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.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 cc {
  21
  22 class LayerScrollOffsetDelegate;
  23
  24 class CC_EXPORT InputHandlerClient {
  25  public:
  26   virtual ~InputHandlerClient() {}
  27
  28   virtual void WillShutdown() = 0;
  29   virtual void Animate(base::TimeTicks time) = 0;
  30   virtual void MainThreadHasStoppedFlinging() = 0;
  31
  32   // Called when scroll deltas reaching the root scrolling layer go unused.
  33   // The accumulated overscroll is scoped by the most recent call to
  34   // InputHandler::ScrollBegin.
  35   virtual void DidOverscroll(gfx::Vector2dF accumulated_overscroll,
  36                              gfx::Vector2dF current_fling_velocity) = 0;
  37
  38  protected:
  39   InputHandlerClient() {}
  40
  41  private:
  42   DISALLOW_COPY_AND_ASSIGN(InputHandlerClient);
  43 };
  44
  45 // The InputHandler is a way for the embedders to interact with the impl thread
  46 // side of the compositor implementation. There is one InputHandler per
  47 // LayerTreeHost. To use the input handler, implement the InputHanderClient
  48 // interface and bind it to the handler on the compositor thread.
  49 class CC_EXPORT InputHandler {
  50  public:
  51   enum ScrollStatus { ScrollOnMainThread, ScrollStarted, ScrollIgnored };
  52   enum ScrollInputType { Gesture, Wheel, NonBubblingGesture };
  53
  54   // Binds a client to this handler to receive notifications. Only one client
  55   // can be bound to an InputHandler. The client must live at least until the
  56   // handler calls WillShutdown() on the client.
  57   virtual void BindToClient(InputHandlerClient* client) = 0;
  58
  59   // Selects a layer to be scrolled at a given point in viewport (logical
  60   // pixel) coordinates. Returns ScrollStarted if the layer at the coordinates
  61   // can be scrolled, ScrollOnMainThread if the scroll event should instead be
  62   // delegated to the main thread, or ScrollIgnored if there is nothing to be
  63   // scrolled at the given coordinates.
  64   virtual ScrollStatus ScrollBegin(gfx::Point viewport_point,
  65                                    ScrollInputType type) = 0;
  66
  67   // Scroll the selected layer starting at the given position. If the scroll
  68   // type given to ScrollBegin was a gesture, then the scroll point and delta
  69   // should be in viewport (logical pixel) coordinates. Otherwise they are in
  70   // scrolling layer's (logical pixel) space. If there is no room to move the
  71   // layer in the requested direction, its first ancestor layer that can be
  72   // scrolled will be moved instead. If no layer can be moved in the requested
  73   // direction at all, then false is returned. If any layer is moved, then
  74   // true is returned.
  75   // If the scroll delta hits the root layer, and the layer can no longer move,
  76   // the root overscroll accumulated within this ScrollBegin() scope is reported
  77   // to the client.
  78   // Should only be called if ScrollBegin() returned ScrollStarted.
  79   virtual bool ScrollBy(gfx::Point viewport_point,
  80                         gfx::Vector2dF scroll_delta) = 0;
  81
  82   virtual bool ScrollVerticallyByPage(
  83       gfx::Point viewport_point,
  84       ScrollDirection direction) = 0;
  85
  86   // Returns ScrollStarted if a layer was being actively being scrolled,
  87   // ScrollIgnored if not.
  88   virtual ScrollStatus FlingScrollBegin() = 0;
  89
  90   virtual void NotifyCurrentFlingVelocity(gfx::Vector2dF velocity) = 0;
  91
  92   // Stop scrolling the selected layer. Should only be called if ScrollBegin()
  93   // returned ScrollStarted.
  94   virtual void ScrollEnd() = 0;
  95
  96   virtual void SetRootLayerScrollOffsetDelegate(
  97       LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) = 0;
  98
  99   // Called when the value returned by
 100   // LayerScrollOffsetDelegate.GetTotalScrollOffset has changed for reasons
 101   // other than a SetTotalScrollOffset call.
 102   // NOTE: This should only called after a valid delegate was set via a call to
 103   // SetRootLayerScrollOffsetDelegate.
 104   virtual void OnRootLayerDelegatedScrollOffsetChanged() = 0;
 105
 106   virtual void PinchGestureBegin() = 0;
 107   virtual void PinchGestureUpdate(float magnify_delta, gfx::Point anchor) = 0;
 108   virtual void PinchGestureEnd() = 0;
 109
 110   virtual void StartPageScaleAnimation(gfx::Vector2d target_offset,
 111                                        bool anchor_point,
 112                                        float page_scale,
 113                                        base::TimeTicks start_time,
 114                                        base::TimeDelta duration) = 0;
 115
 116   // Request another callback to InputHandlerClient::Animate().
 117   virtual void ScheduleAnimation() = 0;
 118
 119   virtual bool HaveTouchEventHandlersAt(gfx::Point viewport_point) = 0;
 120
 121   virtual void DidReceiveLastInputEventForBeginFrame(
 122       base::TimeTicks frame_time) = 0;
 123
 124  protected:
 125   InputHandler() {}
 126   virtual ~InputHandler() {}
 127
 128  private:
 129   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 130 };
 131
 132 }  // namespace cc
 133
 134 #endif  // CC_INPUT_INPUT_HANDLER_H_