Added TreeView to ControlCatalog.

samples/ControlCatalog/ControlCatalog.csproj

@@ -127,6 +127,9 @@
     <Compile Include="Pages\SliderPage.xaml.cs">
       <DependentUpon>SliderPage.xaml</DependentUpon>
     </Compile>
+    <Compile Include="Pages\TreeViewPage.xaml.cs">
+      <DependentUpon>TreeViewPage.xaml</DependentUpon>
+    </Compile>
     <Compile Include="Pages\TextBoxPage.xaml.cs">
       <DependentUpon>TextBoxPage.xaml</DependentUpon>
     </Compile>
@@ -207,6 +210,11 @@
   <ItemGroup>
     <EmbeddedResource Include="Assets\test_icon.ico" />
   </ItemGroup>
+  <ItemGroup>
+    <EmbeddedResource Include="Pages\TreeViewPage.xaml">
+      <SubType>Designer</SubType>
+    </EmbeddedResource>
+  </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.

samples/ControlCatalog/MainWindow.xaml

@@ -20,5 +20,6 @@
     <TabItem Header="Slider"><pages:SliderPage/></TabItem>
     <TabItem Header="TextBox"><pages:TextBoxPage/></TabItem>
     <TabItem Header="ToolTip"><pages:ToolTipPage/></TabItem>
+    <TabItem Header="TreeView"><pages:TreeViewPage/></TabItem>
   </TabControl>
 </Window>

samples/ControlCatalog/Pages/TreeViewPage.xaml

@@ -0,0 +1,19 @@
+<UserControl xmlns="https://github.com/avaloniaui">
+  <StackPanel Orientation="Vertical" Gap="4">
+    <TextBlock Classes="h1">TreeView</TextBlock>
+    <TextBlock Classes="h2">Displays a hierachical tree of data.</TextBlock>
+
+    <StackPanel Orientation="Horizontal"
+              Margin="0,16,0,0"
+              HorizontalAlignment="Center"
+              Gap="16">
+      <TreeView Items="{Binding}" Width="250" Height="350">
+        <TreeView.ItemTemplate>
+          <TreeDataTemplate ItemsSource="{Binding Children}">
+            <TextBlock Text="{Binding Header}"/>
+          </TreeDataTemplate>
+        </TreeView.ItemTemplate>
+      </TreeView>
+    </StackPanel>
+  </StackPanel>
+</UserControl>

samples/ControlCatalog/Pages/TreeViewPage.xaml.cs

@@ -0,0 +1,37 @@
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace ControlCatalog.Pages
+{
+    public class TreeViewPage : UserControl
+    {
+        public TreeViewPage()
+        {
+            this.InitializeComponent();
+            DataContext = CreateNodes(0);
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+
+        private IList<Node> CreateNodes(int level)
+        {
+            return Enumerable.Range(0, 10).Select(x => new Node
+            {
+                Header = $"Item {x}",
+                Children = level < 5 ? CreateNodes(level + 1) : null,
+            }).ToList();
+        }
+
+        private class Node
+        {
+            public string Header { get; set; }
+            public IList<Node> Children { get; set; }
+        }
+    }
+}