PlatformImageExtension

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace Foobar.Helpers
{
    public class PlatformImageExtension : IMarkupExtension<string>
    {
        /// <summary>
        /// Image source to use
        /// </summary>
        public string SourceImage { get; set; }

        /// <summary>
        /// Return value to the XAML serializer, correct iamge path in this case
        /// </summary>
        /// <param name="serviceProvider"></param>
        /// <returns></returns>
        /// <exception cref="ArgumentOutOfRangeException"></exception>
        public string ProvideValue(IServiceProvider serviceProvider)
        {
            if (SourceImage == null)
            {
                return null;
            }


            string imagePath;
            switch (Device.RuntimePlatform)
            {
                case Device.Android:
                    imagePath = SourceImage;
                    break;
                case Device.iOS:
                    imagePath = SourceImage + ".png";
                    break;
                case Device.UWP:
                    imagePath = "Images/" + SourceImage + ".png";
                    break;
                default:
                    throw new ArgumentOutOfRangeException();
            }
            return imagePath;
        }

        object IMarkupExtension.ProvideValue(IServiceProvider serviceProvider)
        {
            return ProvideValue(serviceProvider);
        }
    }
}