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      1 // Copyright 2011 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CC_INPUT_INPUT_HANDLER_H_
      6 #define CC_INPUT_INPUT_HANDLER_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "base/time/time.h"
     10 #include "cc/base/cc_export.h"
     11 #include "cc/input/scrollbar.h"
     12 
     13 namespace gfx {
     14 class Point;
     15 class PointF;
     16 class Vector2d;
     17 class Vector2dF;
     18 }
     19 
     20 namespace ui { struct LatencyInfo; }
     21 
     22 namespace cc {
     23 
     24 class LayerScrollOffsetDelegate;
     25 
     26 struct DidOverscrollParams {
     27   gfx::Vector2dF accumulated_overscroll;
     28   gfx::Vector2dF latest_overscroll_delta;
     29   gfx::Vector2dF current_fling_velocity;
     30 };
     31 
     32 class CC_EXPORT InputHandlerClient {
     33  public:
     34   virtual ~InputHandlerClient() {}
     35 
     36   virtual void WillShutdown() = 0;
     37   virtual void Animate(base::TimeTicks time) = 0;
     38   virtual void MainThreadHasStoppedFlinging() = 0;
     39 
     40   // Called when scroll deltas reaching the root scrolling layer go unused.
     41   // The accumulated overscroll is scoped by the most recent call to
     42   // InputHandler::ScrollBegin.
     43   virtual void DidOverscroll(const DidOverscrollParams& params) = 0;
     44 
     45  protected:
     46   InputHandlerClient() {}
     47 
     48  private:
     49   DISALLOW_COPY_AND_ASSIGN(InputHandlerClient);
     50 };
     51 
     52 // The InputHandler is a way for the embedders to interact with the impl thread
     53 // side of the compositor implementation. There is one InputHandler per
     54 // LayerTreeHost. To use the input handler, implement the InputHanderClient
     55 // interface and bind it to the handler on the compositor thread.
     56 class CC_EXPORT InputHandler {
     57  public:
     58   enum ScrollStatus { ScrollOnMainThread, ScrollStarted, ScrollIgnored };
     59   enum ScrollInputType { Gesture, Wheel, NonBubblingGesture };
     60 
     61   // Binds a client to this handler to receive notifications. Only one client
     62   // can be bound to an InputHandler. The client must live at least until the
     63   // handler calls WillShutdown() on the client.
     64   virtual void BindToClient(InputHandlerClient* client) = 0;
     65 
     66   // Selects a layer to be scrolled at a given point in viewport (logical
     67   // pixel) coordinates. Returns ScrollStarted if the layer at the coordinates
     68   // can be scrolled, ScrollOnMainThread if the scroll event should instead be
     69   // delegated to the main thread, or ScrollIgnored if there is nothing to be
     70   // scrolled at the given coordinates.
     71   virtual ScrollStatus ScrollBegin(gfx::Point viewport_point,
     72                                    ScrollInputType type) = 0;
     73 
     74   // Scroll the selected layer starting at the given position. If the scroll
     75   // type given to ScrollBegin was a gesture, then the scroll point and delta
     76   // should be in viewport (logical pixel) coordinates. Otherwise they are in
     77   // scrolling layer's (logical pixel) space. If there is no room to move the
     78   // layer in the requested direction, its first ancestor layer that can be
     79   // scrolled will be moved instead. If no layer can be moved in the requested
     80   // direction at all, then false is returned. If any layer is moved, then
     81   // true is returned.
     82   // If the scroll delta hits the root layer, and the layer can no longer move,
     83   // the root overscroll accumulated within this ScrollBegin() scope is reported
     84   // to the client.
     85   // Should only be called if ScrollBegin() returned ScrollStarted.
     86   virtual bool ScrollBy(gfx::Point viewport_point,
     87                         gfx::Vector2dF scroll_delta) = 0;
     88 
     89   virtual bool ScrollVerticallyByPage(
     90       gfx::Point viewport_point,
     91       ScrollDirection direction) = 0;
     92 
     93   // Returns ScrollStarted if a layer was being actively being scrolled,
     94   // ScrollIgnored if not.
     95   virtual ScrollStatus FlingScrollBegin() = 0;
     96 
     97   virtual void NotifyCurrentFlingVelocity(gfx::Vector2dF velocity) = 0;
     98 
     99   // Stop scrolling the selected layer. Should only be called if ScrollBegin()
    100   // returned ScrollStarted.
    101   virtual void ScrollEnd() = 0;
    102 
    103   virtual void SetRootLayerScrollOffsetDelegate(
    104       LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) = 0;
    105 
    106   // Called when the value returned by
    107   // LayerScrollOffsetDelegate.GetTotalScrollOffset has changed for reasons
    108   // other than a SetTotalScrollOffset call.
    109   // NOTE: This should only called after a valid delegate was set via a call to
    110   // SetRootLayerScrollOffsetDelegate.
    111   virtual void OnRootLayerDelegatedScrollOffsetChanged() = 0;
    112 
    113   virtual void PinchGestureBegin() = 0;
    114   virtual void PinchGestureUpdate(float magnify_delta, gfx::Point anchor) = 0;
    115   virtual void PinchGestureEnd() = 0;
    116 
    117   virtual void StartPageScaleAnimation(gfx::Vector2d target_offset,
    118                                        bool anchor_point,
    119                                        float page_scale,
    120                                        base::TimeTicks start_time,
    121                                        base::TimeDelta duration) = 0;
    122 
    123   // Request another callback to InputHandlerClient::Animate().
    124   virtual void ScheduleAnimation() = 0;
    125 
    126   virtual bool HaveTouchEventHandlersAt(gfx::Point viewport_point) = 0;
    127 
    128   virtual void SetLatencyInfoForInputEvent(
    129       const ui::LatencyInfo& latency_info) = 0;
    130 
    131  protected:
    132   InputHandler() {}
    133   virtual ~InputHandler() {}
    134 
    135  private:
    136   DISALLOW_COPY_AND_ASSIGN(InputHandler);
    137 };
    138 
    139 }  // namespace cc
    140 
    141 #endif  // CC_INPUT_INPUT_HANDLER_H_
    142