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 ScrollOffset;
  19 class Vector2d;
  20 class Vector2dF;
  21 }
  22
  23 namespace ui {
  24 class LatencyInfo;
  25 }
  26
  27 namespace cc {
  28
  29 class LayerScrollOffsetDelegate;
  30 class ScrollElasticityHelper;
  31
  32 struct CC_EXPORT InputHandlerScrollResult {
  33   InputHandlerScrollResult();
  34   // Did any layer scroll as a result this ScrollBy call?
  35   bool did_scroll;
  36   // Was any of the scroll delta argument to this ScrollBy call not used?
  37   bool did_overscroll_root;
  38   // The total overscroll that has been accumulated by all ScrollBy calls that
  39   // have had overscroll since the last ScrollBegin call. This resets upon a
  40   // ScrollBy with no overscroll.
  41   gfx::Vector2dF accumulated_root_overscroll;
  42   // The amount of the scroll delta argument to this ScrollBy call that was not
  43   // used for scrolling.
  44   gfx::Vector2dF unused_scroll_delta;
  45 };
  46
  47 class CC_EXPORT InputHandlerClient {
  48  public:
  49   virtual ~InputHandlerClient() {}
  50
  51   virtual void WillShutdown() = 0;
  52   virtual void Animate(base::TimeTicks time) = 0;
  53   virtual void MainThreadHasStoppedFlinging() = 0;
  54   virtual void ReconcileElasticOverscrollAndRootScroll() = 0;
  55
  56  protected:
  57   InputHandlerClient() {}
  58
  59  private:
  60   DISALLOW_COPY_AND_ASSIGN(InputHandlerClient);
  61 };
  62
  63 // The InputHandler is a way for the embedders to interact with the impl thread
  64 // side of the compositor implementation. There is one InputHandler per
  65 // LayerTreeHost. To use the input handler, implement the InputHanderClient
  66 // interface and bind it to the handler on the compositor thread.
  67 class CC_EXPORT InputHandler {
  68  public:
  69   // Note these are used in a histogram. Do not reorder or delete existing
  70   // entries.
  71   enum ScrollStatus {
  72     SCROLL_ON_MAIN_THREAD = 0,
  73     SCROLL_STARTED,
  74     SCROLL_IGNORED,
  75     SCROLL_UNKNOWN,
  76     // This must be the last entry.
  77     ScrollStatusCount
  78   };
  79   enum ScrollInputType { GESTURE, WHEEL, NON_BUBBLING_GESTURE };
  80
  81   // Binds a client to this handler to receive notifications. Only one client
  82   // can be bound to an InputHandler. The client must live at least until the
  83   // handler calls WillShutdown() on the client.
  84   virtual void BindToClient(InputHandlerClient* client) = 0;
  85
  86   // Selects a layer to be scrolled at a given point in viewport (logical
  87   // pixel) coordinates. Returns SCROLL_STARTED if the layer at the coordinates
  88   // can be scrolled, SCROLL_ON_MAIN_THREAD if the scroll event should instead
  89   // be delegated to the main thread, or SCROLL_IGNORED if there is nothing to
  90   // be scrolled at the given coordinates.
  91   virtual ScrollStatus ScrollBegin(const gfx::Point& viewport_point,
  92                                    ScrollInputType type) = 0;
  93
  94   // Similar to ScrollBegin, except the hit test is skipped and scroll always
  95   // targets at the root layer.
  96   virtual ScrollStatus RootScrollBegin(ScrollInputType type) = 0;
  97   virtual ScrollStatus ScrollAnimated(const gfx::Point& viewport_point,
  98                                       const gfx::Vector2dF& scroll_delta) = 0;
  99
 100   // Scroll the selected layer starting at the given position. If the scroll
 101   // type given to ScrollBegin was a gesture, then the scroll point and delta
 102   // should be in viewport (logical pixel) coordinates. Otherwise they are in
 103   // scrolling layer's (logical pixel) space. If there is no room to move the
 104   // layer in the requested direction, its first ancestor layer that can be
 105   // scrolled will be moved instead. The return value's |did_scroll| field is
 106   // set to false if no layer can be moved in the requested direction at all,
 107   // and set to true if any layer is moved.
 108   // If the scroll delta hits the root layer, and the layer can no longer move,
 109   // the root overscroll accumulated within this ScrollBegin() scope is reported
 110   // in the return value's |accumulated_overscroll| field.
 111   // Should only be called if ScrollBegin() returned SCROLL_STARTED.
 112   virtual InputHandlerScrollResult ScrollBy(
 113       const gfx::Point& viewport_point,
 114       const gfx::Vector2dF& scroll_delta) = 0;
 115
 116   virtual bool ScrollVerticallyByPage(const gfx::Point& viewport_point,
 117                                       ScrollDirection direction) = 0;
 118
 119   // Returns SCROLL_STARTED if a layer was being actively being scrolled,
 120   // SCROLL_IGNORED if not.
 121   virtual ScrollStatus FlingScrollBegin() = 0;
 122
 123   virtual void MouseMoveAt(const gfx::Point& mouse_position) = 0;
 124
 125   // Stop scrolling the selected layer. Should only be called if ScrollBegin()
 126   // returned SCROLL_STARTED.
 127   virtual void ScrollEnd() = 0;
 128
 129   virtual void SetRootLayerScrollOffsetDelegate(
 130       LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) = 0;
 131
 132   // Called when the value returned by
 133   // LayerScrollOffsetDelegate.GetTotalScrollOffset has changed for reasons
 134   // other than a SetTotalScrollOffset call. This passes along the new value of
 135   // GetTotalScrollOffset.
 136   // NOTE: This should only called after a valid delegate was set via a call to
 137   // SetRootLayerScrollOffsetDelegate.
 138   virtual void OnRootLayerDelegatedScrollOffsetChanged(
 139       const gfx::ScrollOffset& root_offset) = 0;
 140
 141   virtual void PinchGestureBegin() = 0;
 142   virtual void PinchGestureUpdate(float magnify_delta,
 143                                   const gfx::Point& anchor) = 0;
 144   virtual void PinchGestureEnd() = 0;
 145
 146   // Request another callback to InputHandlerClient::Animate().
 147   virtual void SetNeedsAnimateInput() = 0;
 148
 149   // If there is a scroll active, this reports whether the scroll is on the
 150   // root layer, or on some other sublayer.
 151   virtual bool IsCurrentlyScrollingRoot() const = 0;
 152
 153   // Whether the layer under |viewport_point| is the currently scrolling layer.
 154   virtual bool IsCurrentlyScrollingLayerAt(const gfx::Point& viewport_point,
 155                                            ScrollInputType type) const = 0;
 156
 157   virtual bool HaveWheelEventHandlersAt(const gfx::Point& viewport_point) = 0;
 158
 159   // Whether the page should be given the opportunity to suppress scrolling by
 160   // consuming touch events that started at |viewport_point|.
 161   virtual bool DoTouchEventsBlockScrollAt(const gfx::Point& viewport_point) = 0;
 162
 163   // Calling CreateLatencyInfoSwapPromiseMonitor() to get a scoped
 164   // LatencyInfoSwapPromiseMonitor. During the life time of the
 165   // LatencyInfoSwapPromiseMonitor, if SetNeedsRedraw() or SetNeedsRedrawRect()
 166   // is called on LayerTreeHostImpl, the original latency info will be turned
 167   // into a LatencyInfoSwapPromise.
 168   virtual scoped_ptr<SwapPromiseMonitor> CreateLatencyInfoSwapPromiseMonitor(
 169       ui::LatencyInfo* latency) = 0;
 170
 171   virtual ScrollElasticityHelper* CreateScrollElasticityHelper() = 0;
 172
 173  protected:
 174   InputHandler() {}
 175   virtual ~InputHandler() {}
 176
 177  private:
 178   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 179 };
 180
 181 }  // namespace cc
 182
 183 #endif  // CC_INPUT_INPUT_HANDLER_H_