Support targeting for gestures in ViewTargeter

ui/views/widget/root_view.h

 // Copyright (c) 2012 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 UI_VIEWS_WIDGET_ROOT_VIEW_H_
 #define UI_VIEWS_WIDGET_ROOT_VIEW_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
 #include "ui/events/event_processor.h"
 #include "ui/views/focus/focus_manager.h"
 #include "ui/views/focus/focus_search.h"
 #include "ui/views/view.h"
 #include "ui/views/view_targeter_delegate.h"
 
 namespace views {
 
 namespace test {
+class ViewTargeterTest;
 class WidgetTest;
 }
 
+class ViewTargeter;
 class Widget;
 
 // This is a views-internal API and should not be used externally.
 // Widget exposes this object as a View*.
 namespace internal {
 class PreEventDispatchHandler;
 
 ////////////////////////////////////////////////////////////////////////////////
 // RootView class
 //
@@ skipping 83 matching lines @@
   virtual void ViewHierarchyChanged(
       const ViewHierarchyChangedDetails& details) OVERRIDE;
   virtual void VisibilityChanged(View* starting_from, bool is_visible) OVERRIDE;
   virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
   virtual gfx::Vector2d CalculateOffsetToAncestorWithLayer(
       ui::Layer** layer_parent) OVERRIDE;
   virtual View::DragInfo* GetDragInfo() OVERRIDE;
 
  private:
   friend class ::views::View;
+  friend class ::views::ViewTargeter;
   friend class ::views::Widget;
+  friend class ::views::test::ViewTargeterTest;
   friend class ::views::test::WidgetTest;
 
   // Input ---------------------------------------------------------------------
 
   // TODO(tdanderson): Remove RootView::DispatchGestureEvent() once
   //                   its targeting and dispatch logic has been moved
   //                   elsewhere. See crbug.com/348083.
   void DispatchGestureEvent(ui::GestureEvent* event);
 
   // Update the cursor given a mouse event. This is called by non mouse_move
@@ skipping 43 matching lines @@
 
   // true if mouse_pressed_handler_ has been explicitly set
   bool explicit_mouse_handler_;
 
   // Last position/flag of a mouse press/drag. Used if capture stops and we need
   // to synthesize a release.
   int last_mouse_event_flags_;
   int last_mouse_event_x_;
   int last_mouse_event_y_;
 
-  // The view currently handling gesture events. When set, this handler receives
-  // all gesture events.
+  // The View currently handling gesture events.
   View* gesture_handler_;
 
+  // If true, then gesture events received from Widget should be dispatched to
+  // |gesture_handler_|.
+  bool dispatch_to_gesture_handler_;

[tdanderson, 2014/08/16 20:34:23]

I admit that introducing this member does feel a bit clumsy and it would be
really nice if it could be avoided. But it seems this is necessary because it
keeps track of information which is currently (implicitly) tracked by
RootView::DispatchGestureEvent()'s soon-to-be-removed loops. That is, we know
whether or not |gesture_handler_| was established by a previous gesture event
simply by which loop we're inside in DispatchGestureEvent().

+
   scoped_ptr<internal::PreEventDispatchHandler> pre_dispatch_handler_;
   scoped_ptr<internal::PostEventDispatchHandler> post_dispatch_handler_;
 
   // Focus ---------------------------------------------------------------------
 
   // The focus search algorithm.
   FocusSearch focus_search_;
 
   // Whether this root view belongs to the current active window.
   // bool activated_;
@@ skipping 13 matching lines @@
   // Tracks drag state for a view.
   View::DragInfo drag_info_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(RootView);
 };
 
 }  // namespace internal
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_ROOT_VIEW_H_