teach rebaseline_server to generate diffs of rendered SKPs

gm/rebaseline_server/imagepairset.py

 #!/usr/bin/python
 
 """
 Copyright 2014 Google Inc.
 
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 
 ImagePairSet class; see its docstring below.
 """
 
 # System-level imports
 import posixpath
 
-# Local imports
+# Must fix up PYTHONPATH before importing from within Skia
+import fix_pythonpath  # pylint: disable=W0611
+
+# Imports from within Skia
 import column
 import imagediffdb
+from py.utils import gs_utils
 
 # Keys used within dictionary representation of ImagePairSet.
 # NOTE: Keep these in sync with static/constants.js
 KEY__ROOT__EXTRACOLUMNHEADERS = 'extraColumnHeaders'
 KEY__ROOT__EXTRACOLUMNORDER = 'extraColumnOrder'
 KEY__ROOT__HEADER = 'header'
 KEY__ROOT__IMAGEPAIRS = 'imagePairs'
 KEY__ROOT__IMAGESETS = 'imageSets'
 KEY__IMAGESETS__FIELD__BASE_URL = 'baseUrl'
 KEY__IMAGESETS__FIELD__DESCRIPTION = 'description'
@@ skipping 18 matching lines @@
     """
     Args:
       diff_base_url: base URL indicating where diff images can be loaded from
       descriptions: a (string, string) tuple describing the two image sets.
           If not specified, DEFAULT_DESCRIPTIONS will be used.
     """
     self._column_header_factories = {}
     self._descriptions = descriptions or DEFAULT_DESCRIPTIONS
     self._extra_column_tallies = {}  # maps column_id -> values
                                      #                -> instances_per_value
-    self._image_pair_dicts = []
     self._image_base_url = None
     self._diff_base_url = diff_base_url
 
+    # We build self._image_pair_objects incrementally as calls come into
+    # add_image_pair(); self._image_pair_dicts is filled in lazily (so that
+    # we put off asking ImageDiffDB for results as long as possible).
+    self._image_pair_objects = []
+    self._image_pair_dicts = None
+
   def add_image_pair(self, image_pair):
     """Adds an ImagePair; this may be repeated any number of times."""
     # Special handling when we add the first ImagePair...
-    if not self._image_pair_dicts:
+    if not self._image_pair_objects:
       self._image_base_url = image_pair.base_url
 
     if image_pair.base_url != self._image_base_url:
       raise Exception('added ImagePair with base_url "%s" instead of "%s"' % (
           image_pair.base_url, self._image_base_url))
-    self._image_pair_dicts.append(image_pair.as_dict())
+    self._image_pair_objects.append(image_pair)
     extra_columns_dict = image_pair.extra_columns_dict
     if extra_columns_dict:
       for column_id, value in extra_columns_dict.iteritems():
         self._add_extra_column_value_to_summary(column_id, value)
 
   def set_column_header_factory(self, column_id, column_header_factory):
     """Overrides the default settings for one of the extraColumn headers.
 
     Args:
       column_id: string; unique ID of this column (must match a key within
@@ skipping 54 matching lines @@
       column_header_factory = self.get_column_header_factory(column_id)
       asdict[column_id] = column_header_factory.create_as_dict(
           values_for_column)
     return asdict
 
   def as_dict(self, column_ids_in_order=None):
     """Returns a dictionary describing this package of ImagePairs.
 
     Uses the KEY__* constants as keys.
 
-    Params:
+    Args:
       column_ids_in_order: A list of all extracolumn IDs in the desired display
           order.  If unspecified, they will be displayed in alphabetical order.
           If specified, this list must contain all the extracolumn IDs!
           (It may contain extra column IDs; they will be ignored.)
     """
     all_column_ids = set(self._extra_column_tallies.keys())
     if column_ids_in_order == None:
       column_ids_in_order = sorted(all_column_ids)
     else:
       # Make sure the caller listed all column IDs, and throw away any extras.
       specified_column_ids = set(column_ids_in_order)
       forgotten_column_ids = all_column_ids - specified_column_ids
       assert not forgotten_column_ids, (
           'column_ids_in_order %s missing these column_ids: %s' % (
               column_ids_in_order, forgotten_column_ids))
       column_ids_in_order = [c for c in column_ids_in_order
                              if c in all_column_ids]
 
     key_description = KEY__IMAGESETS__FIELD__DESCRIPTION
     key_base_url = KEY__IMAGESETS__FIELD__BASE_URL
+    if gs_utils.GSUtils.is_gs_url(self._image_base_url):
+      value_base_url = self._convert_gs_url_to_http_url(self._image_base_url)
+    else:
+      value_base_url = self._image_base_url
+
+    # We've waited as long as we can to ask ImageDiffDB for details of the
+    # image diffs, so that it has time to compute them.
+    if self._image_pair_dicts == None:
+      self._image_pair_dicts = [ip.as_dict() for ip in self._image_pair_objects]
+
     return {
         KEY__ROOT__EXTRACOLUMNHEADERS: self._column_headers_as_dict(),
         KEY__ROOT__EXTRACOLUMNORDER: column_ids_in_order,
         KEY__ROOT__IMAGEPAIRS: self._image_pair_dicts,
         KEY__ROOT__IMAGESETS: {
             KEY__IMAGESETS__SET__IMAGE_A: {
                 key_description: self._descriptions[0],
-                key_base_url: self._image_base_url,
+                key_base_url: value_base_url,
             },
             KEY__IMAGESETS__SET__IMAGE_B: {
                 key_description: self._descriptions[1],
-                key_base_url: self._image_base_url,
+                key_base_url: value_base_url,
             },
             KEY__IMAGESETS__SET__DIFFS: {
                 key_description: 'color difference per channel',
                 key_base_url: posixpath.join(
                     self._diff_base_url, imagediffdb.RGBDIFFS_SUBDIR),
             },
             KEY__IMAGESETS__SET__WHITEDIFFS: {
                 key_description: 'differing pixels in white',
                 key_base_url: posixpath.join(
                     self._diff_base_url, imagediffdb.WHITEDIFFS_SUBDIR),
             },
         },
     }
+
+  @staticmethod
+  def _convert_gs_url_to_http_url(gs_url):
+    """Returns HTTP URL that can be used to download this Google Storage file.
+
+    TODO(epoger): Create functionality like this within gs_utils.py instead of
+    here?  See https://codereview.chromium.org/428493005/ ('create
+    anyfile_utils.py for copying files between HTTP/GS/local filesystem')
+
+    Args:
+      gs_url: "gs://bucket/path" format URL
+    """
+    bucket, path = gs_utils.GSUtils.split_gs_url(gs_url)
+    http_url = 'http://storage.cloud.google.com/' + bucket
+    if path:
+      http_url += '/' + path
+    return http_url