WIP: Use ItemsRepeater as base for ItemsPresenter #2

.ncrunch/Avalonia.Controls.DataGrid.v3.ncrunchproject

@@ -3,5 +3,6 @@
     <HiddenComponentWarnings>
       <Value>MissingOrIgnoredProjectReference</Value>
     </HiddenComponentWarnings>
+    <InstrumentOutputAssembly>False</InstrumentOutputAssembly>
   </Settings>
 </ProjectConfiguration>

.ncrunch/Avalonia.ReactiveUI.Events.UnitTests.v3.ncrunchproject

@@ -0,0 +1,5 @@
+<ProjectConfiguration>
+  <Settings>
+    <IgnoreThisComponentCompletely>True</IgnoreThisComponentCompletely>
+  </Settings>
+</ProjectConfiguration>

.ncrunch/Avalonia.Themes.Default.v3.ncrunchproject

@@ -3,6 +3,7 @@
     <HiddenComponentWarnings>
       <Value>MissingOrIgnoredProjectReference</Value>
     </HiddenComponentWarnings>
+    <InstrumentOutputAssembly>False</InstrumentOutputAssembly>
     <PreviouslyBuiltSuccessfully>True</PreviouslyBuiltSuccessfully>
   </Settings>
 </ProjectConfiguration>

.ncrunch/Avalonia.Win32.Interop.v3.ncrunchproject

@@ -3,6 +3,7 @@
     <HiddenComponentWarnings>
       <Value>MissingOrIgnoredProjectReference</Value>
     </HiddenComponentWarnings>
+    <IgnoreThisComponentCompletely>True</IgnoreThisComponentCompletely>
     <PreviouslyBuiltSuccessfully>True</PreviouslyBuiltSuccessfully>
   </Settings>
 </ProjectConfiguration>

.ncrunch/Avalonia.Win32.v3.ncrunchproject

@@ -3,6 +3,7 @@
     <HiddenComponentWarnings>
       <Value>MissingOrIgnoredProjectReference</Value>
     </HiddenComponentWarnings>
+    <IgnoreThisComponentCompletely>True</IgnoreThisComponentCompletely>
     <PreviouslyBuiltSuccessfully>True</PreviouslyBuiltSuccessfully>
   </Settings>
 </ProjectConfiguration>

.ncrunch/Direct3DInteropSample.v3.ncrunchproject

@@ -3,6 +3,7 @@
     <HiddenComponentWarnings>
       <Value>MissingOrIgnoredProjectReference</Value>
     </HiddenComponentWarnings>
+    <IgnoreThisComponentCompletely>True</IgnoreThisComponentCompletely>
     <PreviouslyBuiltSuccessfully>True</PreviouslyBuiltSuccessfully>
   </Settings>
 </ProjectConfiguration>

Directory.Build.props

@@ -4,5 +4,6 @@
       <AvaloniaPreviewerNetCoreToolPath>$(MSBuildThisFileDirectory)\src\tools\Avalonia.Designer.HostApp\bin\$(Configuration)\netcoreapp2.0\Avalonia.Designer.HostApp.dll</AvaloniaPreviewerNetCoreToolPath>
       <!-- https://github.com/dotnet/msbuild/issues/2661 -->
       <AddSyntheticProjectReferencesForSolutionDependencies>false</AddSyntheticProjectReferencesForSolutionDependencies>
+      <RunApiCompat>false</RunApiCompat>
   </PropertyGroup>
 </Project>

samples/ControlCatalog/Pages/CarouselPage.xaml

@@ -11,7 +11,7 @@
       </Button>
       <Carousel Name="carousel">
         <Carousel.PageTransition>
-          <PageSlide Duration="0.25" Orientation="Vertical" />
+          <PageSlide Duration="0.25" Orientation="Horizontal" />
         </Carousel.PageTransition>
         <Image Source="/Assets/delicate-arch-896885_640.jpg"/>
         <Image Source="/Assets/hirsch-899118_640.jpg"/>
@@ -33,7 +33,7 @@
 
     <StackPanel Orientation="Horizontal" Spacing="4">
       <TextBlock VerticalAlignment="Center">Orientation</TextBlock>
-      <ComboBox Name="orientation" SelectedIndex="1" VerticalAlignment="Center">
+      <ComboBox Name="orientation" SelectedIndex="0" VerticalAlignment="Center">
         <ComboBoxItem>Horizontal</ComboBoxItem>
         <ComboBoxItem>Vertical</ComboBoxItem>
       </ComboBox>

samples/ControlCatalog/Pages/ListBoxPage.xaml

@@ -1,6 +1,8 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             x:Class="ControlCatalog.Pages.ListBoxPage">
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             x:Class="ControlCatalog.Pages.ListBoxPage"
+             d:DesignWidth="800" d:DesignHeight="600">
   <DockPanel>
     <StackPanel DockPanel.Dock="Top" Margin="4">
       <TextBlock Classes="h1">ListBox</TextBlock>
@@ -12,12 +14,20 @@
       <CheckBox IsChecked="{Binding AlwaysSelected}">AlwaysSelected</CheckBox>
       <CheckBox IsChecked="{Binding AutoScrollToSelectedItem}">AutoScrollToSelectedItem</CheckBox>
     </StackPanel>
-    <StackPanel DockPanel.Dock="Bottom" Orientation="Horizontal" Margin="4">
+    <StackPanel DockPanel.Dock="Bottom">
+      <TextBlock x:Name="realizedCount">Initializing...</TextBlock>
+    </StackPanel>  
+    <StackPanel DockPanel.Dock="Bottom" Orientation="Horizontal" Margin="4" Spacing="4">
       <Button Command="{Binding AddItemCommand}">Add</Button>
       <Button Command="{Binding RemoveItemCommand}">Remove</Button>
       <Button Command="{Binding SelectRandomItemCommand}">Select Random Item</Button>
+      <ComboBox SelectedIndex="{Binding ItemType}">
+        <ComboBoxItem>From DataTemplate</ComboBoxItem>
+        <ComboBoxItem>Inline ListBoxItems</ComboBoxItem>
+      </ComboBox>
     </StackPanel>
-    <ListBox Items="{Binding Items}"
+    <ListBox x:Name="listBox"
+             Items="{Binding Items}"
              Selection="{Binding Selection}"
              AutoScrollToSelectedItem="{Binding AutoScrollToSelectedItem}"
              SelectionMode="{Binding SelectionMode^}"/>

samples/ControlCatalog/Pages/ListBoxPage.xaml.cs

@@ -1,15 +1,38 @@
+using System;
 using Avalonia.Controls;
+using Avalonia.Controls.Presenters;
 using Avalonia.Markup.Xaml;
 using ControlCatalog.ViewModels;
 
 namespace ControlCatalog.Pages
 {
     public class ListBoxPage : UserControl
     {
+        private ListBox _listBox;
+        private IItemsPresenter _presenter;
+        private TextBlock _realizedCount;
+
         public ListBoxPage()
         {
             InitializeComponent();
             DataContext = new ListBoxPageViewModel();
+
+            _listBox = this.FindControl<ListBox>("listBox");
+            _realizedCount = this.FindControl<TextBlock>("realizedCount");
+            LayoutUpdated += OnLayoutUpdated;
+        }
+
+        private void OnLayoutUpdated(object sender, EventArgs e)
+        {
+            LayoutUpdated -= OnLayoutUpdated;
+            _presenter = _listBox.Presenter;
+            _presenter.VisualChildren.CollectionChanged += (s, e) => UpdateRealizedCount();
+            UpdateRealizedCount();
+        }
+
+        private void UpdateRealizedCount()
+        {
+            _realizedCount.Text = $"{_presenter.VisualChildren.Count} containers realized";
         }
 
         private void InitializeComponent()

samples/ControlCatalog/SideBar.xaml

@@ -13,6 +13,9 @@
         <Setter Property="TabStripPlacement" Value="Left"/>
         <Setter Property="Padding" Value="8 0 0 0"/>
         <Setter Property="Background" Value="{DynamicResource SystemAccentColor}"/>
+        <Setter Property="Layout">
+          <NonVirtualizingStackLayout Orientation="Vertical"/>
+        </Setter>
         <Setter Property="Template">
             <ControlTemplate>
                 <Border 
@@ -28,9 +31,7 @@
                             DockPanel.Dock="Left">
                             <ItemsPresenter
                                 Name="PART_ItemsPresenter"                          
-                                Items="{TemplateBinding Items}"
-                                ItemsPanel="{TemplateBinding ItemsPanel}"
-                                ItemTemplate="{TemplateBinding ItemTemplate}">
+                                ItemsView="{TemplateBinding ItemsView}">
                             </ItemsPresenter>
                         </ScrollViewer>
                         <ContentControl Content="{TemplateBinding Tag}" HorizontalContentAlignment="Right" DockPanel.Dock="Bottom"/>

samples/ControlCatalog/ViewModels/ListBoxPageViewModel.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Collections;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Linq;
 using System.Reactive;
@@ -10,18 +12,30 @@ namespace ControlCatalog.ViewModels
 {
     public class ListBoxPageViewModel : ViewModelBase
     {
+        private IList _items;
         private bool _multiple;
         private bool _toggle;
         private bool _alwaysSelected;
         private bool _autoScrollToSelectedItem = true;
-        private int _counter;
+        private ItemTypes _itemType;
         private IObservable<SelectionMode> _selectionMode;
 
         public ListBoxPageViewModel()
         {
-            Items = new ObservableCollection<string>(Enumerable.Range(1, 10000).Select(i => GenerateItem()));
+            this.WhenAnyValue(x => x.ItemType)
+                .Subscribe(x =>
+                {
+                    Items = x switch
+                    {
+                        ItemTypes.FromDataTemplate => new ObservableCollection<string>(
+                            Enumerable.Range(0, 10000).Select(i => GenerateContent(i))),
+                        ItemTypes.ListBoxItems => new ObservableCollection<ListBoxItem>(
+                            Enumerable.Range(0, 200).Select(i => GenerateItem(i))),
+                        _ => throw new NotSupportedException(),
+                    };
+                });
 
-            Selection = new SelectionModel<string>();
+            Selection = new SelectionModel<object>();
             Selection.Select(1);
 
             _selectionMode = this.WhenAnyValue(
@@ -33,7 +47,17 @@ public ListBoxPageViewModel()
                     (t ? Avalonia.Controls.SelectionMode.Toggle : 0) |
                     (a ? Avalonia.Controls.SelectionMode.AlwaysSelected : 0));
 
-            AddItemCommand = MiniCommand.Create(() => Items.Add(GenerateItem()));
+            AddItemCommand = MiniCommand.Create(() =>
+            {
+                if (ItemType == ItemTypes.FromDataTemplate)
+                {
+                    Items.Add(GenerateContent(Items.Count));
+                }
+                else
+                {
+                    Items.Add(GenerateItem(Items.Count));
+                }
+            });
 
             RemoveItemCommand = MiniCommand.Create(() =>
             {
@@ -49,16 +73,24 @@ public ListBoxPageViewModel()
             {
                 var random = new Random();
 
-                using (Selection.BatchUpdate())
+                if (Items.Count > 0)
                 {
-                    Selection.Clear();
-                    Selection.Select(random.Next(Items.Count - 1));
+                    using (Selection.BatchUpdate())
+                    {
+                        Selection.Clear();
+                        Selection.Select(random.Next(Items.Count - 1));
+                    }
                 }
             });
         }
 
-        public ObservableCollection<string> Items { get; }
-        public SelectionModel<string> Selection { get; }
+        public IList Items 
+        {
+            get => _items;
+            private set => this.RaiseAndSetIfChanged(ref _items, value);
+        }
+
+        public SelectionModel<object> Selection { get; }
         public IObservable<SelectionMode> SelectionMode => _selectionMode;
 
         public bool Multiple
@@ -85,10 +117,26 @@ public bool AutoScrollToSelectedItem
             set => this.RaiseAndSetIfChanged(ref _autoScrollToSelectedItem, value);
         }
 
+        public ItemTypes ItemType
+        {
+            get => _itemType;
+            set => this.RaiseAndSetIfChanged(ref _itemType, value);
+        }
+
         public MiniCommand AddItemCommand { get; }
         public MiniCommand RemoveItemCommand { get; }
         public MiniCommand SelectRandomItemCommand { get; }
 
-        private string GenerateItem() => $"Item {_counter++.ToString()}";
+        private string GenerateContent(int index) => $"Item {index}";
+        private ListBoxItem GenerateItem(int index) => new ListBoxItem 
+        { 
+            Content = "ListBoxItem " + GenerateContent(index) 
+        };
+
+        public enum ItemTypes
+        {
+            FromDataTemplate,
+            ListBoxItems,
+        }
     }
 }

samples/RenderDemo/SideBar.xaml

@@ -18,9 +18,8 @@
                 Background="{TemplateBinding Background}">
               <ItemsPresenter
                   Name="PART_ItemsPresenter"
-                  Items="{TemplateBinding Items}"
-                  ItemsPanel="{TemplateBinding ItemsPanel}"
-                  ItemTemplate="{TemplateBinding ItemTemplate}">
+                  ItemsView="{TemplateBinding ItemsView}"
+                  Layout="{TemplateBinding Layout}">
               </ItemsPresenter>
             </ScrollViewer>
             <ContentPresenter

samples/VirtualizationDemo/MainWindow.xaml

@@ -47,14 +47,8 @@
                  Items="{Binding Items}" 
                  Selection="{Binding Selection}"
                  SelectionMode="Multiple"
-                 VirtualizationMode="{Binding VirtualizationMode}"
                  ScrollViewer.HorizontalScrollBarVisibility="{Binding HorizontalScrollBarVisibility, Mode=TwoWay}"
                  ScrollViewer.VerticalScrollBarVisibility="{Binding VerticalScrollBarVisibility, Mode=TwoWay}">
-            <ListBox.ItemsPanel>
-                <ItemsPanelTemplate>
-                    <VirtualizingStackPanel Orientation="{Binding Orientation}"/>
-                </ItemsPanelTemplate>
-            </ListBox.ItemsPanel>
             <ListBox.ItemTemplate>
                 <DataTemplate>
                     <TextBlock Text="{Binding Header}" Height="{Binding Height}" TextWrapping="Wrap"/>

samples/VirtualizationDemo/ViewModels/MainWindowViewModel.cs

@@ -21,7 +21,6 @@ internal class MainWindowViewModel : ViewModelBase
         private ScrollBarVisibility _horizontalScrollBarVisibility = ScrollBarVisibility.Auto;
         private ScrollBarVisibility _verticalScrollBarVisibility = ScrollBarVisibility.Auto;
         private Orientation _orientation = Orientation.Vertical;
-        private ItemVirtualizationMode _virtualizationMode = ItemVirtualizationMode.Simple;
 
         public MainWindowViewModel()
         {
@@ -81,15 +80,6 @@ public ScrollBarVisibility VerticalScrollBarVisibility
         public IEnumerable<ScrollBarVisibility> ScrollBarVisibilities =>
             Enum.GetValues(typeof(ScrollBarVisibility)).Cast<ScrollBarVisibility>();
 
-        public ItemVirtualizationMode VirtualizationMode
-        {
-            get { return _virtualizationMode; }
-            set { this.RaiseAndSetIfChanged(ref _virtualizationMode, value); }
-        }
-
-        public IEnumerable<ItemVirtualizationMode> VirtualizationModes => 
-            Enum.GetValues(typeof(ItemVirtualizationMode)).Cast<ItemVirtualizationMode>();
-
         public MiniCommand AddItemCommand { get; private set; }
         public MiniCommand RecreateCommand { get; private set; }
         public MiniCommand RemoveItemCommand { get; private set; }

src/Avalonia.Controls/Carousel.cs

@@ -1,8 +1,6 @@
 using Avalonia.Animation;
 using Avalonia.Controls.Primitives;
-using Avalonia.Controls.Templates;
 using Avalonia.Controls.Utils;
-using Avalonia.Input;
 
 namespace Avalonia.Controls
 {
@@ -23,20 +21,12 @@ public class Carousel : SelectingItemsControl
         public static readonly StyledProperty<IPageTransition> PageTransitionProperty =
             AvaloniaProperty.Register<Carousel, IPageTransition>(nameof(PageTransition));
 
-        /// <summary>
-        /// The default value of <see cref="ItemsControl.ItemsPanelProperty"/> for 
-        /// <see cref="Carousel"/>.
-        /// </summary>
-        private static readonly ITemplate<IPanel> PanelTemplate =
-            new FuncTemplate<IPanel>(() => new Panel());
-
         /// <summary>
         /// Initializes static members of the <see cref="Carousel"/> class.
         /// </summary>
         static Carousel()
         {
             SelectionModeProperty.OverrideDefaultValue<Carousel>(SelectionMode.AlwaysSelected);
-            ItemsPanelProperty.OverrideDefaultValue<Carousel>(PanelTemplate);
         }
 
         /// <summary>