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 {
  23 class LatencyInfo;
  24 }
  25
  26 namespace cc {
  27
  28 class LayerScrollOffsetDelegate;
  29 class ScrollElasticityHelper;
  30
  31 struct CC_EXPORT InputHandlerScrollResult {
  32   InputHandlerScrollResult();
  33   // Did any layer scroll as a result this ScrollBy call?
  34   bool did_scroll;
  35   // Was any of the scroll delta argument to this ScrollBy call not used?
  36   bool did_overscroll_root;
  37   // The total overscroll that has been accumulated by all ScrollBy calls that
  38   // have had overscroll since the last ScrollBegin call. This resets upon a
  39   // ScrollBy with no overscroll.
  40   gfx::Vector2dF accumulated_root_overscroll;
  41   // The amount of the scroll delta argument to this ScrollBy call that was not
  42   // used for scrolling.
  43   gfx::Vector2dF unused_scroll_delta;
  44 };
  45
  46 class CC_EXPORT InputHandlerClient {
  47  public:
  48   virtual ~InputHandlerClient() {}
  49
  50   virtual void WillShutdown() = 0;
  51   virtual void Animate(base::TimeTicks time) = 0;
  52   virtual void MainThreadHasStoppedFlinging() = 0;
  53   virtual void ReconcileElasticOverscrollAndRootScroll() = 0;
  54
  55  protected:
  56   InputHandlerClient() {}
  57
  58  private:
  59   DISALLOW_COPY_AND_ASSIGN(InputHandlerClient);
  60 };
  61
  62 // The InputHandler is a way for the embedders to interact with the impl thread
  63 // side of the compositor implementation. There is one InputHandler per
  64 // LayerTreeHost. To use the input handler, implement the InputHanderClient
  65 // interface and bind it to the handler on the compositor thread.
  66 class CC_EXPORT InputHandler {
  67  public:
  68   // Note these are used in a histogram. Do not reorder or delete existing
  69   // entries.
  70   enum ScrollStatus {
  71     SCROLL_ON_MAIN_THREAD = 0,
  72     SCROLL_STARTED,
  73     SCROLL_IGNORED,
  74     SCROLL_UNKNOWN,
  75     // This must be the last entry.
  76     ScrollStatusCount
  77   };
  78   enum ScrollInputType { GESTURE, WHEEL, NON_BUBBLING_GESTURE };
  79
  80   // Binds a client to this handler to receive notifications. Only one client
  81   // can be bound to an InputHandler. The client must live at least until the
  82   // handler calls WillShutdown() on the client.
  83   virtual void BindToClient(InputHandlerClient* client) = 0;
  84
  85   // Selects a layer to be scrolled at a given point in viewport (logical
  86   // pixel) coordinates. Returns SCROLL_STARTED if the layer at the coordinates
  87   // can be scrolled, SCROLL_ON_MAIN_THREAD if the scroll event should instead
  88   // be delegated to the main thread, or SCROLL_IGNORED if there is nothing to
  89   // be scrolled at the given coordinates.
  90   virtual ScrollStatus ScrollBegin(const gfx::Point& viewport_point,
  91                                    ScrollInputType type) = 0;
  92
  93   // Similar to ScrollBegin, except the hit test is skipped and scroll always
  94   // targets at the root layer.
  95   virtual ScrollStatus RootScrollBegin(ScrollInputType type) = 0;
  96   virtual ScrollStatus ScrollAnimated(const gfx::Point& viewport_point,
  97                                       const gfx::Vector2dF& scroll_delta) = 0;
  98
  99   // Scroll the selected layer starting at the given position. If the scroll
 100   // type given to ScrollBegin was a gesture, then the scroll point and delta
 101   // should be in viewport (logical pixel) coordinates. Otherwise they are in
 102   // scrolling layer's (logical pixel) space. If there is no room to move the
 103   // layer in the requested direction, its first ancestor layer that can be
 104   // scrolled will be moved instead. The return value's |did_scroll| field is
 105   // set to false if no layer can be moved in the requested direction at all,
 106   // and set to true if any layer is moved.
 107   // If the scroll delta hits the root layer, and the layer can no longer move,
 108   // the root overscroll accumulated within this ScrollBegin() scope is reported
 109   // in the return value's |accumulated_overscroll| field.
 110   // Should only be called if ScrollBegin() returned SCROLL_STARTED.
 111   virtual InputHandlerScrollResult ScrollBy(
 112       const gfx::Point& viewport_point,
 113       const gfx::Vector2dF& scroll_delta) = 0;
 114
 115   virtual bool ScrollVerticallyByPage(const gfx::Point& viewport_point,
 116                                       ScrollDirection direction) = 0;
 117
 118   // Returns SCROLL_STARTED if a layer was being actively being scrolled,
 119   // SCROLL_IGNORED if not.
 120   virtual ScrollStatus FlingScrollBegin() = 0;
 121
 122   virtual void MouseMoveAt(const gfx::Point& mouse_position) = 0;
 123
 124   // Stop scrolling the selected layer. Should only be called if ScrollBegin()
 125   // returned SCROLL_STARTED.
 126   virtual void ScrollEnd() = 0;
 127
 128   virtual void SetRootLayerScrollOffsetDelegate(
 129       LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) = 0;
 130
 131   // Called when the value returned by
 132   // LayerScrollOffsetDelegate.GetTotalScrollOffset has changed for reasons
 133   // other than a SetTotalScrollOffset call.
 134   // NOTE: This should only called after a valid delegate was set via a call to
 135   // SetRootLayerScrollOffsetDelegate.
 136   virtual void OnRootLayerDelegatedScrollOffsetChanged() = 0;
 137
 138   virtual void PinchGestureBegin() = 0;
 139   virtual void PinchGestureUpdate(float magnify_delta,
 140                                   const gfx::Point& anchor) = 0;
 141   virtual void PinchGestureEnd() = 0;
 142
 143   // Request another callback to InputHandlerClient::Animate().
 144   virtual void SetNeedsAnimateInput() = 0;
 145
 146   // Whether the layer under |viewport_point| is the currently scrolling layer.
 147   virtual bool IsCurrentlyScrollingLayerAt(const gfx::Point& viewport_point,
 148                                            ScrollInputType type) = 0;
 149
 150   virtual bool HaveWheelEventHandlersAt(const gfx::Point& viewport_point) = 0;
 151
 152   // Whether the page should be given the opportunity to suppress scrolling by
 153   // consuming touch events that started at |viewport_point|.
 154   virtual bool DoTouchEventsBlockScrollAt(const gfx::Point& viewport_point) = 0;
 155
 156   // Calling CreateLatencyInfoSwapPromiseMonitor() to get a scoped
 157   // LatencyInfoSwapPromiseMonitor. During the life time of the
 158   // LatencyInfoSwapPromiseMonitor, if SetNeedsRedraw() or SetNeedsRedrawRect()
 159   // is called on LayerTreeHostImpl, the original latency info will be turned
 160   // into a LatencyInfoSwapPromise.
 161   virtual scoped_ptr<SwapPromiseMonitor> CreateLatencyInfoSwapPromiseMonitor(
 162       ui::LatencyInfo* latency) = 0;
 163
 164   virtual ScrollElasticityHelper* CreateScrollElasticityHelper() = 0;
 165
 166  protected:
 167   InputHandler() {}
 168   virtual ~InputHandler() {}
 169
 170  private:
 171   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 172 };
 173
 174 }  // namespace cc
 175
 176 #endif  // CC_INPUT_INPUT_HANDLER_H_