Overscroll and Elasticity for views::ScrollView

ui/events/blink/input_scroll_elasticity_controller.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 UI_EVENTS_BLINK_INPUT_SCROLL_ELASTICITY_CONTROLLER_H_
 #define UI_EVENTS_BLINK_INPUT_SCROLL_ELASTICITY_CONTROLLER_H_
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "cc/input/scroll_elasticity_helper.h"
@@ skipping 27 matching lines @@
  */
 
 namespace cc {
 struct InputHandlerScrollResult;
 }  // namespace cc
 
 namespace ui {
 
 class InputScrollElasticityController {
  public:
-  explicit InputScrollElasticityController(cc::ScrollElasticityHelper* helper);
+  InputScrollElasticityController();
   virtual ~InputScrollElasticityController();
 
   base::WeakPtr<InputScrollElasticityController> GetWeakPtr();
 
+  void SetActiveHelper(const base::WeakPtr<cc::ScrollElasticityHelper>& helper);
+
+  void ObserveRealScrollBegin(bool enter_momentum, bool leave_momentum);
+  void ObserveScrollUpdate(const gfx::Vector2dF& event_delta,
+                           const gfx::Vector2dF& unused_scroll_delta,
+                           const base::TimeTicks& event_timestamp,
+                           bool has_momentum);
+  void ObserveRealScrollEnd(const base::TimeTicks& event_timestamp);
+
   // Update the overscroll state based a gesture event that has been processed.
   // Note that this assumes that all events are coming from a single input
   // device. If the user simultaneously uses multiple input devices, Cocoa may
   // not correctly pass all the gesture begin and end events. In this case,
   // this class may disregard some scrolls that come in at unexpected times.
   void ObserveGestureEventAndResult(
       const blink::WebGestureEvent& gesture_event,
       const cc::InputHandlerScrollResult& scroll_result);
 
   void Animate(base::TimeTicks time);
@@ skipping 36 matching lines @@
   // Returns true if |direction| is pointing in a direction in which it is not
   // possible to scroll any farther horizontally (or vertically). It is only in
   // this circumstance that an overscroll in that direction may begin.
   bool PinnedHorizontally(float direction) const;
   bool PinnedVertically(float direction) const;
   // Whether or not the content of the page is scrollable horizontaly (or
   // vertically).
   bool CanScrollHorizontally() const;
   bool CanScrollVertically() const;
 
-  cc::ScrollElasticityHelper* helper_;
+  base::WeakPtr<cc::ScrollElasticityHelper> helper_;
   State state_;
 
   // If there is no overscroll, require a minimum overscroll delta before
   // starting the rubber-band effect. Track the amount of scrolling that has
   // has occurred but has not yet caused rubber-band stretching in
   // |pending_overscroll_delta_|.
   gfx::Vector2dF pending_overscroll_delta_;
 
   // Maintain a calculation of the velocity of the scroll, based on the input
   // scroll delta divide by the time between input events. Track this velocity
@@ skipping 19 matching lines @@
   // behavior as would happen if the scroll were caused by an active scroll).
   bool momentum_animation_reset_at_next_frame_;
 
   base::WeakPtrFactory<InputScrollElasticityController> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(InputScrollElasticityController);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_BLINK_INPUT_SCROLL_ELASTICITY_CONTROLLER_H_