Support reading fonts from files (#14783)

src/FileSystem/FileSystem.uwp.cs

@@ -50,31 +50,6 @@ Task<bool> PlatformAppPackageFileExistsAsync(string filename)
 		}
 	}
 
-	static partial class FileSystemUtils
-	{
-		public static bool AppPackageFileExists(string filename)
-		{
-			var file = PlatformGetFullAppPackageFilePath(filename);
-			return File.Exists(file);
-		}
-
-		public static string PlatformGetFullAppPackageFilePath(string filename)
-		{
-			if (filename == null)
-				throw new ArgumentNullException(nameof(filename));
-
-			filename = NormalizePath(filename);
-
-			string root;
-			if (AppInfoUtils.IsPackagedApp)
-				root = Package.Current.InstalledLocation.Path;
-			else
-				root = AppContext.BaseDirectory;
-
-			return Path.Combine(root, filename);
-		}
-	}
-
 	public partial class FileBase
 	{
 		internal FileBase(IStorageFile file)

src/FileSystem/FileSystemUtils.uwp.cs

@@ -0,0 +1,52 @@
+#nullable enable
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.IO;
+using Microsoft.Maui.ApplicationModel;
+using Package = Windows.ApplicationModel.Package;
+
+namespace Microsoft.Maui.Storage
+{
+	static partial class FileSystemUtils
+	{
+		public static bool AppPackageFileExists(string filename)
+		{
+			var file = PlatformGetFullAppPackageFilePath(filename);
+			return File.Exists(file);
+		}
+
+		public static string PlatformGetFullAppPackageFilePath(string filename)
+		{
+			if (filename is null)
+				throw new ArgumentNullException(nameof(filename));
+
+			filename = NormalizePath(filename);
+
+			string root;
+			if (AppInfoUtils.IsPackagedApp)
+				root = Package.Current.InstalledLocation.Path;
+			else
+				root = AppContext.BaseDirectory;
+
+			return Path.Combine(root, filename);
+		}
+
+		public static bool TryGetAppPackageFileUri(string filename, [NotNullWhen(true)] out string? uri)
+		{
+			var path = PlatformGetFullAppPackageFilePath(filename);
+
+			if (File.Exists(path))
+			{
+				if (AppInfoUtils.IsPackagedApp)
+					uri = $"ms-appx:///{filename.Replace('\\', '/')}";
+				else
+					uri = $"file:///{path.Replace('\\', '/')}";
+
+				return true;
+			}
+
+			uri = null;
+			return false;
+		}
+	}
+}