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//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//

#include <QTime>
#include <QPointer>
#include <QObject>
#include <qkineticscroller.h>
#include <QEvent>
#include <QElapsedTimer>

QT_BEGIN_NAMESPACE

class QKineticScrollerPrivate : public QObject
{
    Q_OBJECT
    Q_DECLARE_PUBLIC(QKineticScroller)

public:
    QKineticScrollerPrivate();
    virtual ~QKineticScrollerPrivate();
    void init();

    void setState(QKineticScroller::State s);

    bool pressWhileInactive(QKineticScroller::Input input, const QPointF &position, qint64 timestamp);
    bool moveWhilePressed(QKineticScroller::Input input, const QPointF &position, qint64 timestamp);
    bool releaseWhilePressed(QKineticScroller::Input input, const QPointF &position, qint64 timestamp);
    bool moveWhileDragging(QKineticScroller::Input input, const QPointF &position, qint64 timestamp);
    bool releaseWhileDragging(QKineticScroller::Input input, const QPointF &position, qint64 timestamp);
    bool pressWhileScrolling(QKineticScroller::Input input, const QPointF &position, qint64 timestamp);

    void timerEvent(QTimerEvent *);
    void timerEventWhileDragging(qint64 deltaTime);
    void timerEventWhileScrolling(qint64 deltaTime);

    void handleDrag(const QPointF &position, qint64 timestamp);
    void updateVelocity(const QPointF &deltaPixel, qint64 deltaTime);
    void setContentPositionHelper(const QPointF &position);

    static const char *stateName(QKineticScroller::State state);
    static const char *inputName(QKineticScroller::Input input);

    // metrics

    qreal dragVelocitySmoothingFactor;
    qreal frictionCoefficent;
    qreal overshootSpringConstant;
    qreal overshootDragResistanceFactor;
    QPointF overshootMaximumDistance;
    qreal overshootMaximumVelocity;
    qreal dragStartDistance;
    qreal dragStartDirectionErrorMargin;
    qreal maximumVelocity;
    qreal minimumVelocity;
    qreal maximumNonAcceleratedVelocity;
    qreal maximumClickThroughVelocity;
    qreal axisLockThreshold;
    qreal fastSwipeBaseVelocity;
    qreal fastSwipeMinimumVelocity;
    qreal fastSwipeMaximumTime;
    int framesPerSecond;

    // state

    bool enabled;
    QKineticScroller::State state;
    QKineticScroller::OvershootPolicy overshootPolicy;
    QPointF velocity;
    QPointF oldVelocity;

    QPointF pressPosition;
    QPointF lastPosition;
    qint64  pressTimestamp;
    qint64  lastTimestamp;

    QPointF dragDistance;
    QPointF overshootDistance;

    QPointF scrollToPosition;
    bool    scrollToX;
    bool    scrollToY;

    qreal pixelPerMeter;

    QElapsedTimer dragTimer;
    QElapsedTimer scrollTimer;
    int timerId;

    QKineticScroller *q_ptr;
};

QT_END_NAMESPACE