Added script optimize-ico-files.

tools/resources/optimize-ico-files.py

+#!/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."""

[oshima, 2015/08/18 01:41:26]

2 indent

[Matt Giuca, 2015/08/18 04:43:45]

https://google-styleguide.googlecode.com/svn/trunk/pyguide.html#Indentation says
4 spaces.

As below, maybe it's better to use 2-space for consistency with the rest of the
Chromium scripts. I thought the consistency rule was per-file, and if you're
starting a new script, you should follow the style guide.

I can change it, up to you.

[oshima, 2015/08/18 06:36:34]

Actually, https://www.chromium.org/chromium-os/python-style-guidelines says we
should use 2 indent and PascalCase. 

[Matt Giuca, 2015/08/18 07:26:22]

Hmm, that's a strange place to have the policy! (It's in ChromiumOS, not
Chromium.) I couldn't find it when I looked.

OK, updated to 2-space indents and TitleCase.

+
+def is_png(png_data):

[oshima, 2015/08/18 01:41:26]

looks like google style guide recommends underscore, while many chromium python
scripts including this directory use pascal case. Let's be consistent.

[Matt Giuca, 2015/08/18 04:43:45]

See previous comment.

+    """Determines whether a sequence of bytes is a PNG."""
+    return png_data.startswith('\x89PNG\r\n\x1a\n')
+
+def optimize_png_file(temp_dir, png_filename):
+    """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...')
+    result = subprocess.call([OPTIMIZE_PNG_FILES, temp_dir],
+                             stdout=sys.stderr)

[oshima, 2015/08/18 01:41:26]

pass optimization level. you can just pass -o2, or add an option to this script.

[Matt Giuca, 2015/08/18 04:43:45]

I tested this and found that -o2 took a LOT longer (maybe 10x) and made exactly
no difference (for the small icons I tested). So I definitely don't want to make
it the default. I'll make it an option.

[oshima, 2015/08/18 06:36:34]

Yep, -o2 is more for batch operation so option is file.

+    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 optimize_png(png_data):
+    """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 optimize_png_file(temp_dir, png_filename)
+
+    finally:
+        if os.path.exists(png_filename):
+            os.unlink(png_filename)
+        os.rmdir(temp_dir)
+
+def optimize_ico_file(infile, outfile):
+    """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 = is_png(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 = optimize_png(icon_data)
+        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)
+
+        size = len(icon_data)

[oshima, 2015/08/18 01:41:26]

new_size ? (just to be clear)

[Matt Giuca, 2015/08/18 04:43:45]

Done.

+        current_offset += size
+        icon_dir_entries[i] = (width % 256, height % 256, num_colors, r1, r2,
+                               r3, 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('-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)
+        optimize_ico_file(file, buf)
+
+        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())