Eager Gesture Recognizer (WIP)

ui/events/gestures/gesture_event_queue.h

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_EVENTS_GESTURES_GESTURE_EVENT_QUEUE_H_
+#define UI_EVENTS_GESTURES_GESTURE_EVENT_QUEUE_H_
+
+#include <list>
+#include <set>
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "ui/events/event.h"
+#include "ui/events/gestures/touch_point_state.h"
+
+namespace ui {
+class TouchEvent;
+
+class GestureEventQueueDelegate {
+ public:
+  virtual ~GestureEventQueueDelegate() {};
+  virtual void DispatchGestureEvent(GestureEvent* event) = 0;
+};
+
+class GestureEventQueueTimerInterface {
+ public:
+  virtual void TimerFired() = 0;
+  virtual void TimerCancelled() = 0;
+};
+
+// A GestureEventQueue consumes a stream of gestures, and a stream of touch
+// acks. It sends the |GestureEventQueueDelegate| a filtered stream of gestures,
+// with some gestures removed due to touches having been consumed.
+class EVENTS_EXPORT GestureEventQueue : public GestureEventQueueTimerInterface {
+ public:
+  GestureEventQueue(GestureEventQueueDelegate* geqd);
+  virtual ~GestureEventQueue();
+
+  void OnTouchEvent(const TouchEvent& event);
+
+  void OnTouchEventAck(const TouchEvent& event,
+                       EventResult result);
+
+  // Takes ownership of event.
+  void QueueGestureEvent(GestureEvent* event,
+                         TouchPointState::RequiresAck requires_ack);
+
+  virtual void TimerFired() OVERRIDE;
+  virtual void TimerCancelled() OVERRIDE;
+
+ protected:
+  void QueueGestureEvent(
+      GestureEvent* event,
+      std::vector<TouchPointState*>& touch_point_states);
+
+  class GestureWithState {
+   public:
+    // Clears touch_point_states, and takes ownership of its members.
+    GestureWithState(GestureEvent* event,
+                     std::vector<TouchPointState*>& touch_point_states);
+    ~GestureWithState();
+    GestureEvent* event() { return event_.get(); }
+    std::vector<TouchPointState*>& touch_point_states() {
+      return touch_point_states_.get();
+    }
+
+   private:
+    scoped_ptr<GestureEvent> event_;
+    ScopedVector<TouchPointState> touch_point_states_;
+    DISALLOW_COPY_AND_ASSIGN(GestureWithState);
+  };
+
+  typedef ScopedVector<GestureWithState> Sequence;
+  // sequences_ owns all of the TouchPointState objects keeping tracking of
+  // which acks a given event depends on.
+  std::list<Sequence*> sequences_;
+
+ private:
+  void SendGestureEvent(GestureEvent* event);
+
+  // Returns true if we've seen unconsumed acks in the current sequence for
+  // every touch contributing to |gesture_touches|.
+  bool CanSend(const std::vector<TouchPointState*>& gesture_touches) const;
+
+  // Returns true if we've seen consumed acks in the current sequence for any
+  // touch contributing to |gesture_touches|.
+  bool CanDelete(const std::vector<TouchPointState*>& gesture_touches) const;
+
+  void SendAckedEvents();
+  void DeleteConsumedEvents();
+  void RemoveEmptyFirstSequence();
+
+  ScopedVector<TouchPointState> touch_point_states_;
+  ScopedVector<TouchPointState> acked_touch_point_states_;
+  ScopedVector<TouchPointState> consumed_touch_point_states_;
+  GestureEventQueueDelegate* gesture_event_queue_delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(GestureEventQueue);
+};
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_GESTURES_GESTURE_EVENT_QUEUE_H_