Binding SkiaSharp's PaintSurface with Xamarin Forms and Prism - xamarin

Question

I'm trying to get SkiaSharp working with Xamarin Forms and Prism. I have it working with the following page behind code
public partial class RoomLayoutPage : ContentPage
{
SKCanvasView canvasView;
public RoomLayoutPage()
{
InitializeComponent();
canvasView = new SKCanvasView();
canvasView.PaintSurface += OnCanvasViewPaintSurface;
Content = canvasView;
}
private void OnCanvasViewPaintSurface(object sender, SKPaintSurfaceEventArgs e)
{
SKSurface surface = e.Surface;
SKCanvas canvas = surface.Canvas;
canvas.Clear();
SKPaint blackPaint = new SKPaint
{
Color = SKColors.Black,
};
canvas.DrawRect(0, 0, 100, 100, blackPaint);
}
}
but now I want to move this to my Prism ViewModel. If I move it then Content is not valid
How do I reference a xaml element from a ViewModel? I'd prefer not to do it this way because my ViewModel is then coupled to the view.
(Prefered way) If I put an SKCanvasView on my page
I can bind to the event with the EventToCommandBehaviour
<forms:SKCanvasView>
<forms:SKCanvasView.Behaviors>
<behaviors:EventToCommandBehavior Command="{Binding OnCanvasViewPaintSurface}" EventName="PaintSurface"/>
</forms:SKCanvasView.Behaviors>
</forms:SKCanvasView>
But I'm not sure how to bind the SKPaintSurfaceEventArgs for
OnCanvasViewPaintSurface = new DelegateCommand<SKPaintSurfaceEventArgs>(OnCanvasViewPaintAction);
I'm assuming it's one of the EventArgs options from here https://prismlibrary.github.io/docs/xamarin-forms/EventToCommandBehavior.html ?
Thank you

Answer 1

So using a value converter solves it..
public class SkiaEventArgsConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
var sKPaintSurfaceEventArgs = value as SKPaintSurfaceEventArgs;
if (sKPaintSurfaceEventArgs == null)
{
throw new ArgumentException("Expected value to be of type SKPaintSurfaceEventArgs", nameof(value));
}
return sKPaintSurfaceEventArgs;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
Not entirely sure why it couldn't convert it automagically but it works