QQuickWidget将信号从C ++发送到QML中的插槽

Question

I have a application and I want make a little animation for it. I did a qml file and used QQuickWidget to open and show it in my display. Now a I want make iteration between c++ and QML. I want, for example, when a function in c++ is called, a ball move in my display. But I could not make a connection between c++ and qml.

Every help is welcome.

A little part of my code: c++

QQuickWidget *quickWidget = new QQuickWidget;

quickWidget->setSource(QUrl("qrc:/QML/main.qml"));
auto rootObject = quickWidget->rootObject();

// Connect C++ signal to QML slot
connect(this, SIGNAL(cppSignal()), rootObject, SLOT(qmlSlot()));

emit cppSignal();

QML

Rectangle {
id: tela
visible: true
width: 715
height: 77
color: '#E8E8E8'


//        NumberAnimation {
//            running: true
//            target: bolinha
//            property: "x"
//            duration: 1000
//            to: 600
//        }

function qmlSlot() {
    bolinha.visible= enabled
    animBolinha.start();
    }
}

enter image description here

What I can do to solve it?

Answer 1

I am not sure if you can call a QML method from C++ code as you did.

The recommended way from QT documentation is:

All QML methods are exposed to the meta-object system. As the functions are exposed to meta-object system, you can use QMetaObject::invokeMethod() , to invoke the QML function.

Probably in your case, you should call as said below (not tested).

auto rootObject = quickWidget->rootObject();
QMetaObject::invokeMethod(rootObject, "qmlSlot");

Look documentation (search for Invoking QML Methods )

As said in documentation, you can use Q_ARG to pass the arguments and Q_RETURN_ARG for receiving return arguments.