ui/events/gestures/gesture_recognizer.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 UI_EVENTS_GESTURES_GESTURE_RECOGNIZER_H_
   6 #define UI_EVENTS_GESTURES_GESTURE_RECOGNIZER_H_
   7
   8 #include <vector>
   9
  10 #include "base/memory/scoped_vector.h"
  11 #include "ui/events/event_constants.h"
  12 #include "ui/events/events_export.h"
  13 #include "ui/events/gestures/gesture_types.h"
  14 #include "ui/gfx/geometry/point_f.h"
  15
  16 namespace ui {
  17 // A GestureRecognizer is an abstract base class for conversion of touch events
  18 // into gestures.
  19 class EVENTS_EXPORT GestureRecognizer {
  20  public:
  21   static GestureRecognizer* Create();
  22   static GestureRecognizer* Get();
  23   static void Reset();
  24
  25   // List of GestureEvent*.
  26   typedef ScopedVector<GestureEvent> Gestures;
  27
  28   virtual ~GestureRecognizer() {}
  29
  30   // Invoked for each touch event that could contribute to the current gesture.
  31   // Returns list of zero or more GestureEvents identified after processing
  32   // TouchEvent.
  33   // Caller would be responsible for freeing up Gestures.
  34   virtual Gestures* ProcessTouchEventForGesture(const TouchEvent& event,
  35                                                 ui::EventResult result,
  36                                                 GestureConsumer* consumer) = 0;
  37
  38   // This is called when the consumer is destroyed. So this should cleanup any
  39   // internal state maintained for |consumer|. Returns true iff there was
  40   // state relating to |consumer| to clean up.
  41   virtual bool CleanupStateForConsumer(GestureConsumer* consumer) = 0;
  42
  43   // Return the window which should handle this TouchEvent, in the case where
  44   // the touch is already associated with a target.
  45   // Otherwise, returns null.
  46   virtual GestureConsumer* GetTouchLockedTarget(const TouchEvent& event) = 0;
  47
  48   // Return the window which should handle this GestureEvent.
  49   virtual GestureConsumer* GetTargetForGestureEvent(
  50       const GestureEvent& event) = 0;
  51
  52   // Returns the target of the nearest active touch with source device of
  53   // |source_device_id|, within
  54   // GestureConfiguration::max_separation_for_gesture_touches_in_pixels of
  55   // |location|, or NULL if no such point exists.
  56   virtual GestureConsumer* GetTargetForLocation(
  57       const gfx::PointF& location, int source_device_id) = 0;
  58
  59   // Makes |new_consumer| the target for events previously targeting
  60   // |current_consumer|. All other targets are canceled.
  61   // The caller is responsible for updating the state of the consumers to
  62   // be aware of this transfer of control (there are no ENTERED/EXITED events).
  63   // If |new_consumer| is NULL, all events are canceled.
  64   // If |old_consumer| is NULL, all events not already targeting |new_consumer|
  65   // are canceled.
  66   virtual void TransferEventsTo(GestureConsumer* current_consumer,
  67                                 GestureConsumer* new_consumer) = 0;
  68
  69   // If a gesture is underway for |consumer| |point| is set to the last touch
  70   // point and true is returned. If no touch events have been processed for
  71   // |consumer| false is returned and |point| is untouched.
  72   virtual bool GetLastTouchPointForTarget(GestureConsumer* consumer,
  73                                           gfx::PointF* point) = 0;
  74
  75   // Sends a touch cancel event for every active touch. Returns true iff any
  76   // touch cancels were sent.
  77   virtual bool CancelActiveTouches(GestureConsumer* consumer) = 0;
  78
  79   // Subscribes |helper| for dispatching async gestures such as long press.
  80   // The Gesture Recognizer does NOT take ownership of |helper| and it is the
  81   // responsibility of the |helper| to call |RemoveGestureEventHelper()| on
  82   // destruction.
  83   virtual void AddGestureEventHelper(GestureEventHelper* helper) = 0;
  84
  85   // Unsubscribes |helper| from async gesture dispatch.
  86   // Since the GestureRecognizer does not own the |helper|, it is not deleted
  87   // and must be cleaned up appropriately by the caller.
  88   virtual void RemoveGestureEventHelper(GestureEventHelper* helper) = 0;
  89 };
  90
  91 }  // namespace ui
  92
  93 #endif  // UI_EVENTS_GESTURES_GESTURE_RECOGNIZER_H_