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39
40#ifndef QQUICKDRAGHANDLER_H
41#define QQUICKDRAGHANDLER_H
42
43//
44// W A R N I N G
45// -------------
46//
47// This file is not part of the Qt API. It exists purely as an
48// implementation detail. This header file may change from version to
49// version without notice, or even be removed.
50//
51// We mean it.
52//
53
54#include "qquickmultipointhandler_p.h"
55#include "qquickdragaxis_p.h"
56
57QT_BEGIN_NAMESPACE
58
59class Q_QUICK_PRIVATE_EXPORT QQuickDragHandler : public QQuickMultiPointHandler
60{
61 Q_OBJECT
62 Q_PROPERTY(QQuickDragAxis * xAxis READ xAxis CONSTANT)
63 Q_PROPERTY(QQuickDragAxis * yAxis READ yAxis CONSTANT)
64 Q_PROPERTY(QVector2D translation READ translation NOTIFY translationChanged)
65 Q_PROPERTY(SnapMode snapMode READ snapMode WRITE setSnapMode NOTIFY snapModeChanged REVISION 14)
66 QML_NAMED_ELEMENT(DragHandler)
67 QML_ADDED_IN_MINOR_VERSION(12)
68
69public:
70 enum SnapMode {
71 NoSnap = 0,
72 SnapAuto,
73 SnapIfPressedOutsideTarget,
74 SnapAlways
75 };
76 Q_ENUM(SnapMode)
77
78 explicit QQuickDragHandler(QQuickItem *parent = nullptr);
79
80 void handlePointerEventImpl(QQuickPointerEvent *event) override;
81
82 QQuickDragAxis *xAxis() { return &m_xAxis; }
83 QQuickDragAxis *yAxis() { return &m_yAxis; }
84
85 QVector2D translation() const { return m_translation; }
86 void setTranslation(const QVector2D &trans);
87 QQuickDragHandler::SnapMode snapMode() const;
88 void setSnapMode(QQuickDragHandler::SnapMode mode);
89
90 void enforceConstraints();
91
92Q_SIGNALS:
93 void translationChanged();
94 Q_REVISION(14) void snapModeChanged();
95
96protected:
97 void onActiveChanged() override;
98 void onGrabChanged(QQuickPointerHandler *grabber, QQuickEventPoint::GrabTransition transition, QQuickEventPoint *point) override;
99
100private:
101 void ungrab();
102 void enforceAxisConstraints(QPointF *localPos);
103 bool targetContainsCentroid();
104 QPointF targetCentroidPosition();
105
106private:
107 QPointF m_pressTargetPos; // We must also store the local targetPos, because we cannot deduce
108 // the press target pos from the scene pos in case there was e.g a
109 // flick in one of the ancestors during the drag.
110 QVector2D m_translation;
111
112 QQuickDragAxis m_xAxis;
113 QQuickDragAxis m_yAxis;
114 QQuickDragHandler::SnapMode m_snapMode = SnapAuto;
115 bool m_pressedInsideTarget = false;
116
117 friend class QQuickDragAxis;
118};
119
120QT_END_NAMESPACE
121
122QML_DECLARE_TYPE(QQuickDragHandler)
123QML_DECLARE_TYPE(QQuickDragAxis)
124
125#endif // QQUICKDRAGHANDLER_H
126

source code of qtdeclarative/src/quick/handlers/qquickdraghandler_p.h