Eager Gesture Recognition on Aura

ui/events/gestures/gesture_recognizer.h

 // Copyright (c) 2012 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_RECOGNIZER_H_
 #define UI_EVENTS_GESTURES_GESTURE_RECOGNIZER_H_
 
 #include <vector>
 
 #include "base/memory/scoped_vector.h"
 #include "ui/events/event_constants.h"
 #include "ui/events/events_export.h"
 #include "ui/events/gestures/gesture_types.h"
 #include "ui/gfx/geometry/point_f.h"
 
 namespace ui {
 // A GestureRecognizer is an abstract base class for conversion of touch events
 // into gestures.
 class EVENTS_EXPORT GestureRecognizer {
  public:
   static GestureRecognizer* Create();
   static GestureRecognizer* Get();
   static void Reset();
 
   // List of GestureEvent*.
   typedef ScopedVector<GestureEvent> Gestures;
 
   virtual ~GestureRecognizer() {}
 
-  // Invoked for each touch event that could contribute to the current gesture.
-  // Returns list of zero or more GestureEvents identified after processing
-  // TouchEvent.
-  // Caller would be responsible for freeing up Gestures.
-  virtual Gestures* ProcessTouchEventForGesture(const TouchEvent& event,
-                                                ui::EventResult result,
-                                                GestureConsumer* consumer) = 0;
+  virtual bool ProcessTouchEventPreDispatch(const TouchEvent& event,
+                                            GestureConsumer* consumer) = 0;
+  virtual Gestures* ProcessTouchEventPostDispatch(const TouchEvent& event,

[jdduke (slow), 2014/08/01 14:27:22]

This is great! Probably worth keeping the comment about the caller's
responsibility for freeing |Gestures*| (and the semantic difference between
PostDispatch and OnAsyncAck).  Thanks!

[tdresser, 2014/08/01 18:54:00]

Done.

+                                             ui::EventResult result,
+                                             GestureConsumer* consumer) = 0;
+  virtual Gestures* ProcessTouchEventOnAsyncAck(const TouchEvent& event,
+                                               ui::EventResult result,
+                                               GestureConsumer* consumer) = 0;
 
   // This is called when the consumer is destroyed. So this should cleanup any
   // internal state maintained for |consumer|. Returns true iff there was
   // state relating to |consumer| to clean up.
   virtual bool CleanupStateForConsumer(GestureConsumer* consumer) = 0;
 
   // Return the window which should handle this TouchEvent, in the case where
   // the touch is already associated with a target.
   // Otherwise, returns null.
   virtual GestureConsumer* GetTouchLockedTarget(const TouchEvent& event) = 0;
@@ skipping 37 matching lines @@
 
   // Unsubscribes |helper| from async gesture dispatch.
   // Since the GestureRecognizer does not own the |helper|, it is not deleted
   // and must be cleaned up appropriately by the caller.
   virtual void RemoveGestureEventHelper(GestureEventHelper* helper) = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURES_GESTURE_RECOGNIZER_H_