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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 <stdint.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 before event dispatch. If the event is invalid given the current
// touch sequence, returns false.
virtual bool ProcessTouchEventPreDispatch(TouchEvent* event,
GestureConsumer* consumer) = 0;
// Returns a list of zero or more GestureEvents. The caller is responsible for
// freeing the returned events. Acks the gesture packet in the queue which
// matches with unique_event_id.
virtual Gestures* AckTouchEvent(uint32_t unique_event_id,
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;
// Returns the target of the nearest active touch with source device of
// |source_device_id|, within
// GestureConfiguration::max_separation_for_gesture_touches_in_pixels of
// |location|, or NULL if no such point exists.
virtual GestureConsumer* GetTargetForLocation(
const gfx::PointF& location, int source_device_id) = 0;
// Cancels all touches except those targeted to |not_cancelled|. If
// |not_cancelled| == nullptr, cancels all touches.
virtual void CancelActiveTouchesExcept(GestureConsumer* not_cancelled) = 0;
// Makes |new_consumer| the target for events previously targeting
// |current_consumer|. Touches targeting 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).
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::PointF* point) = 0;
// Sends a touch cancel event for every active touch. Returns true iff any
// touch cancels were sent.
virtual bool 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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