Recive Signal inside QML Object

[MAthias_Va]

I am little bit confused how to receive a signal, I have a signal called onvalueChanged, and according to it I will append data inside my plot! any Advice how to handle it?

ChartView {
    id:chartView1
 onvalueChanged: lineseries1.append(i, value)
}

[J.Hilk]

@MAthias_Va

that depends on where the signal actually comes from, can you explain a but more?

• is it a c++ class somewhere
• a signal declared inside an other QML-file
• is it part of the ChartView itself?
• ....

In any case, in QML you can access usually signals that are bound to properties by the following Syntax;

on + propertyName + Changed
in your case, most likely onValueChanged, but this may or may not be sufficient, you'll have to say where the signal comes from

[MAthias_Va]

Thanks @J.Hilk for your clarification, it is from C++, Q_PROPERTY
like this on; http://doc.qt.io/qt-5/qtqml-cppintegration-exposecppattributes.html

 Q_PROPERTY(QString value READ value WRITE setValue NOTIFY valueChanged)

[J.Hilk]

@MAthias_Va
alight,
that means, the signal you're actually listening to is indeed

onValueChanged: //do something

attention to the capital V

followup question, how do you instantiate the c++ class?

If it's registered as a qml component, you'll have to add the line inside that body.
If it's a context property you'll have to use Connect

[MAthias_Va]

at the moment I can receive the signal inside my QML file, but My problem is, I canto integrate it as I need!!

for example If I create a timer inside my ChartView I can receive the signal as below example; which is working as expected

ChartView {
    id:chartView1
Timer {
          id:timer
          interval: 200 ; running: true; repeat: true;
          onTriggered: onvalueChanged: lineseries1.append(i, value) //here I don't receive error

           }
        }                     

but I don't want to use this Timer, I need to receive the signal as my beginning example! Any Ideas?

ChartView {
    id:chartView1
 onvalueChanged: lineseries1.append(i, value) //here I have error: Cannot assign to non-existent property
}

[J.Hilk]

@MAthias_Va
I'm puzzled the timer works at all!!?!?

again, how to you access the c++ class?

did you use

• qmlRegisterType<yourClass>
• or setContextProperty
• or something else

?

[MAthias_Va]

@J.Hilk I use: setContextProperty

[J.Hilk]

@MAthias_Va said in Recive Signal inside QML Object:

@J.Hilk I use: setContextProperty

alight, assuming the following :

rootContext()->setContextProperty("myClass", myClassInstance);

than you can do the following

ChartView {
    id:chartView1

    Connections{
            target: myClass

            onValueChanged: console.log("c++ value changed to:", value);
     }
}

[MAthias_Va]

Thanks @J.Hilk so much, this one is working :) :)