Change RawHandleWrapper so that we can create it

[Jakkestt]

Objective

The winit windowing backend does not require a mutable reference to the window to be able to change it. For example you can set the window fullscreen or change the title without needing a mutable reference. The same cannot be said for other windowing backends like glfw. This becomes a problem when, to create a WindowWrapper, you need to give it ownership of the window. And you need a WindowWrapper to create a RawHandleWrapper which you need to render things to the window. There doesn't seem to be any reason to give ownership of the window to the WindowWrapper, but in doing so, there is no easy way of getting a mutable reference to the window anymore.

Solution

The solution that I came to was to remove _window field from the RawHandleWrapper so that I could construct a RawHandleWrapper without needing to give ownership of the window itself. I don't know what the _window field did, but removing it didn't seem to do anything.

Testing

I ran a window_resizing example and 2d_shapes example and they both ran well enough. I didn't really change much and I think that any errors should have been caught when building the engine.

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[alice-i-cecile]

I'm pretty sure the _window marker is to mark the resource as !Send, but that's a very weird way to do it. What does the commit history say?

[hymm]

It's needed to drop the window at the correct time. See this comment on window wrapper. https://docs.rs/bevy/latest/bevy/window/struct.WindowWrapper.html

[Friz64]

Hello, I came up with this wrapper.

This becomes a problem when, to create a WindowWrapper, you need to give it ownership of the window. And you need a WindowWrapper to create a RawHandleWrapper which you need to render things to the window.

This is very much by design. If you want a mutable reference to the inner window, you're gonna need to use a Mutex (or similar). I know it's ugly. Sorry.

[Jakkestt]

Hello, I came up with this wrapper.

This becomes a problem when, to create a WindowWrapper, you need to give it ownership of the window. And you need a WindowWrapper to create a RawHandleWrapper which you need to render things to the window.

This is very much by design. If you want a mutable reference to the inner window, you're gonna need to use a Mutex (or similar). I know it's ugly. Sorry.

And how exactly would I do that?

[alice-i-cecile]

Closing this out, but do continue discussing workarounds and alternatives: this is something that would be nice to ensure is possible.

[Friz64]

@Jakkestt Hmm, you're right, it's not as straightforward as I thought. The thing is that winit makes all this very easy for us. On top of their Window type only having "immutable" methods, it also implements Send + Sync, unlike GLFW's window. It's definitely possible to cook something up that'll work, but you'll need some carefully considered unsafe blocks. If you want to, you can contact me on Discord (friz64) or Matrix (@Friz64:gitter.im) for help brainstorming a good solution for your case.