Qt Qml连接到Context属性的QObject属性的信号

Question

所以这可能看起来像一个奇怪的设置。为简单起见，我有一个C ++对象，它继承自QObject，称为“MasterGuiLogic”。它是使用指向另一个名为“MainEventBroker”的对象的指针创建的，您可能会猜测它处理我的所有应用程序事件。 MasterGuiLogic对象在qml中注册为上下文属性，因此它的属性可以在我的qml中的任何位置使用。所以main.cpp看起来像这样：

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

    MasterEventBroker *MainEventBroker = new MasterEventBroker();
    MasterGuiLogic *MainGuiLogic = new MasterGuiLogic(*MainEventBroker);

    qmlRegisterUncreatableType<MasterGuiLogic>("GrblCom", 1, 0, "MasterGuiLogic", "");
    qmlRegisterUncreatableType<GuiLogic_SerialCom>("GrblCom", 1, 0, "GuiLogic_SerialCom", "");

    QQmlApplicationEngine engine;
    QQmlContext* context = engine.rootContext();

    context->setContextProperty("MasterGuiLogic", &(*MainGuiLogic));

    engine.load(QUrl(QLatin1String("qrc:/QmlGui/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

MasterGuiLogic创建另一个名为SerialCom的类的实例，该类设置为Q_PROPERTY，以便可以通过MasterGuiLogic属性在qml中访问它的属性和公共槽。

MasterGuiLogic.h：

class MasterGuiLogic : public QObject
{
    Q_OBJECT
    Q_PROPERTY(GuiLogic_SerialCom* serialCom READ serialCom CONSTANT)
public:
    MasterEventBroker *eventBroker;

    explicit MasterGuiLogic(MasterEventBroker &ev, QObject *parent = nullptr);


    GuiLogic_SerialCom* serialCom() const {
        return Gui_SerialCom;
    }

private:

    GuiLogic_SerialCom *Gui_SerialCom;

MasterGuiLogic.cpp：

MasterGuiLogic::MasterGuiLogic(MasterEventBroker &ev, QObject *parent) : QObject(parent)
{
    this->eventBroker = &ev;
    this->Gui_SerialCom = new GuiLogic_SerialCom(this);
}

SerialCom.h：

//Forward Declare our parent
class MasterGuiLogic;

class GuiLogic_SerialCom : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QStringList portNames READ portNames NOTIFY portNamesChanged)
    Q_PROPERTY(bool connectedToPort READ connectedToPort NOTIFY connectedToPortChanged)
public:

    MasterGuiLogic *parent;
    explicit GuiLogic_SerialCom(MasterGuiLogic *parent = nullptr);

    std::map<QString, QSerialPortInfo> portsMap;


    QStringList portNames() {
        return _portNames;
    }

    bool connectedToPort() {
        return _connectedToPort;
    }

private:

    QStringList _portNames;
    bool _connectedToPort = false;


signals:

    void portNamesChanged(const QStringList &);
    void connectedToPortChanged(const bool &);

public slots:

    void connectToPort(const QString portName);
    void disconnectFromPort(const QString portName);

};

SerialCom.cpp：

GuiLogic_SerialCom::GuiLogic_SerialCom(MasterGuiLogic *parent) : QObject(qobject_cast<QObject *>(parent))
{
    this->parent = parent;


    QList<QSerialPortInfo> allPorts = QSerialPortInfo::availablePorts();

    for (int i = 0; i < allPorts.size(); ++i) {
        this->_portNames.append(allPorts.at(i).portName());
        this->portsMap[allPorts.at(i).portName()] = allPorts.at(i);
    }

    emit portNamesChanged(_portNames);

}

void GuiLogic_SerialCom::connectToPort(const QString portName) {
    //TODO: Connect To Port Logic Here;

    //Set Connected
    this->_connectedToPort = true;
    emit connectedToPortChanged(this->_connectedToPort);

    qDebug() << portName;
}

void GuiLogic_SerialCom::disconnectFromPort(const QString portName) {
    //TODO: DisConnect To Port Logic Here;

    //Set DisConnected
    this->_connectedToPort = false;
    emit connectedToPortChanged(this->_connectedToPort);

    qDebug() << portName;
}

因此，从qml中可以很容易地读取任何这些属性，甚至可以将信号从qml发送到c ++

例如，这很好用：

connectCom.onClicked: {
        if (MasterGuiLogic.serialCom.connectedToPort === false) {
            MasterGuiLogic.serialCom.connectToPort(comPort.currentText);
        } else {
            MasterGuiLogic.serialCom.disconnectFromPort(comPort.currentText);
        }
    }

问题是，我似乎无法找到一种方法来连接从SerialCom发出的信号。我以为我可以这样做：

Connections: {
        target: MasterGuiLogic.serialCom;
        onConnectedToPortChanged: {
            if (MasterGuiLogic.serialCom.connectedToPort === false) {
                connectCom.text = "Disconnect";
                comPort.enabled = false;
            } else {
                connectCom.text = "Connect";
                comPort.enabled = true;
            }
        }
    }

这应该监听SerialCom上的boolean属性来改变，但是我得到以下错误：

QQmlApplicationEngine failed to load component
qrc:/QmlGui/main.qml:21 Type Page1 unavailable
qrc:/QmlGui/Page1.qml:49 Invalid attached object assignment

这只是意味着我无法使用上面的目标行“连接”。有没有其他方法可以连接到ContextProperty中QObject类型的Q_PROPERTY的信号？

Answer 1

另一答案