Add ClipNode when Render Surface Inherits Clip

cc/trees/property_tree_builder.cc

 // Copyright 2014 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/property_tree_builder.h"
 
 #include <map>
 #include <set>
 
 #include "cc/base/math_util.h"
@@ skipping 61 matching lines @@
   const bool render_surface_may_grow_due_to_clip_children =
       layer->render_surface() && layer->num_unclipped_descendants() > 0;
 
   if (layer->masks_to_bounds() || layer->mask_layer() ||
       render_surface_may_grow_due_to_clip_children)
     return true;
 
   if (!render_surface_applies_clip)
     return false;
 
+  if (layer->parent())
+    return true;
+
   bool axis_aligned_with_respect_to_parent =

[ajuma, 2015/08/05 13:51:09]

Will this ever be true now? If we reach this point, we're at the root layer,
which can't be non-axis aligned.

[jaydasika, 2015/08/05 15:07:20]

Done.

       data.transform_tree->Are2DAxisAligned(layer->transform_tree_index(),
                                             parent_transform_id);
 
   return !axis_aligned_with_respect_to_parent;
 }
 
 template <typename LayerType>
 static bool LayerClipsSubtree(LayerType* layer) {
   return layer->masks_to_bounds() || layer->mask_layer();
 }
 
 template <typename LayerType>
 void AddClipNodeIfNeeded(const DataForRecursion<LayerType>& data_from_ancestor,
                          LayerType* layer,
                          bool created_transform_node,
                          DataForRecursion<LayerType>* data_for_children) {
   ClipNode* parent = GetClipParent(data_from_ancestor, layer);
   int parent_id = parent->id;
 
   bool ancestor_clips_subtree =
       data_from_ancestor.ancestor_clips_subtree ||
       (layer->clip_parent() && layer->clip_parent()->is_clipped());
 
   data_for_children->ancestor_clips_subtree = false;
   bool has_unclipped_surface = false;
+  bool use_clip_parent_for_layer = false;
 
   if (layer->has_render_surface()) {
     if (ancestor_clips_subtree && layer->num_unclipped_descendants() > 0)
       data_for_children->ancestor_clips_subtree = true;
     else if (!ancestor_clips_subtree && !layer->num_unclipped_descendants())
       has_unclipped_surface = true;
   } else {
     data_for_children->ancestor_clips_subtree = ancestor_clips_subtree;
   }
 
   if (LayerClipsSubtree(layer))
     data_for_children->ancestor_clips_subtree = true;
 
   if (has_unclipped_surface)
     parent_id = 0;
 
   if (!RequiresClipNode(layer, data_from_ancestor, parent->data.transform_id,
-                        data_for_children->ancestor_clips_subtree)) {
+                        ancestor_clips_subtree)) {
     // Unclipped surfaces reset the clip rect.
     data_for_children->clip_tree_parent = parent_id;
   } else {
     LayerType* transform_parent = data_for_children->transform_tree_parent;
     if (layer->position_constraint().is_fixed_position() &&
         !created_transform_node) {
       transform_parent = data_for_children->transform_fixed_parent;
     }
     ClipNode node;
     node.data.clip = gfx::RectF(
         gfx::PointF() + layer->offset_to_transform_parent(), layer->bounds());
     node.data.transform_id = transform_parent->transform_tree_index();
     node.data.target_id =
         data_for_children->render_target->transform_tree_index();
     node.owner_id = layer->id();
-
+    node.data.inherit_parent_target_space_clip =
+        !data_for_children->ancestor_clips_subtree &&
+        layer->has_render_surface() && ancestor_clips_subtree;
+    if (node.data.inherit_parent_target_space_clip)
+      use_clip_parent_for_layer = true;
     data_for_children->clip_tree_parent =
         data_for_children->clip_tree->Insert(node, parent_id);
   }
 
   layer->SetClipTreeIndex(
       has_unclipped_surface ? 0 : data_for_children->clip_tree_parent);
+  if (use_clip_parent_for_layer)
+    layer->SetClipTreeIndex(data_from_ancestor.clip_tree_parent);
 
   layer->set_is_clipped(data_for_children->ancestor_clips_subtree);
 
   // TODO(awoloszyn): Right now when we hit a node with a replica, we reset the
   // clip for all children since we may need to draw. We need to figure out a
   // better way, since we will need both the clipped and unclipped versions.
 }
 
 template <typename LayerType>
 bool AddTransformNodeIfNeeded(
@@ skipping 342 matching lines @@
     const gfx::Rect& viewport,
     const gfx::Transform& device_transform,
     PropertyTrees* property_trees) {
   BuildPropertyTreesTopLevelInternal(
       root_layer, page_scale_layer, inner_viewport_scroll_layer,
       outer_viewport_scroll_layer, page_scale_factor, device_scale_factor,
       viewport, device_transform, property_trees);
 }
 
 }  // namespace cc