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/memory/scoped_ptr.h"
  10 #include "base/time/time.h"
  11 #include "cc/base/cc_export.h"
  12 #include "cc/input/scrollbar.h"
  13 #include "cc/trees/swap_promise_monitor.h"
  14
  15 namespace gfx {
  16 class Point;
  17 class PointF;
  18 class Vector2d;
  19 class Vector2dF;
  20 }
  21
  22 namespace ui { struct LatencyInfo; }
  23
  24 namespace cc {
  25
  26 class LayerScrollOffsetDelegate;
  27 class ScrollElasticityHelper;
  28
  29 struct CC_EXPORT InputHandlerScrollResult {
  30   InputHandlerScrollResult();
  31   // Did any layer scroll as a result this ScrollBy call?
  32   bool did_scroll;
  33   // Was any of the scroll delta argument to this ScrollBy call not used?
  34   bool did_overscroll_root;
  35   // The total overscroll that has been accumulated by all ScrollBy calls that
  36   // have had overscroll since the last ScrollBegin call. This resets upon a
  37   // ScrollBy with no overscroll.
  38   gfx::Vector2dF accumulated_root_overscroll;
  39   // The amount of the scroll delta argument to this ScrollBy call that was not
  40   // used for scrolling.
  41   gfx::Vector2dF unused_scroll_delta;
  42 };
  43
  44 class CC_EXPORT InputHandlerClient {
  45  public:
  46   virtual ~InputHandlerClient() {}
  47
  48   virtual void WillShutdown() = 0;
  49   virtual void Animate(base::TimeTicks time) = 0;
  50   virtual void MainThreadHasStoppedFlinging() = 0;
  51   virtual void ReconcileElasticOverscrollAndRootScroll() = 0;
  52
  53  protected:
  54   InputHandlerClient() {}
  55
  56  private:
  57   DISALLOW_COPY_AND_ASSIGN(InputHandlerClient);
  58 };
  59
  60 // The InputHandler is a way for the embedders to interact with the impl thread
  61 // side of the compositor implementation. There is one InputHandler per
  62 // LayerTreeHost. To use the input handler, implement the InputHanderClient
  63 // interface and bind it to the handler on the compositor thread.
  64 class CC_EXPORT InputHandler {
  65  public:
  66   // Note these are used in a histogram. Do not reorder or delete existing
  67   // entries.
  68   enum ScrollStatus {
  69     SCROLL_ON_MAIN_THREAD = 0,
  70     SCROLL_STARTED,
  71     SCROLL_IGNORED,
  72     SCROLL_UNKNOWN,
  73     // This must be the last entry.
  74     ScrollStatusCount
  75   };
  76   enum ScrollInputType { GESTURE, WHEEL, NON_BUBBLING_GESTURE };
  77
  78   // Binds a client to this handler to receive notifications. Only one client
  79   // can be bound to an InputHandler. The client must live at least until the
  80   // handler calls WillShutdown() on the client.
  81   virtual void BindToClient(InputHandlerClient* client) = 0;
  82
  83   // Selects a layer to be scrolled at a given point in viewport (logical
  84   // pixel) coordinates. Returns SCROLL_STARTED if the layer at the coordinates
  85   // can be scrolled, SCROLL_ON_MAIN_THREAD if the scroll event should instead
  86   // be delegated to the main thread, or SCROLL_IGNORED if there is nothing to
  87   // be scrolled at the given coordinates.
  88   virtual ScrollStatus ScrollBegin(const gfx::Point& viewport_point,
  89                                    ScrollInputType type) = 0;
  90
  91   // Similar to ScrollBegin, except the hit test is skipped and scroll always
  92   // targets at the root layer.
  93   virtual ScrollStatus RootScrollBegin(ScrollInputType type) = 0;
  94   virtual ScrollStatus ScrollAnimated(const gfx::Point& viewport_point,
  95                                       const gfx::Vector2dF& scroll_delta) = 0;
  96
  97   // Scroll the selected layer starting at the given position. If the scroll
  98   // type given to ScrollBegin was a gesture, then the scroll point and delta
  99   // should be in viewport (logical pixel) coordinates. Otherwise they are in
 100   // scrolling layer's (logical pixel) space. If there is no room to move the
 101   // layer in the requested direction, its first ancestor layer that can be
 102   // scrolled will be moved instead. The return value's |did_scroll| field is
 103   // set to false if no layer can be moved in the requested direction at all,
 104   // and set to true if any layer is moved.
 105   // If the scroll delta hits the root layer, and the layer can no longer move,
 106   // the root overscroll accumulated within this ScrollBegin() scope is reported
 107   // in the return value's |accumulated_overscroll| field.
 108   // Should only be called if ScrollBegin() returned SCROLL_STARTED.
 109   virtual InputHandlerScrollResult ScrollBy(
 110       const gfx::Point& viewport_point,
 111       const gfx::Vector2dF& scroll_delta) = 0;
 112
 113   virtual bool ScrollVerticallyByPage(const gfx::Point& viewport_point,
 114                                       ScrollDirection direction) = 0;
 115
 116   // Returns SCROLL_STARTED if a layer was being actively being scrolled,
 117   // SCROLL_IGNORED if not.
 118   virtual ScrollStatus FlingScrollBegin() = 0;
 119
 120   virtual void MouseMoveAt(const gfx::Point& mouse_position) = 0;
 121
 122   // Stop scrolling the selected layer. Should only be called if ScrollBegin()
 123   // returned SCROLL_STARTED.
 124   virtual void ScrollEnd() = 0;
 125
 126   virtual void SetRootLayerScrollOffsetDelegate(
 127       LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) = 0;
 128
 129   // Called when the value returned by
 130   // LayerScrollOffsetDelegate.GetTotalScrollOffset has changed for reasons
 131   // other than a SetTotalScrollOffset call.
 132   // NOTE: This should only called after a valid delegate was set via a call to
 133   // SetRootLayerScrollOffsetDelegate.
 134   virtual void OnRootLayerDelegatedScrollOffsetChanged() = 0;
 135
 136   virtual void PinchGestureBegin() = 0;
 137   virtual void PinchGestureUpdate(float magnify_delta,
 138                                   const gfx::Point& anchor) = 0;
 139   virtual void PinchGestureEnd() = 0;
 140
 141   // Request another callback to InputHandlerClient::Animate().
 142   virtual void SetNeedsAnimateInput() = 0;
 143
 144   // Whether the layer under |viewport_point| is the currently scrolling layer.
 145   virtual bool IsCurrentlyScrollingLayerAt(const gfx::Point& viewport_point,
 146                                            ScrollInputType type) = 0;
 147
 148   virtual bool HaveWheelEventHandlersAt(const gfx::Point& viewport_point) = 0;
 149
 150   // Whether the page should be given the opportunity to suppress scrolling by
 151   // consuming touch events that started at |viewport_point|.
 152   virtual bool DoTouchEventsBlockScrollAt(const gfx::Point& viewport_point) = 0;
 153
 154   // Calling CreateLatencyInfoSwapPromiseMonitor() to get a scoped
 155   // LatencyInfoSwapPromiseMonitor. During the life time of the
 156   // LatencyInfoSwapPromiseMonitor, if SetNeedsRedraw() or SetNeedsRedrawRect()
 157   // is called on LayerTreeHostImpl, the original latency info will be turned
 158   // into a LatencyInfoSwapPromise.
 159   virtual scoped_ptr<SwapPromiseMonitor> CreateLatencyInfoSwapPromiseMonitor(
 160       ui::LatencyInfo* latency) = 0;
 161
 162   virtual ScrollElasticityHelper* CreateScrollElasticityHelper() = 0;
 163
 164  protected:
 165   InputHandler() {}
 166   virtual ~InputHandler() {}
 167
 168  private:
 169   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 170 };
 171
 172 }  // namespace cc
 173
 174 #endif  // CC_INPUT_INPUT_HANDLER_H_