c# - Why is my custom ButtonRenderer not working?

Question

I'm trying to create a custom ButtonRenderer for Xamarin.Forms. Here is a simple test I've been trying to put up together following some tutorials, but I can's seem to make it work.

Here is my .xaml page:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="TestProject.MainPage">
    <ContentPage.Content>
        <Button VerticalOptions="Center" HorizontalOptions="Center"></Button>
    </ContentPage.Content>
</ContentPage>

And here is my custom rendered: (it is placed in the Android project)

[assembly: ExportRenderer(typeof(Xamarin.Forms.Button), typeof(CustomButtonRenderer))]
namespace TestProject.Droid.CustomRenderers
{
    public class CustomButtonRenderer: ButtonRenderer
    {
        public CustomButtonRenderer(Context context) : base(context)
        {
        }

        protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.Button> e)
        {
            base.OnElementChanged(e);
            Control.SetBackgroundColor(Android.Graphics.Color.Red);
        }
    }
}

But it never gets called and my app crashes. My logcat shows:

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> Java.Lang.ClassNotFoundException: Didn't find class "md5dba8ede99752acada1f5ba384c7cf839.CustomButtonRenderer" on path: DexPathList[[zip file "/data/app/com.companyname.TestProject-1/base.apk"],nativeLibraryDirectories=[/data/app/com.companyname.GN.Mobile.TestProject-1/lib/arm, /data/app/com.companyname.GN.Mobile.TestProject-1/base.apk!/lib/armeabi-v7a, /vendor/lib, /system/lib]]

Am I missing something here?

Answer 1

I'm still investigating on this. Your class gets shrunk because it's not statically linked in your PCL. You avoid that by giving a name to your classes like this:

[Activity(Name = "somepackage.custombuttonrenderer")]
public class CustomButtonRenderer: ButtonRenderer
{ }

If you're able to target the minimum Android version to Android 5.0 (Api 21) this problem should disappear as another version of the Dex file is used.