Migrate from obselete QGLWidget to QOpenGLWidget

[martyngigg]

Description of work.

QGLWidget has not been formally deprecated but there are several issues with it and the docs
mark it has obselete.

On macOS it also seems impossible to correct deal with moving an OpenGL window between
monitors with different pixel densities, while the new widget seems to deal with it seamlessly.
We have removed almost all glViewport calls as the base widget now handles this for us.

It has been necessary to set the default OpenGL profile to compatability mode as the current
code uses older OpenGL api calls. Future work will need to tackle this issue as it is outside of
the scope. A note has been added to the maintenance board.

Provides an alternate and better solution to #35058.

To test:

This needs to be tested on a mac with retina screen and an additional lower-resolution screen connected.
Use the following script to determine this information:

from qtpy.QtWidgets import QApplication
for screen in QApplication.screens():
    print(screen.name())
    print(screen.devicePixelRatio())

It should print 2.0 for a retina display and 1.0 for a standard external screen.
If all values are the same then the test of moving the window between screens will not be valid.

All tests will need a workspace with an instrument. Use the following script to create a test data set from
the training course data:

# import mantid algorithms, numpy and matplotlib
from mantid.simpleapi import *
import matplotlib.pyplot as plt
import numpy as np

SXD23767 = Load(Filename='SXD23767.raw', LoadMonitors='Exclude')
peaksws = Load('peaks_qLab.nxs')
FindUBUsingFFT(PeaksWorkspace='peaksws', MinD=0.8, MaxD=10)
IndexPeaks(peaksws, Tolerance=0.05)

1. Open on Retina Screen

• Move workbench to the retina screen
• Click show instrument and check the instrument image is full size in the viewport
• Change to one of the unwrapped views, i.e CylinderY and the image should still be fullsize in the viewport

2. Open on the Standard Def Screen

• Close any instrument view windows
• Move workbench to the standard definition screen
• Click show instrument and check the instrument image is full size in the viewport
• Change to one of the unwrapped views, i.e CylinderY and the image should still be fullsize in the viewport

3. Move Window Between Screens

• Close any instrument view windows
• Click show instrument and check the instrument image is full size in the viewport
• Drag the window to the retina screen and check that one the drag is complete the image is still full size in the viewport
• Drag the window back and check again.
• Do the above for the unwrapped view too.

Zooming

• When on the Render tab use the mouse to select a rectangle and ensure the zoom takes you to the expected place.

Overlay peaks workspace

• Close an instrument view windows
• Load the SXD data set from the training course data
• Also load the peaks_qLab.nxs from the training course data
• Show the instrument on the data workspace
• Drag and drop the peaks workspace onto the instrument
• In the "Display Settings" alternate between "Use OpenGL" checked and unchecked
• The peaks should be in the same positions.

Pick Tab

• Move to the Pick tab
• Move the mouse over the display and check the miniplot updates with the spectrum values
• Move the mouse over peaks that are labeled and check the miniplot displays the HKL values on the miniplot
• Select the peak picking tool
  • click on a peak on the instrument
  • click at the top of the peak that appears frozen in the miniplot and a new table workspace should have the expected peak values (check the values match those with OpenGL disabled)

Fixes #34081

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Reviewer

Please comment on the following (full description):

Code Review

• Is the code of an acceptable quality?
• Does the code conform to the coding standards?
• Are the unit tests small and test the class in isolation?
• If there is GUI work does it follow the GUI standards?
• If there are changes in the release notes then do they describe the changes appropriately?
• Are the release notes saved in a separate file, using Issue or PR number for file name and in the correct location?

Functional Tests

• Do changes function as described? Add comments below that describe the tests performed?
• Do the changes handle unexpected situations, e.g. bad input?
• Has the relevant (user and developer) documentation been added/updated?

Does everything look good? Mark the review as Approve. A member of @mantidproject/gatekeepers will take care of it.

[DanielMurphy22]

The main instrument view shrink when using a retina + external low resolution screen on MacOS is fixed!
The following remaining problems exist on just the retina, even without the second screen:

• On an unwrapped view like Cylindrical Y , the Zoombox does not always appear. It also doesn't zoom in on the area you selected. On the normal low res screen zooming works fine. Zooming also works fine when you disable opengl rendering.
• Scrolling to zoom on Full 3D doesn't zoom on the cursor.
• Overlaid peaks appear in a different place whether opengl is turned on or not. Again on the normal low res screen this works fine.

Also, as we are now in the OpenGL compatibility mode, we get this message on launching workbench:

An OpenGL surfcace format was requested that is either not version 3.2 or higher or a not Core Profile.
Chromium on macOS will fall back to software rendering in this case.
Hardware acceleration and features such as WebGL will not be available.

[martyngigg]

The main instrument view shrink when using a retina + external low resolution screen on MacOS is fixed! The following remaining problems exist on just the retina, even without the second screen:

* On an unwrapped view like `Cylindrical Y` , the Zoombox does not always appear. It also doesn't zoom in on the area you selected. On the normal low res screen zooming works fine. Zooming also works fine when you disable opengl rendering.

* Scrolling to zoom on Full 3D doesn't zoom on the cursor.

* Overlaid peaks appear in a different place whether opengl is turned on or not. Again on the normal low res screen this works fine.

I think I have fixed all of the☝🏻points.

Also, as we are now in the OpenGL compatibility mode, we get this message on launching workbench:

An OpenGL surfcace format was requested that is either not version 3.2 or higher or a not Core Profile.
Chromium on macOS will fall back to software rendering in this case.
Hardware acceleration and features such as WebGL will not be available.

I can't decide whether we should hide this or not. It's macOS only and users will not see it as they will not a get a terminal when launching it via the GUI. I like the idea of it being in the face of developers that there is a deprecation issue so perhaps we just need to put a note in the developer docs that this is a known warning - what do you think?

[DanielMurphy22]

Yes I think I agree that keeping the deprecation warning is good. Whether it's in the dev-docs or a code comment, please include the full error. If I was going looking for it, I'd probably do a git grep and that should help find your note!

[DanielMurphy22]

Can you add the full warning message to the issue you raised to move away from this compatibility mode?

[DanielMurphy22]

Works a treat! Great to have the up to date QOpenGL widget!