macOS/iOS: Use raw-window-metal to get a CAMetalLayer from raw-window-handle

[madsmtm]

1. Update documentation to reflect any user-facing changes - in this repository.
2. Make sure that the changes are covered by unit-tests.
   • I've done this in the raw-window-metal crate itself. Surface construction should be covered by existing examples.
3. Run cargo clippy on the changes.
4. Run cargo +nightly fmt on the changes.
5. Please put changelog entries in the description of this Pull Request
6. Describe in common words what is the purpose of this change, related GitHub Issues, and highlight important implementation aspects.

The logic for creating the CAMetalLayer if it doesn't exist is complex, and currently Vulkano does it wrong and prevents Winit from scheduling redraw events at the correct time. I have abstracted this away into raw-window-metal, see the major PR here, it works is by creating a layer, and inserting that as a sublayer, just like we did on iOS before. The bounds are then kept in-sync with an observer, ensuring smooth resizing.

This PR also fixes the compilation errors on iOS, and adds preliminary support for tvOS.

The implementation now solely uses VK_EXT_metal_surface, which was added in 2018, and I've removed support for VK_MVK_ios_surface / VK_MVK_macos_surface, which are deprecated, and only available a year and a half earlier anyhow.

See also corresponding PR to ash and PR to wgpu.

Changelog:

### Breaking changes
Changes to `Surface`:
- `Surface::update_ios_sublayer_on_resize` was removed as it is no longer necessary.
- `Surface::from_window_ref` was changed to use `VK_EXT_metal_surface` internally on macOS and iOS.

### Additions
- Add support for tvOS.

### Bugs fixed
- Make resizing smooth on macOS and iOS, and let it interoperate better with windowing libraries.
- Fix compiling on iOS.

[Rua]

I don't think support for extensions should be removed. Vulkano should work on any Vulkan-supporting device, including old ones with deprecated extensions.

[marc0246]

Also note that vulkano-win is deprecated. If you revert the breaking changes to Surface, you don't need to update vulkano-win. There's no point updating it.

[madsmtm]

Thing is, the support that Vulkano previously used for these two included the somewhat implicit feature that you can pass CAMetalLayer directly. This feature was only added to the spec in 2020, see the diff. So this PR is actually only improving the support that Vulkano has for older versions.

But sure, I'll keep the extension code itself in.

[madsmtm]

I've released raw-window-metal v1.0.0 now, so this is ready to be reviewed.

I guess if we wanted to keep this free from breaking changes, we could keep the update_ios_sublayer_on_resize as a no-op, and deprecate it instead?

[marc0246]

I think removing that function is fine. Apple support was certainly scuffed and this looks like a fine improvement which I'm grateful for. I just don't like the idea of removing support for extensions and updating vulkano-win.

[madsmtm]

About vulkano-win, I felt like if given you still have it in the git repo, then I might as well update it. I don't really care whether you end up releasing the changes or not.

[marc0246]

Yes that's certainly the problem with deprecation. We have to keep releasing versions otherwise it wouldn't be deprecation. I would have preferred vulkano-win would just die already because people keep updating it despite it being deprecated, not part of the workspace, and despite this comment. The idea of deprecation is that it strictly continues to work. Anything more is a waste of time on everyone's part, and even has the potential to instroduce new bugs like every change does.

Anyway, that's enough ranting from me. The PR LGTM but neither I nor Rua have a way to test it. @hakolao would you happen to have time?

[hakolao]

My mac's so slow nowadays so I don't want to do much with it. I ran the triangle fine, anything else to test? @marc0246. Resizing was smooth

[marc0246]

Thanks Okko! The examples all do the windowing the same so surely that's enough. @Rua do you have anything else to add?

[Rua]

No, looks good now. Just a merge conflict.

[marc0246]

Thank you for blessing us with raw-window-metal @madsmtm! It looks like an awesome addition to the ecosystem ❤️