args:
+    png_data: The raw bytes of a PNG file.
+
+  Returns:
+    The raw bytes of a PNG file, an optimized version of the input.
+  """
+  temp_dir = tempfile.mkdtemp()
+  try:
+    logging.debug('temp_dir = %s', temp_dir)
+    png_filename = os.path.join(temp_dir, 'image.png')
+    with open(png_filename, 'wb') as png_file:
+      png_file.write(png_data)
+    return OptimizePngFile(temp_dir, png_filename,
+                           optimization_level=optimization_level)
+
+  finally:
+    if os.path.exists(png_filename):
+      os.unlink(png_filename)
+    os.rmdir(temp_dir)
+
+def OptimizeIcoFile(infile, outfile, optimization_level=None):
+  """Read an ICO file, optimize its PNGs, and write the output to outfile.
+
+  Args:
+    infile: The file to read from. Must be a seekable file-like object
+      containing a Microsoft ICO file.
+    outfile: The file to write to.
+  """
+  filename = os.path.basename(infile.name)
+  icondir = infile.read(6)
+  zero, image_type, num_images = struct.unpack('<HHH', icondir)
+  if zero != 0:
+    raise InvalidFile('First word must be 0.')
+  if image_type not in (1, 2):
+    raise InvalidFile('Image type must be 1 or 2.')
+
+  # Read and unpack each ICONDIRENTRY.
+  icon_dir_entries = []
+  for i in range(num_images):
+    icondirentry = infile.read(16)
+    icon_dir_entries.append(struct.unpack('<BBBBHHLL', icondirentry))
+
+  # Read each icon's bitmap data, crush PNGs, and update icon dir entries.
+  current_offset = infile.tell()
+  icon_bitmap_data = []
+  for i in range(num_images):
+    width, height, num_colors, r1, r2, r3, size, _ = icon_dir_entries[i]
+    width = width or 256
+    height = height or 256
+    offset = current_offset
+    icon_data = infile.read(size)
+    if len(icon_data) != size:
+      raise EOFError()
+
+    entry_is_png = IsPng(icon_data)
+    logging.info('%s entry #%d: %dx%d, %d bytes (%s)', filename, i + 1, width,
+                 height, size, 'PNG' if entry_is_png else 'BMP')
+
+    if entry_is_png:
+      icon_data = OptimizePng(icon_data, optimization_level=optimization_level)
+    elif width >= 256 or height >= 256:
+      # TODO(mgiuca): Automatically convert large BMP images to PNGs.
+      logging.warning('Entry #%d is a large image in uncompressed BMP format. '
+                      'Please manually convert to PNG format before running '
+                      'this utility.', i + 1)
+
+    new_size = len(icon_data)
+    current_offset += new_size
+    icon_dir_entries[i] = (width % 256, height % 256, num_colors, r1, r2, r3,
+                           new_size, offset)
+    icon_bitmap_data.append(icon_data)
+
+  # Write the data back to outfile.
+  outfile.write(icondir)
+  for icon_dir_entry in icon_dir_entries:
+    outfile.write(struct.pack('<BBBBHHLL', *icon_dir_entry))
+  for icon_bitmap in icon_bitmap_data:
+    outfile.write(icon_bitmap)
+
+def main(args=None):
+  if args is None:
+    args = sys.argv[1:]
+
+  parser = argparse.ArgumentParser(description='Crush Windows ICO files.')
+  parser.add_argument('files', metavar='ICO', type=argparse.FileType('r+b'),
+                      nargs='+', help='.ico files to be crushed')
+  parser.add_argument('-o', dest='optimization_level', metavar='OPT', type=int,
+                      help='optimization level')
+  parser.add_argument('-d', '--debug', dest='debug', action='store_true',
+                      help='enable debug logging')
+
+  args = parser.parse_args()
+
+  if args.debug:
+    logging.getLogger().setLevel(logging.DEBUG)
+
+  for file in args.files:
+    buf = StringIO.StringIO()
+    file.seek(0, os.SEEK_END)
+    old_length = file.tell()
+    file.seek(0, os.SEEK_SET)
+    OptimizeIcoFile(file, buf, args.optimization_level)
+
+    new_length = len(buf.getvalue())
+    if new_length >= old_length:
+      logging.info('%s : Could not reduce file size.', file.name)
+    else:
+      file.truncate(new_length)
+      file.seek(0)
+      file.write(buf.getvalue())
+
+      saving = old_length - new_length
+      saving_percent = float(saving) / old_length
+      logging.info('%s : %d => %d (%d bytes : %d %%)', file.name, old_length,
+                   new_length, saving, int(saving_percent * 100))
+
+if __name__ == '__main__':
+  sys.exit(main())