将某些内容绑定到使用qmlRegisterSingletonType注册的类型的属性

#ifndef SINGLETONMANAGER_H
#define SINGLETONMANAGER_H

#include <QObject>

class SingletonManager : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString content READ content WRITE setContent NOTIFY contentChanged)

public:
    explicit SingletonManager(QObject *parent = nullptr);

    QString content() const;
    void setContent(const QString &content);

signals:
    void contentChanged();

private:
    QString m_content;
};

#endif // SINGLETONMANAGER_H

#include "SingletonManager.h"

SingletonManager::SingletonManager(QObject *parent) : QObject(parent)
{
}

QString SingletonManager::content() const
{
    return m_content;
}

void SingletonManager::setContent(const QString &content)
{
    if (m_content != content) {
        m_content = content;
        emit contentChanged();
    }
}

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "SingletonManager.h"

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

    QGuiApplication app(argc, argv);

    qmlRegisterSingletonType<SingletonManager>("com.example", 1, 0, "SingletonManager", [](QQmlEngine *engine, QJSEngine *scriptEngine) -> QObject * {
        Q_UNUSED(engine)
        Q_UNUSED(scriptEngine)

        SingletonManager *singleton = new SingletonManager();
        return singleton;
    });

    QQmlApplicationEngine engine;
    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();
}

import com.example 1.0

Item {
    width: 200
    height: 200

    Text {
        text: SingletonManager.content
        anchors.centerIn: parent
    }
}