feat: update to finish functionality, start to build theme.

demo/Ursa.Demo/Converters/IconNameConverter.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using Avalonia;
+using Avalonia.Controls.Shapes;
+using Avalonia.Data.Converters;
+using Avalonia.Media;
+using Avalonia.Metadata;
+
+namespace Ursa.Demo.Converters;
+
+public class IconNameConverter: IValueConverter
+{
+    [Content]
+    public Dictionary<string, PathGeometry> Paths { get; set; } = new();
+
+    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        if (value is null) return null;
+        if (value is string s)
+        {
+            return Paths.TryGetValue(s, out var path)? path: AvaloniaProperty.UnsetValue;
+        }
+        return AvaloniaProperty.UnsetValue;
+    }
+
+    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        throw new NotImplementedException();
+    }
+}