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   virtual void UpdateRootLayerStateForSynchronousInputHandler(
  56       const gfx::ScrollOffset& total_scroll_offset,
  57       const gfx::ScrollOffset& max_scroll_offset,
  58       const gfx::SizeF& scrollable_size,
  59       float page_scale_factor,
  60       float min_page_scale_factor,
  61       float max_page_scale_factor) = 0;
  62
  63  protected:
  64   InputHandlerClient() {}
  65
  66  private:
  67   DISALLOW_COPY_AND_ASSIGN(InputHandlerClient);
  68 };
  69
  70 // The InputHandler is a way for the embedders to interact with the impl thread
  71 // side of the compositor implementation. There is one InputHandler per
  72 // LayerTreeHost. To use the input handler, implement the InputHanderClient
  73 // interface and bind it to the handler on the compositor thread.
  74 class CC_EXPORT InputHandler {
  75  public:
  76   // Note these are used in a histogram. Do not reorder or delete existing
  77   // entries.
  78   enum ScrollStatus {
  79     SCROLL_ON_MAIN_THREAD = 0,
  80     SCROLL_STARTED,
  81     SCROLL_IGNORED,
  82     SCROLL_UNKNOWN,
  83     // This must be the last entry.
  84     ScrollStatusCount
  85   };
  86   enum ScrollInputType { GESTURE, WHEEL, NON_BUBBLING_GESTURE };
  87
  88   // Binds a client to this handler to receive notifications. Only one client
  89   // can be bound to an InputHandler. The client must live at least until the
  90   // handler calls WillShutdown() on the client.
  91   virtual void BindToClient(InputHandlerClient* client) = 0;
  92
  93   // Selects a layer to be scrolled at a given point in viewport (logical
  94   // pixel) coordinates. Returns SCROLL_STARTED if the layer at the coordinates
  95   // can be scrolled, SCROLL_ON_MAIN_THREAD if the scroll event should instead
  96   // be delegated to the main thread, or SCROLL_IGNORED if there is nothing to
  97   // be scrolled at the given coordinates.
  98   virtual ScrollStatus ScrollBegin(const gfx::Point& viewport_point,
  99                                    ScrollInputType type) = 0;
 100
 101   // Similar to ScrollBegin, except the hit test is skipped and scroll always
 102   // targets at the root layer.
 103   virtual ScrollStatus RootScrollBegin(ScrollInputType type) = 0;
 104   virtual ScrollStatus ScrollAnimated(const gfx::Point& viewport_point,
 105                                       const gfx::Vector2dF& scroll_delta) = 0;
 106
 107   // Scroll the selected layer starting at the given position. If the scroll
 108   // type given to ScrollBegin was a gesture, then the scroll point and delta
 109   // should be in viewport (logical pixel) coordinates. Otherwise they are in
 110   // scrolling layer's (logical pixel) space. If there is no room to move the
 111   // layer in the requested direction, its first ancestor layer that can be
 112   // scrolled will be moved instead. The return value's |did_scroll| field is
 113   // set to false if no layer can be moved in the requested direction at all,
 114   // and set to true if any layer is moved.
 115   // If the scroll delta hits the root layer, and the layer can no longer move,
 116   // the root overscroll accumulated within this ScrollBegin() scope is reported
 117   // in the return value's |accumulated_overscroll| field.
 118   // Should only be called if ScrollBegin() returned SCROLL_STARTED.
 119   virtual InputHandlerScrollResult ScrollBy(
 120       const gfx::Point& viewport_point,
 121       const gfx::Vector2dF& scroll_delta) = 0;
 122
 123   virtual bool ScrollVerticallyByPage(const gfx::Point& viewport_point,
 124                                       ScrollDirection direction) = 0;
 125
 126   // Returns SCROLL_STARTED if a layer was being actively being scrolled,
 127   // SCROLL_IGNORED if not.
 128   virtual ScrollStatus FlingScrollBegin() = 0;
 129
 130   virtual void MouseMoveAt(const gfx::Point& mouse_position) = 0;
 131
 132   // Stop scrolling the selected layer. Should only be called if ScrollBegin()
 133   // returned SCROLL_STARTED.
 134   virtual void ScrollEnd() = 0;
 135
 136   // Requests a callback to UpdateRootLayerStateForSynchronousInputHandler()
 137   // giving the current root scroll and page scale information.
 138   virtual void RequestUpdateForSynchronousInputHandler() = 0;
 139
 140   // Called when the root scroll offset has been changed in the synchronous
 141   // input handler by the application (outside of input event handling).
 142   virtual void SetSynchronousInputHandlerRootScrollOffset(
 143       const gfx::ScrollOffset& root_offset) = 0;
 144
 145   virtual void PinchGestureBegin() = 0;
 146   virtual void PinchGestureUpdate(float magnify_delta,
 147                                   const gfx::Point& anchor) = 0;
 148   virtual void PinchGestureEnd() = 0;
 149
 150   // Request another callback to InputHandlerClient::Animate().
 151   virtual void SetNeedsAnimateInput() = 0;
 152
 153   // If there is a scroll active, this reports whether the scroll is on the
 154   // root layer, or on some other sublayer.
 155   virtual bool IsCurrentlyScrollingRoot() const = 0;
 156
 157   // Whether the layer under |viewport_point| is the currently scrolling layer.
 158   virtual bool IsCurrentlyScrollingLayerAt(const gfx::Point& viewport_point,
 159                                            ScrollInputType type) const = 0;
 160
 161   virtual bool HaveWheelEventHandlersAt(const gfx::Point& viewport_point) = 0;
 162
 163   // Whether the page should be given the opportunity to suppress scrolling by
 164   // consuming touch events that started at |viewport_point|.
 165   virtual bool DoTouchEventsBlockScrollAt(const gfx::Point& viewport_point) = 0;
 166
 167   // Calling CreateLatencyInfoSwapPromiseMonitor() to get a scoped
 168   // LatencyInfoSwapPromiseMonitor. During the life time of the
 169   // LatencyInfoSwapPromiseMonitor, if SetNeedsRedraw() or SetNeedsRedrawRect()
 170   // is called on LayerTreeHostImpl, the original latency info will be turned
 171   // into a LatencyInfoSwapPromise.
 172   virtual scoped_ptr<SwapPromiseMonitor> CreateLatencyInfoSwapPromiseMonitor(
 173       ui::LatencyInfo* latency) = 0;
 174
 175   virtual ScrollElasticityHelper* CreateScrollElasticityHelper() = 0;
 176
 177  protected:
 178   InputHandler() {}
 179   virtual ~InputHandler() {}
 180
 181  private:
 182   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 183 };
 184
 185 }  // namespace cc
 186
 187 #endif  // CC_INPUT_INPUT_HANDLER_H_