Update to PyQT6

[minseungchoi]

• Updated from PyQT5 to PyQT6
• Use QOpenGLWidget in place of QGLWidget
• Remove dependency on qimage2ndarray
• visual_stim.framework.idle_background is now a RGBA tuple: visual_stim.framework.set_idle_background color argument can be monochrome, RGB, or RGBA.
• Clear viewports for visual_stim more sparingly: Clearing screen used to occur at every visual_stim.framework.paintGL call, and clearing subscreen viewports used to occur at every paintGL call while stim was not loaded or started. Now, clearing the whole screen only occurs at framework.initializeGL, and clearing viewports only occur through the clear_viewports_flag once at each load_stim call and once at each stop_stim call.

To check:

• [ ] Works on subscreen setup (e.g. 24HrFitness)
• [ ] Works on multiscreen setup (e.g. 40HrFitness / Bruker)

[minseungchoi]

Currently there is severe screen tearing on 40HrFitness. It appears that Vsync isn't really working, as the benchmark framerate suggests that it's rendering frames faster than the screen refresh rate. Also, even without Vsync, in the old version, screen didn't tear as badly. I tried using PyQt5's QOpenGlWidget and got the same outcome. So it seems that this has less to do with Qt version and more to do with QOpenGlWidget vs QGLWidget of the past.

Here's potentially a clue as to what's going on: https://doc.qt.io/qt-6/qopenglwidget.html#alternatives

Adding a QOpenGLWidget into a window turns on OpenGL-based compositing for the entire window. In some special cases this may not be ideal, and the old QGLWidget-style behavior with a separate, native child window is desired. Desktop applications that understand the limitations of this approach (for example when it comes to overlaps, transparency, scroll views and MDI areas), can use QOpenGLWindow with QWidget::createWindowContainer(). This is a modern alternative to QGLWidget and is faster than QOpenGLWidget due to the lack of the additional composition step. It is strongly recommended to limit the usage of this approach to cases where there is no other choice. Note that this option is not suitable for most embedded and mobile platforms, and it is known to have issues on certain desktop platforms (e.g. macOS) too. The stable, cross-platform solution is always QOpenGLWidget.

[minseungchoi]

For installing QT6 on Ubuntu versions < 22.04: sudo add-apt-repository ppa:savoury1/qt-6-2 sudo apt-get update sudo apt install qt6-base-dev (When all the issues above are resolved)