Pinch/Zoom Infrastructure & Plumbing CL

cc/test/layer_tree_json_parser.cc

 // Copyright 2013 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.
 
 #include "cc/test/layer_tree_json_parser.h"
 
 #include "base/test/values_test_util.h"
 #include "base/values.h"
 #include "cc/layers/content_layer.h"
 #include "cc/layers/layer.h"
@@ skipping 83 matching lines @@
 
   double opacity;
   if (dict->GetDouble("Opacity", &opacity))
     new_layer->SetOpacity(opacity);
 
   bool contents_opaque;
   if (dict->GetBoolean("ContentsOpaque", &contents_opaque))
     new_layer->SetContentsOpaque(contents_opaque);
 
   bool scrollable;
+  // TODO(wjmaclean) At some time in the future we may wish to test that a
+  // reconstructed layer tree contains the correct linkage for the scroll
+  // clip layer. This is complicated by the fact that the json output doesn't
+  // (currently) re-construct the tree with the same layer IDs as the original.
+  // But, since a clip layer is always an ancestor of the scrollable layer, we
+  // can just count the number of upwards hops to the clip layer and write that
+  // into the json file (with 0 hops implying no clip layer, i.e. not
+  // scrollable). Reconstructing the tree can then be accomplished by passing
+  // the parent pointer to this function and traversing the same number of
+  // ancestors to determine the pointer to the clip layer. The LayerTreesMatch()
+  // function should then check that both original and reconstructed layers
+  // have the same positioning with respect to their clip layers.
+  //
+  // For now, we can safely indicate a layer is scrollable by giving it a
+  // pointer to itself, something not normally allowed in a working tree.
+  //
+  // https://code.google.com/p/chromium/issues/detail?id=330622
+  //
   if (dict->GetBoolean("Scrollable", &scrollable))
-    new_layer->SetScrollable(scrollable);
+    new_layer->SetScrollClipLayer(scrollable ? new_layer.get() : NULL);
 
   bool wheel_handler;
   if (dict->GetBoolean("WheelHandler", &wheel_handler))
     new_layer->SetHaveWheelEventHandlers(wheel_handler);
 
   if (dict->HasKey("TouchRegion")) {
     success &= dict->GetList("TouchRegion", &list);
     Region touch_region;
     for (size_t i = 0; i < list->GetSize(); ) {
       int rect_x, rect_y, rect_width, rect_height;
@@ skipping 29 matching lines @@
 
 }  // namespace
 
 scoped_refptr<Layer> ParseTreeFromJson(std::string json,
                                        ContentLayerClient* content_client) {
   scoped_ptr<base::Value> val = base::test::ParseJson(json);
   return ParseTreeFromValue(val.get(), content_client);
 }
 
 }  // namespace cc