fix: Adjust measure/arrange phase

This change removes the reliance on NSView.NeedsLayout to invalidate the measure/arrange phases for self and parents. NeedsLayout is set to true when NSView.Frame is changed, causing a chain of multiple unneeded updates for the element and its parents.

src/Uno.UI/UI/Xaml/Controls/ContentPresenter/ContentPresenter.macOS.cs

@@ -29,7 +29,7 @@ public ContentPresenter()
 		private void SetUpdateTemplate()
 		{
 			UpdateContentTemplateRoot();
-			this.SetNeedsLayout();
+			this.InvalidateMeasure();
 		}
 
 		partial void RegisterContentTemplateRoot()

src/Uno.UI/UI/Xaml/Controls/Image/Image.macOS.cs

@@ -209,7 +209,7 @@ private void SetNeedsLayoutOrDisplay()
 			}
 			else
 			{
-				this.SetNeedsLayout();
+				this.InvalidateMeasure();
 			}
 		}
 

src/Uno.UI/UI/Xaml/Controls/MenuBar/NativeMenuBarPresenter.macOS.cs

@@ -8,7 +8,7 @@
 
 namespace Windows.UI.Xaml.Controls
 {
-	public class NativeMenuBarPresenter : FrameworkElement
+	public partial class NativeMenuBarPresenter : FrameworkElement
 	{
 		private MenuBar _menuBar;
 

src/Uno.UI/UI/Xaml/Controls/Panel/Panel.macOS.cs

@@ -54,13 +54,13 @@ partial void OnBorderBrushChangedPartial(Brush oldValue, Brush newValue)
 
 		partial void OnBorderThicknessChangedPartial(Thickness oldValue, Thickness newValue)
 		{
-			NeedsLayout = true;
+			InvalidateMeasure();
 			UpdateBackground();
 		}
 
 		partial void OnPaddingChangedPartial(Thickness oldValue, Thickness newValue)
 		{
-			NeedsLayout = true;
+			InvalidateMeasure();
 		}
 
 		protected override void OnBackgroundChanged(DependencyPropertyChangedEventArgs args)
@@ -114,7 +114,7 @@ private void UpdateBackground(NSImage backgroundImage = null)
 
 		protected virtual void OnChildrenChanged()
 		{
-			NeedsLayout = true;
+			InvalidateMeasure();
 		}
 
 		protected override void OnAfterArrange()

src/Uno.UI/UI/Xaml/Controls/ScrollContentPresenter/ScrollContentPresenter.macOS.cs

@@ -22,6 +22,8 @@ public ScrollContentPresenter()
 			InitializeScrollContentPresenter();
 
 			Notifications.ObserveDidLiveScroll(this, OnLiveScroll);
+
+			DrawsBackground = false;
 		}
 
 		public nfloat ZoomScale {

src/Uno.UI/UI/Xaml/FrameworkElement.macOS.cs

@@ -33,15 +33,38 @@ public override bool NeedsLayout
 					base.NeedsLayout = value;
 				}
 
-				RequiresMeasure = true;
-				RequiresArrange = true;
-
 				if (ShouldInterceptInvalidate)
 				{
 					return;
 				}
+			}
+		}
+
+		protected internal override void OnInvalidateMeasure()
+		{
+			base.OnInvalidateMeasure();
+
+			// Note that the reliance on NSView.NeedsLayout to invalidate the measure / arrange phases for
+			// self and parents.NeedsLayout is set to true when NSView.Frame is different from iOS, causing
+			// a chain of multiple unneeded updates for the element and its parents. OnInvalidateMeasure
+			// sets NeedsLayout to true and propagates to the parent but NeedsLayout by itself does not.
 
-				SetSuperviewNeedsLayout();
+			if (!RequiresMeasure)
+			{
+				RequiresArrange = true;
+				RequiresMeasure = true;
+
+				if (Parent is FrameworkElement fe)
+				{
+					if (!fe.RequiresMeasure)
+					{
+						fe.InvalidateMeasure();
+					}
+				}
+				else if (Parent is IFrameworkElement ife)
+				{
+					ife.InvalidateMeasure();
+				}
 			}
 		}
 
@@ -60,33 +83,33 @@ public override void Layout()
 		{
 			try
 			{
-				try
+				_inLayoutSubviews = true;
+
+				if (RequiresMeasure)
 				{
-					_inLayoutSubviews = true;
+					XamlMeasure(Bounds.Size);
+				}
 
-					if (RequiresMeasure)
-					{
-						XamlMeasure(Bounds.Size);
-					}
+				OnBeforeArrange();
 
-					OnBeforeArrange();
+				var size = SizeFromUISize(Bounds.Size);
 
-					var size = SizeFromUISize(Bounds.Size);
-					_layouter.Arrange(new Rect(0, 0, size.Width, size.Height));
+				_layouter.Arrange(new Rect(0, 0, size.Width, size.Height));
 
-					OnAfterArrange();
-				}
-				finally
-				{
-					_inLayoutSubviews = false;
-					RequiresArrange = false;
-				}
+				OnAfterArrange();
 			}
 			catch (Exception e)
 			{
 				this.Log().Error($"Layout failed in {GetType()}", e);
 			}
+			finally
+			{
+				_inLayoutSubviews = false;
+				RequiresMeasure = false;
+				RequiresArrange = false;
+			}
 		}
+
 		/// <summary>
 		/// Called before Arrange is called, this method will be deprecated
 		/// once OnMeasure/OnArrange will be implemented completely
@@ -107,7 +130,7 @@ protected virtual void OnAfterArrange()
 
 		}
 
-		private CGSize? XamlMeasure(CGSize availableSize)
+		internal CGSize? XamlMeasure(CGSize availableSize)
 		{
 			// If set layout has not been called, we can 
 			// return a previously cached result for the same available size.

src/Uno.UI/UI/Xaml/IFrameworkElement.cs

@@ -266,7 +266,7 @@ public static CGSize Measure(this IFrameworkElement element, _Size availableSize
 			}
 			else if (element is FrameworkElement fe)
 			{
-				fe.Measure(new Size(availableSize.Width, availableSize.Height));
+				fe.XamlMeasure(new CoreGraphics.CGSize(availableSize.Width, availableSize.Height));
 				var desiredSize = fe.DesiredSize;
 				return new CGSize(desiredSize.Width, desiredSize.Height);
 			}
@@ -298,7 +298,7 @@ public static CGSize Measure(this View element, _Size availableSize)
 			}
 			else if (element is FrameworkElement fe)
 			{
-				fe.Measure(new Size(availableSize.Width, availableSize.Height));
+				fe.XamlMeasure(new Size(availableSize.Width, availableSize.Height));
 				var desiredSize = fe.DesiredSize;
 				return new CGSize(desiredSize.Width, desiredSize.Height);
 			}

src/Uno.UI/UI/Xaml/IFrameworkElementImplementation.macOS.tt

@@ -189,10 +189,14 @@ namespace <#= mixin.NamespaceName #>
 		{
 			// Resolve the property only once, to avoid paying the cost of the interop.
 			var actualSuperview = Superview;
-
-			if (actualSuperview != null)
+
+            if(actualSuperview is FrameworkElement fe)
+            {
+                fe.InvalidateMeasure();
+            }
+			else if (actualSuperview is IFrameworkElement ife)
 			{
-				actualSuperview.NeedsLayout = true;
+				ife.InvalidateMeasure();
 			}
 		}
 
@@ -576,7 +580,7 @@ namespace <#= mixin.NamespaceName #>
 			base.ViewDidMoveToSuperview();
 			OnViewDidMoveToSuperview();
 
-			this.SetNeedsLayout();
+			this.InvalidateMeasure();
 		}
 
 		partial void OnViewDidMoveToSuperview();
@@ -599,7 +603,7 @@ namespace <#= mixin.NamespaceName #>
 		{
 			IsLoaded = true;
 
-			this.SetNeedsLayout();
+			this.InvalidateMeasure();
 			OnLoadedPartial();
 
 			Loaded?.Invoke(this, new RoutedEventArgs(this));
@@ -706,7 +710,7 @@ namespace <#= mixin.NamespaceName #>
 			if (base.Hidden != newVisibility.IsHidden())
 			{
 				base.Hidden = newVisibility.IsHidden();
-				this.SetNeedsLayout();
+				this.InvalidateMeasure();
 
 				if (newVisibility == Visibility.Visible)
 				{
@@ -990,7 +994,18 @@ namespace <#= mixin.NamespaceName #>
 		private static void OnGenericPropertyUpdated(object dependencyObject, DependencyPropertyChangedEventArgs args)
 		{
 			OnGenericPropertyUpdatedPartial(dependencyObject, args);
-			((NSView)dependencyObject).SetNeedsLayout();
+
+#if <#= mixin.IsFrameworkElement #>
+            if(dependencyObject is FrameworkElement fe)
+            {
+                fe.InvalidateMeasure();
+            }
+#else
+            if(dependencyObject is IFrameworkElement ife)
+            {
+                ife.InvalidateMeasure();
+            }
+#endif
 		}
 
 		static partial void OnGenericPropertyUpdatedPartial(object dependencyObject, DependencyPropertyChangedEventArgs args);

src/Uno.UI/UI/Xaml/Shapes/Path.iOSmacOS.cs

@@ -25,7 +25,7 @@ protected override CGPath GetPath(Size availableSize)
 
 		partial void OnDataChanged()
 		{
-			this.SetNeedsLayout();
+			this.InvalidateMeasure();
 		}
 	}
 }