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// 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"
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();
// 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;
// This is called when the consumer is destroyed. So this should cleanup any
// internal state maintained for |consumer|.
virtual void 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;
// Return the window which should handle this GestureEvent.
virtual GestureConsumer* GetTargetForGestureEvent(
const GestureEvent& event) = 0;
// If there is an active touch within
// GestureConfiguration::max_separation_for_gesture_touches_in_pixels,
// of |location|, returns the target of the nearest active touch.
virtual GestureConsumer* GetTargetForLocation(const gfx::Point& location) = 0;
// Makes |new_consumer| the target for events previously targeting
// |current_consumer|. All other targets are canceled.
// The caller is responsible for updating the state of the consumers to
// be aware of this transfer of control (there are no ENTERED/EXITED events).
// If |new_consumer| is NULL, all events are canceled.
// If |old_consumer| is NULL, all events not already targeting |new_consumer|
// are canceled.
virtual void TransferEventsTo(GestureConsumer* current_consumer,
GestureConsumer* new_consumer) = 0;
// If a gesture is underway for |consumer| |point| is set to the last touch
// point and true is returned. If no touch events have been processed for
// |consumer| false is returned and |point| is untouched.
virtual bool GetLastTouchPointForTarget(GestureConsumer* consumer,
gfx::Point* point) = 0;
// Sends a touch cancel event for every active touch.
virtual void CancelActiveTouches(GestureConsumer* consumer) = 0;
// Subscribes |helper| for dispatching async gestures such as long press.
// The Gesture Recognizer does NOT take ownership of |helper| and it is the
// responsibility of the |helper| to call |RemoveGestureEventHelper()| on
// destruction.
virtual void AddGestureEventHelper(GestureEventHelper* helper) = 0;
// 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_
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