Add IViewScreenshot for third-party screenshot extensibility

src/Core/src/ScreenshotDispatch.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Maui.Media;
@@ -7,50 +6,36 @@ namespace Microsoft.Maui
 {
 	/// <summary>
 	/// Internal helper that routes <see cref="ViewExtensions.CaptureAsync(IView)"/>
-	/// and <see cref="WindowExtensions.CaptureAsync(IWindow)"/> through a keyed DI
-	/// hook when MAUI is built for a non-built-in platform TFM and therefore has no
-	/// compile-time screenshot implementation.
+	/// and <see cref="WindowExtensions.CaptureAsync(IWindow)"/> through the registered
+	/// screenshot service when MAUI is built for a non-built-in platform TFM and
+	/// therefore has no compile-time screenshot implementation.
 	/// </summary>
 	/// <remarks>
-	/// Third-party platform backends (e.g. macOS AppKit, Linux/GTK) register a
-	/// <see cref="Func{T, TResult}"/> of <see cref="object"/> to
-	/// <see cref="Task{TResult}"/> of nullable <see cref="IScreenshotResult"/>
-	/// (i.e. <c>Func&lt;object, Task&lt;IScreenshotResult?&gt;&gt;</c>) under one of
-	/// the well-known keys defined on this type. The lambda receives the handler's
-	/// <see cref="IElementHandler.PlatformView"/> object and returns a task whose
-	/// result is the screenshot (or <see langword="null"/> if capture is not
-	/// supported for that view). A hook that returns a <see langword="null"/>
-	/// task is treated as unsupported and produces a <see langword="null"/> result.
-	/// This contract intentionally uses only BCL types so it can ship without any
-	/// MAUI public API addition.
+	/// Third-party platform backends (e.g. macOS AppKit, Linux/GTK) register an
+	/// <see cref="IScreenshot"/> implementation that also implements
+	/// <see cref="IViewScreenshot"/> in the app's <see cref="System.IServiceProvider"/>.
+	/// The dispatch resolves that service from the handler's
+	/// <see cref="IElementHandler.MauiContext"/> and forwards the handler's platform
+	/// view (or, for views, its container) to
+	/// <see cref="IViewScreenshot.CaptureViewAsync(object)"/>. When no capable
+	/// service is registered (or capture is unsupported) the result is
+	/// <see langword="null"/>, preserving the extension methods' graceful contract.
 	/// </remarks>
 	static class ScreenshotDispatch
 	{
-		/// <summary>
-		/// DI service key for the <see cref="IView"/> screenshot hook.
-		/// </summary>
-		public const string ViewCaptureKey = "Microsoft.Maui.ViewCapture";
-
-		/// <summary>
-		/// DI service key for the <see cref="IWindow"/> screenshot hook.
-		/// </summary>
-		public const string WindowCaptureKey = "Microsoft.Maui.WindowCapture";
-
-		public static Task<IScreenshotResult?> CaptureAsync(IElementHandler? handler, string serviceKey)
+		public static Task<IScreenshotResult?> CaptureAsync(IElementHandler? handler, object? captureView)
 		{
-			var platformView = handler?.PlatformView;
-			if (platformView is null)
+			if (captureView is null)
 				return Task.FromResult<IScreenshotResult?>(null);
 
-			if (handler!.MauiContext?.Services is not IKeyedServiceProvider keyedProvider)
-				return Task.FromResult<IScreenshotResult?>(null);
-
-			var capture = keyedProvider.GetKeyedService<Func<object, Task<IScreenshotResult?>>>(serviceKey);
-
-			if (capture is null)
+			if (handler?.MauiContext?.Services?.GetService(typeof(IScreenshot)) is not IScreenshot screenshot
+				|| !screenshot.IsCaptureSupported
+				|| screenshot is not IViewScreenshot viewScreenshot)
+			{
 				return Task.FromResult<IScreenshotResult?>(null);
+			}
 
-			return capture(platformView) ?? Task.FromResult<IScreenshotResult?>(null);
+			return viewScreenshot.CaptureViewAsync(captureView) ?? Task.FromResult<IScreenshotResult?>(null);
 		}
 	}
 }

src/Core/src/ViewExtensions.cs

@@ -72,19 +72,19 @@ void BuildFlatList(IView view, List<IView> flatList)
 		/// <remarks>
 		/// On non-built-in platform TFMs (e.g. <c>net10.0-macos</c> AppKit backends,
 		/// <c>net10.0</c> Linux/GTK backends) where MAUI does not ship a screenshot
-		/// implementation, capture is routed through a keyed DI hook. Third-party
-		/// platform backends can opt in by registering a
-		/// <see cref="Func{T, TResult}"/> of <see cref="object"/> to
-		/// <c>Task&lt;IScreenshotResult?&gt;</c> under the service key
-		/// <c>"Microsoft.Maui.ViewCapture"</c>:
+		/// implementation, capture is routed through the registered screenshot service.
+		/// Third-party platform backends opt in by registering an <see cref="IScreenshot"/>
+		/// implementation that also implements <see cref="IViewScreenshot"/> in the app's
+		/// <see cref="System.IServiceProvider"/>:
 		/// <code>
-		/// builder.Services.AddKeyedSingleton&lt;Func&lt;object, Task&lt;IScreenshotResult?&gt;&gt;&gt;(
-		///     "Microsoft.Maui.ViewCapture",
-		///     (_, _) =&gt; platformView =&gt; ((AppKit.NSView)platformView).CaptureAsync());
+		/// builder.Services.AddSingleton&lt;IScreenshot, AppKitScreenshotImplementation&gt;();
 		/// </code>
-		/// If no hook is registered (or the <see cref="IElementHandler.PlatformView"/>
-		/// is <see langword="null"/>), the returned task resolves to
-		/// <see langword="null"/>.
+		/// The dispatch resolves that service from the handler's
+		/// <see cref="IElementHandler.MauiContext"/> and forwards the view's container view
+		/// (or, failing that, its platform view) to
+		/// <see cref="IViewScreenshot.CaptureViewAsync(object)"/>. When no capable service is
+		/// registered (or the <see cref="IElementHandler.PlatformView"/> is
+		/// <see langword="null"/>), the returned task resolves to <see langword="null"/>.
 		/// </remarks>
 		public static Task<IScreenshotResult?> CaptureAsync(this IView view)
 		{
@@ -97,7 +97,13 @@ void BuildFlatList(IView view, List<IView> flatList)
 
 			return CaptureAsync(platformView);
 #else
-			return ScreenshotDispatch.CaptureAsync(view?.Handler, ScreenshotDispatch.ViewCaptureKey);
+			// Prefer the container view (clip/shadow/border) like the #if PLATFORM path's
+			// view.ToPlatform() does; fall back to the raw platform view. The shared dispatch
+			// helper resolves the registered IViewScreenshot and stays graceful (returns null
+			// when capture is unavailable) to preserve this path's contract.
+			var handler = view?.Handler;
+			var captureView = (handler as IViewHandler)?.ContainerView ?? handler?.PlatformView;
+			return ScreenshotDispatch.CaptureAsync(handler, captureView);
 #endif
 		}
 

src/Core/src/WindowExtensions.cs

@@ -22,19 +22,18 @@ public static partial class WindowExtensions
 		/// <remarks>
 		/// On non-built-in platform TFMs (e.g. <c>net10.0-macos</c> AppKit backends,
 		/// <c>net10.0</c> Linux/GTK backends) where MAUI does not ship a screenshot
-		/// implementation, capture is routed through a keyed DI hook. Third-party
-		/// platform backends can opt in by registering a
-		/// <see cref="Func{T, TResult}"/> of <see cref="object"/> to
-		/// <c>Task&lt;IScreenshotResult?&gt;</c> under the service key
-		/// <c>"Microsoft.Maui.WindowCapture"</c>:
+		/// implementation, capture is routed through the registered screenshot service.
+		/// Third-party platform backends opt in by registering an <see cref="IScreenshot"/>
+		/// implementation that also implements <see cref="IViewScreenshot"/> in the app's
+		/// <see cref="System.IServiceProvider"/>:
 		/// <code>
-		/// builder.Services.AddKeyedSingleton&lt;Func&lt;object, Task&lt;IScreenshotResult?&gt;&gt;&gt;(
-		///     "Microsoft.Maui.WindowCapture",
-		///     (_, _) =&gt; platformWindow =&gt; ((AppKit.NSWindow)platformWindow).CaptureAsync());
+		/// builder.Services.AddSingleton&lt;IScreenshot, AppKitScreenshotImplementation&gt;();
 		/// </code>
-		/// If no hook is registered (or the <see cref="IElementHandler.PlatformView"/>
-		/// is <see langword="null"/>), the returned task resolves to
-		/// <see langword="null"/>.
+		/// The dispatch resolves that service from the handler's
+		/// <see cref="IElementHandler.MauiContext"/> and forwards the window's platform view
+		/// to <see cref="IViewScreenshot.CaptureViewAsync(object)"/>. When no capable service
+		/// is registered (or the <see cref="IElementHandler.PlatformView"/> is
+		/// <see langword="null"/>), the returned task resolves to <see langword="null"/>.
 		/// </remarks>
 		public static Task<IScreenshotResult?> CaptureAsync(this IWindow window)
 		{
@@ -47,7 +46,8 @@ public static partial class WindowExtensions
 
 			return CaptureAsync(platformView);
 #else
-			return ScreenshotDispatch.CaptureAsync(window?.Handler, ScreenshotDispatch.WindowCaptureKey);
+			var handler = window?.Handler;
+			return ScreenshotDispatch.CaptureAsync(handler, handler?.PlatformView);
 #endif
 		}