Crashing in QRunner threads with numpy

by Martin Fitzpatrick Last updated FAQ
Heads up! You've already completed this tutorial.

Elliot_Young | 2020-05-11 06:42:47 UTC | #1

Thanks for the great write-up. I'm attempting to use this example to stream a live video feed (numpy array -> QImage -> QPixmap -> QLabel inside a QScrollArea) but I am frequently encountering crashes when the label is resized too quickly, or the scroll area is scrolled too quickly. I have seen people mention that it could be a problem with QImage memory buffer getting cleared before the QPixmap can update the QPainter event, but I tried storing a .copy() of the QImage and that didn't work.

Is this something you think can be fixed, or does it sound like a fundamental issue with the way threads work with Python/PyQt5?

Elliot_Young | 2020-05-11 06:44:24 UTC | #2

Well only about 30 minutes later, I was able to implement a new signal (bool, 'result' signal) that gets emitted when the QImage is converted. I also moved the setPixmap event to a separate function that only runs when the 'result' signal is emitted and now I haven't experienced any crashes. Thanks so much for your tutorials - I just bought the book!

Well done, you've finished this tutorial! Mark As Complete
[[ user.completed.length ]] completed [[ user.streak+1 ]] day streak

For a complete guide to building GUI applications with Python, see our PyQt6 tutorial. Using another library? We also have a PyQt5 tutorial, PySide6 tutorial and PySide2 tutorial.

Martin Fitzpatrick

Crashing in QRunner threads with numpy was written by Martin Fitzpatrick .

Martin Fitzpatrick has been developing Python/Qt apps for 8 years. Building desktop applications to make data-analysis tools more user-friendly, Python was the obvious choice. Starting with Tk, later moving to wxWidgets and finally adopting PyQt. Martin founded PythonGUIs to provide easy to follow GUI programming tutorials to the Python community. He has written a number of popular https://www.martinfitzpatrick.com/browse/books/ on the subject.

Crashing in QRunner threads with numpy was published in faq on (updated ) . Feedback & Corrections can be submitted here.