How to make a Enum known to QML if it is inside a QObject derived class

[maxwell31]

Hi,

I have a Q_OBJECT derived class, which has several Q_PROPERTY values. One of them is an enum, defined in that class. In order to make it known to QML, I would need to do Q_DECLARE_METATYPE(MarkGui), but this is not possible as Q_DECLARE_METATYPE requires a copy constructor, which is forbidden for Q_OBJECT derived classes. What is the way to do it?

[raven-worx]

@maxwell31 said in How to make a Enum known to QML if it is inside a QObject derived class:

I would need to do Q_DECLARE_METATYPE(MarkGui)

No.
Actually you need Q_ENUM

enum MyEnum {
    ...
};
Q_ENUM(MyEnum)

[maxwell31]

Hm, I was using Q_ENUMS. But When I try to use it, I get the following error:

  QMetaProperty::read: Unable to handle unregistered datatype 'myEnumType' for property 'QQmlDMObjectData::myEnumType'.

I also registered the class which hosts the enum:

  qmlRegisterType<MyClass>("MyClass",1,0,"MyClass");

So the problem seems to be, that I use the enum as a property

[raven-worx]

@maxwell31
how does your Q_PROPERTY declaration look like?
Did you add the class namespace to the enum type in the property declaration?

[maxwell31]

Here the class:

class MarkGui: public QObject {
  Q_OBJECT
  Q_PROPERTY(MarkType markType READ markType WRITE       setMarkType NOTIFY markTypeChanged)

public:
  MarkGui(QObject *parent = 0);
  explicit MarkGui(Mark * m, QObject *parent = 0);
  enum MarkType {
    MOMENT,
    TIMERANGE,
  };
   Q_ENUM(MarkType);

I tried with adding the class namespace, but it leads to the same result

[maxwell31]

Hm, it seems I need to register the enum seperatly
qRegisterMetaTypeMarkGui::MarkType("MarkGui::MarkType");

[ODБOï]

This post is deleted!

[Gojir4]

Hi @maxwell31,

Usually you have not to register the enum. This would be a pain when you have tens of enums declared.
But you need to register the class hosting the enum, because you need a keyword to access the enum from QML side.

So Q_ENUM(MarkType) more calling qmlRegisterType<MarkGui>("MarkGui",1,0,"MarkGui"); at runtime should be enough to retrieve the enum from QML.

This works perfectly on my side:

#ifndef MARKGUI_H
#define MARKGUI_H

#include <QObject>
#include <QtQml>

class MarkGui: public QObject {
    Q_OBJECT
    Q_PROPERTY(MarkType markType READ markType WRITE setMarkType NOTIFY markTypeChanged)

public:
    MarkGui(QObject *parent = 0) : QObject(parent){};

    enum MarkType {
        MOMENT,
        TIMERANGE,
    };
    Q_ENUM(MarkType);

    MarkType markType() const
    {
        return m_markType;
    }
    static void declareQml(){
        qmlRegisterType<MarkGui>("MarkGui", 1, 0, "MarkGui");
    }
public slots:
    void setMarkType(MarkType markType)
    {
        if (m_markType == markType)
            return;

        m_markType = markType;
        emit markTypeChanged(m_markType);
    }
signals:
    void markTypeChanged(MarkType markType);
private:
    MarkType m_markType;
};
#endif // MARKGUI_H

//main()
//...
    MarkGui markGui;
    MarkGui::declareQml();

    QQmlApplicationEngine engine;
    engine.rootContext()->setContextProperty("markGui", &markGui);
...

Then from QML:

     import MarkGui 1.0
     ...
     markGui.markType = MarkGui.MOMENT
     console.log(markGui.markType)
     markGui.markType = MarkGui.TIMERANGE
     console.log(markGui.markType)

Output:

qml: 0
qml: 1

[maxwell31]

Ok, good to know.Thank you for your help!