RadioButtonAutomationPeer WIP

src/Avalonia.Controls/Automation/Peers/RadioButtonAutomationPeer.cs

@@ -0,0 +1,70 @@
+using System;
+using Avalonia.Automation;
+using Avalonia.Automation.Peers;
+using Avalonia.Automation.Provider;
+
+namespace Avalonia.Controls.Automation.Peers
+{
+    public class RadioButtonAutomationPeer : ToggleButtonAutomationPeer, ISelectionItemProvider
+    {
+        public RadioButtonAutomationPeer(RadioButton owner) : base(owner)
+        {
+            owner.PropertyChanged += (a, e) =>
+            {
+                if (e.Property == RadioButton.IsCheckedProperty)
+                {
+                    RaiseToggleStatePropertyChangedEvent((bool)e.OldValue, (bool)e.NewValue);
+                }
+                
+            };
+        }
+
+        override protected string GetClassNameCore()
+        {
+            return "RadioButton";
+        }
+
+        override protected AutomationControlType GetAutomationControlTypeCore()
+        {
+            return AutomationControlType.RadioButton;
+        }
+
+        public bool IsSelected => ((RadioButton)Owner).IsChecked == true;
+
+        public ISelectionProvider? SelectionContainer
+        {
+            get
+            {
+                return null;
+            }
+        }
+
+        public void AddToSelection()
+        {
+            if (((RadioButton)Owner).IsChecked != true)
+                throw new InvalidOperationException("Operation cannot be performed");
+        }
+
+        public void RemoveFromSelection()
+        {
+            if (((RadioButton)Owner).IsChecked == true)
+                throw new InvalidOperationException("Operation cannot be performed");
+        }
+
+        public void Select()
+        {
+            if (!IsEnabled())
+                throw new InvalidOperationException("Element is disabled thus it cannot be selected");
+
+            ((RadioButton)Owner).IsChecked = true;
+        }
+
+        internal virtual void RaiseToggleStatePropertyChangedEvent(bool? oldValue, bool? newValue)
+        {
+            RaisePropertyChangedEvent(
+                SelectionItemPatternIdentifiers.IsSelectedProperty,
+                oldValue == true,
+                newValue == true);
+        }
+    }
+}

src/Avalonia.Controls/Automation/SelectionItemPatternIdentifiers.cs

@@ -0,0 +1,16 @@
+using Avalonia.Automation.Provider;
+
+namespace Avalonia.Automation
+{
+    /// <summary>
+    /// Contains values used as identifiers by <see cref="ISelectionItemProvider"/>.
+    /// </summary>
+    public static class SelectionItemPatternIdentifiers
+    {
+        /// <summary>Indicates the element is currently selected.</summary>
+        public static AutomationProperty IsSelectedProperty { get; } = new AutomationProperty();
+
+        /// <summary>Indicates the element is currently selected.</summary>
+        public static AutomationProperty SelectionContainerProperty { get; } = new AutomationProperty();
+    }
+}

src/Avalonia.Controls/RadioButton.cs

@@ -2,6 +2,8 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Runtime.CompilerServices;
+using Avalonia.Automation.Peers;
+using Avalonia.Controls.Automation.Peers;
 using Avalonia.Controls.Primitives;
 using Avalonia.Reactive;
 using Avalonia.Rendering;
@@ -147,6 +149,11 @@ namespace Avalonia.Controls
             }
         }
 
+        protected override AutomationPeer OnCreateAutomationPeer()
+        {
+            return new RadioButtonAutomationPeer(this);
+        }
+
         private void SetGroupName(string? newGroupName)
         {
             var oldGroupName = GroupName;

src/Windows/Avalonia.Win32/Automation/AutomationNode.cs

@@ -41,6 +41,8 @@ namespace Avalonia.Win32.Automation
             { SelectionPatternIdentifiers.CanSelectMultipleProperty, UiaPropertyId.SelectionCanSelectMultiple },
             { SelectionPatternIdentifiers.IsSelectionRequiredProperty, UiaPropertyId.SelectionIsSelectionRequired },
             { SelectionPatternIdentifiers.SelectionProperty, UiaPropertyId.SelectionSelection },
+            { SelectionItemPatternIdentifiers.IsSelectedProperty, UiaPropertyId.SelectionItemIsSelected },
+            { SelectionItemPatternIdentifiers.SelectionContainerProperty, UiaPropertyId.SelectionItemSelectionContainer }
         };
 
         private static ConditionalWeakTable<AutomationPeer, AutomationNode> s_nodes = new();