Move grit from DEPS into src.

tools/grit/grit/gather/chrome_scaled_image.py

Index: tools/grit/grit/gather/chrome_scaled_image.py
diff --git a/tools/grit/grit/gather/chrome_scaled_image.py b/tools/grit/grit/gather/chrome_scaled_image.py
new file mode 100755
index 0000000000000000000000000000000000000000..864c9bddf602b0e18083868298f1fa920af1785a
--- /dev/null
+++ b/tools/grit/grit/gather/chrome_scaled_image.py
@@ -0,0 +1,157 @@
+#!/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.
+
+'''Gatherer for <structure type="chrome_scaled_image">.
+'''
+
+import os
+import struct
+
+from grit import exception
+from grit import lazy_re
+from grit import util
+from grit.gather import interface
+
+
+_PNG_SCALE_CHUNK = '\0\0\0\0csCl\xc1\x30\x60\x4d'
+
+
+def _RescaleImage(data, from_scale, to_scale):
+  if from_scale != to_scale:
+    assert from_scale == 100
+    # Rather than rescaling the image we add a custom chunk directing Chrome to
+    # rescale it on load. Just append it to the PNG data since
+    # _MoveSpecialChunksToFront will move it later anyway.
+    data += _PNG_SCALE_CHUNK
+  return data
+
+
+_PNG_MAGIC = '\x89PNG\r\n\x1a\n'
+
+'''Mandatory first chunk in order for the png to be valid.'''
+_FIRST_CHUNK = 'IHDR'
+
+'''Special chunks to move immediately after the IHDR chunk. (so that the PNG
+remains valid.)
+'''
+_SPECIAL_CHUNKS = frozenset('csCl npTc'.split())
+
+'''Any ancillary chunk not in this list is deleted from the PNG.'''
+_ANCILLARY_CHUNKS_TO_LEAVE = frozenset(
+    'bKGD cHRM gAMA iCCP pHYs sBIT sRGB tRNS'.split())
+
+
+def _MoveSpecialChunksToFront(data):
+  '''Move special chunks immediately after the IHDR chunk (so that the PNG
+  remains valid). Also delete ancillary chunks that are not on our whitelist.
+  '''
+  first = [_PNG_MAGIC]
+  special_chunks = []
+  rest = []
+  for chunk in _ChunkifyPNG(data):
+    type = chunk[4:8]
+    critical = type < 'a'
+    if type == _FIRST_CHUNK:
+      first.append(chunk)
+    elif type in _SPECIAL_CHUNKS:
+      special_chunks.append(chunk)
+    elif critical or type in _ANCILLARY_CHUNKS_TO_LEAVE:
+      rest.append(chunk)
+  return ''.join(first + special_chunks + rest)
+
+
+def _ChunkifyPNG(data):
+  '''Given a PNG image, yield its chunks in order.'''
+  assert data.startswith(_PNG_MAGIC)
+  pos = 8
+  while pos != len(data):
+    length = 12 + struct.unpack_from('>I', data, pos)[0]
+    assert 12 <= length <= len(data) - pos
+    yield data[pos:pos+length]
+    pos += length
+
+
+def _MakeBraceGlob(strings):
+  '''Given ['foo', 'bar'], return '{foo,bar}', for error reporting.
+  '''
+  if len(strings) == 1:
+    return strings[0]
+  else:
+    return '{' + ','.join(strings) + '}'
+
+
+class ChromeScaledImage(interface.GathererBase):
+  '''Represents an image that exists in multiple layout variants
+  (e.g. "default", "touch") and multiple scale variants
+  (e.g. "100_percent", "200_percent").
+  '''
+
+  split_context_re_ = lazy_re.compile(r'(.+)_(\d+)_percent\Z')
+
+  def _FindInputFile(self):
+    output_context = self.grd_node.GetRoot().output_context
+    match = self.split_context_re_.match(output_context)
+    if not match:
+      raise exception.MissingMandatoryAttribute(
+          'All <output> nodes must have an appropriate context attribute'
+          ' (e.g. context="touch_200_percent")')
+    req_layout, req_scale = match.group(1), int(match.group(2))
+
+    layouts = [req_layout]
+    try_default_layout = self.grd_node.GetRoot().fallback_to_default_layout
+    if try_default_layout and 'default' not in layouts:
+      layouts.append('default')
+
+    # TODO(tdanderson): Search in descending order of all image scales
+    #                   instead of immediately falling back to 100.
+    #                   See crbug.com/503643.
+    scales = [req_scale]
+    try_low_res = self.grd_node.FindBooleanAttribute(
+        'fallback_to_low_resolution', default=False, skip_self=False)
+    if try_low_res and 100 not in scales:
+      scales.append(100)
+
+    for layout in layouts:
+      for scale in scales:
+        dir = '%s_%s_percent' % (layout, scale)
+        path = os.path.join(dir, self.rc_file)
+        if os.path.exists(self.grd_node.ToRealPath(path)):
+          return path, scale, req_scale
+
+    if not try_default_layout:
+      # The file was not found in the specified output context and it was
+      # explicitly indicated that the default context should not be searched
+      # as a fallback, so return an empty path.
+      return None, 100, req_scale
+
+    # The file was found in neither the specified context nor the default
+    # context, so raise an exception.
+    dir = "%s_%s_percent" % (_MakeBraceGlob(layouts),
+                             _MakeBraceGlob(map(str, scales)))
+    raise exception.FileNotFound(
+        'Tried ' + self.grd_node.ToRealPath(os.path.join(dir, self.rc_file)))
+
+  def GetInputPath(self):
+    path, scale, req_scale = self._FindInputFile()
+    return path
+
+  def Parse(self):
+    pass
+
+  def GetTextualIds(self):
+    return [self.extkey]
+
+  def GetData(self, *args):
+    path, scale, req_scale = self._FindInputFile()
+    if path is None:
+      return None
+
+    data = util.ReadFile(self.grd_node.ToRealPath(path), util.BINARY)
+    data = _RescaleImage(data, scale, req_scale)
+    data = _MoveSpecialChunksToFront(data)
+    return data
+
+  def Translate(self, *args, **kwargs):
+    return self.GetData()