feat: add placement.

src/Ursa/Controls/IconButton.cs

@@ -1,11 +1,17 @@
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
+using Ursa.Common;
 
 namespace Ursa.Controls;
 
+[PseudoClasses(PC_Right)]
 public class IconButton: Button
 {
+    public const string PC_Right = ":right";
+    
     public static readonly StyledProperty<object?> IconProperty = AvaloniaProperty.Register<IconButton, object?>(
         nameof(Icon));
 
@@ -32,4 +38,32 @@ public class IconButton: Button
         get => GetValue(IsLoadingProperty);
         set => SetValue(IsLoadingProperty, value);
     }
+
+    public static readonly StyledProperty<IconPlacement> IconPlacementProperty = AvaloniaProperty.Register<IconButton, IconPlacement>(
+        nameof(IconPlacement), defaultValue: IconPlacement.Left);
+
+    public IconPlacement IconPlacement
+    {
+        get => GetValue(IconPlacementProperty);
+        set => SetValue(IconPlacementProperty, value);
+    }
+
+    static IconButton()
+    {
+        IconPlacementProperty.Changed.AddClassHandler<IconButton, IconPlacement>((o, e) =>
+        {
+            o.SetPlacement(e.NewValue.Value);
+        });
+    }
+
+    protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
+    {
+        base.OnApplyTemplate(e);
+        SetPlacement(IconPlacement);
+    }
+
+    private void SetPlacement(IconPlacement placement)
+    {
+        PseudoClasses.Set(PC_Right, placement == IconPlacement.Right);
+    }
 }