1/****************************************************************************
2**
3** Copyright (C) 2014 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Milian Wolff <milian.wolff@kdab.com>
4** Contact: https://www.qt.io/licensing/
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39
40#ifndef SIGNALHANDLER_H
41#define SIGNALHANDLER_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 for the convenience
48// of other Qt classes. 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 <Qt3DCore/qt3dcore_global.h>
55#include <QtCore/QDebug>
56#include <QtCore/QHash>
57#include <QtCore/QMetaMethod>
58#include <QtCore/QObject>
59#include <QtCore/QVector>
60
61QT_BEGIN_NAMESPACE
62
63namespace Qt3DCore {
64
65class Q_3DCORESHARED_EXPORT PropertyChangeHandlerBase : public QObject
66{
67 Q_OBJECT
68public:
69 PropertyChangeHandlerBase(QObject *parent = nullptr);
70
71 /**
72 * Connect to the change signal of @p property in @p object.
73 */
74 void connectToPropertyChange(const QObject *object, int propertyIndex);
75
76 /**
77 * Disconnect from the change signal of @p property in @p object.
78 */
79 void disconnectFromPropertyChange(const QObject *object, int propertyIndex);
80};
81
82/**
83 * The property change handler is similar to QSignalSpy, but geared towards the usecase of Qt3D.
84 *
85 * It allows connecting to any number of property change signals of the receiver object and forwards
86 * the signal invocations to the Receiver by calling its propertyChanged function.
87 */
88template<class Receiver>
89class PropertyChangeHandler : public PropertyChangeHandlerBase
90{
91public:
92 PropertyChangeHandler(Receiver *receiver, QObject *parent = nullptr);
93
94 /**
95 * @internal
96 *
97 * Custom implementation of qt_metacall which calls propertyChanged() on the receiver for
98 * connected signals.
99 */
100 int qt_metacall(QMetaObject::Call call, int methodId, void **args) override;
101
102private:
103 Receiver *m_receiver;
104};
105
106template<class Receiver>
107PropertyChangeHandler<Receiver>::PropertyChangeHandler(Receiver *receiver, QObject *parent)
108 : PropertyChangeHandlerBase(parent)
109 , m_receiver(receiver)
110{
111}
112
113template<class Receiver>
114int PropertyChangeHandler<Receiver>::qt_metacall(QMetaObject::Call call, int methodId, void **args)
115{
116 methodId = QObject::qt_metacall(call, methodId, args);
117 if (methodId < 0)
118 return methodId;
119
120 if (call == QMetaObject::InvokeMetaMethod) {
121 m_receiver->propertyChanged(methodId);
122 return -1;
123 }
124 return methodId;
125}
126
127}
128
129QT_END_NAMESPACE
130
131#endif // SIGNALHANDLER_H
132

source code of qt3d/src/core/nodes/propertychangehandler_p.h