cc/input/input_handler.h

   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_