QDialog showing busy while loop is running

mikael.larsson

I have a problem figuring out how I should solve my problem.
I made my own QDialog which I execute open() on.
And then run my while loop, the problem is that this way the QDialog is black/transparent in the cases I've tried.

I want it to run and show a Cancel button with a spinning indiator while my loop is running.
Therefore .exec() isn't the solution since then it wouldn't run my loop.

QDialog dlg
dlg.show();

while (true) {
 //do stuff
}

What would be the best solution here?

Christian Ehrlicher

@mikael-larsson said in QDialog showing busy while loop is running:

What would be the best solution here?

Don't block the event loop. What are you doing in your while loop?

stryga42

Never run "endless" loops (anything which takes longer than the blink of your eyes) in your GUI thread. This will freeze your GUI. Either you can split your do-stuff-task in small chunks - then you can pack it in a QTimer callback and start the timer with zero delay - or you have to learn true multi threading. See for example https://doc.qt.io/qt-5/threads-technologies.html as a starting point.

mikael.larsson

@Christian-Ehrlicher running an external program where I wait for it to finish.

I was hoping theere would be an easy solution, if I had any progress I could just have ran QProgressDialog but since I have no indication on how far the progress have come I'm stuck with just saying that the program is running.

jsulm

@mikael-larsson said in QDialog showing busy while loop is running:

running an external program where I wait for it to finish

There is no reason to "wait" for it to finish - there is https://doc.qt.io/qt-5/qprocess.html#finished signal.