1// Copyright (C) 2017 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Milian Wolff <milian.wolff@kdab.com>
2// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
3#ifndef SIGNALHANDLER_H
4#define SIGNALHANDLER_H
5
6//
7// W A R N I N G
8// -------------
9//
10// This file is not part of the Qt API. It exists for the convenience
11// of other Qt classes. This header file may change from version to
12// version without notice, or even be removed.
13//
14// We mean it.
15//
16
17#include <Qt3DCore/qt3dcore_global.h>
18#include <QtCore/QDebug>
19#include <QtCore/QHash>
20#include <QtCore/QMetaMethod>
21#include <QtCore/QObject>
22#include <private/qglobal_p.h>
23
24QT_BEGIN_NAMESPACE
25
26namespace Qt3DCore {
27
28class Q_3DCORESHARED_EXPORT PropertyChangeHandlerBase : public QObject
29{
30 Q_OBJECT
31public:
32 PropertyChangeHandlerBase(QObject *parent = nullptr);
33
34 /**
35 * Connect to the change signal of @p property in @p object.
36 */
37 void connectToPropertyChange(const QObject *object, int propertyIndex);
38
39 /**
40 * Disconnect from the change signal of @p property in @p object.
41 */
42 void disconnectFromPropertyChange(const QObject *object, int propertyIndex);
43};
44
45/**
46 * The property change handler is similar to QSignalSpy, but geared towards the usecase of Qt3D.
47 *
48 * It allows connecting to any number of property change signals of the receiver object and forwards
49 * the signal invocations to the Receiver by calling its propertyChanged function.
50 */
51template<class Receiver>
52class PropertyChangeHandler : public PropertyChangeHandlerBase
53{
54public:
55 PropertyChangeHandler(Receiver *receiver, QObject *parent = nullptr);
56
57 /**
58 * @internal
59 *
60 * Custom implementation of qt_metacall which calls propertyChanged() on the receiver for
61 * connected signals.
62 */
63 int qt_metacall(QMetaObject::Call call, int methodId, void **args) override;
64
65private:
66 Receiver *m_receiver;
67};
68
69template<class Receiver>
70PropertyChangeHandler<Receiver>::PropertyChangeHandler(Receiver *receiver, QObject *parent)
71 : PropertyChangeHandlerBase(parent)
72 , m_receiver(receiver)
73{
74}
75
76template<class Receiver>
77int PropertyChangeHandler<Receiver>::qt_metacall(QMetaObject::Call call, int methodId, void **args)
78{
79 methodId = QObject::qt_metacall(call, methodId, args);
80 if (methodId < 0)
81 return methodId;
82
83 if (call == QMetaObject::InvokeMetaMethod) {
84 m_receiver->propertyChanged(methodId);
85 return -1;
86 }
87 return methodId;
88}
89
90}
91
92QT_END_NAMESPACE
93
94#endif // SIGNALHANDLER_H
95

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