QML调用C++方法

1. 使用QQmlContext (setContextProperty)注册

#include 

// 必须继承QObject
class MainModel : public QObject
{
    Q_OBJECT
public:
    // 需提供此构造方法
    MainModel(QObject *parent = nullptr);

    // 可供调用的方法
    Q_INVOKABLE void test();
};

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;

    // 示例
    MainModel mainModel;
    engine.rootContext()->setContextProperty("MainModel", &mainModel);

    
    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();
}

2. QML 中调用

Button {
    text: "test"

    Connections {
        function onClicked() {
            MainModel.test()
        }
    }
}

备注：直接通过注册的名称调用，无效导入

1. 使用 qmlRegisterType 注册

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;

    // 示例
    qmlRegisterType("MainModel.module", 1, 0, "MainModel");

    
    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();
}

备注：MainModel类同方法一中

2. QML 中调用

import MainModel.module 1.0

MainModel {
    id: mainModel
}

Connections {
    // 响应C++信号示例
    function onConnected() {
        stateLine.color = "green"
    }

    function onDisconnected() {
        stateLine.color = "red"
    }
}

Connections {
    function onClick() {
        var filePath = filePathEdit._text.trim()
        
        if (filePath.length == 0)
            return

        // 调用C++方法示例
        mainModel.sendFile(filePath.replace("file:///", ""))
    }
}