[release/7.0.2xx] [net7.0] Blank image when Source set to null or on …

…image loading error (#14071)

* Blank image when Source set to null or on image loading error Fixes #8787

* Auto-format source code

* Null check cleanup

* Fix test

---------

Co-authored-by: E.Z. Hart <hartez@gmail.com>
Co-authored-by: GitHub Actions Autoformatter <autoformat@example.com>

src/Core/src/Platform/Android/ImageSourcePartExtensions.cs

@@ -70,6 +70,7 @@ internal static class ImageSourcePartExtensions
 			}
 			catch (Exception ex)
 			{
+				setImage?.Invoke(null);
 				events?.LoadingFailed(ex);
 			}
 			finally

src/Core/src/Platform/ImageSourcePartLoader.cs

@@ -42,6 +42,7 @@ public ImageSourcePartLoader(
 		{
 			Handler = handler;
 			_imageSourcePart = imageSourcePart;
+
 			SetImage = setImage;
 		}
 
@@ -52,27 +53,28 @@ public void Reset()
 
 		public async Task UpdateImageSourceAsync()
 		{
-			if (PlatformView != null)
+			if (PlatformView is null)
 			{
-				var token = this.SourceManager.BeginLoad();
-				var imageSource = _imageSourcePart();
+				return;
+			}
+
+			var token = this.SourceManager.BeginLoad();
+			var imageSource = _imageSourcePart();
 
-				if (imageSource != null)
-				{
+			if (imageSource?.Source is not null)
+			{
 #if __IOS__ || __ANDROID__ || WINDOWS || TIZEN
-					var result = await imageSource.UpdateSourceAsync(PlatformView, ImageSourceServiceProvider, SetImage!, token)
-						.ConfigureAwait(false);
+				var result = await imageSource.UpdateSourceAsync(PlatformView, ImageSourceServiceProvider, SetImage!, token)
+					.ConfigureAwait(false);
 
-					SourceManager.CompleteLoad(result);
+				SourceManager.CompleteLoad(result);
 #else
-					await Task.CompletedTask;
+				await Task.CompletedTask;
 #endif
-				}
-				else
-				{
-					SetImage?.Invoke(null);
-					SourceManager.CompleteLoad(null);
-				}
+			}
+			else
+			{
+				SetImage?.Invoke(null);
 			}
 		}
 	}

src/Core/src/Platform/Windows/ImageSourcePartExtensions.cs

@@ -56,6 +56,7 @@ internal static class ImageSourcePartExtensions
 			}
 			catch (Exception ex)
 			{
+				setImage?.Invoke(null);
 				events?.LoadingFailed(ex);
 			}
 			finally

src/Core/src/Platform/iOS/ImageSourcePartExtensions.cs

@@ -54,6 +54,7 @@ internal static class ImageSourcePartExtensions
 			}
 			catch (Exception ex)
 			{
+				setImage?.Invoke(null);
 				events?.LoadingFailed(ex);
 			}
 			finally

src/Core/tests/DeviceTests/Handlers/Image/ImageHandlerTests.cs

@@ -5,6 +5,7 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Maui.DeviceTests.Stubs;
 using Xunit;
+using System.ComponentModel;
 
 #if ANDROID
 using Android.Graphics.Drawables;
@@ -333,7 +334,10 @@ await InvokeOnMainThreadAsync(async () =>
 
 				await image.Wait();
 
-				Assert.Empty(handler.ImageEvents);
+				// We expect that if the Image is created with no Source set, the platform image view
+				// will get a `null` image set
+				Assert.NotEmpty(handler.ImageEvents);
+				Assert.Null(handler.ImageEvents[0].Value);
 
 				await handler.PlatformView.AssertContainsColor(expectedColor);
 			});
@@ -460,5 +464,57 @@ protected TCustomHandler CreateHandler<TCustomHandler>(IView view)
 		static int GetDrawableId(string image) =>
 			MauiProgram.DefaultContext.Resources.GetDrawableId(MauiProgram.DefaultContext.PackageName, image);
 #endif
+
+		[Fact]
+		public async Task UpdatingSourceToNullClearsImage()
+		{
+			var image = new TStub
+			{
+				Background = new SolidPaintStub(Colors.Black),
+				Source = new FileImageSourceStub("red.png"),
+			};
+
+			await InvokeOnMainThreadAsync(async () =>
+			{
+				var handler = CreateHandler<CountedImageHandler>(image);
+
+				await image.Wait();
+
+				await handler.PlatformView.AssertContainsColor(Colors.Red);
+
+				handler.ImageEvents.Clear();
+
+				image.Source = null;
+				handler.UpdateValue(nameof(IImage.Source));
+
+				await image.Wait();
+
+				await handler.PlatformView.AssertDoesNotContainColor(Colors.Red);
+			});
+		}
+
+		[Fact]
+		public async Task UpdatingSourceToNonexistentSourceClearsImage()
+		{
+			var image = new TStub
+			{
+				Background = new SolidPaintStub(Colors.Black),
+				Source = new FileImageSourceStub("red.png"),
+			};
+
+			await InvokeOnMainThreadAsync(async () =>
+			{
+				var handler = CreateHandler<ImageHandler>(image);
+				await image.Wait();
+				await handler.PlatformView.AssertContainsColor(Colors.Red);
+
+				image.Source = new FileImageSourceStub("fail.png");
+				handler.UpdateValue(nameof(IImage.Source));
+				await handler.PlatformView.AttachAndRun(() => { });
+
+				await image.Wait(5000);
+				await handler.PlatformView.AssertDoesNotContainColor(Colors.Red);
+			});
+		}
 	}
 }

src/TestUtils/src/DeviceTests/AssertionExtensions.Android.cs

@@ -11,6 +11,7 @@
 using Microsoft.Maui.Graphics;
 using Microsoft.Maui.Platform;
 using Xunit;
+using Xunit.Sdk;
 using AColor = Android.Graphics.Color;
 using AView = Android.Views.View;
 
@@ -296,7 +297,13 @@ public static Bitmap AssertColorAtTopRight(this Bitmap bitmap, AColor expectedCo
 			return bitmap.AssertColorAtPoint(expectedColor, bitmap.Width - 1, bitmap.Height - 1);
 		}
 
-		public static Bitmap AssertContainsColor(this Bitmap bitmap, AColor expectedColor)
+		public static Task<Bitmap> AssertContainsColor(this Bitmap bitmap, Graphics.Color expectedColor, Func<Maui.Graphics.RectF, Maui.Graphics.RectF>? withinRectModifier = null)
+			=> Task.FromResult(bitmap.AssertContainsColor(expectedColor.ToPlatform()));
+
+		public static Task<Bitmap> AssertDoesNotContainColor(this Bitmap bitmap, Graphics.Color unexpectedColor, Func<Maui.Graphics.RectF, Maui.Graphics.RectF>? withinRectModifier = null)
+			=> Task.FromResult(bitmap.AssertDoesNotContainColor(unexpectedColor.ToPlatform()));
+
+		public static Bitmap AssertContainsColor(this Bitmap bitmap, AColor expectedColor, Func<Maui.Graphics.RectF, Maui.Graphics.RectF>? withinRectModifier = null)
 		{
 			for (int x = 0; x < bitmap.Width; x++)
 			{
@@ -309,19 +316,48 @@ public static Bitmap AssertContainsColor(this Bitmap bitmap, AColor expectedColo
 				}
 			}
 
-			Assert.True(false, CreateColorError(bitmap, $"Color {expectedColor} not found."));
+			throw new XunitException($"Color {expectedColor} not found.");
+		}
+
+		public static Bitmap AssertDoesNotContainColor(this Bitmap bitmap, AColor unexpectedColor, Func<Maui.Graphics.RectF, Maui.Graphics.RectF>? withinRectModifier = null)
+		{
+			var imageRect = new Graphics.RectF(0, 0, bitmap.Width, bitmap.Height);
+
+			if (withinRectModifier is not null)
+				imageRect = withinRectModifier.Invoke(imageRect);
+
+			for (int x = (int)imageRect.X; x < (int)imageRect.Width; x++)
+			{
+				for (int y = (int)imageRect.Y; y < (int)imageRect.Height; y++)
+				{
+					if (bitmap.ColorAtPoint(x, y, true).IsEquivalent(unexpectedColor))
+					{
+						throw new XunitException($"Color {unexpectedColor} was found at point {x}, {y}.");
+					}
+				}
+			}
+
 			return bitmap;
 		}
 
 		public static Task<Bitmap> AssertContainsColor(this AView view, Graphics.Color expectedColor) =>
 			AssertContainsColor(view, expectedColor.ToPlatform());
 
+		public static Task<Bitmap> AssertDoesNotContainColor(this AView view, Graphics.Color unexpectedColor) =>
+			AssertDoesNotContainColor(view, unexpectedColor.ToPlatform());
+
 		public static async Task<Bitmap> AssertContainsColor(this AView view, AColor expectedColor)
 		{
 			var bitmap = await view.ToBitmap();
 			return AssertContainsColor(bitmap, expectedColor);
 		}
 
+		public static async Task<Bitmap> AssertDoesNotContainColor(this AView view, AColor unexpectedColor)
+		{
+			var bitmap = await view.ToBitmap();
+			return AssertDoesNotContainColor(bitmap, unexpectedColor);
+		}
+
 		public static async Task<Bitmap> AssertColorAtPointAsync(this AView view, AColor expectedColor, int x, int y)
 		{
 			var bitmap = await view.ToBitmap();

src/TestUtils/src/DeviceTests/AssertionExtensions.iOS.cs

@@ -300,10 +300,22 @@ public static async Task<UIImage> AssertContainsColor(this UIView view, UIColor
 			return bitmap.AssertContainsColor(expectedColor);
 		}
 
+		public static async Task<UIImage> AssertDoesNotContainColor(this UIView view, UIColor unexpectedColor)
+		{
+			var bitmap = await view.ToBitmap();
+			return bitmap.AssertDoesNotContainColor(unexpectedColor);
+		}
+
 		public static Task<UIImage> AssertContainsColor(this UIView view, Microsoft.Maui.Graphics.Color expectedColor) =>
 			AssertContainsColor(view, expectedColor.ToPlatform());
 
-		public static UIImage AssertContainsColor(this UIImage bitmap, UIColor expectedColor)
+		public static Task<UIImage> AssertDoesNotContainColor(this UIView view, Microsoft.Maui.Graphics.Color unexpectedColor) =>
+			AssertDoesNotContainColor(view, unexpectedColor.ToPlatform());
+
+		public static Task<UIImage> AssertContainsColor(this UIImage image, Graphics.Color expectedColor, Func<Graphics.RectF, Graphics.RectF>? withinRectModifier = null)
+			=> Task.FromResult(image.AssertContainsColor(expectedColor.ToPlatform(), withinRectModifier));
+
+		public static UIImage AssertContainsColor(this UIImage bitmap, UIColor expectedColor, Func<Graphics.RectF, Graphics.RectF>? withinRectModifier = null)
 		{
 			for (int x = 0; x < bitmap.Size.Width; x++)
 			{
@@ -316,10 +328,31 @@ public static UIImage AssertContainsColor(this UIImage bitmap, UIColor expectedC
 				}
 			}
 
-			Assert.True(false, CreateColorError(bitmap, $"Color {expectedColor} not found."));
+			throw new XunitException($"Color {expectedColor} not found.");
+		}
+
+		public static UIImage AssertDoesNotContainColor(this UIImage bitmap, UIColor unexpectedColor, Func<Graphics.RectF, Graphics.RectF>? withinRectModifier = null)
+		{
+			var imageRect = new Graphics.RectF(0, 0, (float)bitmap.Size.Width.Value, (float)bitmap.Size.Height.Value);
+
+			if (withinRectModifier is not null)
+				imageRect = withinRectModifier.Invoke(imageRect);
+
+			for (int x = (int)imageRect.X; x < (int)imageRect.Width; x++)
+			{
+				for (int y = (int)imageRect.Y; y < (int)imageRect.Height; y++)
+				{
+					if (ColorComparison.ARGBEquivalent(bitmap.ColorAtPoint(x, y), unexpectedColor))
+					{
+						throw new XunitException($"Color {unexpectedColor} was found at point {x}, {y}.");
+					}
+				}
+			}
+
 			return bitmap;
 		}
 
+
 		public static Task AssertEqualAsync(this UIImage bitmap, UIImage other)
 		{
 			Assert.NotNull(bitmap);