Mozart: Implement hit testing.

mojo/services/gfx/composition/interfaces/hit_tests.mojom

 // Copyright 2015 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.
 
 [DartPackage="mojo_services"]
 module mojo.gfx.composition;
 
 import "mojo/services/geometry/interfaces/geometry.mojom";
 import "mojo/services/gfx/composition/interfaces/scene_token.mojom";
 
@@ skipping 23 matching lines @@
     //
     // Invisible targets are useful for explicitly suppressing hit testing
     // for a node and its children when combined with the |prune| flag.
     INVISIBLE,
   };
 
   // Specifies the visibility of the node for hit testing purposes.
   // The default is opaque.
   Visibility visibility = Visibility.OPAQUE;
 
-  // When set to true, prevents a node's children from being hit tested.
+  // When set to true, prevents a node's children or reference scenes from
+  // being hit tested.
   bool prune = false;
 
   // The rectangle within the node's content space to test for hits.
   // If null, the node's entire clip region is tested for hits.
   //
   // TODO(jeffbrown): Support more complex hit test regions and masks.
   mojo.Rect? hit_rect;
 };
 
 // A hit testing service for scene graphs.
@@ skipping 35 matching lines @@
 
   // The version of the scene which was consulted at the time the hit test
   // was performed.
   uint32 scene_version;
 
   // The array of hits within this scene, in dispatch order.
   // This list always contains at least one entry.
   array<Hit> hits;
 };
 
-// Describes the point of intersection of a hit test with a node.
+// Describes the intersection of a hit test with a node.
 struct NodeHit {
   // The node id of the node which was hit.
   uint32 node_id;
 
-  // The coordinates of the hit within the node's content space.
-  mojo.Point intersection;
+  // The transformation from the global coordinate system of the scene graph
+  // to the local coordinate system of the node's content space at the time
+  // the hit test was performed.
+  //
+  // To obtain the point of intersection of the hit test within the node's
+  // content space, multiple this transformation matrix by the hit test point.

[abarth, 2016/03/09 04:02:48]

s/multiple/multiply/

[jeffbrown, 2016/03/09 20:32:11]

Done.

+  mojo.Transform transform;
 };