Try this:
public class CustomPickerRenderer : PickerRenderer
{
public CustomPickerRenderer(Context context) : base(context)
{
}
private AlertDialog alert;
private CustomPicker element;
private int selectedIndex;
public LayerDrawable AddPickerStyles(string imagePath)
{
ColorDrawable borderColorDrawable = new ColorDrawable(Xamarin.Forms.Color.FromHex("#43addf").ToAndroid());
ColorDrawable backgroundColorDrawable = new ColorDrawable(Xamarin.Forms.Color.FromHex("#7e1b80").ToAndroid());
Drawable[] drawables = new Drawable[]
{
borderColorDrawable, backgroundColorDrawable
};
LayerDrawable layerDrawable = new LayerDrawable(drawables);
layerDrawable.SetLayerInset(1, 0, 0, 0, 5);
return layerDrawable;
}
protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
{
base.OnElementChanged(e);
element = (CustomPicker)this.Element;
if (Control != null && this.Element != null)
{
Control.Background = AddPickerStyles(element.Image);
}
}
}