Windows image loader error handling (#260)

* Repros for various image issues

* Log image loading errors

* Better repro instructions and user interface

* Image loading tests now running on WinRT/UWP phone/tablet/desktop

* Move FailImageSource into shared project

* Move FailImageSource into shared project

* Update docs

1 files changed, 51 insertions, 0 deletions

diff --git a/Xamarin.Forms.Platform.WinRT/UriImageSourceHandler.cs b/Xamarin.Forms.Platform.WinRT/UriImageSourceHandler.cs
new file mode 100644
index 00000000..1263c355
--- /dev/null
+++ b/Xamarin.Forms.Platform.WinRT/UriImageSourceHandler.cs
@@ -0,0 +1,51 @@
+using System;
+using System.Diagnostics;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using Windows.Storage.Streams;
+using Windows.UI.Xaml.Media.Imaging;
+
+#if WINDOWS_UWP
+
+namespace Xamarin.Forms.Platform.UWP
+#else
+
+namespace Xamarin.Forms.Platform.WinRT
+#endif
+{
+	public sealed class UriImageSourceHandler : IImageSourceHandler
+	{
+		public async Task<Windows.UI.Xaml.Media.ImageSource> LoadImageAsync(ImageSource imagesource, CancellationToken cancellationToken = new CancellationToken())
+		{
+			var imageLoader = imagesource as UriImageSource;
+			if (imageLoader?.Uri == null)
+				return null;
+
+			Stream streamImage = await imageLoader.GetStreamAsync(cancellationToken);
+			if (streamImage == null || !streamImage.CanRead)
+			{
+				return null;
+			}
+
+			using (IRandomAccessStream stream = streamImage.AsRandomAccessStream())
+			{
+				try
+				{
+					var image = new BitmapImage();
+					await image.SetSourceAsync(stream);
+					return image;
+				}
+				catch (Exception ex) 
+				{
+					Log.Warning("Image Loading", $"{nameof(UriImageSourceHandler)} could not load {imageLoader.Uri}: {ex}");
+
+					// According to https://msdn.microsoft.com/library/windows/apps/jj191522
+					// this can happen if the image data is bad or the app is close to its 
+					// memory limit
+					return null;
+				}
+			}
+		}
+	}
+}
\ No newline at end of file