Parse JavaScript QML item to C++ QT

Question

I have a JavaScript function in QML which creates and returns a component (Item):

function addMyComponent() {
    var component = Qt.createComponent('MyComponent.qml');
    var obj = component.createObject(container, {'x': 0, 'y': 0});
    return obj; // Not sure weather to return obj or component for my C++ to use
}

I also have some QML in main.qml which is using a custom C++ class I have made:

// ...
import com.acidic.customclass 1.0
import "AddMyComponent.js" as AddMyComponent

ApplicationWindow {
    visible: true
    width: 1280
    height: 800

    CustomClass {
        id: customClass
    }

    Button {
        onClicked: {
            customClass.receiveComponent(AddMyComponent.addMyComponent)
        }
    }
}

And my C++ class header:

Q_INVOKABLE void receiveComponent(const QObject& obj /* QObject ref doesn't work */);

and body:

void CustomClass::receiveComponent(const QObject& obj) {
    qDebug(obj.property("width")); // To see if we have received it correctly
}

How can I parse a component created with JavaScript and Qt.createComponent into my custom C++ class' function parameter?

You should use Q_INVOKABLE void receiveComponent(QObject* pObj);. — Alexander V
– Alexander V, Commented Feb 6, 2018 at 7:35
@AlexanderVX that worked! Thank you, I'd be willing to accept it as an answer if you post it — Ari Seyhun
– Ari Seyhun, Commented Feb 6, 2018 at 9:00
@Acidic Just cannot remember the proper link to docs but there few. I posted "Data Type Conversion Between QML and C++" link with the answer. At least that is some clarification. — Alexander V
– Alexander V, Commented Feb 6, 2018 at 14:48

Alexander V · Accepted Answer · 2018-02-06 14:45:25Z

3

We have QML UI objects derived from QQuickItem (for Qt Quick) which is QObject and other 'auxiliary' objects also used in QML derived from QObject base:

// QObject pointer should work with QML objects
Q_INVOKABLE void receiveComponent(QObject* pObj);

Mind that there also QString, QVariant, QVariantList, QVariantMap and other Qt primitives. For the reference.

answered Feb 6, 2018 at 14:45

Alexander V

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1 Comment

Jason R. Mick Over a year ago

Also, I would recommend @Acidic tries Q_INVOKABLE void receiveComponent(QQuickItem* pQuickItem); as the initializer varlist tells me that it's likely a QQuickItem. The more specific the typing, the better the runtime performance / readability, as a general rule.

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