fix: Properly warn the user about UpdateZoomedContentAlignment

src/Uno.UI/UI/Xaml/Controls/ScrollViewer/ScrollViewer.Managed.cs

@@ -27,10 +27,6 @@ namespace Windows.UI.Xaml.Controls
 			set => global::Windows.Foundation.Metadata.ApiInformation.TryRaiseNotImplemented("Windows.UI.Xaml.Controls.ScrollContentPresenter", "Color ScrollContentPresenter.BackgroundColor");
 		}
 
-		[NotImplemented]
-		private void UpdateZoomedContentAlignment()
-			=> global::Windows.Foundation.Metadata.ApiInformation.TryRaiseNotImplemented("Windows.UI.Xaml.Controls.ScrollContentPresenter", "float ZoomFactor");
-
 		private bool ChangeViewNative(double? horizontalOffset, double? verticalOffset, double? zoomFactor, bool disableAnimation)
 			=> (_presenter as ScrollContentPresenter)?.Set(horizontalOffset, verticalOffset, disableAnimation: disableAnimation) ?? true;
 

src/Uno.UI/UI/Xaml/Controls/ScrollViewer/ScrollViewer.crossruntime.cs

+using Uno;
+using Uno.Foundation.Logging;
+
+namespace Windows.UI.Xaml.Controls;
+
+partial class ScrollViewer
+{
+	private static bool _warnedAboutZoomedContentAlignment;
+
+	[NotImplemented]
+	private void UpdateZoomedContentAlignment()
+	{
+		if (_warnedAboutZoomedContentAlignment)
+		{
+			return;
+		}
+
+		_warnedAboutZoomedContentAlignment = true;
+		if (this.Log().IsEnabled(LogLevel.Warning))
+		{
+			this.Log().LogWarning("Zoom-based content alignment is not implemented on this platform.");
+		}
+	}
+}

src/Uno.UI/UI/Xaml/Controls/ScrollViewer/ScrollViewer.wasm.cs

@@ -12,10 +12,6 @@ namespace Windows.UI.Xaml.Controls
 	{
 		internal Size ScrollBarSize => (_presenter as ScrollContentPresenter)?.ScrollBarSize ?? default;
 
-		private void UpdateZoomedContentAlignment()
-		{
-		}
-
 		// Disable clipping for Scrollviewer (edge seems to disable scrolling if
 		// the clipping is enabled to the size of the scrollviewer, even if overflow-y is auto)
 		bool ICustomClippingElement.AllowClippingToLayoutSlot => true;