feat: initialize marquee, add demo.

demo/Ursa.Demo/Pages/MarqueeDemo.axaml

@@ -0,0 +1,20 @@
+<UserControl
+    x:Class="Ursa.Demo.Pages.MarqueeDemo"
+    xmlns="https://github.com/avaloniaui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:u="https://irihi.tech/ursa"
+    d:DesignHeight="450"
+    d:DesignWidth="800"
+    mc:Ignorable="d">
+    <StackPanel>
+        <u:EnumSelector Name="direction" EnumType="{x:Type u:Direction}" />
+        <u:Marquee
+            Background="Red"
+            Height="100" 
+            Direction="{Binding #direction.Value}" >
+            <TextBlock Text="Hello World" VerticalAlignment="Center"/>
+        </u:Marquee>
+    </StackPanel>
+</UserControl>

demo/Ursa.Demo/Pages/MarqueeDemo.axaml.cs

@@ -0,0 +1,13 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace Ursa.Demo.Pages;
+
+public partial class MarqueeDemo : UserControl
+{
+    public MarqueeDemo()
+    {
+        InitializeComponent();
+    }
+}

demo/Ursa.Demo/ViewModels/MainViewViewModel.cs

@@ -54,6 +54,7 @@ public partial class MainViewViewModel : ViewModelBase
             MenuKeys.MenuKeyIpBox => new IPv4BoxDemoViewModel(),
             MenuKeys.MenuKeyKeyGestureInput => new KeyGestureInputDemoViewModel(),
             MenuKeys.MenuKeyLoading => new LoadingDemoViewModel(),
+            MenuKeys.MenuKeyMarquee => new MarqueeDemoViewModel(),
             MenuKeys.MenuKeyMessageBox => new MessageBoxDemoViewModel(),
             MenuKeys.MenuKeyMultiComboBox => new MultiComboBoxDemoViewModel(),
             MenuKeys.MenuKeyNavMenu => new NavMenuDemoViewModel(),

demo/Ursa.Demo/ViewModels/MarqueeDemoViewModel.cs

@@ -0,0 +1,8 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+
+namespace Ursa.Demo.ViewModels;
+
+public class MarqueeDemoViewModel: ViewModelBase
+{
+    
+}

demo/Ursa.Demo/ViewModels/MenuViewModel.cs

@@ -35,6 +35,7 @@ public class MenuViewModel : ViewModelBase
             new() { MenuHeader = "IPv4Box", Key = MenuKeys.MenuKeyIpBox },
             new() { MenuHeader = "KeyGestureInput", Key = MenuKeys.MenuKeyKeyGestureInput },
             new() { MenuHeader = "Loading", Key = MenuKeys.MenuKeyLoading },
+            new() { MenuHeader = "Marquee", Key = MenuKeys.MenuKeyMarquee },
             new() { MenuHeader = "Message Box", Key = MenuKeys.MenuKeyMessageBox },
             new() { MenuHeader = "MultiComboBox", Key = MenuKeys.MenuKeyMultiComboBox, Status = "Updated" },
             new() { MenuHeader = "Nav Menu", Key = MenuKeys.MenuKeyNavMenu },
@@ -89,6 +90,7 @@ public static class MenuKeys
     public const string MenuKeyIpBox = "IPv4Box";
     public const string MenuKeyKeyGestureInput = "KeyGestureInput";
     public const string MenuKeyLoading = "Loading";
+    public const string MenuKeyMarquee = "Marquee";
     public const string MenuKeyMessageBox = "MessageBox";
     public const string MenuKeyMultiComboBox = "MultiComboBox";
     public const string MenuKeyNavMenu = "NavMenu";