chore: complete avalonia button style.

src/Avalonia/HandyControl_Avalonia/Controls/Attach/BackgroundSwitchElement.cs

@@ -0,0 +1,27 @@
+using Avalonia;
+using Avalonia.Media;
+
+namespace HandyControl.Controls;
+
+public class BackgroundSwitchElement
+{
+    public static readonly AttachedProperty<IBrush> MouseHoverBackgroundProperty =
+        AvaloniaProperty.RegisterAttached<BackgroundSwitchElement, AvaloniaObject, IBrush>("MouseHoverBackground",
+            defaultValue: Brushes.Transparent, inherits: true);
+
+    public static void SetMouseHoverBackground(AvaloniaObject element, IBrush value) =>
+        element.SetValue(MouseHoverBackgroundProperty, value);
+
+    public static IBrush GetMouseHoverBackground(AvaloniaObject element) =>
+        element.GetValue(MouseHoverBackgroundProperty);
+
+    public static readonly AttachedProperty<IBrush> MouseDownBackgroundProperty =
+        AvaloniaProperty.RegisterAttached<BackgroundSwitchElement, AvaloniaObject, IBrush>("MouseDownBackground",
+            defaultValue: Brushes.Transparent, inherits: true);
+
+    public static void SetMouseDownBackground(AvaloniaObject element, IBrush value) =>
+        element.SetValue(MouseDownBackgroundProperty, value);
+
+    public static IBrush GetMouseDownBackground(AvaloniaObject element) =>
+        element.GetValue(MouseDownBackgroundProperty);
+}

src/Avalonia/HandyControl_Avalonia/Controls/Attach/BorderElement.cs

@@ -0,0 +1,51 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Data;
+using HandyControl.Tools.Converter;
+
+namespace HandyControl.Controls;
+
+public class BorderElement
+{
+    public static readonly AttachedProperty<CornerRadius> CornerRadiusProperty =
+        AvaloniaProperty.RegisterAttached<BorderElement, AvaloniaObject, CornerRadius>("CornerRadius", inherits: true);
+
+    public static void SetCornerRadius(AvaloniaObject element, CornerRadius value) =>
+        element.SetValue(CornerRadiusProperty, value);
+
+    public static CornerRadius GetCornerRadius(AvaloniaObject element) => element.GetValue(CornerRadiusProperty);
+
+    public static readonly AttachedProperty<bool> CircularProperty =
+        AvaloniaProperty.RegisterAttached<BorderElement, AvaloniaObject, bool>("Circular");
+
+    public static void SetCircular(AvaloniaObject element, bool value) => element.SetValue(CircularProperty, value);
+
+    public static bool GetCircular(AvaloniaObject element) => element.GetValue(CircularProperty);
+
+    static BorderElement()
+    {
+        CircularProperty.Changed.AddClassHandler<AvaloniaObject>(OnCircularChanged);
+    }
+
+    private static void OnCircularChanged(AvaloniaObject d, AvaloniaPropertyChangedEventArgs e)
+    {
+        if (d is not Border border)
+        {
+            return;
+        }
+
+        if (e.GetNewValue<bool>())
+        {
+            var binding = new Binding(Visual.BoundsProperty.Name)
+            {
+                Converter = new BorderCircularConverter(),
+                Source = border,
+            };
+            border.Bind(Border.CornerRadiusProperty, binding);
+        }
+        else
+        {
+            border.ClearValue(Border.CornerRadiusProperty);
+        }
+    }
+}

src/Avalonia/HandyControl_Avalonia/Controls/Attach/IconElement.cs

@@ -0,0 +1,27 @@
+using Avalonia;
+using Avalonia.Media;
+
+namespace HandyControl.Controls;
+
+public class IconElement
+{
+    public static readonly AttachedProperty<Geometry> GeometryProperty =
+        AvaloniaProperty.RegisterAttached<IconElement, AvaloniaObject, Geometry>("Geometry");
+
+    public static void SetGeometry(AvaloniaObject element, Geometry value) => element.SetValue(GeometryProperty, value);
+
+    public static Geometry GetGeometry(AvaloniaObject element) => element.GetValue(GeometryProperty);
+
+    public static readonly AttachedProperty<double> WidthProperty =
+        AvaloniaProperty.RegisterAttached<IconElement, AvaloniaObject, double>("Width", defaultValue: double.NaN);
+
+    public static void SetWidth(AvaloniaObject element, double value) => element.SetValue(WidthProperty, value);
+
+    public static double GetWidth(AvaloniaObject element) => element.GetValue(WidthProperty);
+
+    public static readonly AttachedProperty<double> HeightProperty =
+        AvaloniaProperty.RegisterAttached<IconElement, AvaloniaObject, double>("Height", defaultValue: double.NaN);
+
+    public static void SetHeight(AvaloniaObject element, double value) => element.SetValue(HeightProperty, value);
+    public static double GetHeight(AvaloniaObject element) => element.GetValue(HeightProperty);
+}

src/Avalonia/HandyControl_Avalonia/Themes/Basic/Converters.axaml

@@ -3,5 +3,7 @@
                     xmlns:converter="clr-namespace:HandyControl.Tools.Converter">
 
     <converter:BorderClipConverter x:Key="BorderClipConverter" />
+    <converter:BorderCircularConverter x:Key="BorderCircularConverter"/>
+    <converter:GeometrySpacingConverter x:Key="GeometrySpacingConverter" />
 
 </ResourceDictionary>