feat: update demo

demo/Ursa.Demo/Pages/IPv4BoxDemo.axaml.cs

@@ -1,6 +1,9 @@
+using System;
+using System.Net;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
+using CommunityToolkit.Mvvm.ComponentModel;
 
 namespace Ursa.Demo.Pages;
 
@@ -9,10 +12,18 @@ public partial class IPv4BoxDemo : UserControl
     public IPv4BoxDemo()
     {
         InitializeComponent();
+        DataContext = new IPv4DemoViewMode();
     }
+}
 
-    private void InitializeComponent()
+public partial class IPv4DemoViewMode: ObservableObject
+{
+    [ObservableProperty]
+    private IPAddress? _address;
+
+    public void ChangeAddress()
     {
-        AvaloniaXamlLoader.Load(this);
+        long l = Random.Shared.NextInt64(0x00000000FFFFFFFF);
+        Address = new IPAddress(l);
     }
 }