Fix continuous RunMode in glium backend

[parasyte]

The primary change here is that the winit control flow is set according to RunMode, and not assumed to be Wait. I also had to change the event handler to RedrawEventsCleared.

Prior to this patch, the Continuous run mode didn't work correctly in the glium backend. But it does work as expected in the web backend.

[emilk]

Thanks for the PR!

Prior to this patch, the Continuous run mode didn't work correctly in the glium backend

Can you elaborate what was incorrect? For me master works as it should, i.e. repainting at 60 FPS on my 60 Hz display..

I ask, because trying this PR the Reactive mode is now definitely broken on my Mac: it repaints the GUI even when the window is in the background (the point of the Reactive mode is to avoid unnecessary repaints).

[parasyte]

On Windows 10, both modes act completely identically. No updates occur unless an event is delivered (especially moving the mouse cursor). I believe this is caused by a bug in winit. See rust-windowing/winit#987 and rust-windowing/winit#1619

Continuous mode does work correctly on macOS. And this PR also breaks Reactive mode on macOS. So I'll have to go back to the drawing board on this.

[parasyte]

@emilk I force-pushed a new patch for this. Tested on Windows and macOS. I haven't tested on Linux (X11 or Wayland).

Neither event handler RedrawRequested or RedrawEventsCleared worked on both platforms, so I decided to use the latter for Windows and the former (original event) for all other platforms. I wasn't able to come up with a good pattern for platform-specific event handling, so I moved all of the code into a closure. It hurts diff readability, but I don't know of another way to solve that. (The "Hide whitespace changes" feature in github helps a bit.)

I also had to add another request_redraw() call for Continuous mode to work on macOS.

[parasyte]

And rebased on master.

[emilk]

Great, nice work!

[bel8z]

A bit late here, but this fix doesn't work as expected for me.

RedrawEventsCleared is raised at the vsync frequency, causing the Reactive mode to behave as Continuous. Removing the platform-dependent handling and responding to RedrawRequested only does the work on my machine. Is this fix still needed?

Using master on Windows 10 btw.

[parasyte]

There are two winit issues linked in a comment above. Until those are addressed, I think egui_glium needs to handle this edge case specifically.

I also see that Reactive mode is behaving the same as Continuous mode on Windows 10. This is opposite of what the PR fixed. It's possible that the change to event_loop.run_return() is the cause. But that's a guess just from looking at the code. This should be reported and tracked in a new ticket, IMHO.