[SOLVED] QWidget::repaint: Recursive repaint detected
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I have a project which has multiple threads. Each thread has a "worker class" which updates a single progress bar located in the main thread (MainWindow).
The progress bar's pointer is passed to the "worker class" at at the time it was instantiated. I didn't subclass QThread but instead, I used QObject::moveToThread() to pass the worker class to a thread.@
QThread1 ---> QProgressBar1
QThread2 ---> QProgressBar2
QThread3 ---> QProgressBar3
....
@when there are multiple threads/worker class created, "QWidget::repaint: Recursive repaint detected" error comes out.
I am thinking that it was caused by passing the pointer of the progress bar to another thread.
What is the solution for this? Thanks -
You can not (directly) update widgets from within threads.
I suspect you're using methods like setValue on the progress bar from within the threads, right? Don't do that. Instead, use a signal-slot connection. The setValue method is already a slot, so there is very little code overhead. The signal-slot mechanism will take care of making this updating thread save.
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[quote author="Andre" date="1361176505"]You can not (directly) update widgets from within threads.
I suspect you're using methods like setValue on the progress bar from within the threads, right? Don't do that. Instead, use a signal-slot connection. The setValue method is already a slot, so there is very little code overhead. The signal-slot mechanism will take care of making this updating thread save.[/quote]
Yes, you are right. I will try to rewrite the code. Thanks.
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[quote author="Andre" date="1361176505"]You can not (directly) update widgets from within threads.
I suspect you're using methods like setValue on the progress bar from within the threads, right? Don't do that. Instead, use a signal-slot connection. The setValue method is already a slot, so there is very little code overhead. The signal-slot mechanism will take care of making this updating thread save.[/quote]
Yes, you are right. I will try to rewrite the code. Thanks.
@Code_ReaQtor, and andre,
that is exactly the issue I had for the last 2 hours of debugging. Thanks a lot for the solution I found here 10 years later