Implemented LabeledBy.

samples/IntegrationTestApp/MainWindow.axaml

@@ -12,6 +12,10 @@
         <TextBlock Name="NotTheAutomationId" AutomationProperties.AutomationId="TextBlockWithNameAndAutomationId">
           TextBlockWithNameAndAutomationId
         </TextBlock>
+        <TextBlock Name="TextBlockAsLabel">Label for TextBox</TextBlock>
+        <TextBox Name="LabeledByTextBox" AutomationProperties.LabeledBy="{Binding #TextBlockAsLabel}">
+          Foo
+        </TextBox>
       </StackPanel>
     </TabItem>
     <TabItem Header="Button">

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

@@ -101,6 +101,12 @@ namespace Avalonia.Automation.Peers
         /// </summary>
         public string GetClassName() => GetClassNameCore() ?? string.Empty;
 
+        /// <summary>
+        /// Gets the automation peer for the label that is targeted to the element.
+        /// </summary>
+        /// <returns></returns>
+        public AutomationPeer? GetLabeledBy() => GetLabeledByCore();
+
         /// <summary>
         /// Gets a human-readable localized string that represents the type of the control that is
         /// associated with this automation peer.
@@ -207,6 +213,7 @@ namespace Avalonia.Automation.Peers
         protected abstract Rect GetBoundingRectangleCore();
         protected abstract IReadOnlyList<AutomationPeer> GetOrCreateChildrenCore();
         protected abstract string GetClassNameCore();
+        protected abstract AutomationPeer? GetLabeledByCore();
         protected abstract string? GetNameCore();
         protected abstract AutomationPeer? GetParentCore();
         protected abstract bool HasKeyboardFocusCore();

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

@@ -94,6 +94,7 @@ namespace Avalonia.Automation.Peers
 
             protected override string? GetAutomationIdCore() => null;
             protected override string GetClassNameCore() => typeof(ComboBoxItem).Name;
+            protected override AutomationPeer? GetLabeledByCore() => null;
             protected override AutomationPeer? GetParentCore() => _owner;
             protected override AutomationControlType GetAutomationControlTypeCore() => AutomationControlType.ListItem;
 

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

@@ -43,8 +43,24 @@ namespace Avalonia.Automation.Peers
         }
 
         protected override void BringIntoViewCore() => Owner.BringIntoView();
-        protected override string? GetAutomationIdCore() => AutomationProperties.GetAutomationId(Owner) ?? Owner.Name;
-        protected override Rect GetBoundingRectangleCore() => GetBounds(Owner.TransformedBounds);
+
+        protected override IReadOnlyList<AutomationPeer> GetOrCreateChildrenCore()
+        {
+            var children = _children ?? Array.Empty<AutomationPeer>();
+
+            if (_childrenValid)
+                return children;
+
+            var newChildren = GetChildrenCore() ?? Array.Empty<AutomationPeer>();
+
+            foreach (var peer in children.Except(newChildren))
+                peer.TrySetParent(null);
+            foreach (var peer in newChildren)
+                peer.TrySetParent(this);
+
+            _childrenValid = true;
+            return _children = newChildren;
+        }
 
         protected virtual IReadOnlyList<AutomationPeer>? GetChildrenCore()
         {
@@ -66,6 +82,24 @@ namespace Avalonia.Automation.Peers
             return result;
         }
 
+        protected override AutomationPeer? GetLabeledByCore()
+        {
+            var label = AutomationProperties.GetLabeledBy(Owner);
+            return label is Control c ? GetOrCreatePeer(c) : null;
+        }
+
+        protected override string? GetNameCore()
+        {
+            var result = AutomationProperties.GetName(Owner);
+
+            if (string.IsNullOrWhiteSpace(result) && GetLabeledBy() is AutomationPeer labeledBy)
+            {
+                return labeledBy.GetName();
+            }
+
+            return null;
+        }
+
         protected override AutomationPeer? GetParentCore()
         {
             EnsureConnected();
@@ -90,34 +124,6 @@ namespace Avalonia.Automation.Peers
             _parentValid = false;
         }
 
-        protected override IReadOnlyList<AutomationPeer> GetOrCreateChildrenCore()
-        {
-            var children = _children ?? Array.Empty<AutomationPeer>();
-
-            if (_childrenValid)
-                return children;
-
-            var newChildren = GetChildrenCore() ?? Array.Empty<AutomationPeer>();
-
-            foreach (var peer in children.Except(newChildren))
-                peer.TrySetParent(null);
-            foreach (var peer in newChildren)
-                peer.TrySetParent(this);
-
-            _childrenValid = true;
-            return _children = newChildren;
-        }
-
-        protected override AutomationControlType GetAutomationControlTypeCore() => AutomationControlType.Custom;
-        protected override string GetClassNameCore() => Owner.GetType().Name;
-        protected override string? GetNameCore() => AutomationProperties.GetName(Owner);
-        protected override bool HasKeyboardFocusCore() => Owner.IsFocused;
-        protected override bool IsContentElementCore() => true;
-        protected override bool IsControlElementCore() => true;
-        protected override bool IsEnabledCore() => Owner.IsEnabled;
-        protected override bool IsKeyboardFocusableCore() => Owner.Focusable;
-        protected override void SetFocusCore() => Owner.Focus();
-
         protected override bool ShowContextMenuCore()
         {
             var c = Owner;
@@ -142,6 +148,17 @@ namespace Avalonia.Automation.Peers
             return true;
         }
 
+        protected override string? GetAutomationIdCore() => AutomationProperties.GetAutomationId(Owner) ?? Owner.Name;
+        protected override Rect GetBoundingRectangleCore() => GetBounds(Owner.TransformedBounds);
+        protected override AutomationControlType GetAutomationControlTypeCore() => AutomationControlType.Custom;
+        protected override string GetClassNameCore() => Owner.GetType().Name;
+        protected override bool HasKeyboardFocusCore() => Owner.IsFocused;
+        protected override bool IsContentElementCore() => true;
+        protected override bool IsControlElementCore() => true;
+        protected override bool IsEnabledCore() => Owner.IsEnabled;
+        protected override bool IsKeyboardFocusableCore() => Owner.Focusable;
+        protected override void SetFocusCore() => Owner.Focus();
+
         private Rect GetBounds(TransformedBounds? bounds)
         {
             return bounds?.Bounds.TransformToAABB(bounds!.Value.Transform) ?? default;

src/Avalonia.Controls/Automation/Peers/TextAutomationPeer.cs → src/Avalonia.Controls/Automation/Peers/TextBlockAutomationPeer.cs

@@ -5,19 +5,21 @@ using Avalonia.Controls;
 
 namespace Avalonia.Automation.Peers
 {
-    public class TextAutomationPeer : ControlAutomationPeer
+    public class TextBlockAutomationPeer : ControlAutomationPeer
     {
-        public TextAutomationPeer(IAutomationNodeFactory factory, Control owner)
+        public TextBlockAutomationPeer(IAutomationNodeFactory factory, TextBlock owner)
             : base(factory, owner)
         {
         }
 
+        public new TextBlock Owner => (TextBlock)base.Owner;
+
         protected override AutomationControlType GetAutomationControlTypeCore()
         {
             return AutomationControlType.Text;
         }
 
-        protected override string? GetNameCore() => Owner.GetValue(TextBlock.TextProperty);
+        protected override string? GetNameCore() => Owner.Text;
 
         protected override bool IsControlElementCore()
         {

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

@@ -6,7 +6,7 @@ using Avalonia.Controls;
 
 namespace Avalonia.Automation.Peers
 {
-    public class TextBoxAutomationPeer : TextAutomationPeer, IValueProvider
+    public class TextBoxAutomationPeer : ControlAutomationPeer, IValueProvider
     {
         public TextBoxAutomationPeer(IAutomationNodeFactory factory, TextBox owner)
             : base(factory, owner)
@@ -17,5 +17,10 @@ namespace Avalonia.Automation.Peers
         public bool IsReadOnly => Owner.IsReadOnly;
         public string? Value => Owner.Text;
         public void SetValue(string? value) => Owner.Text = value;
+
+        protected override AutomationControlType GetAutomationControlTypeCore()
+        {
+            return AutomationControlType.Edit;
+        }
     }
 }

src/Avalonia.Controls/TextBlock.cs

@@ -536,7 +536,7 @@ namespace Avalonia.Controls
 
         protected override AutomationPeer OnCreateAutomationPeer(IAutomationNodeFactory factory)
         {
-            return new TextAutomationPeer(factory, this);
+            return new TextBlockAutomationPeer(factory, this);
         }
 
         private static bool IsValidMaxLines(int maxLines) => maxLines >= 0;

tests/Avalonia.IntegrationTests.Win32/AutomationTests.cs

@@ -25,5 +25,15 @@ namespace Avalonia.IntegrationTests.Win32
             var byName = _session.FindElementByAccessibilityId("TextBlockWithName");
             var byAutomationId = _session.FindElementByAccessibilityId("TextBlockWithNameAndAutomationId");
         }
+
+        [Fact]
+        public void LabeledBy()
+        {
+            var label = _session.FindElementByAccessibilityId("TextBlockAsLabel");
+            var labeledTextBox = _session.FindElementByAccessibilityId("LabeledByTextBox");
+
+            Assert.Equal("Label for TextBox", label.Text);
+            Assert.Equal("Label for TextBox", labeledTextBox.GetAttribute("Name"));
+        }
     }
 }