cc: More documentation of the Layer API

And SetShouldFlattenTransformFromPropertyTree() becomes
SetShouldFlattenScreenSpaceTransformFromPropertyTree() as per the TODO
to rename it more appropritely.

R=enne@chromium.org

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I783e8474f39899de99ca6cf51e102f5ea604b836
Reviewed-on: https://chromium-review.googlesource.com/1101915Reviewed-by: weiliangc <weiliangc@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568235}

cc/layers/layer.cc

@@ -85,7 +85,7 @@ Layer::Layer()
       clip_tree_index_(ClipTree::kInvalidNodeId),
       scroll_tree_index_(ScrollTree::kInvalidNodeId),
       property_tree_sequence_number_(-1),
-      should_flatten_transform_from_property_tree_(false),
+      should_flatten_screen_space_transform_from_property_tree_(false),
       draws_content_(false),
       should_check_backface_visibility_(false),
       cache_render_surface_(false),
@@ -1195,8 +1195,8 @@ void Layer::PushPropertiesTo(LayerImpl* layer) {
   layer->SetTouchActionRegion(inputs_.touch_action_region);
   layer->SetContentsOpaque(inputs_.contents_opaque);
   layer->SetPosition(inputs_.position);
-  layer->SetShouldFlattenTransformFromPropertyTree(
-      should_flatten_transform_from_property_tree_);
+  layer->SetShouldFlattenScreenSpaceTransformFromPropertyTree(
+      should_flatten_screen_space_transform_from_property_tree_);
   layer->SetUseParentBackfaceVisibility(inputs_.use_parent_backface_visibility);
   layer->SetShouldCheckBackfaceVisibility(should_check_backface_visibility_);
 
@@ -1317,10 +1317,12 @@ void Layer::SetSubtreePropertyChanged() {
   SetNeedsPushProperties();
 }
 
-void Layer::SetShouldFlattenTransformFromPropertyTree(bool should_flatten) {
-  if (should_flatten_transform_from_property_tree_ == should_flatten)
+void Layer::SetShouldFlattenScreenSpaceTransformFromPropertyTree(
+    bool should_flatten) {
+  if (should_flatten_screen_space_transform_from_property_tree_ ==
+      should_flatten)
     return;
-  should_flatten_transform_from_property_tree_ = should_flatten;
+  should_flatten_screen_space_transform_from_property_tree_ = should_flatten;
   SetNeedsPushProperties();
 }
 

cc/layers/layer_impl.cc

@@ -52,7 +52,7 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl, int id)
       main_thread_scrolling_reasons_(
           MainThreadScrollingReason::kNotScrollingOnMain),
       scrollable_(false),
-      should_flatten_transform_from_property_tree_(false),
+      should_flatten_screen_space_transform_from_property_tree_(false),
       layer_property_changed_not_from_property_trees_(false),
       layer_property_changed_from_property_trees_(false),
       may_contain_video_(false),
@@ -305,8 +305,8 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   layer->has_transform_node_ = has_transform_node_;
   layer->offset_to_transform_parent_ = offset_to_transform_parent_;
   layer->main_thread_scrolling_reasons_ = main_thread_scrolling_reasons_;
-  layer->should_flatten_transform_from_property_tree_ =
-      should_flatten_transform_from_property_tree_;
+  layer->should_flatten_screen_space_transform_from_property_tree_ =
+      should_flatten_screen_space_transform_from_property_tree_;
   layer->masks_to_bounds_ = masks_to_bounds_;
   layer->contents_opaque_ = contents_opaque_;
   layer->may_contain_video_ = may_contain_video_;

cc/layers/layer_impl.h

@@ -112,11 +112,12 @@ class CC_EXPORT LayerImpl {
     return offset_to_transform_parent_;
   }
 
-  void SetShouldFlattenTransformFromPropertyTree(bool should_flatten) {
-    should_flatten_transform_from_property_tree_ = should_flatten;
+  void SetShouldFlattenScreenSpaceTransformFromPropertyTree(
+      bool should_flatten) {
+    should_flatten_screen_space_transform_from_property_tree_ = should_flatten;
   }
-  bool should_flatten_transform_from_property_tree() const {
-    return should_flatten_transform_from_property_tree_;
+  bool should_flatten_screen_space_transform_from_property_tree() const {
+    return should_flatten_screen_space_transform_from_property_tree_;
   }
 
   bool is_clipped() const { return draw_properties_.is_clipped; }
@@ -493,7 +494,7 @@ class CC_EXPORT LayerImpl {
   // |scroll_container_bounds|).
   bool scrollable_ : 1;
 
-  bool should_flatten_transform_from_property_tree_ : 1;
+  bool should_flatten_screen_space_transform_from_property_tree_ : 1;
 
   // Tracks if drawing-related properties have changed since last redraw.
   // TODO(wutao): We want to distinquish the sources of change so that we can

cc/trees/draw_property_utils.cc

@@ -563,7 +563,7 @@ static gfx::Transform ScreenSpaceTransformInternal(LayerType* layer,
                        layer->offset_to_transform_parent().y());
   gfx::Transform ssxform = tree.ToScreen(layer->transform_tree_index());
   xform.ConcatTransform(ssxform);
-  if (layer->should_flatten_transform_from_property_tree())
+  if (layer->should_flatten_screen_space_transform_from_property_tree())
     xform.FlattenTo2d();
   return xform;
 }
@@ -889,7 +889,7 @@ gfx::Transform DrawTransform(const LayerImpl* layer,
   transform_tree.property_trees()->GetToTarget(
       layer->transform_tree_index(), layer->render_target_effect_tree_index(),
       &xform);
-  if (layer->should_flatten_transform_from_property_tree())
+  if (layer->should_flatten_screen_space_transform_from_property_tree())
     xform.FlattenTo2d();
   xform.Translate(layer->offset_to_transform_parent().x(),
                   layer->offset_to_transform_parent().y());

cc/trees/property_tree_builder.cc

@@ -482,7 +482,7 @@ bool PropertyTreeBuilderContext<LayerType>::AddTransformNodeIfNeeded(
     }
     layer->SetOffsetToTransformParent(source_offset + source_to_parent +
                                       local_offset);
-    layer->SetShouldFlattenTransformFromPropertyTree(
+    layer->SetShouldFlattenScreenSpaceTransformFromPropertyTree(
         data_from_ancestor.should_flatten);
     layer->SetTransformTreeIndex(parent_index);
     return false;
@@ -617,7 +617,7 @@ bool PropertyTreeBuilderContext<LayerType>::AddTransformNodeIfNeeded(
   layer->SetOffsetToTransformParent(gfx::Vector2dF());
 
   // Flattening (if needed) will be handled by |node|.
-  layer->SetShouldFlattenTransformFromPropertyTree(false);
+  layer->SetShouldFlattenScreenSpaceTransformFromPropertyTree(false);
 
   return true;
 }
@@ -1145,7 +1145,8 @@ void PropertyTreeBuilderContext<LayerType>::AddScrollNodeIfNeeded(
     node.bounds = layer->bounds();
     node.container_bounds = layer->scroll_container_bounds();
     node.offset_to_transform_parent = layer->offset_to_transform_parent();
-    node.should_flatten = layer->should_flatten_transform_from_property_tree();
+    node.should_flatten =
+        layer->should_flatten_screen_space_transform_from_property_tree();
     node.user_scrollable_horizontal = UserScrollableHorizontal(layer);
     node.user_scrollable_vertical = UserScrollableVertical(layer);
     node.element_id = layer->element_id();