cc : Create effect nodes for non axis aligned clips

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 <stddef.h>
 
 #include <map>
 #include <set>
@@ skipping 38 matching lines @@
   bool in_subtree_of_page_scale_layer;
   bool affected_by_inner_viewport_bounds_delta;
   bool affected_by_outer_viewport_bounds_delta;
   bool should_flatten;
   bool is_hidden;
   uint32_t main_thread_scrolling_reasons;
   bool scroll_tree_parent_created_by_uninheritable_criteria;
   const gfx::Transform* device_transform;
   gfx::Transform compound_transform_since_render_target;
   bool axis_align_since_render_target;
+  bool not_axis_aligned_since_last_clip;
   SkColor safe_opaque_background_color;
 };
 
 static LayerPositionConstraint PositionConstraint(Layer* layer) {
   return layer->position_constraint();
 }
 
 static LayerPositionConstraint PositionConstraint(LayerImpl* layer) {
   return layer->test_properties()->position_constraint;
 }
@@ skipping 815 matching lines @@
   const bool has_potential_filter_animation =
       HasPotentiallyRunningFilterAnimation(layer);
   const bool has_proxied_opacity =
       !!(layer->mutable_properties() & MutableProperty::kOpacity);
   const bool should_create_render_surface = ShouldCreateRenderSurface(
       layer, data_from_ancestor.compound_transform_since_render_target,
       data_from_ancestor.axis_align_since_render_target);
   data_for_children->axis_align_since_render_target &=
       AnimationsPreserveAxisAlignment(layer);
 
+  bool not_axis_aligned_since_last_clip =
+      data_from_ancestor.not_axis_aligned_since_last_clip
+          ? true
+          : !AnimationsPreserveAxisAlignment(layer) ||
+                !Transform(layer).Preserves2dAxisAlignment();

[chrishtr, 2017/05/16 23:36:42]

What about transforms that don't have effects?

[jaydasika, 2017/05/16 23:46:28]

The recursion variable not_axis_aligned_since_last_clip is updated for every
layer, not just for effects. So, if there is a non-axis aligned transform with
no effect, data_for_children->not_axis_aligned_since_last_clip should be true
for descendants. Am I missing something ?

[chrishtr, 2017/05/17 00:44:49]

Oh I see. AddEffectNodeIfNeeded is called unconditionally. It seems it
would be cleaner to update for children outside of this method, since it
is not specific to effect nodes.

[jaydasika, 2017/05/17 21:20:46]

The reason I put it here is to avoid duplicating the code. Since we create an
effect node for this, this code has to exist here also. I added it to property
tree builder too to update the children.

+  bool has_non_axis_aligned_clip =
+      not_axis_aligned_since_last_clip && LayerClipsSubtree(layer);
+  data_for_children->not_axis_aligned_since_last_clip =
+      !has_non_axis_aligned_clip;
+
   bool requires_node = is_root || has_transparency ||
                        has_potential_opacity_animation || has_proxied_opacity ||
+                       has_non_axis_aligned_clip ||
                        should_create_render_surface;
 
   int parent_id = data_from_ancestor.effect_tree_parent;
 
   if (!requires_node) {
     layer->SetEffectTreeIndex(parent_id);
     data_for_children->effect_tree_parent = parent_id;
     data_for_children->compound_transform_since_render_target *=
         Transform(layer);
     return false;
@@ skipping 360 matching lines @@
   data_for_recursion.is_hidden = false;
   data_for_recursion.main_thread_scrolling_reasons =
       MainThreadScrollingReason::kNotScrollingOnMain;
   data_for_recursion.scroll_tree_parent_created_by_uninheritable_criteria =
       true;
   data_for_recursion.device_transform = &device_transform;
 
   data_for_recursion.property_trees->clear();
   data_for_recursion.compound_transform_since_render_target = gfx::Transform();
   data_for_recursion.axis_align_since_render_target = true;
+  data_for_recursion.not_axis_aligned_since_last_clip = false;
   data_for_recursion.property_trees->transform_tree.set_device_scale_factor(
       device_scale_factor);
   data_for_recursion.safe_opaque_background_color = color;
 
   ClipNode root_clip;
   root_clip.clip_type = ClipNode::ClipType::APPLIES_LOCAL_CLIP;
   root_clip.clip = gfx::RectF(viewport);
   root_clip.transform_id = TransformTree::kRootNodeId;
   data_for_recursion.clip_tree_parent =
       data_for_recursion.property_trees->clip_tree.Insert(
@@ skipping 93 matching lines @@
       root_layer, page_scale_layer, inner_viewport_scroll_layer,
       outer_viewport_scroll_layer, overscroll_elasticity_layer,
       elastic_overscroll, page_scale_factor, device_scale_factor, viewport,
       device_transform, property_trees, color);
   property_trees->effect_tree.CreateOrReuseRenderSurfaces(
       &render_surfaces, root_layer->layer_tree_impl());
   property_trees->ResetCachedData();
 }
 
 }  // namespace cc