IContainer proposal

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

@@ -0,0 +1,76 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Microsoft.Maui.Controls
+{
+	public abstract partial class Layout<T>
+	{
+		int ICollection<IView>.Count => _children.Count;
+		bool ICollection<IView>.IsReadOnly => ((ICollection<IView>) _children).IsReadOnly;
+		public IView this[int index] { get => _children[index]; set => _children[index] = (T)value; }
+
+		public void Add(IView child)
+		{
+			if (child is T view)
+			{
+				_children.Add(view);
+			}
+		}
+
+		public bool Remove(IView child)
+		{
+			if (child is T view)
+			{
+				_children.Remove(view);
+				return true;
+			}
+
+			return false;
+		}
+
+		int IList<IView>.IndexOf(IView child)
+		{
+			return _children.IndexOf(child);
+		}
+
+		void IList<IView>.Insert(int index, IView child)
+		{
+			if (child is T view)
+			{
+				_children.Insert(index, view);
+			}
+		}
+
+		void IList<IView>.RemoveAt(int index)
+		{
+			_children.RemoveAt(index);
+		}
+
+		void ICollection<IView>.Clear()
+		{
+			_children.Clear();
+		}
+
+		bool ICollection<IView>.Contains(IView child)
+		{
+			return _children.Contains(child);
+		}
+
+		void ICollection<IView>.CopyTo(IView[] array, int arrayIndex)
+		{
+			_children.CopyTo(array, arrayIndex);
+		}
+
+		IEnumerator<IView> IEnumerable<IView>.GetEnumerator()
+		{
+			return _children.GetEnumerator();
+		}
+
+		IEnumerator IEnumerable.GetEnumerator()
+		{
+			return _children.GetEnumerator();
+		}
+	}
+}

src/Controls/src/Core/Layout.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Collections.Specialized;
@@ -10,11 +11,8 @@
 namespace Microsoft.Maui.Controls
 {
 	[ContentProperty(nameof(Children))]
-	public abstract class Layout<T> : Layout, Microsoft.Maui.ILayout, IViewContainer<T> where T : View
+	public abstract partial class Layout<T> : Layout, Microsoft.Maui.ILayout, IViewContainer<T> where T : View
 	{
-		// TODO ezhart We should look for a way to optimize this a bit
-		IReadOnlyList<Microsoft.Maui.IView> Microsoft.Maui.IContainer.Children => Children.ToList();
-
 		readonly ElementCollection<T> _children;
 
 		protected Layout() => _children = new ElementCollection<T>(InternalChildren);
@@ -46,28 +44,10 @@ protected virtual void OnAdded(T view)
 		protected virtual void OnRemoved(T view)
 		{
 		}
-
-		public void Add(IView child)
-		{
-			if (child is T view)
-			{
-				Children.Add(view);
-			}
-		}
-
-		public void Remove(IView child)
-		{
-			if (child is T view)
-			{
-				Children.Remove(view);
-			}
-		}
 	}
 
-	public abstract class Layout : View, ILayout, ILayoutController, IPaddingElement, IFrameworkElement, Microsoft.Maui.IContainer
+	public abstract class Layout : View, ILayout, ILayoutController, IPaddingElement, IFrameworkElement//, Microsoft.Maui.IContainer
 	{
-		IReadOnlyList<Microsoft.Maui.IView> Microsoft.Maui.IContainer.Children => InternalChildren.OfType<IView>().ToList();
-
 		public static readonly BindableProperty IsClippedToBoundsProperty =
 			BindableProperty.Create(nameof(IsClippedToBounds), typeof(bool), typeof(Layout), false);
 

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

@@ -231,10 +231,10 @@ public override void Add(IView child)
 			}
 		}
 
-		public override void Remove(IView child)
+		public override bool Remove(IView child)
 		{
 			_viewInfo.Remove(child);
-			base.Remove(child);
+			return base.Remove(child);
 		}
 
 		protected override ILayoutManager CreateLayoutManager() => new GridLayoutManager(this);

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

@@ -8,78 +8,106 @@
 namespace Microsoft.Maui.Controls.Layout2
 {
 	[ContentProperty(nameof(Children))]
-	public abstract class Layout : View, Microsoft.Maui.ILayout, IEnumerable<IView>
+	public abstract class Layout : View, Maui.ILayout, IList<IView>
 	{
 		ILayoutManager _layoutManager;
 		ILayoutManager LayoutManager => _layoutManager ??= CreateLayoutManager();
 
-		readonly List<IView> _children = new List<IView>();
+		// The actual backing store for the IViews in the ILayout
+		readonly List<IView> _children = new();
 
-		public IReadOnlyList<IView> Children { get => _children.AsReadOnly(); }
+		// This provides a Children property for XAML 
+		public IList<IView> Children => this;
 
 		public ILayoutHandler LayoutHandler => Handler as ILayoutHandler;
 
+		public int Count => _children.Count;
+
+		public bool IsReadOnly => ((ICollection<IView>)_children).IsReadOnly;
+
+		public IView this[int index] { get => _children[index]; set => _children[index] = value; }
+
 		protected abstract ILayoutManager CreateLayoutManager();
 
 		public IEnumerator<IView> GetEnumerator() => _children.GetEnumerator();
-
 		IEnumerator IEnumerable.GetEnumerator() => _children.GetEnumerator();
-
 #pragma warning disable CS0672 // Member overrides obsolete member
 		public override SizeRequest GetSizeRequest(double widthConstraint, double heightConstraint)
 #pragma warning restore CS0672 // Member overrides obsolete member
 		{
 			var size = (this as IFrameworkElement).Measure(widthConstraint, heightConstraint);
 			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();
-
 			foreach (var child in Children)
 			{
 				child.InvalidateMeasure();
 			}
 		}
-
 		public virtual void Add(IView child)
 		{
 			if (child == null)
 				return;
-
 			_children.Add(child);
+			if (child is Element element)
+				element.Parent = this;
+			InvalidateMeasure();
+			LayoutHandler?.Add(child);
+		}
+
+		public void Clear()
+		{
+			for (int n = _children.Count - 1; n >= 0; n--)
+			{
+				Remove(this[n]);
+			}
+		}
+
+		public bool Contains(IView item)
+		{
+			return _children.Contains(item);
+		}
+
+		public void CopyTo(IView[] array, int arrayIndex)
+		{
+			_children.CopyTo(array, arrayIndex);
+		}
+
+		public int IndexOf(IView item)
+		{
+			return _children.IndexOf(item);
+		}
+
+		public void Insert(int index, IView child)
+		{
+			if (child == null)
+				return;
+
+			_children.Insert(index, child);
 
 			if (child is Element element)
 				element.Parent = this;
@@ -89,12 +117,33 @@ public virtual void Add(IView child)
 			LayoutHandler?.Add(child);
 		}
 
-		public virtual void Remove(IView child)
+		public virtual bool Remove(IView child)
 		{
 			if (child == null)
+				return false;
+
+			var result = _children.Remove(child);
+
+			if (child is Element element)
+				element.Parent = null;
+
+			InvalidateMeasure();
+
+			LayoutHandler?.Remove(child);
+
+			return result;
+		}
+
+		public void RemoveAt(int index)
+		{
+			if (index >= Count)
+			{
 				return;
+			}
+
+			var child = _children[index];
 
-			_children.Remove(child);
+			_children.RemoveAt(index);
 
 			if (child is Element element)
 				element.Parent = null;
@@ -104,4 +153,4 @@ public virtual void Remove(IView child)
 			LayoutHandler?.Remove(child);
 		}
 	}
-}
+}

src/Core/src/Core/IContainer.cs

@@ -5,11 +5,8 @@ namespace Microsoft.Maui
 	/// <summary>
 	/// Provides functionality to act as containers for views. 
 	/// </summary>
-	public interface IContainer
+	public interface IContainer : IList<IView>
 	{
-		/// <summary>
-		/// Gets the collection of children that the Container contains.
-		/// </summary>
-		IReadOnlyList<IView> Children { get; }
+
 	}
 }

src/Core/src/Core/ILayout.cs

@@ -8,22 +8,9 @@ namespace Microsoft.Maui
 	/// </summary>
 	public interface ILayout : IView, IContainer
 	{
-
 		/// <summary>
 		/// Gets the Layout Handler.
 		/// </summary>
 		ILayoutHandler LayoutHandler { get; }
-
-		/// <summary>
-		/// Add a child View to the Layout.
-		/// </summary>
-		/// <param name="child">The child View to add to the Layout.</param>
-		void Add(IView child);
-
-		/// <summary>
-		/// Remove a child View from the Layout.
-		/// </summary>
-		/// <param name="child">The child View to remove from the Layout.</param>
-		void Remove(IView child);
 	}
 }

src/Core/src/Handlers/Layout/LayoutHandler.Android.cs

@@ -33,7 +33,7 @@ public override void SetVirtualView(IView view)
 			NativeView.CrossPlatformArrange = VirtualView.Arrange;
 
 			NativeView.RemoveAllViews();
-			foreach (var child in VirtualView.Children)
+			foreach (var child in VirtualView)
 			{
 				NativeView.AddView(child.ToNative(MauiContext));
 			}

src/Core/src/Handlers/Layout/LayoutHandler.iOS.cs

@@ -38,7 +38,7 @@ public override void SetVirtualView(IView view)
 			var oldChildren = NativeView.Subviews.ToList();
 			oldChildren.ForEach(x => x.RemoveFromSuperview());
 
-			foreach (var child in VirtualView.Children)
+			foreach (var child in VirtualView)
 			{
 				NativeView.AddSubview(child.ToNative(MauiContext));
 			}

src/Core/src/HotReload/HotReloadExtensions.cs

@@ -29,7 +29,7 @@ public static void CheckHandlers(this IView view)
 
 			if (view is IContainer layout)
 			{
-				foreach (var v in layout.Children)
+				foreach (var v in layout)
 					CheckHandlers(v);
 			}
 		}

src/Core/src/Layouts/FlexLayoutManager.cs

@@ -17,7 +17,7 @@ public void ArrangeChildren(Rectangle childBounds)
 		{
 			FlexLayout.Layout(childBounds.Width, childBounds.Height);
 
-			foreach (var child in FlexLayout.Children)
+			foreach (var child in FlexLayout)
 			{
 				var frame = FlexLayout.GetFlexFrame(child);
 				if (double.IsNaN(frame.X)