feat: Add support DataTemplate is container host

src/SamplesApp/SamplesApp.Skia/SamplesApp.Skia.csproj

@@ -42,7 +42,7 @@
 	<Import Project="..\SamplesApp.UnitTests.Shared\SamplesApp.UnitTests.Shared.projitems" Label="Shared" />
 
 	<ItemGroup>
-		<Content Update="@(Content)" CopyToOutputDirectory="Always" />
+		<Content Update="@(Content)" CopyToOutputDirectory="PreserveNewest" />
 	</ItemGroup>
 
 </Project>

src/Uno.UI.Tests/Windows_UI_XAML_Controls/ItemsControlTests/Given_ItemsControl.cs

@@ -186,6 +186,62 @@ public void When_ObservableVectorChanged()
 			source.Remove(1);
 			Assert.AreEqual(7, count);
 		}
+
+		[TestMethod]
+		public void When_ContainerStyleSet()
+		{
+			var count = 0;
+			var panel = new StackPanel();
+
+			var source = new ObservableVector<int>() { 1, 2, 3 };
+
+			var SUT = new ItemsControl()
+			{
+				ItemsPanelRoot = panel,
+				ItemContainerStyle = BuildBasicContainerStyle(),
+				InternalItemsPanelRoot = panel,
+				ItemTemplate = new DataTemplate(() =>
+				{
+					count++;
+					return new Border();
+				})
+			};
+
+			SUT.ApplyTemplate();
+
+			Assert.AreEqual(0, count);
+
+			SUT.ItemsSource = source;
+			Assert.AreEqual(3, count);
+
+			source.Add(4);
+			Assert.AreEqual(7, count);
+
+			source.Remove(1);
+			Assert.AreEqual(7, count);
+		}
+
+		private Style BuildBasicContainerStyle() =>
+			new Style(typeof(Windows.UI.Xaml.Controls.ListViewItem))
+			{
+				Setters =  {
+					new Setter<ListViewItem>("Template", t =>
+						t.Template = Funcs.Create(() =>
+							new Grid
+							{
+								Children = {
+									new ContentPresenter()
+										.Apply(p => {
+											p.SetBinding(ContentPresenter.ContentTemplateProperty, new Binding(){ Path = "ContentTemplate", RelativeSource = RelativeSource.TemplatedParent });
+											p.SetBinding(ContentPresenter.ContentProperty, new Binding(){ Path = "Content", RelativeSource = RelativeSource.TemplatedParent });
+										})
+								}
+							}
+						)
+					)
+				}
+			};
+
 	}
 
 	public class MyItemsControl : ItemsControl

src/Uno.UI.Tests/Windows_UI_XAML_Controls/ListViewBaseTests/Given_ListViewBase.cs

@@ -619,26 +619,156 @@ public void When_ItemClick()
 			Assert.AreEqual(0, selectionChanged[0].RemovedItems.Count);
 		}
 
+		[TestMethod]
+		public void When_ContainerSet_Then_ContentShouldBeSet()
+		{
+			var SUT = new ListView()
+			{
+				ItemsPanel = new ItemsPanelTemplate(() => new StackPanel()),
+				ItemContainerStyle = BuildBasicContainerStyle(),
+				ItemTemplate = new DataTemplate(() =>
+				{
+					var tb = new TextBlock();
+					tb.SetBinding(TextBlock.TextProperty, new Binding());
+					return tb;
+				}),
+				Template = new ControlTemplate(() => new ItemsPresenter()),
+			};
+
+			SUT.ForceLoaded();
+
+			var source = new[] {
+				"item 0",
+			};
+
+			SUT.ItemsSource = source;
+
+			Assert.AreEqual(-1, SUT.SelectedIndex);
+
+			var si = SUT.ContainerFromItem(source[0]) as SelectorItem;
+			Assert.IsNotNull(si);
+
+			var tb = si.ContentTemplateRoot as TextBlock;
+			Assert.AreEqual("item 0", tb?.Text);
+		}
+
+		[TestMethod]
+		public void When_IsItsOwnItemContainer_FromSource()
+		{
+			var SUT = new ListView()
+			{
+				Style = null,
+				ItemsPanel = new ItemsPanelTemplate(() => new StackPanel()),
+				ItemContainerStyle = BuildBasicContainerStyle(),
+				Template = new ControlTemplate(() => new ItemsPresenter()),
+				SelectionMode = ListViewSelectionMode.Single,
+			};
+
+			SUT.ForceLoaded();
+
+			var source = new[] {
+				new ListViewItem(){ Content = "item 1" },
+				new ListViewItem(){ Content = "item 2" },
+				new ListViewItem(){ Content = "item 3" },
+				new ListViewItem(){ Content = "item 4" },
+			};
+
+			SUT.ItemsSource = source;
+
+			var si = SUT.ContainerFromItem(source[0]) as ListViewItem;
+			Assert.IsNotNull(si);
+			Assert.AreEqual("item 1", si.Content);
+		}
+
+		[TestMethod]
+		public void When_NoItemTemplate()
+		{
+			var SUT = new ListView()
+			{
+				Style = null,
+				ItemsPanel = new ItemsPanelTemplate(() => new StackPanel()),
+				ItemContainerStyle = BuildBasicContainerStyle(),
+				ItemTemplate = null,
+				ItemTemplateSelector = null,
+				Template = new ControlTemplate(() => new ItemsPresenter()),
+			};
+
+			SUT.ForceLoaded();
+
+			var source = new[] {
+				"Item 1"
+			};
+
+			SUT.ItemsSource = source;
+
+			var si = SUT.ContainerFromItem(source[0]) as ListViewItem;
+			Assert.IsNotNull(si);
+			Assert.AreEqual("Item 1", si.Content);
+			Assert.IsInstanceOfType(si.ContentTemplateRoot, typeof(ImplicitTextBlock));
+			Assert.AreEqual("Item 1", (si.ContentTemplateRoot as TextBlock).Text);
+		}
+
+		[TestMethod]
+		public void When_IsItsOwnItemContainer_FromSource_With_DataTemplate()
+		{
+			var SUT = new ListView()
+			{
+				Style = null,
+				ItemsPanel = new ItemsPanelTemplate(() => new StackPanel()),
+				ItemContainerStyle = BuildBasicContainerStyle(),
+				ItemTemplate = new DataTemplate(() =>
+				{
+					var tb = new TextBlock();
+					tb.SetBinding(TextBlock.TextProperty, new Binding());
+					return tb;
+				}),
+				Template = new ControlTemplate(() => new ItemsPresenter()),
+				SelectionMode = ListViewSelectionMode.Single,
+			};
+
+			SUT.ForceLoaded();
+
+			var source = new object[] {
+				new ListViewItem(){ Content = "item 1" },
+				"item 2"
+			};
+
+			SUT.ItemsSource = source;
+
+			var si = SUT.ContainerFromItem(source[0]) as ListViewItem;
+			Assert.IsNotNull(si);
+			Assert.AreEqual("item 1", si.Content);
+			Assert.AreSame(si, source[0]);
+			Assert.IsFalse(si.IsGeneratedContainer);
+
+			var si2 = SUT.ContainerFromItem(source[1]) as ListViewItem;
+			Assert.IsNotNull(si2);
+			Assert.AreNotSame(si, source[1]);
+			Assert.AreEqual("item 2", si2.DataContext);
+			Assert.AreEqual("item 2", (si2.Content as TextBlock).Text);
+			Assert.IsTrue(si2.IsGeneratedContainer);
+		}
+
 		private Style BuildBasicContainerStyle() =>
-			new Style(typeof(Windows.UI.Xaml.Controls.ListViewItem))
-			{
-				Setters =  {
-					new Setter<ListViewItem>("Template", t =>
-						t.Template = Funcs.Create(() =>
-							new Grid
-							{
-								Children = {
-									new ContentPresenter()
-										.Apply(p => {
-											p.SetBinding(ContentPresenter.ContentTemplateProperty, new Binding(){ Path = "ContentTemplate", RelativeSource = RelativeSource.TemplatedParent });
-											p.SetBinding(ContentPresenter.ContentProperty, new Binding(){ Path = "Content", RelativeSource = RelativeSource.TemplatedParent });
-										})
-								}
+		new Style(typeof(Windows.UI.Xaml.Controls.ListViewItem))
+		{
+			Setters =  {
+				new Setter<ListViewItem>("Template", t =>
+					t.Template = Funcs.Create(() =>
+						new Grid
+						{
+							Children = {
+								new ContentPresenter()
+									.Apply(p => {
+										p.SetBinding(ContentPresenter.ContentTemplateProperty, new Binding(){ Path = "ContentTemplate", RelativeSource = RelativeSource.TemplatedParent });
+										p.SetBinding(ContentPresenter.ContentProperty, new Binding(){ Path = "Content", RelativeSource = RelativeSource.TemplatedParent });
+									})
 							}
-						)
+						}
 					)
-				}
-			};
+				)
+			}
+		};
 	}
 
 	public class MyModel

src/Uno.UI.Tests/Windows_UI_XAML_Controls/ListViewBaseTests/Given_ListViewBase_CustomContainer.cs

@@ -0,0 +1,122 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Uno.Extensions;
+using Windows.Foundation;
+using Windows.Foundation.Collections;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Controls.Primitives;
+using Windows.UI.Xaml.Data;
+
+namespace Uno.UI.Tests.ItemsControlTests_CustomContainer
+{
+	[TestClass]
+	public class Given_ListViewBase_CustomContainer
+	{
+		[TestMethod]
+		public void When_TemplateRootIsOwnContainer()
+		{
+			var count = 0;
+			var panel = new StackPanel();
+
+			var SUT = new MyItemsControl()
+			{
+				ItemsPanelRoot = panel,
+				ItemTemplate = new DataTemplate(() =>
+				{
+					count++;
+					return new MyCustomItemContainer() { MyValue = 42 };
+				}),
+				Template = new ControlTemplate(() => new ItemsPresenter()),
+			};
+
+			SUT.ApplyTemplate();
+
+			SUT.ItemsSource = new object[]
+			{
+				42
+			};
+
+			var container = SUT.ContainerFromIndex(0) as MyCustomItemContainer;
+
+			Assert.IsNotNull(container);
+			Assert.IsTrue(container.IsGeneratedContainer);
+			Assert.IsFalse(container.ContentTemplateRoot is MyCustomItemContainer);
+			Assert.AreEqual(42, container.Content);
+		}
+
+		[TestMethod]
+		public void When_TemplateSelector_RootIsOwnContainer()
+		{
+			var count = 0;
+			var panel = new StackPanel();
+
+			var itemsPresenter = new MyItemsControl();
+
+			var itemTemplate = new DataTemplate(() =>
+			 {
+				 count++;
+				 return new MyCustomItemContainer() { MyValue = 42 };
+			 });
+
+			var SUT = new MyItemsControl()
+			{
+				ItemsPanelRoot = panel,
+				ItemTemplateSelector = new MyDataTemplateSelector(i => itemTemplate),
+				Template = new ControlTemplate(() => new ItemsPresenter()),
+			};
+
+			SUT.ApplyTemplate();
+
+			SUT.ItemsSource = new object[]
+			{
+				42
+			};
+
+			var container = SUT.ContainerFromIndex(0) as MyCustomItemContainer;
+
+			Assert.IsTrue(container is MyCustomItemContainer);
+			Assert.IsTrue(container.IsGeneratedContainer);
+			Assert.IsFalse(container.ContentTemplateRoot is MyCustomItemContainer);
+			Assert.AreEqual(42, container.Content);
+		}
+	}
+
+	public class MyDataTemplateSelector : DataTemplateSelector
+	{
+		private Func<object, DataTemplate> _selector;
+
+		public MyDataTemplateSelector(Func<object, DataTemplate> selector) => _selector = selector;
+
+		protected override DataTemplate SelectTemplateCore(object item) => _selector.Invoke(item);
+	}
+
+
+	public class MyItemsControl : ListView
+	{
+		protected override DependencyObject GetContainerForItemOverride()
+			=> new MyCustomItemContainer();
+
+		protected override bool IsItemItsOwnContainerOverride(object item)
+			=> item is MyCustomItemContainer;
+	}
+
+	public class MyCustomItemContainer : SelectorItem
+	{
+		public int MyValue
+		{
+			get { return (int)GetValue(MyValueProperty); }
+			set { SetValue(MyValueProperty, value); }
+		}
+
+		// Using a DependencyProperty as the backing store for MyValue.  This enables animation, styling, binding, etc...
+		public static readonly DependencyProperty MyValueProperty =
+			DependencyProperty.Register("MyValue", typeof(int), typeof(MyCustomItemContainer), new PropertyMetadata(0));
+
+
+	}
+}

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

@@ -602,7 +602,7 @@ protected virtual void OnContentChanged(object oldValue, object newValue)
 			}
 		}
 
-		private void TrySetDataContextFromContent(object value)
+		internal void TrySetDataContextFromContent(object value)
 		{
 			if (value != null)
 			{