Prepared buildtools for Safari

imageConversion.py

+# 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')
+
+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')

[Felix Dahlke, 2013/10/15 16:24:38]

I guess I'm missing something here, shouldn't image.convert('LA') do what we
want? If not, worth a comment IMO.

[Sebastian Noack, 2013/10/15 17:06:56]

Image.convert('LA') doesn't work reliable, in all cases. I observed that when
the image uses an indexed palette (mode P), converting it to 'LA', results in an
image that just looks like random gray pixels. However converting to 'L', always
works properly. Also that way an alpha channel is only added if actually needed.

+
+  if alpha:
+    image.putalpha(alpha)
+
+  return image
+
+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()