Add basic support for automation

src/Avalonia.Controls.TreeDataGrid/Automation/Peers/TreeDataGridAutomationPeer.cs

@@ -0,0 +1,18 @@
+using Avalonia.Automation.Peers;
+
+namespace Avalonia.Controls.Automation.Peers;
+
+public class TreeDataGridAutomationPeer : ControlAutomationPeer
+{
+    public TreeDataGridAutomationPeer(TreeDataGrid owner)
+        : base(owner)
+    {
+    }
+
+    public new TreeDataGrid Owner => (TreeDataGrid)base.Owner;
+
+    protected override AutomationControlType GetAutomationControlTypeCore()
+    {
+        return AutomationControlType.DataGrid;
+    }
+}

src/Avalonia.Controls.TreeDataGrid/Automation/Peers/TreeDataGridCellAutomationPeer.cs

@@ -0,0 +1,39 @@
+using Avalonia.Automation.Peers;
+using Avalonia.Controls.Primitives;
+
+namespace Avalonia.Controls.Automation.Peers;
+
+public class TreeDataGridCellAutomationPeer : ControlAutomationPeer
+{
+    public TreeDataGridCellAutomationPeer(TreeDataGridCell owner)
+        : base(owner)
+    {
+    }
+
+    public new TreeDataGridCell Owner => (TreeDataGridCell)base.Owner;
+
+    protected override AutomationControlType GetAutomationControlTypeCore()
+    {
+        return AutomationControlType.Custom;
+    }
+
+    protected override bool IsContentElementCore() => true;
+
+    protected override bool IsControlElementCore() => true;
+
+    protected override string? GetNameCore()
+    {
+        var name = base.GetNameCore();
+        if (!string.IsNullOrEmpty(name))
+        {
+            return name;
+        }
+
+        return Owner switch
+        {
+            TreeDataGridTextCell textCell => textCell.Value,
+            TreeDataGridTemplateCell templateCell => templateCell.Content?.ToString(),
+            _ => Owner.Model?.ToString()
+        };
+    }
+}

src/Avalonia.Controls.TreeDataGrid/Automation/Peers/TreeDataGridColumnHeaderAutomationPeer.cs

@@ -0,0 +1,23 @@
+using Avalonia.Automation.Peers;
+using Avalonia.Controls.Primitives;
+
+namespace Avalonia.Controls.Automation.Peers;
+
+public class TreeDataGridColumnHeaderAutomationPeer : ContentControlAutomationPeer
+{
+    public TreeDataGridColumnHeaderAutomationPeer(TreeDataGridColumnHeader owner)
+        : base(owner)
+    {
+    }
+
+    public new TreeDataGridColumnHeader Owner => (TreeDataGridColumnHeader)base.Owner;
+
+    protected override AutomationControlType GetAutomationControlTypeCore()
+    {
+        return AutomationControlType.HeaderItem;
+    }
+
+    protected override bool IsContentElementCore() => false;
+
+    protected override bool IsControlElementCore() => true;
+}

src/Avalonia.Controls.TreeDataGrid/Automation/Peers/TreeDataGridColumnHeadersPresenterAutomationPeer.cs

@@ -0,0 +1,23 @@
+using Avalonia.Automation.Peers;
+using Avalonia.Controls.Primitives;
+
+namespace Avalonia.Controls.Automation.Peers;
+
+public class TreeDataGridColumnHeadersPresenterAutomationPeer : ControlAutomationPeer
+{
+    public TreeDataGridColumnHeadersPresenterAutomationPeer(TreeDataGridColumnHeadersPresenter owner)
+        : base(owner)
+    {
+    }
+
+    public new TreeDataGridColumnHeadersPresenter Owner => (TreeDataGridColumnHeadersPresenter)base.Owner;
+
+    protected override AutomationControlType GetAutomationControlTypeCore()
+    {
+        return AutomationControlType.Header;
+    }
+
+    protected override bool IsContentElementCore() => false;
+
+    protected override bool IsControlElementCore() => true;
+}

src/Avalonia.Controls.TreeDataGrid/Automation/Peers/TreeDataGridRowAutomationPeer.cs

@@ -0,0 +1,61 @@
+using System;
+using Avalonia.Automation.Peers;
+using Avalonia.Automation.Provider;
+using Avalonia.Controls.Models.TreeDataGrid;
+using Avalonia.Controls.Primitives;
+
+namespace Avalonia.Controls.Automation.Peers;
+
+public class TreeDataGridRowAutomationPeer : ControlAutomationPeer, IToggleProvider, IValueProvider
+{
+    public TreeDataGridRowAutomationPeer(TreeDataGridRow owner)
+        : base(owner)
+    {
+    }
+
+    public new TreeDataGridRow Owner => (TreeDataGridRow)base.Owner;
+
+    public ToggleState ToggleState
+    {
+        get
+        {
+            if (Owner.DataContext is IExpander expander)
+            {
+                return expander.IsExpanded ? ToggleState.On : ToggleState.Off;
+            }
+            return ToggleState.Indeterminate;
+        }
+    }
+
+    public bool IsReadOnly => true;
+
+    public string? Value
+    {
+        get
+        {
+            return Owner.Model?.ToString();
+        }
+    }
+
+    protected override AutomationControlType GetAutomationControlTypeCore()
+    {
+        return AutomationControlType.TreeItem;
+    }
+
+    protected override bool IsContentElementCore() => true;
+
+    protected override bool IsControlElementCore() => true;
+
+    public void Toggle()
+    {
+        if (Owner.DataContext is IExpander expander)
+        {
+            expander.IsExpanded = !expander.IsExpanded;
+        }
+    }
+
+    public void SetValue(string? value)
+    {
+        throw new InvalidOperationException("TreeDataGrid rows are read-only.");
+    }
+}

src/Avalonia.Controls.TreeDataGrid/Primitives/TreeDataGridCell.cs

@@ -1,5 +1,7 @@
 using System;
 using System.ComponentModel;
+using Avalonia.Automation.Peers;
+using Avalonia.Controls.Automation.Peers;
 using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Models.TreeDataGrid;
 using Avalonia.Controls.Selection;
@@ -74,6 +76,11 @@ public virtual void Unrealize()
             Model = null;
         }
 
+        protected override AutomationPeer OnCreateAutomationPeer()
+        {
+            return new TreeDataGridCellAutomationPeer(this);
+        }
+
         protected internal void BeginEdit()
         {
             if (!IsEditing)

src/Avalonia.Controls.TreeDataGrid/Primitives/TreeDataGridColumnHeader.cs

@@ -1,5 +1,7 @@
 using System;
 using System.ComponentModel;
+using Avalonia.Automation.Peers;
+using Avalonia.Controls.Automation.Peers;
 using Avalonia.Controls.Models.TreeDataGrid;
 using Avalonia.Input;
 using Avalonia.Utilities;
@@ -81,6 +83,11 @@ public void Unrealize()
             UpdatePropertiesFromModel();
         }
 
+        protected override AutomationPeer OnCreateAutomationPeer()
+        {
+            return new TreeDataGridColumnHeaderAutomationPeer(this);
+        }
+
         protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
         {
             base.OnApplyTemplate(e);

src/Avalonia.Controls.TreeDataGrid/Primitives/TreeDataGridColumnHeadersPresenter.cs

@@ -1,5 +1,7 @@
 using System;
 using System.Collections.Generic;
+using Avalonia.Automation.Peers;
+using Avalonia.Controls.Automation.Peers;
 using Avalonia.Controls.Models.TreeDataGrid;
 using Avalonia.Layout;
 using Avalonia.LogicalTree;
@@ -12,6 +14,11 @@ public class TreeDataGridColumnHeadersPresenter : TreeDataGridColumnarPresenterB
 
         protected override Orientation Orientation => Orientation.Horizontal;
 
+        protected override AutomationPeer OnCreateAutomationPeer()
+        {
+            return new TreeDataGridColumnHeadersPresenterAutomationPeer(this);
+        }
+
         protected override Size ArrangeOverride(Size finalSize)
         {
             (Items as IColumns)?.CommitActualWidths();

src/Avalonia.Controls.TreeDataGrid/Primitives/TreeDataGridRow.cs

@@ -1,5 +1,7 @@
 using System;
 using System.Text;
+using Avalonia.Automation.Peers;
+using Avalonia.Controls.Automation.Peers;
 using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Models.TreeDataGrid;
 using Avalonia.Controls.Selection;
@@ -112,6 +114,11 @@ public void Unrealize()
             CellsPresenter?.Unrealize();
         }
 
+        protected override AutomationPeer OnCreateAutomationPeer()
+        {
+            return new TreeDataGridRowAutomationPeer(this);
+        }
+
         protected override void OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
             _treeDataGrid = this.FindLogicalAncestorOfType<TreeDataGrid>();

src/Avalonia.Controls.TreeDataGrid/TreeDataGrid.cs

@@ -2,6 +2,8 @@
 using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using Avalonia.Automation.Peers;
+using Avalonia.Controls.Automation.Peers;
 using Avalonia.Controls.Documents;
 using Avalonia.Controls.Models.TreeDataGrid;
 using Avalonia.Controls.Primitives;
@@ -310,6 +312,11 @@ public bool QueryCancelSelection()
             return e.Cancel;
         }
 
+        protected override AutomationPeer OnCreateAutomationPeer()
+        {
+            return new TreeDataGridAutomationPeer(this);
+        }
+
         protected virtual TreeDataGridElementFactory CreateDefaultElementFactory() => new TreeDataGridElementFactory();
 
         protected override void OnApplyTemplate(TemplateAppliedEventArgs e)