如何将枚举类传递给 QML?

2022-01-19 00:00:00 qt enums qml c++

我正在学习使用 Qt 来学习 QML，但在将 enum class 传递给 qml 时遇到了一些麻烦.

I am on learning to QML with Qt and get some trouble with passing enum class to qml.

当我使用带有 int 参数的信号时 - 没关系，代码可以完美运行.

When I use signal with int parameters - it's all right and code work perfectly.

但是，这里有麻烦，如果我使用带有一些 enum class 参数的信号，我在 qml 信号处理程序中有 undefined 值.我试图通过 qmlRegisterType 注册 enum class 但它不起作用.我将不胜感激.

But, and here the trouble, if I use signal with some enum class parameters I have undefined values in qml signal handler. I tried to register enum class through qmlRegisterType but it's not working. I will be grateful for the help.

代码如下:

一些 Helper 类

class Helper : public QObject
{
    Q_OBJECT
    Q_ENUMS(Requester)
    Q_ENUMS(JANSWER)

public:

enum class Requester {
    ReqLogin,
    ReqNull,
    ReqSave,
    ReqError,
    ReqUnknown
};

enum class JANSWER {
    OK,
    Complete,
    Error,
    Unknown
};

};

ma??in.cpp

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

    qmlRegisterType<JsonPackWorker>("com.jsonpackworker", 1, 0, "JsonPackWorker");
    qmlRegisterType<Helper>("com.Helper", 1, 0, "Helper");

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    return app.exec();
}

JsonPackWorker.h

class JsonPackWorker : public QObject
{
    Q_OBJECT
public:
    <...>

signals:    
    <...>
    void sendAnswer(Helper::Requester req, Helper::JANSWER answer);

public slots:
    <...>
};

JsonPackWorker.cpp 中的某处

emit sendAnswer(Helper::Requester::ReqNull, Helper::JANSWER::OK);

ma??in.qml

<...>
import com.jsonpackworker 1.0
import com.Helper 1.0

ApplicationWindow {
    id: mainWindow

    // Requests in answers
    property int reqLogin: Helper.ReqLogin

    <...>

    JsonPackWorker {
        id: packWorker
        <...>
        onSendAnswer: {
            // Here I've got undefined undefined if there enum class parameters
            console.log(req + " " + answer)
            switch(req) {
            case reqLogin: loginDial.checkLogin(answer)
                break;
            default:
            }
        }
    }

}

推荐答案

问题出在 Helper 类中(感谢 Qt 社区).

The problem was in Helper class (thanks to Qt community).

class Helper {
   ...
};
Q_DECLARE_METATYPE(Helper::Requester)
Q_DECLARE_METATYPE(Helper::JANSWER)

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