SurfaceCallback API is missing

[Vincent Autieri II]

Android application type

Classic Xamarin.Android (MonoAndroid12.0, etc.), .NET Android (net7.0-android, etc.)

Affected platform version

VS2022

Description

Xamarin.Android does not seem to provide a wrapper for https://developer.android.com/reference/androidx/car/app/SurfaceCallback

This API is used for Android Auto

Steps to Reproduce

Try to use SurfaceCallback in a Xamarin.Android project
-> Doesn't compile
Look at the Xamarin docs, (not mentioned)

Did you find any workaround?

No

Relevant log output

No response

[Dean Ellis]

@moljac @jpobst looks like we are missing something in androidx? Should we move this issue over to that repo?

[Jonathan Pobst]

Xamarin.Android only provides bindings for Android's base framework android.jar. To use AndroidX API you need to add the relevant NuGet binding package.

This API appears to be in this package:
https://www.nuget.org/packages/Xamarin.AndroidX.Car.App.App

[Vincent Autieri II]

I have 1.2.0.1 installed and have my app already working on their heads up display. I now need to add the surface callback. All I see exposed is ISurfaceCallback which does not have anything to override.

[Jonathan Pobst]

Looks like all the methods on the SurfaceCallback interface are default methods, which I don't think are currently exposed in AndroidX.

Yep, let's move this issue to the AndroidX repository.

[Vincent Autieri II]

Just curious as I have no idea how long it takes to get a nuget with this fix. I can use a nightly build (I think I saw these somewhere) since we are not releasing this for over a month. Any way to do a short term work around?

[Jonathan Pobst]

There are some challenges to work through before packages can be updated to support default interface methods, so I would not expect them in the short term.

You should be able to implement the needed methods in C# with the correct signature and mark them with the [Export] attribute to force the correct Java Callable Wrapper to be generated. (Documentation)

This would look something like:

public void MySurfaceCallback : Java.Lang.Object, ISurfaceCallback
{
  [Export]
  public void OnSurfaceAvailable (SurfaceContainer surfaceContainer) { ... }
}

[Vincent Autieri II]

"This would look something like:" I'm getting surface callbacks now! So this seems to be a workaround.