Improve measure invalidation and legacy Layout(s) performance

- Do not bubble up `MeasureInvalidated` on scrollable views and pages
- Do not synchronously measure/arrange children on legacy layout upon child measure invalidated: simply wait for the next native layout pass

src/Controls/src/Core/BindableObject.cs

@@ -658,7 +658,7 @@ void SetValueActual(BindableProperty property, BindablePropertyContext context,
 			}
 		}
 
-		void ApplyBindings(bool fromBindingContextChanged)
+		internal virtual void ApplyBindings(bool fromBindingContextChanged)
 		{
 			var prop = _properties.Values.ToArray();
 

src/Controls/src/Core/Items/ItemsView.cs

@@ -224,5 +224,10 @@ protected override void OnBindingContextChanged()
 			if (InternalItemsLayout is BindableObject bo)
 				SetInheritedBindingContext(bo, BindingContext);
 		}
+
+		internal override void OnChildMeasureInvalidatedInternal(VisualElement child, InvalidationTrigger trigger)
+		{
+			// No need to trigger and propagate MeasureInvalidated given this is a scrollable area
+		}
 	}
 }

src/Controls/src/Core/ItemsView.cs

@@ -85,5 +85,10 @@ static void OnItemsSourceChanged(BindableObject bindable, object oldValue, objec
 		}
 
 		protected virtual bool ValidateItemTemplate(DataTemplate template) => true;
+
+		internal override void OnChildMeasureInvalidatedInternal(VisualElement child, InvalidationTrigger trigger)
+		{
+			// No need to trigger and propagate MeasureInvalidated given this is a scrollable area
+		}
 	}
 }

src/Controls/src/Core/LegacyLayouts/Layout.cs

@@ -192,8 +192,12 @@ private protected override IList<Element> LogicalChildrenInternalBackingStore
 		public override SizeRequest Measure(double widthConstraint, double heightConstraint, MeasureFlags flags = MeasureFlags.None)
 		{
 			SizeRequest size = base.Measure(widthConstraint - Padding.HorizontalThickness, heightConstraint - Padding.VerticalThickness, flags);
-			return new SizeRequest(new Size(size.Request.Width + Padding.HorizontalThickness, size.Request.Height + Padding.VerticalThickness),
-				new Size(size.Minimum.Width + Padding.HorizontalThickness, size.Minimum.Height + Padding.VerticalThickness));
+			var request = new Size(size.Request.Width + Padding.HorizontalThickness, size.Request.Height + Padding.VerticalThickness);
+			var minimum = new Size(size.Minimum.Width + Padding.HorizontalThickness, size.Minimum.Height + Padding.VerticalThickness);
+
+			DesiredSize = request;
+
+			return new SizeRequest(request, minimum);
 		}
 
 		/// <summary>
@@ -294,13 +298,19 @@ public void RaiseChild(View view)
 			OnChildrenReordered();
 		}
 
+		internal virtual void InvalidateLayoutInternal()
+		{
+			_hasDoneLayout = false;
+			InvalidateMeasureCacheInternal();
+		}
+
 		/// <summary>
 		/// Invalidates the current layout.
 		/// </summary>
 		/// <remarks>Calling this method will invalidate the measure and triggers a new layout cycle.</remarks>
 		protected virtual void InvalidateLayout()
 		{
-			_hasDoneLayout = false;
+			InvalidateLayoutInternal();
 			InvalidateMeasureInternal(InvalidationTrigger.MeasureChanged);
 			if (!_hasDoneLayout)
 			{
@@ -321,8 +331,8 @@ protected virtual void InvalidateLayout()
 
 		internal override void OnChildMeasureInvalidatedInternal(VisualElement child, InvalidationTrigger trigger)
 		{
-			// TODO: once we remove old Xamarin public signatures we can invoke `OnChildMeasureInvalidated(VisualElement, InvalidationTrigger)` directly
 			OnChildMeasureInvalidated(child, new InvalidationEventArgs(trigger));
+			base.OnChildMeasureInvalidatedInternal(child, trigger);
 		}
 
 		/// <summary>
@@ -503,7 +513,7 @@ internal virtual void OnChildMeasureInvalidated(VisualElement child, Invalidatio
 			int count = children.Count;
 			for (var index = 0; index < count; index++)
 			{
-				if (LogicalChildrenInternal[index] is VisualElement v && v.IsVisible && (!v.IsPlatformEnabled || !v.IsPlatformStateConsistent))
+				if (LogicalChildrenInternal[index] is VisualElement { IsVisible: true } v && (!v.IsPlatformEnabled || !v.IsPlatformStateConsistent))
 				{
 					return;
 				}
@@ -517,20 +527,13 @@ internal virtual void OnChildMeasureInvalidated(VisualElement child, Invalidatio
 				{
 					return;
 				}
-				if (trigger == InvalidationTrigger.HorizontalOptionsChanged || trigger == InvalidationTrigger.VerticalOptionsChanged)
+				if (trigger is InvalidationTrigger.HorizontalOptionsChanged or InvalidationTrigger.VerticalOptionsChanged)
 				{
 					ComputeConstraintForView(view);
 				}
 			}
 
-			if (trigger == InvalidationTrigger.RendererReady)
-			{
-				InvalidateMeasureInternal(InvalidationTrigger.RendererReady);
-			}
-			else
-			{
-				InvalidateMeasureInternal(InvalidationTrigger.MeasureChanged);
-			}
+			InvalidateLayoutInternal();
 		}
 
 		internal override void OnIsVisibleChanged(bool oldValue, bool newValue)

src/Controls/src/Core/LegacyLayouts/StackLayout.cs

@@ -92,9 +92,15 @@ internal override void ComputeConstraintForView(View view)
 			ComputeConstraintForView(view, false);
 		}
 
-		internal override void InvalidateMeasureInternal(InvalidationTrigger trigger)
+		internal override void InvalidateLayoutInternal()
 		{
+			base.InvalidateLayoutInternal();
 			_layoutInformation = new LayoutInformation();
+		}
+
+		internal override void InvalidateMeasureInternal(InvalidationTrigger trigger)
+		{
+			InvalidateLayoutInternal();
 			base.InvalidateMeasureInternal(trigger);
 		}
 

src/Controls/src/Core/Page/Page.cs

@@ -499,7 +499,7 @@ protected override void OnBindingContextChanged()
 
 		internal override void OnChildMeasureInvalidatedInternal(VisualElement child, InvalidationTrigger trigger)
 		{
-			// TODO: once we remove old Xamarin public signatures we can invoke `OnChildMeasureInvalidated(VisualElement, InvalidationTrigger)` directly
+			// No need to trigger and propagate MeasureInvalidated considering Page is the root node
 			OnChildMeasureInvalidated(child, new InvalidationEventArgs(trigger));
 		}
 
@@ -510,8 +510,7 @@ internal override void OnChildMeasureInvalidatedInternal(VisualElement child, In
 		/// <param name="e">The event arguments.</param>
 		protected virtual void OnChildMeasureInvalidated(object sender, EventArgs e)
 		{
-			InvalidationTrigger trigger = (e as InvalidationEventArgs)?.Trigger ?? InvalidationTrigger.Undefined;
-			OnChildMeasureInvalidated((VisualElement)sender, trigger);
+			// Nothing to do here: platform will take care of arranging the children if needed on the next layout pass
 		}
 
 		/// <summary>
@@ -583,29 +582,6 @@ protected void UpdateChildrenLayout()
 			}
 		}
 
-		internal virtual void OnChildMeasureInvalidated(VisualElement child, InvalidationTrigger trigger)
-		{
-			var container = this as IPageContainer<Page>;
-			if (container != null)
-			{
-				Page page = container.CurrentPage;
-				if (page != null && page.IsVisible && (!page.IsPlatformEnabled || !page.IsPlatformStateConsistent))
-					return;
-			}
-			else
-			{
-				var logicalChildren = this.InternalChildren;
-				for (var i = 0; i < logicalChildren.Count; i++)
-				{
-					var v = logicalChildren[i] as VisualElement;
-					if (v != null && v.IsVisible && (!v.IsPlatformEnabled || !v.IsPlatformStateConsistent))
-						return;
-				}
-			}
-
-			InvalidateMeasureInternal(InvalidationTrigger.MeasureChanged);
-		}
-
 		internal void OnAppearing(Action action)
 		{
 			if (_hasAppeared)

src/Controls/src/Core/VisualElement/VisualElement.cs

@@ -991,7 +991,7 @@ public bool IsPlatformStateConsistent
 		internal event EventHandler PlatformEnabledChanged;
 
 		/// <summary>
-		/// Gets or sets a value that indicates whether this elements's platform equivalent element is enabled.
+		/// Gets or sets a value that indicates whether this element's platform equivalent element is enabled.
 		/// </summary>
 		/// <remarks>For internal use only. This API can be changed or removed without notice at any time.</remarks>
 		[EditorBrowsable(EditorBrowsableState.Never)]
@@ -1345,6 +1345,25 @@ internal void InvokeFocusChangeRequested(FocusRequestArgs args) =>
 			FocusChangeRequested?.Invoke(this, args);
 		internal bool HasFocusChangeRequestedEvent => FocusChangeRequested is not null;
 
+		internal override void ApplyBindings(bool fromBindingContextChanged)
+		{
+			try
+			{
+				_isApplyingBindings = true;
+				base.ApplyBindings(fromBindingContextChanged);
+			}
+			finally
+			{
+				_isApplyingBindings = false;
+
+				if (_applyingBindingsInvalidationTrigger is {} invalidationTrigger)
+				{
+					_applyingBindingsInvalidationTrigger = null;
+					InvalidateMeasureInternal(invalidationTrigger);
+				}
+			}
+		}
+
 		/// <summary>
 		/// Invalidates the measure of an element.
 		/// </summary>
@@ -1355,9 +1374,32 @@ public void InvalidateMeasureNonVirtual(InvalidationTrigger trigger)
 			InvalidateMeasureInternal(trigger);
 		}
 
+		bool _isApplyingBindings;
+		InvalidationTrigger? _applyingBindingsInvalidationTrigger;
+
 		internal virtual void InvalidateMeasureInternal(InvalidationTrigger trigger)
 		{
-			_measureCache.Clear();
+			if (!IsPlatformEnabled)
+			{
+				// No need to invalidate measure if there's no platform view
+				return;
+			}
+
+			if (_isApplyingBindings)
+			{
+				if (_applyingBindingsInvalidationTrigger == null &&
+				    trigger is InvalidationTrigger.HorizontalOptionsChanged or InvalidationTrigger.VerticalOptionsChanged)
+				{
+					_applyingBindingsInvalidationTrigger = trigger;
+				}
+				else
+				{
+					_applyingBindingsInvalidationTrigger = InvalidationTrigger.Undefined;
+				}
+				return;
+			}
+
+			InvalidateMeasureCacheInternal();
 
 			// TODO ezhart Once we get InvalidateArrange sorted, HorizontalOptionsChanged and 
 			// VerticalOptionsChanged will need to call ParentView.InvalidateArrange() instead
@@ -1377,7 +1419,15 @@ internal virtual void InvalidateMeasureInternal(InvalidationTrigger trigger)
 			MeasureInvalidated?.Invoke(this, new InvalidationEventArgs(trigger));
 			(Parent as VisualElement)?.OnChildMeasureInvalidatedInternal(this, trigger);
 		}
-
+
+		/// <summary>
+		/// Clears the measure cache of a visual element.
+		/// </summary>
+		internal void InvalidateMeasureCacheInternal()
+		{
+			_measureCache.Clear();
+		}
+
 		internal virtual void OnChildMeasureInvalidatedInternal(VisualElement child, InvalidationTrigger trigger)
 		{
 			switch (trigger)

src/Controls/tests/Core.UnitTests/ButtonUnitTest.cs

@@ -10,7 +10,7 @@ public class ButtonUnitTest : VisualElementCommandSourceTests<Button>
 		[Fact]
 		public void MeasureInvalidatedOnTextChange()
 		{
-			var button = new Button();
+			var button = new Button { IsPlatformEnabled = true };
 
 			bool fired = false;
 			button.MeasureInvalidated += (sender, args) => fired = true;
@@ -123,7 +123,7 @@ public void TestBindingContextPropagation()
 		public void TestImageSourcePropertiesChangedTriggerResize()
 		{
 			var source = new FileImageSource();
-			var button = new Button { ImageSource = source };
+			var button = new Button { ImageSource = source, IsPlatformEnabled = true };
 			bool fired = false;
 			button.MeasureInvalidated += (sender, e) => fired = true;
 			Assert.Null(source.File);

src/Controls/tests/Core.UnitTests/GridTests.cs

@@ -1329,7 +1329,7 @@ public void TestEnd()
 		[Fact]
 		public void TestDefaultRowSpacing()
 		{
-			var layout = new Grid();
+			var layout = new Grid { IsPlatformEnabled = true };
 
 			bool preferredSizeChanged = false;
 			layout.MeasureInvalidated += (sender, args) =>
@@ -1349,7 +1349,7 @@ public void TestDefaultRowSpacing()
 		[Fact]
 		public void TestDefaultColumnSpacing()
 		{
-			var layout = new Grid();
+			var layout = new Grid { IsPlatformEnabled = true };
 
 			bool preferredSizeChanged = false;
 			layout.MeasureInvalidated += (sender, args) =>
@@ -1369,7 +1369,7 @@ public void TestDefaultColumnSpacing()
 		[Fact]
 		public void TestAddCell()
 		{
-			var layout = new Grid();
+			var layout = new Grid { IsPlatformEnabled = true };
 			bool preferredSizeChanged = false;
 			layout.MeasureInvalidated += (sender, args) => preferredSizeChanged = true;
 
@@ -1383,7 +1383,7 @@ public void TestAddCell()
 		[Fact]
 		public void TestMoveCell()
 		{
-			var layout = new Grid();
+			var layout = new Grid { IsPlatformEnabled = true };
 			var label = new Label();
 			layout.Children.Add(label, 0, 0);
 

src/Controls/tests/Core.UnitTests/ImageButtonUnitTest.cs

@@ -93,7 +93,7 @@ public void TestFillSizingWithConstrainedWidth()
 		[Fact]
 		public void TestSizeChanged()
 		{
-			var image = new ImageButton { Source = "File0.png" };
+			var image = new ImageButton { Source = "File0.png", IsPlatformEnabled = true };
 			Assert.Equal("File0.png", ((FileImageSource)image.Source).File);
 
 			var preferredSizeChanged = false;
@@ -163,7 +163,7 @@ public void TestFileImageSourceChanged()
 		public void TestFileImageSourcePropertiesChangedTriggerResize()
 		{
 			var source = new FileImageSource();
-			var image = new ImageButton { Source = source };
+			var image = new ImageButton { Source = source, IsPlatformEnabled = true };
 			bool fired = false;
 			image.MeasureInvalidated += (sender, e) => fired = true;
 			Assert.Null(source.File);
@@ -176,7 +176,7 @@ public void TestFileImageSourcePropertiesChangedTriggerResize()
 		public void TestStreamImageSourcePropertiesChangedTriggerResize()
 		{
 			var source = new StreamImageSource();
-			var image = new ImageButton { Source = source };
+			var image = new ImageButton { Source = source, IsPlatformEnabled = true };
 			bool fired = false;
 			EventHandler eventHandler = (sender, e) => fired = true;
 			image.MeasureInvalidated += eventHandler;
@@ -370,7 +370,7 @@ public void TestBindingContextPropagation()
 		public void TestImageSourcePropertiesChangedTriggerResize()
 		{
 			var source = new FileImageSource();
-			var button = new ImageButton { Source = source };
+			var button = new ImageButton { Source = source, IsPlatformEnabled = true };
 			bool fired = false;
 			button.MeasureInvalidated += (sender, e) => fired = true;
 			Assert.Null(source.File);

src/Controls/tests/Core.UnitTests/ImageTests.cs

@@ -95,7 +95,7 @@ public void TestFillSizingWithConstrainedWidth()
 		[Fact]
 		public void TestSizeChanged()
 		{
-			var image = new Image { Source = "File0.png" };
+			var image = new Image { Source = "File0.png", IsPlatformEnabled = true };
 			Assert.Equal("File0.png", ((FileImageSource)image.Source).File);
 
 			var preferredSizeChanged = false;
@@ -165,7 +165,7 @@ public void TestFileImageSourceChanged()
 		public void TestFileImageSourcePropertiesChangedTriggerResize()
 		{
 			var source = new FileImageSource();
-			var image = new Image { Source = source };
+			var image = new Image { Source = source, IsPlatformEnabled = true };
 			bool fired = false;
 			image.MeasureInvalidated += (sender, e) => fired = true;
 			Assert.Null(source.File);
@@ -178,7 +178,7 @@ public void TestFileImageSourcePropertiesChangedTriggerResize()
 		public void TestStreamImageSourcePropertiesChangedTriggerResize()
 		{
 			var source = new StreamImageSource();
-			var image = new Image { Source = source };
+			var image = new Image { Source = source, IsPlatformEnabled = true };
 			bool fired = false;
 			image.MeasureInvalidated += (sender, e) => fired = true;
 			Assert.Null(source.Stream);

src/Controls/tests/Core.UnitTests/LabelTests.cs

@@ -33,7 +33,7 @@ public void TextAndAttributedTextMutuallyExclusive()
 		[Fact]
 		public void InvalidateMeasureWhenTextChanges()
 		{
-			var label = new Label();
+			var label = new Label { IsPlatformEnabled = true };
 
 			bool fired;
 			label.MeasureInvalidated += (sender, args) =>