cc : Rebuild property trees when opacity changes only if its required.

cc/trees/layer_tree_host_common_unittest.cc

 // Copyright 2011 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/trees/layer_tree_host_common.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 9633 matching lines @@
   is_inf_or_nan = std::isinf(child->DrawTransform().matrix().get(1, 1)) ||
                   std::isnan(child->DrawTransform().matrix().get(1, 1));
   EXPECT_TRUE(is_inf_or_nan);
 
   std::vector<LayerImpl*>* rsll = render_surface_layer_list_impl();
   bool root_in_rsll =
       std::find(rsll->begin(), rsll->end(), root) != rsll->end();
   EXPECT_TRUE(root_in_rsll);
 }
 
+TEST_F(LayerTreeHostCommonTest, PropertyTreesRebuildWithOpacityChanges) {
+  const gfx::Transform identity_matrix;
+  scoped_refptr<Layer> root = Layer::Create();
+  scoped_refptr<LayerWithForcedDrawsContent> child =
+      make_scoped_refptr(new LayerWithForcedDrawsContent());
+  root->AddChild(child);
+
+  host()->SetRootLayer(root);
+
+  SetLayerPropertiesForTesting(root.get(), identity_matrix, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(100, 100), true, false);
+  SetLayerPropertiesForTesting(child.get(), identity_matrix, gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(20, 20), true, false);
+
+  root->SetForceRenderSurfaceForTesting(true);

[ajuma, 2016/05/16 22:05:20]

Is this line needed? (Won't the root always get a surface?)

[jaydasika, 2016/05/17 01:40:01]

Done.

+  ExecuteCalculateDrawPropertiesWithPropertyTrees(root.get());
+
+  // Changing the opacity from 1 to non-1 value should trigger rebuild of
+  // property trees as a new effect node will be created.
+  child->SetOpacity(0.5f);
+  PropertyTrees* property_trees = root->layer_tree_host()->property_trees();

[ajuma, 2016/05/16 22:05:20]

"host()->property_trees()" here and in a couple places below (no need for
indirection through the root layer)

[jaydasika, 2016/05/17 01:40:01]

Done.

+  EXPECT_TRUE(property_trees->needs_rebuild);
+
+  ExecuteCalculateDrawPropertiesWithPropertyTrees(root.get());
+  EXPECT_NE(property_trees->effect_id_to_index_map.find(child->id()),
+            property_trees->effect_id_to_index_map.end());
+
+  // child already has an effect node. Changing its opacity shouldn't trigger
+  // a property trees rebuild.
+  child->SetOpacity(0.8f);
+  property_trees = root->layer_tree_host()->property_trees();
+  EXPECT_FALSE(property_trees->needs_rebuild);
+
+  ExecuteCalculateDrawPropertiesWithPropertyTrees(root.get());
+  EXPECT_NE(property_trees->effect_id_to_index_map.find(child->id()),
+            property_trees->effect_id_to_index_map.end());
+
+  // Changing the opacity from non-1 value to 1 should trigger a rebuild of
+  // property trees as the effect node may no longer be needed.
+  child->SetOpacity(1.f);
+  property_trees = root->layer_tree_host()->property_trees();
+  EXPECT_TRUE(property_trees->needs_rebuild);
+
+  ExecuteCalculateDrawPropertiesWithPropertyTrees(root.get());
+  EXPECT_EQ(property_trees->effect_id_to_index_map.find(child->id()),
+            property_trees->effect_id_to_index_map.end());
+}
+
 TEST_F(LayerTreeHostCommonTest, OpacityAnimationsTrackingTest) {
   const gfx::Transform identity_matrix;
   scoped_refptr<Layer> root = Layer::Create();
   scoped_refptr<LayerWithForcedDrawsContent> animated =
       make_scoped_refptr(new LayerWithForcedDrawsContent());
   root->AddChild(animated);
 
   host()->SetRootLayer(root);
 
   SetLayerPropertiesForTesting(root.get(), identity_matrix, gfx::Point3F(),
@@ skipping 264 matching lines @@
   EXPECT_EQ(scroll_child6.id, grand_child10->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, parent3->scroll_tree_index());
   EXPECT_EQ(scroll_child7.id, child8->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, parent4->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, child9->scroll_tree_index());
   EXPECT_EQ(scroll_root1.id, grand_child12->scroll_tree_index());
 }
 
 }  // namespace
 }  // namespace cc