Provide a means to access app package images

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.Shared/ResourceExtensions.cs

@@ -0,0 +1,107 @@
+using System;
+using System.IO;
+using System.Threading.Tasks;
+using Xamarin.Forms;
+
+#if __ANDROID__
+using Xamarin.Forms.Platform.Android;
+using Application = global::Android.App.Application;
+#elif __IOS__ || __MACOS__
+using Foundation;
+#elif __TIZEN__
+using Xamarin.Forms.Platform.Tizen;
+#elif WINDOWS_UWP
+using Windows.ApplicationModel;
+#endif
+
+namespace SkiaSharp.Views.Forms
+{
+	public static class ResourceExtensions
+	{
+		public static async Task<SKData> LoadImageDataAsync(string resource)
+		{
+			if (string.IsNullOrEmpty(resource))
+				throw new ArgumentNullException(nameof(resource));
+
+			resource = NormalizePath(resource);
+
+			if (File.Exists(resource))
+				return SKData.Create(resource);
+
+#if __ANDROID__
+			try
+			{
+				using (var fd = Application.Context.Assets.OpenFd(resource))
+				using (var stream = fd?.CreateInputStream())
+				{
+					if (stream != null)
+						return SKData.Create(stream, fd.Length);
+				}
+			}
+			catch (Java.IO.FileNotFoundException)
+			{
+				// fall through
+			}
+
+			var id = ResourceManager.GetDrawableByName(resource);
+			if (id != 0)
+			{
+				using (var fd = Application.Context.Resources.OpenRawResourceFd(id))
+				using (var stream = fd?.CreateInputStream())
+				{
+					if (stream != null)
+						return SKData.Create(stream, fd.Length);
+				}
+			}
+#elif __IOS__ || __MACOS__
+			resource = NSBundle.MainBundle.PathForResource(resource, null);
+			if (!string.IsNullOrEmpty(resource))
+				return SKData.Create(resource);
+#elif __TIZEN__
+			resource = ResourcePath.GetPath(resource);
+			if (!string.IsNullOrEmpty(resource))
+				return SKData.Create(resource);
+#elif WINDOWS_UWP
+			using (var stream = await Package.Current.InstalledLocation.OpenStreamForReadAsync(resource))
+			{
+				if (stream != null)
+					return SKData.Create(stream);
+			}
+#elif NETSTANDARD
+#else
+#error Missing platform logic
+#endif
+
+			return null;
+		}
+
+		public static async Task<SKImage> DecodeImageAsync(string resource)
+		{
+			using (var data = await LoadImageDataAsync(resource))
+			{
+				if (data != null)
+					return SKImage.FromEncodedData(data);
+			}
+
+			return null;
+		}
+
+		public static async Task<SKBitmap> DecodeBitmapAsync(string resource)
+		{
+			using (var data = await LoadImageDataAsync(resource))
+			{
+				if (data != null)
+					return SKBitmap.Decode(data);
+			}
+
+			return null;
+		}
+
+		private static string NormalizePath(string path) =>
+#if WINDOWS_UWP
+			path.Replace('/', Path.DirectorySeparatorChar);
+#else
+			path.Replace('\\', Path.DirectorySeparatorChar);
+#endif
+	}
+}