1 // Copyright 2013 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.
5 #ifndef CONTENT_BROWSER_RENDERER_HOST_INPUT_TOUCH_EVENT_QUEUE_H_
6 #define CONTENT_BROWSER_RENDERER_HOST_INPUT_TOUCH_EVENT_QUEUE_H_
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"
19 class CoalescedWebTouchEvent;
21 // Interface with which TouchEventQueue can forward touch events, and dispatch
22 // touch event responses.
23 class CONTENT_EXPORT TouchEventQueueClient {
25 virtual ~TouchEventQueueClient() {}
27 virtual void SendTouchEventImmediately(
28 const TouchEventWithLatencyInfo& event) = 0;
30 virtual void OnTouchEventAck(
31 const TouchEventWithLatencyInfo& event,
32 InputEventAckState ack_result) = 0;
35 // A queue for throttling and coalescing touch-events.
36 class CONTENT_EXPORT TouchEventQueue {
39 // The |client| must outlive the TouchEventQueue.
40 explicit TouchEventQueue(TouchEventQueueClient* client);
41 virtual ~TouchEventQueue();
43 // Adds an event to the queue. The event may be coalesced with previously
44 // queued events (e.g. consecutive touch-move events can be coalesced into a
45 // single touch-move event). The event may also be immediately forwarded to
46 // the renderer (e.g. when there are no other queued touch event).
47 void QueueEvent(const TouchEventWithLatencyInfo& event);
49 // Notifies the queue that a touch-event has been processed by the renderer.
50 // At this point, the queue may send one or more gesture events and/or
51 // additional queued touch-events to the renderer.
52 void ProcessTouchAck(InputEventAckState ack_result,
53 const ui::LatencyInfo& latency_info);
55 // When GestureScrollBegin is received, we send a touch cancel to renderer,
56 // route all the following touch events directly to client, and ignore the
57 // ack for the touch cancel. When GestureScrollEnd/GestureFlingStart is
58 // received, we resume the normal flow of sending touch events to renderer.
59 void OnGestureScrollEvent(const GestureEventWithLatencyInfo& gesture_event);
61 // Empties the queue of touch events. This may result in any number of gesture
62 // events being sent to the renderer.
65 // Returns whether the event-queue is empty.
66 bool empty() const WARN_UNUSED_RESULT {
67 return touch_queue_.empty();
70 bool no_touch_to_renderer() const {
71 return no_touch_to_renderer_;
75 friend class TouchEventQueueTest;
77 size_t GetQueueSize() const;
78 const TouchEventWithLatencyInfo& GetLatestEvent() const;
80 // Walks the queue, checking each event for |ShouldForwardToRenderer()|.
81 // If true, forwards the touch event and stops processing further events.
82 // If false, acks the event with |INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS|.
83 void TryForwardNextEventToRenderer();
85 // Pops the touch-event from the top of the queue and sends it to the
86 // TouchEventQueueClient. This reduces the size of the queue by one.
87 void PopTouchEventToClient(InputEventAckState ack_result,
88 const ui::LatencyInfo& renderer_latency_info);
90 bool ShouldForwardToRenderer(const WebKit::WebTouchEvent& event) const;
92 // Handles touch event forwarding and ack'ed event dispatch.
93 TouchEventQueueClient* client_;
95 typedef std::deque<CoalescedWebTouchEvent*> TouchQueue;
96 TouchQueue touch_queue_;
98 // Maintain the ACK status for each touch point.
99 typedef std::map<int, InputEventAckState> TouchPointAckStates;
100 TouchPointAckStates touch_ack_states_;
102 // Used to defer touch forwarding when ack dispatch triggers |QueueEvent()|.
103 // If not NULL, |dispatching_touch_ack_| is the touch event of which the ack
104 // is being dispatched.
105 CoalescedWebTouchEvent* dispatching_touch_ack_;
107 // Don't send touch events to renderer. This is enabled when the page
108 // is scrolling. This behaviour is currently enabled only on aura behind
110 bool no_touch_to_renderer_;
112 DISALLOW_COPY_AND_ASSIGN(TouchEventQueue);
115 } // namespace content
117 #endif // CONTENT_BROWSER_RENDERER_HOST_INPUT_TOUCH_EVENT_QUEUE_H_