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 before event dispatch. If the event is invalid given the current
  31   // touch sequence, returns false.
  32   virtual bool ProcessTouchEventPreDispatch(TouchEvent* event,
  33                                             GestureConsumer* consumer) = 0;
  34
  35   // Returns a list of zero or more GestureEvents. The caller is responsible for
  36   // freeing the returned events. Acks the first gesture packet in the queue.
  37   virtual Gestures* AckAsyncTouchEvent(ui::EventResult result,
  38                                        GestureConsumer* consumer) = 0;
  39
  40   // Returns a list of zero or more GestureEvents. The caller is responsible for
  41   // freeing the returned events. Acks the last gesture packet in the queue.
  42   virtual Gestures* AckSyncTouchEvent(const uint64 unique_event_id,
  43                                       ui::EventResult result,
  44                                       GestureConsumer* consumer) = 0;
  45
  46   // This is called when the consumer is destroyed. So this should cleanup any
  47   // internal state maintained for |consumer|. Returns true iff there was
  48   // state relating to |consumer| to clean up.
  49   virtual bool CleanupStateForConsumer(GestureConsumer* consumer) = 0;
  50
  51   // Return the window which should handle this TouchEvent, in the case where
  52   // the touch is already associated with a target.
  53   // Otherwise, returns null.
  54   virtual GestureConsumer* GetTouchLockedTarget(const TouchEvent& event) = 0;
  55
  56   // Return the window which should handle this GestureEvent.
  57   virtual GestureConsumer* GetTargetForGestureEvent(
  58       const GestureEvent& event) = 0;
  59
  60   // Returns the target of the nearest active touch with source device of
  61   // |source_device_id|, within
  62   // GestureConfiguration::max_separation_for_gesture_touches_in_pixels of
  63   // |location|, or NULL if no such point exists.
  64   virtual GestureConsumer* GetTargetForLocation(
  65       const gfx::PointF& location, int source_device_id) = 0;
  66
  67   // Cancels all touches except those targeted to |not_cancelled|. If
  68   // |not_cancelled| == nullptr, cancels all touches.
  69   virtual void CancelActiveTouchesExcept(GestureConsumer* not_cancelled) = 0;
  70
  71   // Makes |new_consumer| the target for events previously targeting
  72   // |current_consumer|. Touches targeting all other targets are
  73   // canceled. The caller is responsible for updating the state of the
  74   // consumers to be aware of this transfer of control (there are no
  75   // ENTERED/EXITED events).
  76   virtual void TransferEventsTo(GestureConsumer* current_consumer,
  77                                 GestureConsumer* new_consumer) = 0;
  78
  79   // If a gesture is underway for |consumer| |point| is set to the last touch
  80   // point and true is returned. If no touch events have been processed for
  81   // |consumer| false is returned and |point| is untouched.
  82   virtual bool GetLastTouchPointForTarget(GestureConsumer* consumer,
  83                                           gfx::PointF* point) = 0;
  84
  85   // Sends a touch cancel event for every active touch. Returns true iff any
  86   // touch cancels were sent.
  87   virtual bool CancelActiveTouches(GestureConsumer* consumer) = 0;
  88
  89   // Subscribes |helper| for dispatching async gestures such as long press.
  90   // The Gesture Recognizer does NOT take ownership of |helper| and it is the
  91   // responsibility of the |helper| to call |RemoveGestureEventHelper()| on
  92   // destruction.
  93   virtual void AddGestureEventHelper(GestureEventHelper* helper) = 0;
  94
  95   // Unsubscribes |helper| from async gesture dispatch.
  96   // Since the GestureRecognizer does not own the |helper|, it is not deleted
  97   // and must be cleaned up appropriately by the caller.
  98   virtual void RemoveGestureEventHelper(GestureEventHelper* helper) = 0;
  99 };
 100
 101 }  // namespace ui
 102
 103 #endif  // UI_EVENTS_GESTURES_GESTURE_RECOGNIZER_H_