Manual loop

Mehodin

Hello,

I was wondering whether it's possible to manually call everything that QApplication::exec() calls in a loop myself.
For example:

void main_loop() {
    MyOwnApp::DoAThing();
    QApplication::draw();
    QApplication::pollEvents();
    MyOwnApp::DoSomething();
}

Rather than having to use QApplication::exec() or run()

sierdzio

That's quite a deep question :-) If you don't get any answers here, consider asking on Qt interest mailing list. Qt core devs reside there and they should be able to help you. https://lists.qt-project.org/listinfo/interest

I'll start by saying that I don't know the answer. What follows are my guesses. I think that it likely won't work - QCoreApplication is a singleton, and user code can call processEvents() at any point, which would go around your custom loop. You may have more luck if you handle events yourself in a custom event dispatcher. See setEventDispatcher() and QAbstractEventDispatcher.

Mehodin

I uhh, i actually managed to find what i need by simply calling QApplication::processEvents() in a while loop, somehow that was enough so the UI would keep running and wouldn't deadlock

sierdzio

@Mehodin said in Manual loop:

QApplication::processEvents()

Please note that using this method can be quite dangerous at times. It's better, if you can, to spin a custom QEventLoop, use QThread or make your code asynchronous (based on signals and slots).

aha_1980

@Mehodin You can simply use a QTimer to periodically call your user functions regularly and leave everything else standard Qt.

Regards

J.Hilk

@Mehodin said in Manual loop:

I uhh, i actually managed to find what i need by simply calling QApplication::processEvents() in a while loop, somehow that was enough so the UI would keep running and wouldn't deadlock

Please don‘t, with each call to processEvents() a fairy dies !