Use Metal as a backend on Mac Catalyst

[mattleibow]

Description of Change

There is no OpenGL or OpenGL ES on Mac Catalyst - there technically is but it is not meant to be used - so we swap out the backend of the .NET MAUI SKGLView to rather be a SKMetalView on Mac Catalyst.

There needs to be a new GPU view that uses Metal on Apple and maybe Vulkan on Android. But that is for another PR. We need an interface so people can even swap out their preferred backend. #2104

[taublast]

We can let people choose the rendering backend at initialization with .UseSkiaSharp(optional settings) with enum of kind Vulkan, GL, ..., Auto.. so the correct handler will set to be used globally for the SKGLView.
A case when one would want to select backend at run-time I can think of is when one specific backend reveals itself not working on device so dev would want to programmatically select another one?..

[mattleibow]

@taublast I copied your comment to the issue where I am thinking to track that: #2104 (comment)

[gcadmes-extron]

I see this was merged in Feb 2024. Is the SKMetalView supposed to be operational for macOS?
The SKMetalView class doesn't appear to implement the IView. Attempting to add to a VerticalStackLayout or setting the Content of a page, this is the error displayed:
Will this be available soon? Also, still seeing this issue (#2050) regarding SKGLView, so that class is not an option either for macOS.

.NET SDK (x64)
SDK: /usr/local/share/dotnet/sdk/8.0.204/Sdks
SDK Versions:
	8.0.204
	8.0.101
	7.0.400
	7.0.307
	6.0.422
	6.0.421
	6.0.420
	6.0.418
	6.0.417
	6.0.416
	6.0.415
	6.0.414
	6.0.413
MSBuild SDKs: /Applications/Visual Studio.app/Contents/MonoBundle/MSBuild/Current/bin/Sdks

.NET Runtime (x64)
Runtime: /usr/local/share/dotnet/dotnet
Runtime Versions:
	8.0.4
	8.0.1
	7.0.10
	6.0.30
	6.0.29
	6.0.28
	6.0.26
	6.0.25
	6.0.24
	6.0.23
	6.0.22
	6.0.21

Xamarin.Mac
Version: 9.3.0.23 Visual Studio Professional
Hash: 9defd91b3
Branch: xcode14.3
Build date: 2023-10-23 16:14:59-0400

Xamarin.iOS
Version: 16.4.0.23 Visual Studio Professional
Hash: 9defd91b3
Branch: xcode14.3
Build date: 2023-10-23 16:15:00-0400

Operating System
Mac OS X 14.5.0
Darwin 23.5.0 Darwin Kernel Version 23.5.0
    Wed May  1 20:09:52 PDT 2024
    root:xnu-10063.121.3~5/RELEASE_X86_64 x86_64

[taublast]

The issue #2050 is closed, you can use SKGLView on iOS to profit from Metal.
Cannot confirm it for MacCatalyst though.

[gcadmes-extron]

@taublast Thank you for confirming that iOS is operational.
As of right now, SKGLView and SKMetalView are still not supported on macOS.
I sure hope this task (2104) eventually comes to fruition for mac users. It's a bit dated. Other than this task, I'm unable to find any roadmaps that mention adding GPU support.