UI jittering/flickering on fast window resize with `glow`

[cmot17]

Describe the bug
When the window is resized at high speed, the UI starts to flicker/jitter.

To Reproduce
Steps to reproduce the behavior:

1. Run the eframe example.
2. Resize the window fast.

Expected behavior
For the elements of the UI to stay put during resizing

Screenshots
Here's a quick screen recording displaying the issue:

windowresize1080.mov

Desktop (please complete the following information):

• OS: MacOS Montery 12.0.1
• M1 Max SoC - if that's applicable at all

[emilk]

Something similar also happens with egui_web when resizing the browser window.

I would like to get this fix. A good start would probably be to investigate other OpenGL-based GUI/renderers and see if they have the same issue (using winit, glutin and for WebGL canvas).

[emilk]

Interestingly this does not happen with the new egui-wgpu backend (#1564)

[w-ensink]

I have the same issue, also on M1 Max. The same problem arrises when I run some of the examples for imgui-rs.

[yay]

Yeah, it's quite severe. I'm also using this on a mac, but this is not macOS related right?
https://user-images.githubusercontent.com/1799756/171958702-ceb8ef14-7181-4e66-88c0-a36b9b57165d.mp4

[amPerl]

seeing this on latest eframe as well, fresh macos monterey on m1 pro

edit: could it be refresh rate shenanigans?
edit2: nope, switching to fixed 60hz changes nothing

[paulrouget]

bisect points to: b1fd6a4

[emilk]

@paulrouget Thanks for that bisect! So that's when we switched from glium to glow. I wonder what else changed there. How we set up the swap-chain perhaps? Or something about the event loop?

[paulrouget]

Hmm… I found flickering in previous commits as well. But it's less pronounced. It also depends on what's on screen and the speed the mouse move. Going back to 3e1db88 the jitter happens (less pronounced than b1fd6a4 but still happening). Before that, resizing is not jittery anymore, but instead of jitter, we get stretched UI.

Basically, on my Mac M1, no matter how far back I go, resizing doesn't worked properly.

Enabling wgpu backend fixes the issue.

[wareya]

Resizing windows on Windows 10 using eframe 0.19 on my system results in extremely bad hard flickering, like the window pane is getting cleared white between rendering updates. It happens with both rendering backends. 0.18 doesn't have this problem. Is this another manifestation of this bug or should I open a new issue?

(SEIZURE WARNING. 0.19)
https://user-images.githubusercontent.com/585488/191777393-6876e0ce-fbf4-4ff3-a487-e6fd1e541a02.mp4

(0.18)
https://user-images.githubusercontent.com/585488/191777412-5d1d87d7-02f1-4c48-91f0-0abe15a04897.mp4

[yay]

@emilk This is still the case in 0.4:
https://user-images.githubusercontent.com/1799756/194758951-0d0ab6c1-b608-4425-9fc4-87b87c59f899.mp4
This is the same footage played frame by frame:
https://user-images.githubusercontent.com/1799756/194758964-4aedfd50-f0fc-4f4d-a483-422e93c8047a.mp4

It looks like every other frame the layout size is incorrect.