Update layout system to ensure native measure/arrange are called for all controls

src/Compatibility/Core/src/Android/Renderers/PageContainer.cs

@@ -45,7 +45,8 @@ protected override void OnLayout(bool changed, int l, int t, int r, int b)
 				{
 					(l, t, r, b) = Context.ToPixels(ipc.ContainerArea);
 				}
-
+
+				pageViewGroup.Measure(r - l, b - t);
 				pageViewGroup.Layout(l, t, r, b);
 			}
 		}

src/Controls/src/Core/HandlerImpl/ContentPage.Impl.cs

@@ -1,8 +1,5 @@
-using Microsoft.Maui.Controls.Internals;
-using Microsoft.Maui.Graphics;
-using Microsoft.Maui.Hosting;
+using Microsoft.Maui.Graphics;
 using Microsoft.Maui.HotReload;
-using Microsoft.Maui.Layouts;
 
 namespace Microsoft.Maui.Controls
 {
@@ -17,28 +14,16 @@ protected override Size MeasureOverride(double widthConstraint, double heightCon
 		{
 			if (Content is IFrameworkElement frameworkElement)
 			{
-				_ = frameworkElement.Handler?.GetDesiredSize(widthConstraint, heightConstraint);
+				_ = frameworkElement.Measure(widthConstraint, heightConstraint);
 			}
 
 			return new Size(widthConstraint, heightConstraint);
 		}
 
 		protected override Size ArrangeOverride(Rectangle bounds)
 		{
-			// Update the Bounds (Frame) for this page
+			// Update the other stuff on this page (basically the content)
 			Layout(bounds);
-
-			if (Content is IFrameworkElement element and VisualElement visualElement)
-			{
-				// The size checks here are a guard against legacy layouts which try to lay things out before the
-				// native side is ready. We just ignore those invalid values.
-				if (bounds.Size.Width >= 0 && bounds.Size.Height >= 0)
-				{
-					visualElement.Frame = element.ComputeFrame(bounds);
-					element.Handler?.NativeArrange(visualElement.Frame);
-				}
-			}
-
 			return Frame.Size;
 		}
 

src/Controls/src/Core/HandlerImpl/NavigationPage.Impl.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Text;
 using System.Threading.Tasks;
@@ -42,13 +42,6 @@ protected override Size ArrangeOverride(Rectangle bounds)
 		{
 			// Update the Bounds (Frame) for this page
 			Layout(bounds);
-
-			if (Content is IFrameworkElement element and VisualElement visualElement)
-			{
-				visualElement.Frame = element.ComputeFrame(bounds);
-				element.Handler?.NativeArrange(visualElement.Frame);
-			}
-
 			return Frame.Size;
 		}
 

src/Controls/src/Core/HandlerImpl/ScrollView.Impl.cs

@@ -1,4 +1,7 @@
-namespace Microsoft.Maui.Controls
+using Microsoft.Maui.Graphics;
+using Microsoft.Maui.Layouts;
+
+namespace Microsoft.Maui.Controls
 {
 	public partial class ScrollView : IScrollView
 	{
@@ -35,5 +38,30 @@ void IScrollView.RequestScrollTo(double horizontalOffset, double verticalOffset,
 		}
 
 		void IScrollView.ScrollFinished() => SendScrollFinished();
+
+		protected override Size MeasureOverride(double widthConstraint, double heightConstraint)
+		{
+			// We call OnSizeRequest so that the content gets measured appropriately
+			// and then use the standard GetDesiredSize from the handler so the ScrollView's
+			// backing control gets measured. 
+
+			// TODO ezhart 2021-07-14 Verify that we've got the naming correct on this after we resolve the OnSizeRequest obsolete stuff
+#pragma warning disable CS0618 // Type or member is obsolete
+			var request = OnSizeRequest(widthConstraint, heightConstraint);
+#pragma warning restore CS0618 // Type or member is obsolete
+
+			DesiredSize = this.ComputeDesiredSize(widthConstraint, heightConstraint);
+			return DesiredSize;
+		}
+
+		protected override Size ArrangeOverride(Rectangle bounds)
+		{
+			Layout(this.ComputeFrame(bounds));
+
+			// Force a native arrange call; otherwise, the native bookkeeping won't be done and things won't lay out correctly
+			Handler?.NativeArrange(Frame);
+
+			return Frame.Size;
+		}
 	}
 }

src/Controls/src/Core/HandlerImpl/VisualElement.Impl.cs

@@ -60,10 +60,12 @@ Size IFrameworkElement.Arrange(Rectangle bounds)
 			return ArrangeOverride(bounds);
 		}
 
-		// ArrangeOverride provides a way to allow subclasses (e.g., Layout) to override Arrange even though
+		// ArrangeOverride provides a way to allow subclasses (e.g., ScrollView) to override Arrange even though
 		// the interface has to be explicitly implemented to avoid conflict with the old Arrange method
 		protected virtual Size ArrangeOverride(Rectangle bounds)
 		{
+			Frame = this.ComputeFrame(bounds);
+			Handler?.NativeArrange(Frame);
 			return Frame.Size;
 		}
 

src/Controls/src/Core/Layout.cs

@@ -7,11 +7,12 @@
 using System.Linq;
 using Microsoft.Maui.Controls.Internals;
 using Microsoft.Maui.Graphics;
+using Microsoft.Maui.Layouts;
 
 namespace Microsoft.Maui.Controls
 {
 	[ContentProperty(nameof(Children))]
-	public abstract partial class Layout<T> : Layout, Microsoft.Maui.ILayout, IViewContainer<T> where T : View
+	public abstract partial class Layout<T> : Layout, Microsoft.Maui.ILayout, ILayoutManager, IViewContainer<T> where T : View
 	{
 		readonly ElementCollection<T> _children;
 
@@ -21,6 +22,8 @@ public abstract partial class Layout<T> : Layout, Microsoft.Maui.ILayout, IViewC
 
 		public ILayoutHandler LayoutHandler => Handler as ILayoutHandler;
 
+		ILayoutManager Maui.ILayout.LayoutManager => this;
+
 		protected override void OnChildAdded(Element child)
 		{
 			base.OnChildAdded(child);
@@ -44,6 +47,17 @@ protected virtual void OnAdded(T view)
 		protected virtual void OnRemoved(T view)
 		{
 		}
+
+		Size ILayoutManager.Measure(double widthConstraint, double heightConstraint)
+		{
+			return OnMeasure(widthConstraint, heightConstraint);
+		}
+
+		Size ILayoutManager.ArrangeChildren(Rectangle childBounds)
+		{
+			LayoutChildren(childBounds.X, childBounds.Y, childBounds.Width, childBounds.Height);
+			return childBounds.Size;
+		}
 	}
 
 	public abstract class Layout : View, ILayout, ILayoutController, IPaddingElement, IFrameworkElement
@@ -122,6 +136,13 @@ public static void LayoutChildIntoBoundingRegion(VisualElement child, Rectangle
 			if (child.Parent is IFlowDirectionController parent && (isRightToLeft = parent.ApplyEffectiveFlowDirectionToChildContainer && parent.EffectiveFlowDirection.IsRightToLeft()))
 				region = new Rectangle(parent.Width - region.Right, region.Y, region.Width, region.Height);
 
+			if (child is IFrameworkElement fe && fe.Handler != null)
+			{
+				// The new arrange methods will take care of all the alignment and margins and such
+				fe.Arrange(region);
+				return;
+			}
+
 			if (!(child is View view))
 			{
 				child.Layout(region);
@@ -268,6 +289,13 @@ internal static void LayoutChildIntoBoundingRegion(View child, Rectangle region,
 			if (child.Parent is IFlowDirectionController parent && (isRightToLeft = parent.ApplyEffectiveFlowDirectionToChildContainer && parent.EffectiveFlowDirection.IsRightToLeft()))
 				region = new Rectangle(parent.Width - region.Right, region.Y, region.Width, region.Height);
 
+			if (child is IFrameworkElement fe && fe.Handler != null)
+			{
+				// The new arrange methods will take care of all the alignment and margins and such
+				fe.Arrange(region);
+				return;
+			}
+
 			if (region.Size != childSizeRequest.Request)
 			{
 				bool canUseAlreadyDoneRequest = region.Width >= childSizeRequest.Request.Width && region.Height >= childSizeRequest.Request.Height;
@@ -503,23 +531,15 @@ protected override void InvalidateMeasureOverride()
 
 		protected override Size ArrangeOverride(Rectangle bounds)
 		{
-			var size = base.ArrangeOverride(bounds);
+			base.ArrangeOverride(bounds);
 
 			// The SholdLayoutChildren check will catch impossible sizes (negative widths/heights), not-yet-loaded controls,
 			// and other weirdness that comes from the legacy layouts trying to run layout before the native side is ready. 
 			if (!ShouldLayoutChildren())
-				return size;
+				return bounds.Size;
 
 			UpdateChildrenLayout();
 
-			foreach (var child in Children)
-			{
-				if (child is IFrameworkElement frameworkElement)
-				{
-					frameworkElement.Handler?.NativeArrange(frameworkElement.Frame);
-				}
-			}
-
 			return Frame.Size;
 		}
 	}

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

@@ -11,7 +11,7 @@ namespace Microsoft.Maui.Controls.Layout2
 	public abstract class Layout : View, Microsoft.Maui.ILayout, IList<IView>, IPaddingElement
 	{
 		ILayoutManager _layoutManager;
-		ILayoutManager LayoutManager => _layoutManager ??= CreateLayoutManager();
+		public ILayoutManager LayoutManager => _layoutManager ??= CreateLayoutManager();
 
 		// The actual backing store for the IViews in the ILayout
 		readonly List<IView> _children = new();
@@ -47,30 +47,6 @@ public override SizeRequest GetSizeRequest(double widthConstraint, double height
 			return new SizeRequest(size);
 		}
 
-		protected override Size MeasureOverride(double widthConstraint, double heightConstraint)
-		{
-			var margin = (this as IView)?.Margin ?? Thickness.Zero;
-			// Adjust the constraints to account for the margins
-			widthConstraint -= margin.HorizontalThickness;
-			heightConstraint -= margin.VerticalThickness;
-			var sizeWithoutMargins = LayoutManager.Measure(widthConstraint, heightConstraint);
-			DesiredSize = new Size(sizeWithoutMargins.Width + Margin.HorizontalThickness,
-				sizeWithoutMargins.Height + Margin.VerticalThickness);
-			return DesiredSize;
-		}
-
-		protected override Size ArrangeOverride(Rectangle bounds)
-		{
-			base.ArrangeOverride(bounds);
-			Frame = bounds;
-			LayoutManager.ArrangeChildren(Frame);
-			foreach (var child in Children)
-			{
-				child.Handler?.NativeArrange(child.Frame);
-			}
-			return Frame.Size;
-		}
-
 		protected override void InvalidateMeasureOverride()
 		{
 			base.InvalidateMeasureOverride();

src/Controls/src/Core/Page.cs

@@ -259,11 +259,6 @@ protected virtual void LayoutChildren(double x, double y, double width, double h
 				if (child == null)
 					continue;
 
-				if (child is Layout2.Layout)
-				{
-					continue;
-				}
-
 				var page = child as Page;
 				if (page != null && page.IgnoresContainerArea)
 					Maui.Controls.Layout.LayoutChildIntoBoundingRegion(child, originalArea);

src/Controls/src/Core/ScrollView.cs

@@ -3,6 +3,7 @@
 using System.Threading.Tasks;
 using Microsoft.Maui.Controls.Internals;
 using Microsoft.Maui.Graphics;
+using Microsoft.Maui.Layouts;
 
 namespace Microsoft.Maui.Controls
 {
@@ -280,7 +281,7 @@ protected override SizeRequest OnSizeRequest(double widthConstraint, double heig
 
 			if (Content is IFrameworkElement fe && fe.Handler != null)
 			{
-				contentRequest = fe.Handler.GetDesiredSize(widthConstraint, heightConstraint);
+				contentRequest = fe.Measure(widthConstraint, heightConstraint);
 			}
 			else
 			{
@@ -366,19 +367,5 @@ void OnScrollToRequested(ScrollToRequestedEventArgs e)
 
 			Handler?.Invoke(nameof(IScrollView.RequestScrollTo), e.ToRequest());
 		}
-
-		protected override Size MeasureOverride(double widthConstraint, double heightConstraint)
-		{
-			// We call OnSizeRequest so that the content gets measured appropriately
-			// and then use the standard GetDesiredSize from the handler so the ScrollView's
-			// backing control gets measured. 
-
-			// TODO ezhart 2021-07-14 Verify that we've got the naming correct on this after we resolve the OnSizeRequest obsolete stuff
-#pragma warning disable CS0618 // Type or member is obsolete
-			_ = OnSizeRequest(widthConstraint, heightConstraint);
-#pragma warning restore CS0618 // Type or member is obsolete
-
-			return Handler.GetDesiredSize(widthConstraint, heightConstraint);
-		}
 	}
 }

src/Controls/src/Core/VisualElement.cs

@@ -387,8 +387,6 @@ private set
 				Y = value.Y;
 				SetSize(value.Width, value.Height);
 				BatchCommit();
-
-				Handler?.UpdateValue(nameof(IFrameworkElement.Frame));
 			}
 		}
 

src/Controls/tests/Core.UnitTests/Layouts/LayoutCompatTests.cs

@@ -31,59 +31,6 @@ public void BasicContentPage()
 			Assert.AreEqual(expectedSize, button.Bounds.Size);
 		}
 
-		[Test]
-		public void VerticalStackLayoutInsideStackLayout()
-		{
-			var stackLayout = new StackLayout() { IsPlatformEnabled = true };
-			var verticalStackLayout = new VerticalStackLayout() { IsPlatformEnabled = true };
-			var button = new Button() { IsPlatformEnabled = true, HeightRequest = 100, WidthRequest = 100 };
-			var expectedSize = new Size(100, 100);
-
-			var buttonHandler = Substitute.For<IViewHandler>();
-			buttonHandler.GetDesiredSize(default, default).ReturnsForAnyArgs(expectedSize);
-			button.Handler = buttonHandler;
-
-			stackLayout.Children.Add(verticalStackLayout);
-			verticalStackLayout.Add(button);
-
-			var rect = new Rectangle(0, 0, 100, 100);
-			Layout.LayoutChildIntoBoundingRegion(stackLayout, rect);
-
-			// Normally this would get called from the native platform
-			(verticalStackLayout as IFrameworkElement).Arrange(rect);
-
-			Assert.AreEqual(expectedSize, button.Bounds.Size);
-		}
-
-		[Test]
-		public void StackLayoutInsideVerticalStackLayout()
-		{
-			var expectedSize = new Size(100, 100);
-			var expectedRect = new Rectangle(Point.Zero, expectedSize);
-
-			var stackLayout = new StackLayout() { IsPlatformEnabled = true };
-			var slHandler = Substitute.For<ILayoutHandler>();
-			stackLayout.Handler = slHandler;
-
-			var verticalStackLayout = new VerticalStackLayout() { IsPlatformEnabled = true };
-			var vslHandler = Substitute.For<ILayoutHandler>();
-			verticalStackLayout.Handler = vslHandler;
-
-			var button = new Button() { IsPlatformEnabled = true, HeightRequest = 100, WidthRequest = 100 };
-			var buttonHandler = Substitute.For<IViewHandler>();
-			buttonHandler.GetDesiredSize(default, default).ReturnsForAnyArgs(expectedSize);
-			button.Handler = buttonHandler;
-
-			verticalStackLayout.Add(stackLayout);
-			stackLayout.Children.Add(button);
-
-			(verticalStackLayout as IFrameworkElement).Measure(expectedRect.Width, expectedRect.Height);
-			(verticalStackLayout as IFrameworkElement).Arrange(expectedRect);
-
-			slHandler.Received().NativeArrange(expectedRect);
-			Assert.AreEqual(expectedSize, stackLayout.Bounds.Size);
-		}
-
 		[Test]
 		public void GridInsideStackLayout()
 		{

src/Core/src/Core/ILayout.cs

@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using Microsoft.Maui.Layouts;
 
 namespace Microsoft.Maui
 {
@@ -17,5 +17,10 @@ public interface ILayout : IView, IContainer
 		/// The space between the outer edge of the ILayout's content area and its children.
 		/// </summary>
 		Thickness Padding { get; }
+
+		/// <summary>
+		/// The LayoutManager responsible for laying out the children of this ILayout
+		/// </summary>
+		ILayoutManager LayoutManager { get; }
 	}
 }