no mouse interactivity with BackgroundPlotter

[dr-matt]

Describe the bug, what's wrong, and what you expected.

Not sure whether this is a bug or intended behavior. I thought that BackgroundPlotter was supposed to allow mouse interaction while other code is running on the main thread. However, running the example below, the window opens and the sphere displays, but the window is unresponsive to mouse events - e.g., trying to rotate or zoom the camera view. System information and package versions are noted below.

Steps to reproduce the bug.

import pyvista as pv
from pyvistaqt import BackgroundPlotter
plotter = BackgroundPlotter()
plotter.add_mesh(pv.Sphere())

import time
while True:
    time.sleep(1)

System Information

Date: Mon Oct 30 08:31:49 2023 EDT

                OS : Linux
            CPU(s) : 12
           Machine : x86_64
      Architecture : 64bit
       Environment : Python
        GPU Vendor : Mesa
      GPU Renderer : llvmpipe (LLVM 15.0.7, 256 bits)
       GPU Version : 4.5 (Core Profile) Mesa 23.0.4-0ubuntu1~22.04.1
  MathText Support : False

  Python 3.10.12 (main, Jun 11 2023, 05:26:28) [GCC 11.4.0]

           pyvista : 0.41.1
               vtk : 9.2.6
             numpy : 1.24.3
        matplotlib : 3.7.1
            scooby : 0.7.2
             pooch : v1.7.0
           imageio : 2.31.1
         pyvistaqt : 0.11.0
             PyQt5 : 5.15.10
           IPython : 8.13.2
             scipy : 1.11.1
--------------------------------------------------------------------------------

Screenshots

No response

[akaszynski]

To enable interaction with the BackgroundPlotter while running other operations, you should integrate it within a Qt application event loop. Here's how you can modify your code:

import sys
import pyvista as pv
from pyvistaqt import BackgroundPlotter
from PyQt5.QtWidgets import QApplication

if __name__ == '__main__':
    app = QApplication(sys.argv)
    gui = BackgroundPlotter()
    gui.add_mesh(pv.Sphere())
    app.exec_()

When app.exec_() is called, it starts the application's event loop, allowing for UI interaction.