Prepared buildtools for Safari

imageConversion.py

Index: imageConversion.py
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+# coding: utf-8
+
+# This file is part of the Adblock Plus build tools,
+# Copyright (C) 2006-2013 Eyeo GmbH
+#
+# Adblock Plus is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 3 as
+# published by the Free Software Foundation.
+#
+# Adblock Plus 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.
+#
+# You should have received a copy of the GNU General Public License
+# along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import re
+from StringIO import StringIO
+
+import PIL.Image
+
+def get_alpha(image):
+  if image.mode in ('RGBA', 'LA'):
+    return image.split()[image.getbands().index('A')]
+
+  if image.mode == 'P':
+    transparency = image.info.get('transparency')
+
+    if transparency is not None:
+      table = [255] * 256
+      table[transparency] = 0
+
+      return image.point(table, 'L')

[Wladimir Palant, 2013/10/30 13:36:01]

Nit: I would add an explicit |return None| at the end of this function.

+
+def ensure_same_mode(im1, im2):
+  # if both images already have the same mode (and palette, in
+  # case of mode P), don't convert anything. Images with mode P,
+  # and a different palette, are the only case where images
+  # using the same mode, will be incompatible with each other.
+  if im1.mode == im2.mode and (im1.mode != 'P' or im1.getpalette() == im2.getpalette()):
+    return (im1, im2)
+
+  # if any given image has a mode that supports colors convert both
+  # images to RGB or RGBA, otherwise convert both images to L or LA.
+  # If any given image has an alpha channel (or mode P which
+  # can store transparent pixels too) convert both images
+  # to RGBA or LA, otherwise convert both images to RGB or L.
+  mode = max(
+    PIL.Image.getmodebase(im1.mode),
+    PIL.Image.getmodebase(im2.mode),
+
+    key=('L', 'RGB').index
+  )
+
+  if any(im.mode in ('RGBA', 'LA', 'P') for im in (im1, im2)):
+    mode += 'A'
+
+  return (
+    im1 if im1.mode == mode else im1.convert(mode),
+    im2 if im2.mode == mode else im2.convert(mode),
+  )
+
+def filter_grayscale(image, baseDir):
+  alpha = get_alpha(image)
+  image = image.convert('L')
+
+  if alpha:
+    image.putalpha(alpha)
+
+  return image

[Wladimir Palant, 2013/10/30 13:36:01]

Isn't this function equivalent to |return image.convert("LA", dither=None)|? I
asked in the earlier review round but it doesn't look like you replied to that
comment.

[Sebastian Noack, 2013/10/30 16:12:10]

See http://codereview.adblockplus.org/11544056/patch/32001/33004#new-line-67.
Also note that the "dither" argument is ignored, except for conversion to mode
"P" (palette).

+
+def filter_contrastToAlpha(image, baseDir):
+  import PIL.ImageOps
+
+  alpha = PIL.Image.new('L', image.size, 255)
+  alpha.paste(image, mask=get_alpha(image))
+  alpha = PIL.ImageOps.invert(alpha)
+  alpha = PIL.ImageOps.autocontrast(alpha)
+
+  return PIL.Image.merge('LA', [PIL.Image.new('L', image.size), alpha])
+
+def filter_blend(image, baseDir, *args):
+  if len(args) == 2:
+    filename, opacity = args
+
+    overlay = PIL.Image.open(os.path.join(
+      baseDir,
+      *filename.split('/')
+    ))
+  else:
+    red, green, blue, opacity = args
+
+    overlay = PIL.Image.new('RGB', image.size, (
+      int(red),
+      int(green),
+      int(blue),
+    ))
+
+    # if the background image has an alpha channel copy it to
+    # the overlay, so that transparent areas stay transparent.
+    alpha = get_alpha(image)
+    if alpha:
+      overlay.putalpha(alpha)
+
+  image, overlay = ensure_same_mode(image, overlay)
+  return PIL.Image.blend(image, overlay, float(opacity))
+
+def convertImages(params, files):
+  metadata = params['metadata']
+
+  for filename, chain in metadata.items('convert_img'):
+    baseDir = os.path.dirname(metadata.option_source('convert_img', filename))
+    steps = re.split(r'\s*->\s*', chain)
+    image = PIL.Image.open(os.path.join(baseDir, *steps.pop(0).split('/')))
+
+    for step in steps:
+      filter, args = re.match(r'([^(]+)(?:\((.*)\))?', step).groups()
+      args = re.split(r'\s*,\s*', args) if args else ()
+      image = globals()['filter_' + filter](image, baseDir, *args)
+
+    f = StringIO()
+    f.name = filename
+    image.save(f)
+    files[filename] = f.getvalue()