FloatingActionButtonViewRenderer.cs

public class FloatingActionButtonViewRenderer : ViewRenderer<FloatingActionButtonView, FrameLayout>
{
    ...
    private readonly Android.Content.Context context;
    private readonly FloatingActionButton fab;

    public FloatingActionButtonViewRenderer()
    {
        context = Xamarin.Forms.Forms.Context;
	    fab = new FloatingActionButton(context);
	    ...
    }

    protected override void OnElementChanged(ElementChangedEventArgs<FloatingActionButtonView> e)
    {
        base.OnElementChanged(e);

        if (e.OldElement != null || this.Element == null)
            return;

        if (e.OldElement != null)
            e.OldElement.PropertyChanged -= HandlePropertyChanged;

        if (this.Element != null) {
            //UpdateContent ();
            this.Element.PropertyChanged += HandlePropertyChanged;
        }

        Element.Show = Show;
        Element.Hide = Hide;

        SetFabImage(Element.ImageName);

        fab.ColorNormal = Element.ColorNormal.ToAndroid();
        fab.ColorPressed = Element.ColorPressed.ToAndroid();
        fab.ColorRipple = Element.ColorRipple.ToAndroid();

        var frame = new FrameLayout(Forms.Context);
        frame.RemoveAllViews();
        frame.AddView(fab);

        SetNativeControl (frame);
    }

    public void Show(bool animate = true)
    {
        fab.Show(animate);
    }

    public void Hide(bool animate = true)
    {
        fab.Hide(animate);
    }

    void HandlePropertyChanged (object sender, System.ComponentModel.PropertyChangedEventArgs e)
    {
        if (e.PropertyName == "Content") {
            Tracker.UpdateLayout ();
	    } 
        else if (e.PropertyName == FloatingActionButtonView.ColorNormalProperty.PropertyName) 
        {
            fab.ColorNormal = Element.ColorNormal.ToAndroid();
        } 
        else if (e.PropertyName == FloatingActionButtonView.ColorPressedProperty.PropertyName) 
        {
            fab.ColorPressed = Element.ColorPressed.ToAndroid();
        } 
        else if (e.PropertyName == FloatingActionButtonView.ColorRippleProperty.PropertyName) 
        {
            fab.ColorRipple = Element.ColorRipple.ToAndroid();
        }
        ...
    }

    void SetFabImage(string imageName)
    {
        if(!string.IsNullOrWhiteSpace(imageName))
        {
            try
            {
                var drawableNameWithoutExtension = Path.GetFileNameWithoutExtension(imageName);
                var resources = context.Resources;
                var imageResourceName = resources.GetIdentifier(drawableNameWithoutExtension, "drawable", context.PackageName);
                fab.SetImageBitmap(Android.Graphics.BitmapFactory.DecodeResource(context.Resources, imageResourceName));
	        }
	        catch(Exception ex)
            {
                throw new FileNotFoundException("There was no Android Drawable by that name.", ex);
            }
        }
    }
}