QApplication Process seems to hang

[d_stranz]

All you are showing is a class definition without showing how it is being used. There are a number of dependencies that you are also not giving any details on (ViewBox, GraphcsView, PlotWidget, InfiniteLine). Maybe these are extensions provided by PyQt5 - they aren't part of the standard Qt widget set.

So a little context would be helpful.

[SaibotMagd]

The whole code came from: https://github.com/ChristophKirst/ClearMap2. He build a DataViewer to look at tif or numpy converted files.
The Testcode to check if this class is working is:

def _test():
  import numpy as np
  import ClearMap.Visualization.Qt.DataViewer as dv
 
  img1 = np.random.rand(*(100,80,30));
 
  dv.DataViewer(img1)

def _test():
  import numpy as np
  import ClearMap.Visualization.Qt.DataViewer as dv
  
  img1 = np.random.rand(*(100,80,30));

  dv.DataViewer(img1)

To copy to clipboard, switch view to plain text mode 

its in ClearMap/Visualization/Qt/DataViewer.py

I think it's so basic that it isn't helpful at all. Most interesting part is that the creator and at least 2 others are able to use the Viewer. So the problem shouldn't be in the code itself more about dependencies or the OS. I now try to clone the exact OS he's using. As you see I'm just started using linux and python code, so I don't really know what to do.

[d_stranz]

OK, the problem with the test code is that it does not create a QApplication instance, does not call dv.show() (although the __init__ method for DataViewer -does- call it, which it shouldn't). Your test code should look more like this:

def _test() :
    import sys
    from PyQt5.QtWidgets import QApplication
    from PyQt5.QtCore import Qt
 
    import numpy as np
    import ClearMap.Visualization.Qt.DataViewer as dv
 
    app = QApplication(sys.argv)
 
    img1 = np.random.rand(*(100,80,30));
 
    myViewer = dv.DataViewer(img1)
 
    myViewer.show()
 
    sys.exit(app.exec_())

def _test() :
    import sys
    from PyQt5.QtWidgets import QApplication
    from PyQt5.QtCore import Qt

    import numpy as np
    import ClearMap.Visualization.Qt.DataViewer as dv
 
    app = QApplication(sys.argv)

    img1 = np.random.rand(*(100,80,30));
 
    myViewer = dv.DataViewer(img1)

    myViewer.show()

    sys.exit(app.exec_())

To copy to clipboard, switch view to plain text mode 

The reason the widget works inside a normal application is because the application almost certainly creates the QApplication instance and calls its exec() method so that the normal Qt event loop is up and running and the widget is responding to events. The original _test() method did none of that. Modifying it so it behaves like a mini-standalone app fixes that.

[SaibotMagd]

OK, the problem with the test code is that it does not create a QApplication instance, does not call dv.show() (although the __init__ method for DataViewer -does- call it, which it shouldn't). Your test code should look more like this:

The reason the widget works inside a normal application is because the application almost certainly creates the QApplication instance and calls its exec() method so that the normal Qt event loop is up and running and the widget is responding to events. The original _test() method did none of that. Modifying it so it behaves like a mini-standalone app fixes that.

I barely know what to say, Im in tears. Thats phantastic thank you very very much. It works great and I believe I can implement the solution into the package, and I will do it.

Great work!