Queued connection from QML?

[robro]

Hi,

I would like to communicate with QThreads from QML.
Normally I would use a QueuedConnection for that which seems not to be available in QML.

Is there a way to invoke c++ class methods in a queued way?

I know that I can put a c++ class in the middle.
So put all methods which should be invoked from qml as slots to that class and emit queued signals from there to the real thread.

Thanks :-)

[J.Hilk]

hi @robro

unfortunatly, there's no way to force a queued connection, the way you want it. At leas not that I know of.

I think the call of cpp classes from QML and vice versa are already queued be default, but I might be wrong here.

However there's a simple workaround, define a signal in your c++ class, make it accesable by qml via Q_INVOKABLE and make a normal QObject::connection inside your class constructor.
Than simply invoke that signal from the QML side.

[robro]

Thanks for this really nice workaround!
It is working fine :-)

[robro]

Sorry... I have to reopen this thread.

With the described workaround I can make a connection from QML to C++, but how can I make it work the other way round?

Usually I would do something like:

Connections {
        target: classInAnotherThread;
        onSignalABC: {
            //console.log("Got signal")
        }

Here I now get the error that the QML engine is in another thread.

[J.Hilk]

hi @robro

I would say, you solve this with the same workaround.

you can QObject::connect, 2 signals to gether. Use that and forward the signal to the parent, not threaded class to than pass it to qml.

[robro]

This works fine!
Thank you very much :-)