feat: redesign banner demo.

demo/Ursa.Demo/ViewModels/BannerDemoViewModel.cs

@@ -1,6 +1,41 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+
 namespace Ursa.Demo.ViewModels;
 
-public class BannerDemoViewModel: ViewModelBase
+public partial class BannerDemoViewModel : ViewModelBase
 {
-    
+    private string? _oldTitle = string.Empty;
+    private string? _oldContent = string.Empty;
+    [ObservableProperty] private string? _title = "Welcome to Ursa";
+    [ObservableProperty] private string? _content = "This is the Demo of Ursa Banner.";
+    [ObservableProperty] private bool _bordered;
+
+    [ObservableProperty] private bool _setTitleNull = true;
+    [ObservableProperty] private bool _setContentNull = true;
+
+    partial void OnSetTitleNullChanged(bool value)
+    {
+        if (value)
+        {
+            Title = _oldTitle;
+        }
+        else
+        {
+            _oldTitle = Title;
+            Title = null;
+        }
+    }
+
+    partial void OnSetContentNullChanged(bool value)
+    {
+        if (value)
+        {
+            Content = _oldContent;
+        }
+        else
+        {
+            _oldContent = Content;
+            Content = null;
+        }
+    }
 }