Compute if a layer is drawn without LayerTree hierarchy

cc/layers/layer_impl.cc

 // Copyright 2012 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/layers/layer_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 80 matching lines @@
       num_dependents_need_push_properties_(0),
       sorting_context_id_(0),
       current_draw_mode_(DRAW_MODE_NONE),
       element_id_(0),
       mutable_properties_(kMutablePropertyNone),
       force_render_surface_(false),
       frame_timing_requests_dirty_(false),
       visited_(false),
       layer_or_descendant_is_drawn_(false),
       layer_or_descendant_has_input_handler_(false),
-      sorted_for_recursion_(false),
-      is_hidden_from_property_trees_(false) {
+      sorted_for_recursion_(false) {
   DCHECK_GT(layer_id_, 0);
   DCHECK(layer_tree_impl_);
   layer_tree_impl_->RegisterLayer(this);
 
   if (!layer_tree_impl_->settings().use_compositor_animation_timelines) {
     AnimationRegistrar* registrar = layer_tree_impl_->GetAnimationRegistrar();
     layer_animation_controller_ =
         registrar->GetAnimationControllerForId(layer_id_);
     layer_animation_controller_->AddValueObserver(this);
     if (IsActive()) {
@@ skipping 533 matching lines @@
 
   layer->PushScrollOffset(nullptr);
 
   layer->Set3dSortingContextId(sorting_context_id_);
   layer->SetNumDescendantsThatDrawContent(num_descendants_that_draw_content_);
 
   layer->SetTransformTreeIndex(transform_tree_index_);
   layer->SetClipTreeIndex(clip_tree_index_);
   layer->SetEffectTreeIndex(effect_tree_index_);
   layer->set_offset_to_transform_parent(offset_to_transform_parent_);
-  layer->set_is_hidden_from_property_trees(is_hidden_from_property_trees_);
 
   LayerImpl* scroll_parent = nullptr;
   if (scroll_parent_) {
     scroll_parent = layer->layer_tree_impl()->LayerById(scroll_parent_->id());
     DCHECK(scroll_parent);
   }
 
   layer->SetScrollParent(scroll_parent);
   if (scroll_children_) {
     std::set<LayerImpl*>* scroll_children = new std::set<LayerImpl*>;
@@ skipping 311 matching lines @@
 gfx::ScrollOffset LayerImpl::ScrollOffsetForAnimation() const {
   return CurrentScrollOffset();
 }
 
 void LayerImpl::OnFilterAnimated(const FilterOperations& filters) {
   SetFilters(filters);
 }
 
 void LayerImpl::OnOpacityAnimated(float opacity) {
   SetOpacity(opacity);
   UpdatePropertyTreeOpacity();

[jaydasika, 2016/01/21 00:53:09]

Question : Do we need to update property tree opacity here when
hide_layer_and_subtree = true ?

I think we don't need to as hide_layer_and_subtree is not updated on compositor
and so opacity() is going to remain 0 till the next commit.

[ajuma, 2016/01/21 14:38:04]

Yes, you're right that Opacity() won't change in this situation, so we can skip
the property tree update in that case.

 }
 
 void LayerImpl::OnTransformAnimated(const gfx::Transform& transform) {
   SetTransform(transform);
   UpdatePropertyTreeTransform();
   was_ever_ready_since_last_transform_animation_ = false;
 }
 
 void LayerImpl::OnScrollOffsetAnimated(const gfx::ScrollOffset& scroll_offset) {
   // Only layers in the active tree should need to do anything here, since
@@ skipping 911 matching lines @@
 }
 
 gfx::Rect LayerImpl::GetScaledEnclosingRectInTargetSpace(float scale) const {
   gfx::Transform scaled_draw_transform = DrawTransform();
   scaled_draw_transform.Scale(SK_MScalar1 / scale, SK_MScalar1 / scale);
   gfx::Size scaled_bounds = gfx::ScaleToCeiledSize(bounds(), scale);
   return MathUtil::MapEnclosingClippedRect(scaled_draw_transform,
                                            gfx::Rect(scaled_bounds));
 }
 
-bool LayerImpl::LayerIsHidden() const {
+bool LayerImpl::IsHidden() const {
   if (layer_tree_impl()->settings().use_property_trees) {
-    return is_hidden_from_property_trees_;
+    EffectTree& effect_tree = layer_tree_impl_->property_trees()->effect_tree;
+    EffectNode* node = effect_tree.Node(effect_tree_index_);
+    return node->data.screen_space_opacity == 0.f;
   } else {
-    return hide_layer_and_subtree_ || (parent() && parent()->LayerIsHidden());
+    return opacity() == 0.f || (parent() && parent()->IsHidden());
   }
 }
 
 float LayerImpl::GetIdealContentsScale() const {
   float page_scale = IsAffectedByPageScale()
                          ? layer_tree_impl()->current_page_scale_factor()
                          : 1.f;
   float device_scale = layer_tree_impl()->device_scale_factor();
 
   float default_scale = page_scale * device_scale;
   if (!layer_tree_impl()
            ->settings()
            .layer_transforms_should_scale_layer_contents) {
     return default_scale;
   }
 
   gfx::Vector2dF transform_scales = MathUtil::ComputeTransform2dScaleComponents(
       DrawTransform(), default_scale);
   return std::max(transform_scales.x(), transform_scales.y());
 }
 
 }  // namespace cc