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// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
//! [0]
class MySingleton : public QObject {
Q_OBJECT
// Register as default constructed singleton.
QML_ELEMENT
QML_SINGLETON
static int typeId;
// ...
};
//! [0]
/*
//! [1]
MySingleton::typeId = qmlTypeId(...);
//! [1]
*/
void wrapper2() {
//! [2]
// Retrieve as QObject*
QQmlEngine engine;
MySingleton* instance = engine.singletonInstance<MySingleton*>(MySingleton::typeId);
//! [2]
}
/*
//! [3]
// Register with QJSValue callback
int typeId = qmlRegisterSingletonType(...);
//! [3]
*/
void wrapper4(int typeId) {
//! [4]
// Retrieve as QJSValue
QQmlEngine engine;
QJSValue instance = engine.singletonInstance<QJSValue>(typeId);
//! [4]
}
void wrapper5() {
//! [5]
QQmlEngine engine;
MySingleton *singleton = engine.singletonInstance<MySingleton *>("mymodule", "MySingleton");
//! [5]
}
class BackendService {};
//! [6]
class CppSingleton: public QObject {
Q_OBJECT
QML_ELEMENT
QML_SINGLETON
QML_UNCREATABLE("Provided via QQmlEngine::setExternalSingletonInstance")
// Q_PROPERTY(...)
public:
explicit CppSingleton(BackendService *service); // constructor taking a reference to something MySingleton needs
// members, Q_INVOKABLE functions, etc.
};
//! [6]
void wrapper6() {
//! [7]
// create and setup the backend service
BackendService service;
// create your singleton instance
CppSingleton singleton(&service);
QQmlApplicationEngine engine;
engine.setExternalSingletonInstance("com.company.myApp", "MySingleton", &singleton);
engine.loadFromModule("com.company.myApp", "Main");
//! [7]
}