[Windows] Add WindowsBatchPropertyMapper to save unnecessary work when initializing views

src/Core/src/Handlers/View/ViewHandler.cs

@@ -27,6 +27,9 @@ public abstract partial class ViewHandler : ElementHandler, IViewHandler
 #if ANDROID
 			// Use a custom mapper for Android which knows how to batch the initial property sets
 			new AndroidBatchPropertyMapper<IView, IViewHandler>(ElementMapper)
+#elif WINDOWS
+			// Use a custom mapper for Windows which knows how to batch the initial property sets
+			new WindowsBatchPropertyMapper<IView, IViewHandler>(ElementMapper)
 #else
 			new PropertyMapper<IView, IViewHandler>(ElementHandler.ElementMapper)
 #endif

src/Core/src/Handlers/View/WindowsBatchPropertyMapper.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+
+namespace Microsoft.Maui.Handlers;
+
+#if WINDOWS
+class WindowsBatchPropertyMapper<TVirtualView, TViewHandler> : PropertyMapper<TVirtualView, TViewHandler>
+	where TVirtualView : IElement
+	where TViewHandler : IElementHandler
+{
+	// During mass property updates, this list of properties will be skipped
+	public static HashSet<string> SkipList = new(StringComparer.Ordinal)
+	{ 
+		// TranslationX does the work that is necessary to make other properties work.
+		nameof(IView.TranslationY),
+		nameof(IView.Scale),
+		nameof(IView.ScaleX),
+		nameof(IView.ScaleY),
+		nameof(IView.Rotation),
+		nameof(IView.RotationX),
+		nameof(IView.RotationY),
+		nameof(IView.AnchorX),
+		nameof(IView.AnchorY),
+	};
+
+	public WindowsBatchPropertyMapper(params IPropertyMapper[] chained) : base(chained) { }
+
+	public override IEnumerable<string> GetKeys()
+	{
+		foreach (var key in _mapper.Keys)
+		{
+			// When reporting the key list for mass updates up the chain, ignore properties in SkipList.
+			// These will be handled by ViewHandler.SetVirtualView() instead.
+			if (SkipList.Contains(key))
+			{
+				continue;
+			}
+
+			yield return key;
+		}
+
+		if (Chained is not null)
+		{
+			foreach (var chain in Chained)
+				foreach (var key in chain.GetKeys())
+					yield return key;
+		}
+	}
+}
+#endif