cc : Remove subtree skipping in LayerTreeHostCommon

cc/trees/layer_tree_host_common.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>
 
@@ skipping 517 matching lines @@
 };
 
 void CalculateRenderTarget(LayerImpl* layer,
                            PropertyTrees* property_trees,
                            bool subtree_visible_from_ancestor,
                            bool can_render_to_separate_surface) {
   bool layer_is_drawn;
   DCHECK_GE(layer->effect_tree_index(), 0);
   layer_is_drawn = property_trees->effect_tree.Node(layer->effect_tree_index())
                        ->data.is_drawn;
+  bool can_render_to_separate_surface_for_children =
+      can_render_to_separate_surface;
 
   // The root layer cannot be skipped.
   if (!IsRootLayer(layer) &&
       draw_property_utils::LayerShouldBeSkipped(
           layer, layer_is_drawn, property_trees->transform_tree)) {
     layer->draw_properties().render_target = nullptr;
-    return;
-  }
+    can_render_to_separate_surface_for_children = false;

[ajuma, 2016/04/06 22:02:41]

If I'm understanding, in order to completely clean up the skipping logic, it
needs to be possible to skip an ancestor of a layer with a copy request but
still property handle the copy request. In that, this approach (of using
can_render_to_separate_surface to represent that some ancestor has been skipped)
won't work. So I think this needs to be split into a separate argument to be
passed to descendants.

[jaydasika, 2016/04/07 00:32:21]

Just removing it should handle it, right?  

[ajuma, 2016/04/07 15:19:56]

Yes, that works.

+  } else {
+    bool render_to_separate_surface =
+        IsRootLayer(layer) ||
+        (can_render_to_separate_surface && layer->render_surface());
 
-  bool render_to_separate_surface =
-      IsRootLayer(layer) ||
-      (can_render_to_separate_surface && layer->render_surface());
+    if (render_to_separate_surface) {
+      DCHECK(layer->render_surface()) << IsRootLayer(layer)
+                                      << can_render_to_separate_surface
+                                      << layer->has_render_surface();
+      layer->draw_properties().render_target = layer;
 
-  if (render_to_separate_surface) {
-    DCHECK(layer->render_surface()) << IsRootLayer(layer)
-                                    << can_render_to_separate_surface
-                                    << layer->has_render_surface();
-    layer->draw_properties().render_target = layer;
+      if (layer->mask_layer())
+        layer->mask_layer()->draw_properties().render_target = layer;
 
-    if (layer->mask_layer())
-      layer->mask_layer()->draw_properties().render_target = layer;
+      if (layer->replica_layer() && layer->replica_layer()->mask_layer())
+        layer->replica_layer()->mask_layer()->draw_properties().render_target =
+            layer;
 
-    if (layer->replica_layer() && layer->replica_layer()->mask_layer())
-      layer->replica_layer()->mask_layer()->draw_properties().render_target =
-          layer;
-
-  } else {
-    DCHECK(!IsRootLayer(layer));
-    layer->draw_properties().render_target = layer->parent()->render_target();
+    } else {
+      DCHECK(!IsRootLayer(layer));
+      layer->draw_properties().render_target = layer->parent()->render_target();
+    }
   }
   for (size_t i = 0; i < layer->children().size(); ++i) {
     CalculateRenderTarget(
         LayerTreeHostCommon::get_layer_as_raw_ptr(layer->children(), i),
-        property_trees, layer_is_drawn, can_render_to_separate_surface);
+        property_trees, layer_is_drawn,
+        can_render_to_separate_surface_for_children);
   }
 }
 
 void CalculateRenderSurfaceLayerList(
     LayerImpl* layer,
     PropertyTrees* property_trees,
     LayerImplList* render_surface_layer_list,
     LayerImplList* descendants,
     RenderSurfaceImpl* nearest_occlusion_immune_ancestor,
     bool subtree_visible_from_ancestor,
@@ skipping 20 matching lines @@
   layer_is_drawn = property_trees->effect_tree.Node(layer->effect_tree_index())
                        ->data.is_drawn;
 
   // The root layer cannot be skipped.
   if (!IsRootLayer(layer) &&
       draw_property_utils::LayerShouldBeSkipped(
           layer, layer_is_drawn, property_trees->transform_tree)) {
     if (layer->render_surface())
       layer->ClearRenderSurfaceLayerList();
     layer->draw_properties().render_target = nullptr;
+    for (auto* child_layer : layer->children()) {
+      CalculateRenderSurfaceLayerList(
+          child_layer, property_trees, render_surface_layer_list, descendants,
+          nearest_occlusion_immune_ancestor, layer_is_drawn,
+          can_render_to_separate_surface, current_render_surface_layer_list_id,
+          max_texture_size);
+    }
     return;
   }
 
   bool render_to_separate_surface =
       IsRootLayer(layer) ||
       (can_render_to_separate_surface && layer->render_surface());
 
   if (render_to_separate_surface) {
     DCHECK(layer->render_surface());
     draw_property_utils::ComputeSurfaceDrawProperties(property_trees,
@@ skipping 143 matching lines @@
 
   if (render_to_separate_surface && !IsRootLayer(layer) &&
       layer->render_surface()->DrawableContentRect().IsEmpty()) {
     RemoveSurfaceForEarlyExit(layer, render_surface_layer_list);
     return;
   }
 
   // If neither this layer nor any of its children were added, early out.
   if (descendants_size == descendants->size()) {
     DCHECK(!render_to_separate_surface || IsRootLayer(layer));
     return;

[jaydasika, 2016/04/07 00:32:21]

This is a clean up unrelated to the CL. This is now at the end of the function,
so we don't have to return.

   }
 }
 
 static void ComputeMaskLayerDrawProperties(const LayerImpl* layer,
                                            LayerImpl* mask_layer) {
   DrawProperties& mask_layer_draw_properties = mask_layer->draw_properties();
   mask_layer_draw_properties.visible_layer_rect = gfx::Rect(layer->bounds());
   mask_layer_draw_properties.target_space_transform =
       layer->draw_properties().target_space_transform;
   mask_layer_draw_properties.screen_space_transform =
@@ skipping 80 matching lines @@
   }
 
   if (should_measure_property_tree_performance) {
     TRACE_EVENT_BEGIN0(TRACE_DISABLED_BY_DEFAULT("cc.debug.cdp-perf"),
                        "LayerTreeHostCommon::CalculateDrawProperties");
   }
 
   DCHECK(inputs->can_render_to_separate_surface ==
          inputs->property_trees->non_root_surfaces_enabled);
   const bool subtree_visible_from_ancestor = true;
-  for (auto* layer : *inputs->root_layer->layer_tree_impl())
-    layer->draw_properties().render_target = nullptr;
   CalculateRenderTarget(inputs->root_layer, inputs->property_trees,
                         subtree_visible_from_ancestor,
                         inputs->can_render_to_separate_surface);
   for (LayerImpl* layer : visible_layer_list) {
     draw_property_utils::ComputeLayerDrawProperties(
         layer, inputs->property_trees, inputs->layers_always_allowed_lcd_text,
         inputs->can_use_lcd_text);
     if (layer->mask_layer())
       ComputeMaskLayerDrawProperties(layer, layer->mask_layer());
     LayerImpl* replica_mask_layer =
@@ skipping 105 matching lines @@
 
 PropertyTrees* GetPropertyTrees(Layer* layer) {
   return layer->layer_tree_host()->property_trees();
 }
 
 PropertyTrees* GetPropertyTrees(LayerImpl* layer) {
   return layer->layer_tree_impl()->property_trees();
 }
 
 }  // namespace cc