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