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#ifndef QGESTURERECOGNIZER_H
#define QGESTURERECOGNIZER_H

#include "qevent.h"
#include "qlist.h"
#include "qset.h"

QT_BEGIN_NAMESPACE

/*!
    \class QGestureRecognizer

    \brief The base class for implementing custom gestures.

    This is a base class, to create a custom gesture type, you should
    subclass it and implement pure virtual functions.

    Usually gesture recognizer implements state machine, storing its
    state internally in the recognizer object. The recognizer receives
    input events through the QGestureRecognizer::filterEvent() virtual
    function and decides whether the parsed event should change the
    state of the recognizer - i.e. if the event starts or ends a
    gesture or if it isn't related to gesture at all.
*/

/*! \fn QString gestureType() const

    Returns the name of the gesture that is handled by the recognizer.
*/

/*! \fn Result filterEvent(const QEvent *event)

    This is a pure virtual function that need to be implemented in
    subclasses.

    Parses input \a events and returns the result, saying if the event
    sequence is a gesture or not.
*/

/*! \fn QGesture* getGesture()

    Creates a new gesture object that will be send to the widget. This
    function is called when the gesture recognizer returned a
    QGestureRecognizer::GestureStarted or
    QGestureRecognizer::GestureFinished state.

    Created gesture object is owned by the caller.
 */

/*! \fn void reset()

    Resets the internal state of the gesture recognizer.
*/

/*! \fn void stateChanged(QGestureRecognizer::Result result)

    The gesture recognizer might emit the signal when the gesture
    state changes asynchronously, i.e. without any event being
    received.
*/

class QGesture;
class QGestureRecognizerPrivate;
class Q_GUI_EXPORT QGestureRecognizer : public QObject
{
    Q_OBJECT
    Q_DECLARE_PRIVATE(QGestureRecognizer)

public:
    enum Result
    {
        NotGesture,
        GestureStarted,
        GestureFinished,
        MaybeGesture
    };

    explicit QGestureRecognizer(const QString &type);

    QString gestureType() const;

    virtual Result filterEvent(const QEvent* event) = 0;
    virtual QGesture* getGesture() = 0;
    virtual void reset() = 0;

signals:
    void stateChanged(QGestureRecognizer::Result result);

private:
    friend class QDoubleTapGestureRecognizer;
    friend class QTapAndHoldGestureRecognizer;
    friend class QGestureRecognizerPan;
};

QT_END_NAMESPACE

#endif // QGESTURERECOGNIZER_P_H