Make image set insertion work in more cases

grit/gather/chrome_html.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """Prepares a Chrome HTML file by inlining resources and adding references to
 high DPI resources and removing references to unsupported scale factors.
 
 This is a small gatherer that takes a HTML file, looks for src attributes
 and inlines the specified file, producing one HTML file with no external
@@ skipping 13 matching lines @@
 from grit.gather import interface
 
 
 # Distribution string to replace with distribution.
 DIST_SUBSTR = '%DISTRIBUTION%'
 
 
 # Matches a chrome theme source URL.
 _THEME_SOURCE = lazy_re.compile(
     '(?P<baseurl>chrome://theme/IDR_[A-Z0-9_]*)(?P<query>\?.*)?')
-# Matches CSS image urls with the capture group 'filename'.
+# Pattern for matching CSS url() function.
+_CSS_URL_PATTERN = 'url\((?P<quote>"|\'|)(?P<filename>[^"\'()]*)(?P=quote)\)'
+# Matches CSS url() functions with the capture group 'filename'.
+_CSS_URL = lazy_re.compile(_CSS_URL_PATTERN)
+# Matches one or more CSS image urls used in given properties.
 _CSS_IMAGE_URLS = lazy_re.compile(
-    '(?P<attribute>content|background|[\w-]*-image):[ ]*' +
-    'url\((?P<quote>"|\'|)(?P<filename>[^"\'()]*)(?P=quote)')
+    '(?P<attribute>content|background|[\w-]*-image):\s*' +
+        '(?P<urls>(' + _CSS_URL_PATTERN + '\s*,?\s*)+)')
 # Matches CSS image sets.
 _CSS_IMAGE_SETS = lazy_re.compile(
     '(?P<attribute>content|background|[\w-]*-image):[ ]*' +
         '-webkit-image-set\((?P<images>' +
-        '([,\r\n ]*url\((?P<quote>"|\'|)[^"\'()]*(?P=quote)\)[ ]*[0-9.]*x)*)\)',
+        '(\s*,?\s*url\((?P<quote>"|\'|)[^"\'()]*(?P=quote)\)[ ]*[0-9.]*x)*)\)',
     re.MULTILINE)
 # Matches a single image in a CSS image set with the capture group scale.
-_CSS_IMAGE_SET_IMAGE = lazy_re.compile('[,\r\n ]*' +
+_CSS_IMAGE_SET_IMAGE = lazy_re.compile('\s*,?\s*' +
     'url\((?P<quote>"|\'|)[^"\'()]*(?P=quote)\)[ ]*(?P<scale>[0-9.]*x)',
     re.MULTILINE)
 _HTML_IMAGE_SRC = lazy_re.compile(
     '<img[^>]+src=\"(?P<filename>[^">]*)\"[^>]*>')
 
 def GetImageList(
     base_path, filename, scale_factors, distribution,
     filename_expansion_function=None):
   """Generate the list of images which match the provided scale factors.
 
@@ skipping 58 matching lines @@
   Returns:
     string giving a -webkit-image-set rule referencing the provided images.
         (i.e. '-webkit-image-set(url('image.png') 1x, url('2x/image.png') 2x)')
   """
   imageset = []
   for (scale_factor, filename) in images:
     imageset.append("url(%s%s%s) %s" % (quote, filename, quote, scale_factor))
   return "-webkit-image-set(%s)" % (', '.join(imageset))
 
 
-def InsertImageSet(
+def UrlToImageSet(
     src_match, base_path, scale_factors, distribution,
     filename_expansion_function=None):
-  """Regex replace function which inserts -webkit-image-set.
+  """Regex replace function which replaces url() with -webkit-image-set.
 
   Takes a regex match for url('path'). If the file is local, checks for
   files of the same name in folders corresponding to the supported scale
   factors. If the file is from a chrome://theme/ source, inserts the
   supported @Nx scale factor request. In either case inserts a
   -webkit-image-set rule to fetch the appropriate image for the current
   scale factor.
 
   Args:
-    src_match: regex match object from _CSS_IMAGE_URLS
+    src_match: regex match object from _CSS_URLS
     base_path: path to look for relative file paths in
     scale_factors: a list of the supported scale factors (i.e. ['2x'])
     distribution: string that should replace %DISTRIBUTION%.
 
   Returns:
     string
   """
   quote = src_match.group('quote')
   filename = src_match.group('filename')
-  attr = src_match.group('attribute')
   image_list = GetImageList(
       base_path, filename, scale_factors, distribution,
       filename_expansion_function=filename_expansion_function)
 
   # Don't modify the source if there is only one image.
   if len(image_list) == 1:
     return src_match.group(0)
 
-  return "%s: %s" % (attr, GenerateImageSet(image_list, quote)[:-1])
+  return GenerateImageSet(image_list, quote)
+
+
+def InsertImageSet(
+    src_match, base_path, scale_factors, distribution,
+    filename_expansion_function=None):
+  """Regex replace function which inserts -webkit-image-set rules.
+
+  Takes a regex match for `property: url('path')[, url('path')]+`.
+  Replaces one or more occurances of the match with image set rules.
+
+  Args:
+    src_match: regex match object from _CSS_IMAGE_URLS
+    base_path: path to look for relative file paths in
+    scale_factors: a list of the supported scale factors (i.e. ['2x'])
+    distribution: string that should replace %DISTRIBUTION%.
+
+  Returns:
+    string
+  """
+  attr = src_match.group('attribute')
+  urls = _CSS_URL.sub(
+      lambda m: UrlToImageSet(m, base_path, scale_factors, distribution,
+                              filename_expansion_function),
+      src_match.group('urls'))
+
+  return "%s: %s" % (attr, urls)
 
 
 def InsertImageStyle(
     src_match, base_path, scale_factors, distribution,
     filename_expansion_function=None):
   """Regex replace function which adds a content style to an <img>.
 
   Takes a regex match from _HTML_IMAGE_SRC and replaces the attribute with a CSS
   style which defines the image set.
   """
@@ skipping 155 matching lines @@
               filename_expansion_function=self.filename_expansion_function),
           filename_expansion_function=self.filename_expansion_function)
     else:
       distribution = html_inline.GetDistribution()
       self.inlined_text_ = ProcessImageSets(
           os.path.dirname(filename),
           util.ReadFile(filename, 'utf-8'),
           self.scale_factors_,
           distribution,
           filename_expansion_function=self.filename_expansion_function)