[android] eliminate lots of fields in Resource.designer.cs

[jonathanpeppers]

Description of Change

Context: https://github.com/jonathanpeppers/CustomResourceDesigner
Context: dotnet/android#6310

We found a case where a .NET MAUI app that included SkiaSharp and
Telerik controls was setting ~90,000 fields at startup in the
Resource.designer.cs file via the UpdateIdValues() method.

This also would happen in any Xamarin.Android class library:

• Include AndroidX & Google Material
• Include at least one @(AndroidResource) and use the ID from C#
• Resource.designer.cs has 2,700+ fields

So SkiaSharp is not unique to the problem here...

Reviewing the SkiaSharp fields, I found:

source\SkiaSharp.Views.Maui\SkiaSharp.Views.Maui.Controls\obj\Debug\net6.0-android\Resource.designer.cs
5335 fields
source\SkiaSharp.Views.Maui\SkiaSharp.Views.Maui.Core\obj\Debug\net6.0-android\Resource.designer.cs
5313 fields
source\SkiaSharp.Views.Maui\SkiaSharp.Views.Maui.Controls.Compatibility\obj\Debug\net6.0-android\Resource.designer.cs
5335 fields

We can simply set $(AndroidGenerateResourceDesigner) to false in
these projects, as they do not use any of the fields. This will
prevent .NET 6 apps using these libraries from setting 16,005 fields
at startup.

I also did a spot check on SkiaSharp.Views.Android, but it's OK --
it only has 3 fields:

public class Resource
{
    public class Attribute
    {
        public static int ignorePixelScaling;
        //...
    }
    public class Styleable
    {
        public static int[] SKCanvasView;
        public static int SKCanvasView_ignorePixelScaling;
        //...
    }
    //...
}

We are working on a long-term solution for this issue in
Xamarin.Android, but we can do a simple workaround in SkiaSharp for
now.

Bugs Fixed

n/a

API Changes

None

Behavioral Changes

If the three projects require usage of Resource.designer.cs in the future, we could follow the pattern here:

https://github.com/jonathanpeppers/CustomResourceDesigner

PR Checklist

• Has tests (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Updated documentation

[jonathanpeppers]

/cc @mattleibow I guess I don't have permission to ask for a review?

[mattleibow]

Thanks for the PR. Looks good and once CI is green I'll merge.

[jonathanpeppers]

@mattleibow $(AndroidGenerateResourceDesigner) was introduced with .NET 6 RC1. So as long as you're building SkiaSharp with RC1, this will work.

[jonathanpeppers]

Oh looks like you're already all set:

SkiaSharp/scripts/azure-pipelines.yml

Lines 29 to 30 in 68e80fa

	DOTNET_VERSION_PREVIEW: 6.0.100-rc.1.21426.23
	DOTNET_WORKLOAD_SOURCE: 'https://aka.ms/dotnet/maui/rc1/index.json'

[jonathanpeppers]

@mattleibow are my test failures here OK?

ImageScalingMultipleThreadsTest

System.AggregateException : One or more errors occurred. (Object reference not set to an instance of an object.)
---- System.NullReferenceException : Object reference not set to an instance of an object.

[mattleibow]

I think that is just a flakey test. I spin up like 100 threads and sometimes it fails. It used to always fail so I fixed a bug and now it is at 1% failure. So a win?