content/browser/renderer_host/touch_event_queue.h

   1 // Copyright (c) 2012 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 CONTENT_BROWSER_RENDERER_HOST_TOUCH_EVENT_QUEUE_H_
   6 #define CONTENT_BROWSER_RENDERER_HOST_TOUCH_EVENT_QUEUE_H_
   7
   8 #include <deque>
   9 #include <map>
  10
  11 #include "base/basictypes.h"
  12 #include "content/common/content_export.h"
  13 #include "content/port/browser/event_with_latency_info.h"
  14 #include "content/port/common/input_event_ack_state.h"
  15 #include "third_party/WebKit/public/web/WebInputEvent.h"
  16
  17 namespace content {
  18
  19 class CoalescedWebTouchEvent;
  20 class MockRenderWidgetHost;
  21 class RenderWidgetHostImpl;
  22
  23 // A queue for throttling and coalescing touch-events.
  24 class TouchEventQueue {
  25  public:
  26   explicit TouchEventQueue(RenderWidgetHostImpl* host);
  27   virtual ~TouchEventQueue();
  28
  29   // Adds an event to the queue. The event may be coalesced with previously
  30   // queued events (e.g. consecutive touch-move events can be coalesced into a
  31   // single touch-move event). The event may also be immediately forwarded to
  32   // the renderer (e.g. when there are no other queued touch event).
  33   void QueueEvent(const TouchEventWithLatencyInfo& event);
  34
  35   // Notifies the queue that a touch-event has been processed by the renderer.
  36   // At this point, the queue may send one or more gesture events and/or
  37   // additional queued touch-events to the renderer.
  38   void ProcessTouchAck(InputEventAckState ack_result);
  39
  40   // Empties the queue of touch events. This may result in any number of gesture
  41   // events being sent to the renderer.
  42   void FlushQueue();
  43
  44   // Resets all internal state. This does not trigger any touch or gesture
  45   // events to be sent.
  46   void Reset();
  47
  48   // Returns whether the event-queue is empty.
  49   bool empty() const WARN_UNUSED_RESULT {
  50     return touch_queue_.empty();
  51   }
  52
  53  private:
  54   friend class MockRenderWidgetHost;
  55
  56   CONTENT_EXPORT size_t GetQueueSize() const;
  57   CONTENT_EXPORT const TouchEventWithLatencyInfo& GetLatestEvent() const;
  58
  59   // Pops the touch-event from the top of the queue and sends it to the
  60   // RenderWidgetHostView. This reduces the size of the queue by one.
  61   void PopTouchEventToView(InputEventAckState ack_result);
  62
  63   bool ShouldForwardToRenderer(const WebKit::WebTouchEvent& event) const;
  64
  65   // The RenderWidgetHost that owns this event-queue.
  66   RenderWidgetHostImpl* render_widget_host_;
  67
  68   typedef std::deque<CoalescedWebTouchEvent*> TouchQueue;
  69   TouchQueue touch_queue_;
  70
  71   // Maintain the ACK status for each touch point.
  72   typedef std::map<int, InputEventAckState> TouchPointAckStates;
  73   TouchPointAckStates touch_ack_states_;
  74
  75   DISALLOW_COPY_AND_ASSIGN(TouchEventQueue);
  76 };
  77
  78 }  // namespace content
  79
  80 #endif  // CONTENT_BROWSER_RENDERER_HOST_TOUCH_EVENT_QUEUE_H_