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::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_