VR Shell: Allow UI elements to determine hit testing.

chrome/browser/android/vr_shell/ui_elements/ui_element.h

 // Copyright 2016 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 CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 92 matching lines @@
 
   // Indicates whether the element should be tested for cursor input.
   bool IsHitTestable() const;
 
   virtual void Render(VrShellRenderer* renderer,
                       vr::Mat4f view_proj_matrix) const;
 
   virtual void Initialize();
 
   // Controller interaction methods.
-  virtual void OnHoverEnter(gfx::PointF position);
+  virtual void OnHoverEnter(const gfx::PointF& position);
   virtual void OnHoverLeave();
-  virtual void OnMove(gfx::PointF position);
-  virtual void OnButtonDown(gfx::PointF position);
-  virtual void OnButtonUp(gfx::PointF position);
+  virtual void OnMove(const gfx::PointF& position);
+  virtual void OnButtonDown(const gfx::PointF& position);
+  virtual void OnButtonUp(const gfx::PointF& position);
+  // Whether the point (relative to the origin of the element), should be
+  // considered on the element. All elements are considered rectangular by
+  // default though elements may override this function to handle arbitrary
+  // shapes. Points within the rectangular area are mapped from 0:1 as follows,
+  // though will extend outside this range when outside of the element:
+  // [(0.0, 0.0), (1.0, 0.0)
+  //  (1.0, 0.0), (1.0, 1.0)]
+  virtual bool HitTest(const gfx::PointF& point) const;
 
   int id() const { return id_; }
   void set_id(int id) { id_ = id; }
 
   // If a non-negative parent ID is specified, applicable transformations
   // are applied relative to the parent, rather than absolutely.
   int parent_id() const { return parent_id_; }
   void set_parent_id(int id) { parent_id_ = id; }
 
   // If true, this object will be visible.
@@ skipping 164 matching lines @@
   bool dirty_ = false;
 
   Transform transform_;
 
   DISALLOW_COPY_AND_ASSIGN(UiElement);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_H_