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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/base/swap_promise_monitor.h"
     12 #include "cc/input/scrollbar.h"
     13 
     14 namespace gfx {
     15 class Point;
     16 class PointF;
     17 class Vector2d;
     18 class Vector2dF;
     19 }
     20 
     21 namespace ui { struct LatencyInfo; }
     22 
     23 namespace cc {
     24 
     25 class LayerScrollOffsetDelegate;
     26 
     27 class CC_EXPORT InputHandlerClient {
     28  public:
     29   virtual ~InputHandlerClient() {}
     30 
     31   virtual void WillShutdown() = 0;
     32   virtual void Animate(base::TimeTicks time) = 0;
     33   virtual void MainThreadHasStoppedFlinging() = 0;
     34 
     35   // Called when scroll deltas reaching the root scrolling layer go unused.
     36   // The accumulated overscroll is scoped by the most recent call to
     37   // InputHandler::ScrollBegin.
     38   virtual void DidOverscroll(const gfx::Vector2dF& accumulated_overscroll,
     39                              const gfx::Vector2dF& latest_overscroll_delta) = 0;
     40 
     41  protected:
     42   InputHandlerClient() {}
     43 
     44  private:
     45   DISALLOW_COPY_AND_ASSIGN(InputHandlerClient);
     46 };
     47 
     48 // The InputHandler is a way for the embedders to interact with the impl thread
     49 // side of the compositor implementation. There is one InputHandler per
     50 // LayerTreeHost. To use the input handler, implement the InputHanderClient
     51 // interface and bind it to the handler on the compositor thread.
     52 class CC_EXPORT InputHandler {
     53  public:
     54   // Note these are used in a histogram. Do not reorder or delete existing
     55   // entries.
     56   enum ScrollStatus {
     57     ScrollOnMainThread = 0,
     58     ScrollStarted,
     59     ScrollIgnored,
     60     ScrollUnknown,
     61     // This must be the last entry.
     62     ScrollStatusCount
     63   };
     64   enum ScrollInputType { Gesture, Wheel, NonBubblingGesture };
     65 
     66   // Binds a client to this handler to receive notifications. Only one client
     67   // can be bound to an InputHandler. The client must live at least until the
     68   // handler calls WillShutdown() on the client.
     69   virtual void BindToClient(InputHandlerClient* client) = 0;
     70 
     71   // Selects a layer to be scrolled at a given point in viewport (logical
     72   // pixel) coordinates. Returns ScrollStarted if the layer at the coordinates
     73   // can be scrolled, ScrollOnMainThread if the scroll event should instead be
     74   // delegated to the main thread, or ScrollIgnored if there is nothing to be
     75   // scrolled at the given coordinates.
     76   virtual ScrollStatus ScrollBegin(const gfx::Point& viewport_point,
     77                                    ScrollInputType type) = 0;
     78 
     79   // Scroll the selected layer starting at the given position. If the scroll
     80   // type given to ScrollBegin was a gesture, then the scroll point and delta
     81   // should be in viewport (logical pixel) coordinates. Otherwise they are in
     82   // scrolling layer's (logical pixel) space. If there is no room to move the
     83   // layer in the requested direction, its first ancestor layer that can be
     84   // scrolled will be moved instead. If no layer can be moved in the requested
     85   // direction at all, then false is returned. If any layer is moved, then
     86   // true is returned.
     87   // If the scroll delta hits the root layer, and the layer can no longer move,
     88   // the root overscroll accumulated within this ScrollBegin() scope is reported
     89   // to the client.
     90   // Should only be called if ScrollBegin() returned ScrollStarted.
     91   virtual bool ScrollBy(const gfx::Point& viewport_point,
     92                         const gfx::Vector2dF& scroll_delta) = 0;
     93 
     94   virtual bool ScrollVerticallyByPage(const gfx::Point& viewport_point,
     95                                       ScrollDirection direction) = 0;
     96 
     97   // Returns ScrollStarted if a layer was being actively being scrolled,
     98   // ScrollIgnored if not.
     99   virtual ScrollStatus FlingScrollBegin() = 0;
    100 
    101   virtual void MouseMoveAt(const gfx::Point& mouse_position) = 0;
    102 
    103   // Stop scrolling the selected layer. Should only be called if ScrollBegin()
    104   // returned ScrollStarted.
    105   virtual void ScrollEnd() = 0;
    106 
    107   virtual void SetRootLayerScrollOffsetDelegate(
    108       LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) = 0;
    109 
    110   // Called when the value returned by
    111   // LayerScrollOffsetDelegate.GetTotalScrollOffset has changed for reasons
    112   // other than a SetTotalScrollOffset call.
    113   // NOTE: This should only called after a valid delegate was set via a call to
    114   // SetRootLayerScrollOffsetDelegate.
    115   virtual void OnRootLayerDelegatedScrollOffsetChanged() = 0;
    116 
    117   virtual void PinchGestureBegin() = 0;
    118   virtual void PinchGestureUpdate(float magnify_delta,
    119                                   const gfx::Point& anchor) = 0;
    120   virtual void PinchGestureEnd() = 0;
    121 
    122   virtual void StartPageScaleAnimation(const gfx::Vector2d& target_offset,
    123                                        bool anchor_point,
    124                                        float page_scale,
    125                                        base::TimeDelta duration) = 0;
    126 
    127   // Request another callback to InputHandlerClient::Animate().
    128   virtual void SetNeedsAnimate() = 0;
    129 
    130   // Whether the layer under |viewport_point| is the currently scrolling layer.
    131   virtual bool IsCurrentlyScrollingLayerAt(const gfx::Point& viewport_point,
    132                                            ScrollInputType type) = 0;
    133 
    134   virtual bool HaveTouchEventHandlersAt(const gfx::Point& viewport_point) = 0;
    135 
    136   // Calling CreateLatencyInfoSwapPromiseMonitor() to get a scoped
    137   // LatencyInfoSwapPromiseMonitor. During the life time of the
    138   // LatencyInfoSwapPromiseMonitor, if SetNeedsRedraw() or SetNeedsRedrawRect()
    139   // is called on LayerTreeHostImpl, the original latency info will be turned
    140   // into a LatencyInfoSwapPromise.
    141   virtual scoped_ptr<SwapPromiseMonitor> CreateLatencyInfoSwapPromiseMonitor(
    142       ui::LatencyInfo* latency) = 0;
    143 
    144  protected:
    145   InputHandler() {}
    146   virtual ~InputHandler() {}
    147 
    148  private:
    149   DISALLOW_COPY_AND_ASSIGN(InputHandler);
    150 };
    151 
    152 }  // namespace cc
    153 
    154 #endif  // CC_INPUT_INPUT_HANDLER_H_
    155