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

3 files changed, 114 insertions, 0 deletions

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/FailImageSource.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/FailImageSource.cs
new file mode 100644
index 00000000..a3dfbb3b
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/FailImageSource.cs
@@ -0,0 +1,12 @@
+using System.Threading.Tasks;
+
+namespace Xamarin.Forms.Controls
+{
+	public sealed class FailImageSource : ImageSource
+	{
+		public override Task<bool> Cancel()
+		{
+			return Task.FromResult(false);
+		}
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/ImageLoadingErrorHandling.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/ImageLoadingErrorHandling.cs
new file mode 100644
index 00000000..fe1f6356
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/ImageLoadingErrorHandling.cs
@@ -0,0 +1,100 @@
+using System;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+namespace Xamarin.Forms.Controls
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.None, 0, "Image Loading Error Handling", PlatformAffected.WinRT)]
+	public class ImageLoadingErrorHandling : TestContentPage
+	{
+		protected override void Init()
+		{
+			Log.Listeners.Add(
+				new DelegateLogListener((c, m) => Device.BeginInvokeOnMainThread(() => DisplayAlert(c, m, "Cool, Thanks"))));
+
+			var image = new Image() {BackgroundColor = Color.White};
+
+			Grid legit = CreateTest(() => image.Source = ImageSource.FromFile("coffee.png"),
+				"Valid Image",
+				"Clicking this button should load an image at the top of the page.",
+				Color.Silver);
+
+			Grid invalidImageFileName = CreateTest(() => image.Source = ImageSource.FromFile("fake.png"),
+				"Non-existent Image File",
+				"Clicking this button should display an alert dialog with an error that the image failed to load.");
+
+			Grid invalidImageFile = CreateTest(() => image.Source = ImageSource.FromFile("invalidimage.jpg"),
+				"Invalid Image File (bad data)",
+				"Clicking this button should display an alert dialog with an error that the image failed to load.",
+				Color.Silver);
+
+			Grid fakeUri = CreateTest(() => image.Source = ImageSource.FromUri(new Uri("http://not.real")),
+				"Non-existent URI",
+				Device.OS == TargetPlatform.Windows && Device.Idiom == TargetIdiom.Phone 
+				? "Clicking this button should display an alert dialog. The error message should include the text 'NotFound'."
+				: "Clicking this button should display an alert dialog. The error message should include the text 'the server name or address could not be resolved'.");
+
+			// This used to crash the app with an uncatchable error; need to make sure it's not still doing that
+			Grid crashImage = CreateTest(() => image.Source = new FailImageSource(),
+				"Source Throws Exception",
+				"Clicking this button should display an alert dialog. The error messages hould include the test 'error updating image source'.",
+				Color.Silver);
+
+			Grid uriInvalidImageData =
+				CreateTest(() => image.Source = ImageSource.FromUri(new Uri("https://gist.githubusercontent.com/hartez/a2dda6b5c78852bcf4832af18f21a023/raw/39f4cd2e9fe8514694ac7fa0943017eb9308853d/corrupt.jpg")),
+					"Valid URI with invalid image file",
+					"Clicking this button should display an alert dialog. The error message should include the text 'UriImageSourceHandler could not load https://gist.githubusercontent.com/hartez/a2dda6b5c78852bcf4832af18f21a023/raw/39f4cd2e9fe8514694ac7fa0943017eb9308853d/corrupt.jpg'");
+
+			Content = new StackLayout
+			{
+				Children =
+				{
+					image,
+					legit,
+					invalidImageFileName,
+					invalidImageFile,
+					fakeUri,
+					crashImage,
+					uriInvalidImageData
+				}
+			};
+		}
+
+		static Grid CreateTest(Action imageLoadAction, string title, string instructions, Color? backgroundColor = null)
+		{
+			var button = new Button { Text = "Test" };
+
+			button.Clicked += (sender, args) => imageLoadAction();
+
+			var titleLabel = new Label
+			{
+				Text = title,
+				FontAttributes = FontAttributes.Bold
+			};
+
+			var label = new Label
+			{
+				Text = instructions
+			};
+
+			var grid = new Grid
+			{
+				ColumnDefinitions =
+					new ColumnDefinitionCollection { new ColumnDefinition(), new ColumnDefinition(), new ColumnDefinition() },
+				RowDefinitions = new RowDefinitionCollection { new RowDefinition { Height = 80 } }
+			};
+
+			if (backgroundColor.HasValue)
+			{
+				grid.BackgroundColor = backgroundColor.Value;
+			}
+
+			grid.AddChild(titleLabel, 0, 0);
+			grid.AddChild(label, 1, 0);
+			grid.AddChild(button, 2, 0);
+
+			return grid;
+		}
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index cd836f39..30ad7ee4 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -118,6 +118,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla38416.xaml.cs">
       <DependentUpon>Bugzilla38416.xaml</DependentUpon>
     </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)FailImageSource.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)InputTransparentIssue.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)IsInvokeRequiredRaceCondition.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)IsPasswordToggleTest.cs" />
@@ -159,6 +160,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)TestPages\ScreenshotConditionalApp.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla41842.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla42277.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)ImageLoadingErrorHandling.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)_Template.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1028.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue1075.cs" />