Support RedrawRequested event

[parasyte]

Looks like this event is not currently supported: https://docs.rs/winit/0.20.0-alpha4/winit/event/enum.WindowEvent.html#variant.RedrawRequested

The crate supports everything else I need, just this one piece is out of place. See it in context, here:

https://github.com/parasyte/pixels/blob/d33c30dd08d2561cd1643001bea912a77b198c53/examples/invaders/main.rs#L51-L60

[rukai]

e08cac1 I implemented it here.
Does this work for you?
Let me know if you want a crates.io release.

[parasyte]

I’m sure that will function correctly.

Seems like I will have to use an if-else to either draw or update my game state. I also don’t know what kind of timing implications this will have, deferring RedrawRequested until after EventsCleared.

According to rust-windowing/winit#1041 (comment) RedrawRequested should be handled immediately.

[rukai]

Eventscleared is not coming from your OS but from winit itself, just meaning that it has no more events queued up at the moment. So it should be fine to just wait for all queue d events to process before acting on the redrawrequested.

Games will want to redraw every frame anyway so games don't usually bother with redraw requested.

[parasyte]

I was going to get back to this sooner, but while I was testing on Windows, my GPU decided to completely die.

Anyway, The winit issue I linked has some very important details about exactly why they have decided to implement RedrawRequested as a separate event. From what I can tell, the need arises from the way Windows handles resizes. Specifically, Ossipial provided examples like these demonstrating how poor timing will cause ugly artifacts, e.g. while resizing.

I wasn't able to verify any of this when I tested, before my GPU died. All I was able to get out of it was my game "freezing" while the window is resized. And this is with using the recommended strategy. I can't tell if these are just bugs or if it doesn't really matter.

[rukai]

Well, if you want to process the event immediately why do you want winit_input_helper to be involved? It sounds like your current code is fine.

[parasyte]

Just trying to reduce line noise in the source, TBH. You're right, the current code is fine functionally.

[rukai]

Maybe it would be neater if it wasn't on so many lines ;)

if let Event::WindowEvent { event: WindowEvent::RedrawRequested, .. } = event {
    pixels.render(invaders.draw());
}

Unless you have any objections I might revert the changes I did for this issue because, as you have pointed out, its incorrect.

[parasyte]

Yeah, rustfmt is picky. 🤷‍♀

Feel free to revert the change. I was hoping this was something simple. But might end up being a headache that isn't worth it. Returning an enum instead of a bool or whatever. Sounds like Pandora's box.

[rukai]

Changes are reverted