QML使用C++的类

qmlobjectdefine.h

#ifndef QMLOBJECTDEFINE_H
#define QMLOBJECTDEFINE_H

#include <qobjectdefs.h>
#include <qqml.h>

#define QML_FUNCTION                                    Q_INVOKABLE
#define QML_MEMBER_NAME(NAME)                           m_##NAME
#define QML_SIGNAL_NAME(NAME)                           NAME##Changed

#define QML_MEMBER_VARIABLE(TYPE, NAME)                 TYPE m_##NAME
#define QML_MEMBER_SIGNAL(NAME)                         void NAME##Changed()
#define QML_PROPERTY(TYPE, NAME)                        Q_PROPERTY(TYPE NAME MEMBER m_##NAME NOTIFY NAME##Changed)

#define QML_CREATE_PROPERTY(TYPE, NAME)                 QML_MEMBER_SIGNAL(NAME); public:QML_MEMBER_VARIABLE(TYPE, NAME); QML_PROPERTY(TYPE, NAME);

#define QML_REGISTER_TYPE(NAME, MAJOR, MINOR)           qmlRegisterType<NAME>(#NAME, MAJOR, MINOR, #NAME);
#define QML_REGISTER_SINGLETON_TYPE(NAME, MAJOR, MINOR) qmlRegisterSingletonType<NAME>(#NAME, MAJOR, MINOR, #NAME, [](QQmlEngine *engine, QJSEngine *scriptEngine) -> QObject * { Q_UNUSED(engine) Q_UNUSED(scriptEngine) return new ObjectTester; })

#endif // QMLOBJECTDEFINE_H

c++的类注册到qml

#ifndef OBJECTTESTER_H
#define OBJECTTESTER_H

#include <QObject>
#include "qmlobjectdefine.h"

class ObjectTester : public QObject
{
    Q_OBJECT
public: signals:
    QML_CREATE_PROPERTY(QString, name)
public: signals:
    QML_CREATE_PROPERTY(int, age)
public:
    QML_FUNCTION QString output();
public:
    explicit ObjectTester(QObject *parent = nullptr);
};

#endif // OBJECTTESTER_H

main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>

#include <QDebug>
#include <QFontDatabase>
#include <qmlobjectdefine.h>
#include <objecttester.h>

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
#if 1
    QMap<QString, int> objectMap;
    objectMap["ObjectTester"] = QML_REGISTER_SINGLETON_TYPE(ObjectTester, 1, 0);
    ObjectTester* instanceObjectTester = engine.singletonInstance<ObjectTester*>(objectMap["ObjectTester"]);
    instanceObjectTester->m_name = "张三";
    instanceObjectTester->m_age = 15;
#endif
    const QUrl url(QStringLiteral("qrc:/main.qml"));
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                     &app, [url](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

main.qml

import QtQuick 2.12
import QtQuick.Window 2.12

import ObjectTester 1.0

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
    Component.onCompleted:  {
        console.log(ObjectTester.output())
        console.log(ObjectTester.name)
        console.log(ObjectTester.age)
    }
}