qt-everywhere-src-5.14.1/qtdeclarative/src/quick/handlers/qquickdraghandler_p.h

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#ifndef QQUICKDRAGHANDLER_H
#define QQUICKDRAGHANDLER_H

//
//  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 "qquickmultipointhandler_p.h"
#include "qquickdragaxis_p.h"

QT_BEGIN_NAMESPACE

class Q_QUICK_PRIVATE_EXPORT QQuickDragHandler : public QQuickMultiPointHandler
{
    Q_OBJECT
    Q_PROPERTY(QQuickDragAxis * xAxis READ xAxis CONSTANT)
    Q_PROPERTY(QQuickDragAxis * yAxis READ yAxis CONSTANT)
    Q_PROPERTY(QVector2D translation READ translation NOTIFY translationChanged)
    Q_PROPERTY(SnapMode snapMode READ snapMode WRITE setSnapMode NOTIFY snapModeChanged REVISION 14)

public:
    enum SnapMode {
        NoSnap = 0,
        SnapAuto,
        SnapIfPressedOutsideTarget,
        SnapAlways
    };
    Q_ENUM(SnapMode)

    explicit QQuickDragHandler(QQuickItem *parent = nullptr);

    void handlePointerEventImpl(QQuickPointerEvent *event) override;

    QQuickDragAxis *xAxis() { return &m_xAxis; }
    QQuickDragAxis *yAxis() { return &m_yAxis; }

    QVector2D translation() const { return m_translation; }
    void setTranslation(const QVector2D &trans);
    QQuickDragHandler::SnapMode snapMode() const;
    void setSnapMode(QQuickDragHandler::SnapMode mode);

    void enforceConstraints();

Q_SIGNALS:
    void translationChanged();
    Q_REVISION(14) void snapModeChanged();

protected:
    void onActiveChanged() override;
    void onGrabChanged(QQuickPointerHandler *grabber, QQuickEventPoint::GrabTransition transition, QQuickEventPoint *point) override;

private:
    void ungrab();
    void enforceAxisConstraints(QPointF *localPos);
    bool targetContainsCentroid();
    QPointF targetCentroidPosition();

private:
    QPointF m_pressTargetPos;   // We must also store the local targetPos, because we cannot deduce
                                // the press target pos from the scene pos in case there was e.g a
                                // flick in one of the ancestors during the drag.
    QVector2D m_translation;

    QQuickDragAxis m_xAxis;
    QQuickDragAxis m_yAxis;
    QQuickDragHandler::SnapMode m_snapMode = SnapAuto;
    bool m_pressedInsideTarget = false;

    friend class QQuickDragAxis;
};

QT_END_NAMESPACE

QML_DECLARE_TYPE(QQuickDragHandler)
QML_DECLARE_TYPE(QQuickDragAxis)

#endif // QQUICKDRAGHANDLER_H