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/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   virtual ScrollStatus ScrollAnimated(const gfx::Point& viewport_point,
  80                                       const gfx::Vector2dF& scroll_delta) = 0;
  81
  82   // Scroll the selected layer starting at the given position. If the scroll
  83   // type given to ScrollBegin was a gesture, then the scroll point and delta
  84   // should be in viewport (logical pixel) coordinates. Otherwise they are in
  85   // scrolling layer's (logical pixel) space. If there is no room to move the
  86   // layer in the requested direction, its first ancestor layer that can be
  87   // scrolled will be moved instead. If no layer can be moved in the requested
  88   // direction at all, then false is returned. If any layer is moved, then
  89   // true is returned.
  90   // If the scroll delta hits the root layer, and the layer can no longer move,
  91   // the root overscroll accumulated within this ScrollBegin() scope is reported
  92   // to the client.
  93   // Should only be called if ScrollBegin() returned ScrollStarted.
  94   virtual bool ScrollBy(const gfx::Point& viewport_point,
  95                         const gfx::Vector2dF& scroll_delta) = 0;
  96
  97   virtual bool ScrollVerticallyByPage(const gfx::Point& viewport_point,
  98                                       ScrollDirection direction) = 0;
  99
 100   // Returns ScrollStarted if a layer was being actively being scrolled,
 101   // ScrollIgnored if not.
 102   virtual ScrollStatus FlingScrollBegin() = 0;
 103
 104   virtual void MouseMoveAt(const gfx::Point& mouse_position) = 0;
 105
 106   // Stop scrolling the selected layer. Should only be called if ScrollBegin()
 107   // returned ScrollStarted.
 108   virtual void ScrollEnd() = 0;
 109
 110   virtual void SetRootLayerScrollOffsetDelegate(
 111       LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) = 0;
 112
 113   // Called when the value returned by
 114   // LayerScrollOffsetDelegate.GetTotalScrollOffset has changed for reasons
 115   // other than a SetTotalScrollOffset call.
 116   // NOTE: This should only called after a valid delegate was set via a call to
 117   // SetRootLayerScrollOffsetDelegate.
 118   virtual void OnRootLayerDelegatedScrollOffsetChanged() = 0;
 119
 120   virtual void PinchGestureBegin() = 0;
 121   virtual void PinchGestureUpdate(float magnify_delta,
 122                                   const gfx::Point& anchor) = 0;
 123   virtual void PinchGestureEnd() = 0;
 124
 125   virtual void StartPageScaleAnimation(const gfx::Vector2d& target_offset,
 126                                        bool anchor_point,
 127                                        float page_scale,
 128                                        base::TimeDelta duration) = 0;
 129
 130   // Request another callback to InputHandlerClient::Animate().
 131   virtual void SetNeedsAnimate() = 0;
 132
 133   // Whether the layer under |viewport_point| is the currently scrolling layer.
 134   virtual bool IsCurrentlyScrollingLayerAt(const gfx::Point& viewport_point,
 135                                            ScrollInputType type) = 0;
 136
 137   virtual bool HaveTouchEventHandlersAt(const gfx::Point& viewport_point) = 0;
 138
 139   // Calling CreateLatencyInfoSwapPromiseMonitor() to get a scoped
 140   // LatencyInfoSwapPromiseMonitor. During the life time of the
 141   // LatencyInfoSwapPromiseMonitor, if SetNeedsRedraw() or SetNeedsRedrawRect()
 142   // is called on LayerTreeHostImpl, the original latency info will be turned
 143   // into a LatencyInfoSwapPromise.
 144   virtual scoped_ptr<SwapPromiseMonitor> CreateLatencyInfoSwapPromiseMonitor(
 145       ui::LatencyInfo* latency) = 0;
 146
 147  protected:
 148   InputHandler() {}
 149   virtual ~InputHandler() {}
 150
 151  private:
 152   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 153 };
 154
 155 }  // namespace cc
 156
 157 #endif  // CC_INPUT_INPUT_HANDLER_H_