Implement accessibility for ListBox

native/Avalonia.Native/src/OSX/automation.mm

@@ -144,6 +144,7 @@ - (NSAccessibilitySubrole)accessibilitySubrole
 
     auto landmarkType = _peer->GetLandmarkType();
     switch (landmarkType) {
+        case LandmarkNone: break;
         case LandmarkBanner: return @"AXLandmarkBanner";
         case LandmarkComplementary: return @"AXLandmarkComplementary";
         case LandmarkContentInfo: return @"AXLandmarkContentInfo";
@@ -161,6 +162,7 @@ - (NSString *)accessibilityRoleDescription
 {
     auto landmarkType = _peer->GetLandmarkType();
     switch (landmarkType) {
+        case LandmarkNone: break;
         case LandmarkBanner: return @"banner";
         case LandmarkComplementary: return @"complementary";
         case LandmarkContentInfo: return @"content";
@@ -191,6 +193,7 @@ - (id)accessibilityAttributeValue:(NSAccessibilityAttributeName)attribute
     {
         switch (_peer->GetLiveSetting())
         {
+            case LiveSettingOff: break;
             case LiveSettingPolite: return @"polite";
             case LiveSettingAssertive: return @"assertive";
         }
@@ -401,6 +404,49 @@ - (BOOL)isAccessibilitySelected
     return NO;
 }
 
+- (void)setAccessibilitySelected:(BOOL)accessibilitySelected
+{
+    if (!_peer->IsSelectionItemProvider())
+        return;
+    if (accessibilitySelected)
+        _peer->SelectionItemProvider_AddToSelection();
+    else
+        _peer->SelectionItemProvider_RemoveFromSelection();
+}
+
+- (BOOL)accessibilityPerformPick
+{
+    if (!_peer->IsSelectionItemProvider())
+        return NO;
+    _peer->SelectionItemProvider_Select();
+    return YES;
+}
+
+- (NSArray *)accessibilitySelectedChildren
+{
+    if (!_peer->IsSelectionProvider())
+        return nil;
+
+    auto selection = _peer->SelectionProvider_GetSelection();
+    if (selection == nullptr)
+        return nil;
+    auto count = selection->GetCount();
+    NSMutableArray* selectedElements = [[NSMutableArray alloc] initWithCapacity:count];
+
+    for (int i = 0; i < count; ++i)
+    {
+        IAvnAutomationPeer* selectedPeer;
+
+        if (selection->Get(i, &selectedPeer) == S_OK)
+        {
+            id element = [AvnAccessibilityElement acquire:selectedPeer];
+            [selectedElements addObject:element];
+        }
+    }
+
+    return selectedElements;
+}
+
 - (BOOL)isAccessibilitySelectorAllowed:(SEL)selector
 {
     if (selector == @selector(accessibilityPerformShowMenu))
@@ -422,7 +468,11 @@ - (BOOL)isAccessibilitySelectorAllowed:(SEL)selector
     {
         return _peer->IsRangeValueProvider();
     }
-
+    else if (selector == @selector(accessibilityPerformPick))
+    {
+        return _peer->IsSelectionItemProvider();
+    }
+
     return [super isAccessibilitySelectorAllowed:selector];
 }
 

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

@@ -0,0 +1,142 @@
+using System.Collections.Generic;
+using System.Linq;
+using Avalonia.Automation.Provider;
+using Avalonia.Controls;
+using Avalonia.Controls.Selection;
+using Avalonia.Controls.Utils;
+
+namespace Avalonia.Automation.Peers
+{
+    public class ListBoxAutomationPeer : SelectingItemsControlAutomationPeer
+    {
+        public ListBoxAutomationPeer(ListBox owner)
+            : base(owner)
+        {
+            owner.ContainerPrepared += OnContainerPrepared;
+        }
+
+        private void OnContainerPrepared(object? sender, ContainerPreparedEventArgs e)
+        {
+            if (e.Container.GetAutomationPeer() is ListItemAutomationPeer peer)
+                peer.Index = e.Index;
+        }
+
+        protected override void OwnerPropertyChanged(object? sender, AvaloniaPropertyChangedEventArgs e)
+        {
+            base.OwnerPropertyChanged(sender, e);
+
+            if (e.Property == ItemsControl.ItemCountProperty)
+                InvalidateChildren();
+        }
+
+        public new ListBox Owner => (ListBox)base.Owner;
+
+        protected override IReadOnlyList<AutomationPeer>? GetChildrenCore()
+        {
+            if (Owner.ItemCount == 0)
+            {
+                return null;
+            }
+
+            var children = new List<AutomationPeer>();
+
+            for (var i = 0; i < Owner.ItemCount; i++)
+            {
+                var container = Owner.ContainerFromIndex(i);
+
+                if (container == null)
+                {
+                    children.Add(new UnrealizedListItemAutomationPeer(this, i));
+                }
+                else
+                {
+                    var peer = GetOrCreate(container);
+                    if (peer is ListItemAutomationPeer listItemPeer)
+                        listItemPeer.Index = i;
+                    children.Add(peer);
+                }
+            }
+
+            return children;
+        }
+
+        internal class UnrealizedListItemAutomationPeer(ListBoxAutomationPeer owner, int index)
+            : UnrealizedElementAutomationPeer, ISelectionItemProvider
+        {
+            private ListBox _listBox => owner.Owner;
+
+            public bool IsSelected => _listBox.Selection.SelectedIndexes.Contains(index);
+
+            public ISelectionProvider? SelectionContainer => owner.GetProvider<ISelectionProvider>();
+
+            public void Select()
+            {
+                EnsureEnabled();
+                BringIntoView();
+
+                _listBox.SelectedIndex = index;
+            }
+
+            public void AddToSelection()
+            {
+                EnsureEnabled();
+                BringIntoView();
+
+                if (_listBox.GetValue(ListBox.SelectionProperty) is ISelectionModel selectionModel)
+                {
+                    selectionModel.Select(index);
+                }
+            }
+
+            public void RemoveFromSelection()
+            {
+                EnsureEnabled();
+                BringIntoView();
+
+                if (_listBox.GetValue(ListBox.SelectionProperty) is ISelectionModel selectionModel)
+                {
+                    selectionModel.Deselect(index);
+                }
+            }
+
+            protected override void BringIntoViewCore()
+            {
+                var container = _listBox.ContainerFromIndex(index);
+                container?.BringIntoView();
+            }
+
+            protected override string? GetAcceleratorKeyCore() => null;
+            protected override string? GetAccessKeyCore() => null;
+            protected override AutomationControlType GetAutomationControlTypeCore() => AutomationControlType.ListItem;
+            protected override string GetAutomationIdCore() => $"{nameof(ListBoxItem)}: {index}";
+
+            protected override Rect GetBoundingRectangleCore()
+            {
+                var container = _listBox.ContainerFromIndex(index);
+                var peer = container?.GetOrCreateAutomationPeer();
+                return peer?.GetBoundingRectangle() ?? base.GetBoundingRectangleCore();
+            }
+
+            protected override string GetClassNameCore() => nameof(ListBoxItem);
+            protected override AutomationPeer? GetLabeledByCore() => null;
+
+            protected override string? GetNameCore()
+            {
+                using var textBindingEvaluator = BindingEvaluator<string?>.TryCreate(_listBox.DisplayMemberBinding);
+                var item = _listBox.Items.ElementAtOrDefault(index);
+                return textBindingEvaluator?.Evaluate(item);
+            }
+
+            protected override AutomationPeer? GetParentCore() => owner;
+            protected override bool IsContentElementCore() => true;
+            protected override bool IsControlElementCore() => true;
+            protected override bool IsEnabledCore() => _listBox.IsEnabled;
+            protected override bool IsKeyboardFocusableCore() => true;
+
+            protected override void SetFocusCore()
+            {
+                BringIntoView();
+            }
+        }
+    }
+}

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

@@ -8,6 +8,24 @@ namespace Avalonia.Automation.Peers
     public class ListItemAutomationPeer : ContentControlAutomationPeer,
         ISelectionItemProvider
     {
+        private int? _index;
+
+        public int Index
+        {
+            get
+            {
+                if (_index.HasValue)
+                    return _index.Value;
+
+                if (Owner.Parent is ItemsControl parent)
+                    return parent.IndexFromContainer(Owner);
+
+                return -1;
+            }
+
+            set => _index = value;
+        }
+
         public ListItemAutomationPeer(ContentControl owner)
             : base(owner)
         {
@@ -32,38 +50,41 @@ public ISelectionProvider? SelectionContainer
         public void Select()
         {
             EnsureEnabled();
+            BringIntoView();
 
             if (Owner.Parent is SelectingItemsControl parent)
             {
-                var index = parent.IndexFromContainer(Owner);
+                var index = Index;
 
                 if (index != -1)
                     parent.SelectedIndex = index;
             }
         }
 
-        void ISelectionItemProvider.AddToSelection()
+        public void AddToSelection()
         {
             EnsureEnabled();
+            BringIntoView();
 
             if (Owner.Parent is ItemsControl parent &&
                 parent.GetValue(ListBox.SelectionProperty) is ISelectionModel selectionModel)
             {
-                var index = parent.IndexFromContainer(Owner);
+                var index = Index;
 
                 if (index != -1)
                     selectionModel.Select(index);
             }
         }
 
-        void ISelectionItemProvider.RemoveFromSelection()
+        public void RemoveFromSelection()
         {
             EnsureEnabled();
+            BringIntoView();
 
             if (Owner.Parent is ItemsControl parent &&
                 parent.GetValue(ListBox.SelectionProperty) is ISelectionModel selectionModel)
             {
-                var index = parent.IndexFromContainer(Owner);
+                var index = Index;
 
                 if (index != -1)
                     selectionModel.Deselect(index);
@@ -75,7 +96,23 @@ protected override AutomationControlType GetAutomationControlTypeCore()
             return AutomationControlType.ListItem;
         }
 
+        protected override string? GetAutomationIdCore()
+        {
+            var index = Index;
+
+            if (index == -1)
+                return base.GetAutomationIdCore();
+
+            return $"{nameof(ListBoxItem)}: {index}";
+        }
+
         protected override bool IsContentElementCore() => true;
         protected override bool IsControlElementCore() => true;
+
+        protected override void SetFocusCore()
+        {
+            base.SetFocusCore();
+            BringIntoView();
+        }
     }
 }

src/Avalonia.Controls/Automation/Provider/ISelectionItemProvider .cs

@@ -52,10 +52,7 @@ public interface ISelectionItemProvider
         ///   </item>
         ///   <item>
         ///     <term>macOS</term>
-        ///     <description>
-        ///       <c>NSAccessibilityProtocol.accessibilityPerformPick</c> (not implemented).
-        ///       <c>NSAccessibilityProtocol.setAccessibilitySelected</c> (not implemented).
-        ///     </description>
+        ///     <description><c>NSAccessibilityProtocol.setAccessibilitySelected</c></description>
         ///   </item>
         /// </list>
         /// </remarks>
@@ -72,9 +69,7 @@ public interface ISelectionItemProvider
         ///   </item>
         ///   <item>
         ///     <term>macOS</term>
-        ///     <description>
-        ///       <c>NSAccessibilityProtocol.setAccessibilitySelected</c> (not implemented).
-        ///     </description>
+        ///     <description><c>NSAccessibilityProtocol.setAccessibilitySelected</c></description>
         ///   </item>
         /// </list>
         /// </remarks>
@@ -91,7 +86,7 @@ public interface ISelectionItemProvider
         ///   </item>
         ///   <item>
         ///     <term>macOS</term>
-        ///     <description>No mapping.</description>
+        ///     <description><c>NSAccessibilityProtocol.accessibilityPerformPick</c></description>
         ///   </item>
         /// </list>
         /// </remarks>

src/Avalonia.Controls/Automation/Provider/ISelectionProvider.cs

@@ -56,9 +56,7 @@ public interface ISelectionProvider
         ///   </item>
         ///   <item>
         ///     <term>macOS</term>
-        ///     <description>
-        ///       <c>NSAccessibilityProtocol.accessibilitySelectedChildren</c> (not implemented).
-        ///     </description>
+        ///     <description><c>NSAccessibilityProtocol.accessibilitySelectedChildren</c></description>
         ///   </item>
         /// </list>
         /// </remarks>

src/Avalonia.Controls/ListBox.cs

@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
+using Avalonia.Automation.Peers;
 using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Selection;
@@ -155,5 +156,10 @@ protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
             base.OnApplyTemplate(e);
             Scroll = e.NameScope.Find<IScrollable>("PART_ScrollViewer");
         }
+
+        protected override AutomationPeer OnCreateAutomationPeer()
+        {
+            return new ListBoxAutomationPeer(this);
+        }
     }
 }