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c++qtqmlintegration

QtQuick, QML and C++ integration: how to make public variables definied inside .h file visible in QML file?

After integration C++ and QML using the way described here:

QML C++ integration

I have noticed only .h methods are visible outside class (from QML level), I have no access for public variables. After research I found that:

void QQmlContext::setContextProperty(const QString &name, const QVariant &value)

Is this way proper?

If not, how can I get access to my class public variables from QML level ?

Supposedly I can create functions for this purpose, but I don't like this way. It looks for me like way around...

Solution

  • In the following example, I wanted to expose the C++ qVersion() from QtGlobal to QML as System.qtVersion.

    //System.h
#ifndef System_H
#define System_H
#include <QObject>
class System : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString qtVersion READ qtVersion CONSTANT)
public:
    System(QObject* parent = nullptr);
    QString qtVersion() const;
};
#endif

    //System.cpp
#include "System.h"
System::System(QObject * parent) :
    QObject(parent)
{
}
QString System::qtVersion() const
{
    return qVersion();
}
#endif

```c++
//main.cpp
    //...
    qmlRegisterSingletonType<System>("qmlonline", 1, 0, "System", [](QQmlEngine*,QJSEngine*) -> QObject* { return new System(); } );

    I can access the above in QML with the following snippet:

    import QtQuick
import QtQuick.Controls
import qmlonline
Page {
    Text {
        text: System.qtVersion
    }
}

    You can try the QML portion online

    For other examples of C++ wrappings to QML checkout my GitHub projects: