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