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#ifndef QABSTRACTKINETICSCROLLER_H
#define QABSTRACTKINETICSCROLLER_H

#include <QtCore/qmetatype.h>
#include <QtCore/qpoint.h>
#include <QtCore/qrect.h>
#include <QtCore/qvariant.h>

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

QT_MODULE(Gui)

class QKineticScrollerPrivate;

class Q_GUI_EXPORT QKineticScroller
{
public:
    ~QKineticScroller();

    bool isEnabled() const;
    void setEnabled(bool b);

    enum State
    {
        StateInactive,
        StatePressed,
        StateDragging,
        StateScrolling,
    };

    State state() const;
    void reset();

    enum OvershootPolicy
    {
        OvershootWhenScrollable,
        OvershootAlwaysOff,
        OvershootAlwaysOn,
    };

    OvershootPolicy overshootPolicy() const;
    void setOvershootPolicy(OvershootPolicy policy);

    enum ScrollMetric
    {
        DragVelocitySmoothingFactor,             // qreal [0..1/s]  (complex calculation involving time) v = v_new* DASF + v_old * (1-DASF)

        LinearDecelerationFactor,                // qreal [m/s^2]
        ExponentialDecelerationBase,             // qreal [0..1]
        OvershootSpringConstant,                 // qreal [0..1]
        OvershootDragResistanceFactor,           // qreal [0..1]
        OvershootMaximumDistance,                // QPointF([m], [m])
        OvershootMaximumVelocity,                // qreal [m/s]

        DragStartDistance,                       // qreal [m]
        DragStartDirectionErrorMargin,           // qreal [m]

        MinimumVelocity,                         // qreal [m/s]
        MaximumVelocity,                         // qreal [m/s]
        MaximumNonAcceleratedVelocity,           // qreal [m/s]

        MaximumClickThroughVelocity,             // qreal [m/s]
        AxisLockThreshold,                       // qreal [0..1] atan(|min(dx,dy)|/|max(dx,dy)|)

        FramesPerSecond,                         // int [frames/s]

        FastSwipeMaximumTime,                    // qreal [s]
        FastSwipeMinimumVelocity,                // qreal [m/s]
        FastSwipeBaseVelocity,                   // qreal [m/s]

        ScrollMetricCount
    };

    QVariant scrollMetric(ScrollMetric metric) const;
    void setScrollMetric(ScrollMetric metric, const QVariant &value);
    void resetScrollMetrics();

    void scrollTo(const QPointF &pos, int scrollTime = 1000);
    void ensureVisible(const QPointF &pos, int xmargin, int ymargin, int scrollTime = 1000);

    qreal dpi() const;
    void setDpi(qreal dpi);
    void setDpiFromWidget(QWidget *widget);

protected:
    explicit QKineticScroller();

    virtual QSizeF viewportSize() const = 0;
    virtual QPointF maximumContentPosition() const = 0;
    virtual QPointF contentPosition() const = 0;
    virtual void setContentPosition(const QPointF &pos, const QPointF &overshootDelta) = 0;

    virtual void stateChanged(State oldState);
    virtual bool canStartScrollingAt(const QPointF &pos) const;
    virtual void cancelPress(const QPointF &pressPos);

    enum Input {
        InputPress,
        InputMove,
        InputRelease
    };

    bool handleInput(Input input, const QPointF &position, qint64 timestamp);

    QKineticScroller(QKineticScrollerPrivate &dd);
    QScopedPointer<QKineticScrollerPrivate> d_ptr;

private:
    Q_DISABLE_COPY(QKineticScroller)
    Q_DECLARE_PRIVATE(QKineticScroller)
};

QT_END_NAMESPACE

Q_DECLARE_METATYPE(QKineticScroller *)

QT_END_HEADER

#endif // QKINETICSCROLLER_H