cc : Split TransformTree::ComputeTransform

cc/trees/property_tree.h

 // 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.
 
 #ifndef CC_TREES_PROPERTY_TREE_H_
 #define CC_TREES_PROPERTY_TREE_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 136 matching lines @@
   // be computed between any pair of nodes that have an ancestor/descendant
   // relationship. Transforms between other pairs of nodes may only be computed
   // if the following condition holds: let id1 the larger id and let id2 be the
   // other id; then the nearest ancestor of node id1 whose id is smaller than
   // id2 is the lowest common ancestor of the pair of nodes, and the transform
   // from this lowest common ancestor to node id2 is only a 2d translation.
   bool ComputeTransform(int source_id,
                         int dest_id,
                         gfx::Transform* transform) const;
 
+  bool ComputeTransformFromSourceToParent(int source_id,
+                                          int dest_id,
+                                          gfx::Transform* transform) const;

[ajuma, 2016/07/27 15:57:11]

It'd be good if there was some way to enforce that this is used only for
source-to-parent transforms rather than arbitrary transforms. One idea: rename
this ComputeTranslation() with a comment that this can only be called between
pairs of nodes where the transform between nodes is a 2d translation, and then
DCHECK that the computed transform is indeed a 2d translation before returning?

[jaydasika, 2016/07/27 18:42:23]

Done.

+
   void ResetChangeTracking();
   // Updates the parent, target, and screen space transforms and snapping.
   void UpdateTransforms(int id);
   void UpdateTransformChanged(TransformNode* node,
                               TransformNode* parent_node,
                               TransformNode* source_node);
   void UpdateNodeAndAncestorsAreAnimatedOrInvertible(
       TransformNode* node,
       TransformNode* parent_node);
 
@@ skipping 71 matching lines @@
   void SetContentTargetId(int node_id, int content_target_id);
 
   const std::vector<TransformCachedNodeData>& cached_data() const {
     return cached_data_;
   }
 
   void ToProtobuf(proto::PropertyTree* proto) const;
   void FromProtobuf(const proto::PropertyTree& proto,
                     std::unordered_map<int, int>* node_id_to_index_map);
 
-  // Computes the combined transform between |source_id| and |dest_id| and
-  // returns false if the inverse of a singular transform was used. These two
-  // nodes must be on the same ancestor chain.
-  bool CombineTransformsBetween(int source_id,
+  // Computes the combined transform between |source_id| and |dest_id|. These
+  // two nodes must be on the same ancestor chain.
+  void CombineTransformsBetween(int source_id,
                                 int dest_id,
                                 gfx::Transform* transform) const;
 
   // Computes the combined inverse transform between |source_id| and |dest_id|
   // and returns false if the inverse of a singular transform was used. These
   // two nodes must be on the same ancestor chain.
   bool CombineInversesBetween(int source_id,
                               int dest_id,
                               gfx::Transform* transform) const;
 
@@ skipping 322 matching lines @@
 
   void ResetCachedData();
   void UpdateCachedNumber();
   gfx::Transform ToScreenSpaceTransformWithoutSurfaceContentsScale(
       int transform_id,
       int effect_id) const;
   bool ComputeTransformToTarget(int transform_id,
                                 int effect_id,
                                 gfx::Transform* transform) const;
 
+  bool ComputeTransformFromTarget(int transform_id,
+                                  int effect_id,
+                                  gfx::Transform* transform) const;
+
  private:
   gfx::Vector2dF inner_viewport_container_bounds_delta_;
   gfx::Vector2dF outer_viewport_container_bounds_delta_;
   gfx::Vector2dF inner_viewport_scroll_bounds_delta_;
 
   PropertyTreesCachedData cached_data_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROPERTY_TREE_H_