Implement TextPattern support for Text controls

- Implement base integration to AccessibleObject
- Add TextPattern support for TextBox (singleline and multiline) and MaskedTextBox
- Disable managed UiaTextProvider for RichTextBox to use native provider as the native
  Win32 RichEdit control already supports TextPattern.
  Return ControlAccessibleObject as AccessibilityInstance instead TextBoxBaseAccessibleObject
  (the latter supports managed UiaTextProvider).
- Add tests

Fixes #1588

src/System.Windows.Forms/src/PublicAPI.Unshipped.txt

@@ -0,0 +1,3 @@
+~override System.Windows.Forms.RichTextBox.CreateAccessibilityInstance() -> System.Windows.Forms.AccessibleObject
+~override System.Windows.Forms.TextBox.OnKeyUp(System.Windows.Forms.KeyEventArgs e) -> void
+~override System.Windows.Forms.TextBox.OnMouseDown(System.Windows.Forms.MouseEventArgs e) -> void

src/System.Windows.Forms/src/System/Windows/Forms/AccessibleObject.cs

@@ -43,7 +43,9 @@ public partial class AccessibleObject :
         UiaCore.ISelectionItemProvider,
         UiaCore.IRawElementProviderHwndOverride,
         UiaCore.IScrollItemProvider,
-        UiaCore.IMultipleViewProvider
+        UiaCore.IMultipleViewProvider,
+        UiaCore.ITextProvider,
+        UiaCore.ITextProvider2
     {
         /// <summary>
         ///  Specifies the <see cref='IAccessible'/> interface used by this <see cref='AccessibleObject'/>.
@@ -64,6 +66,9 @@ public partial class AccessibleObject :
         // Indicates this object is being used ONLY to wrap a system IAccessible
         private readonly bool systemWrapper;
 
+        private UiaTextProvider? _textProvider;
+        private UiaTextProvider2? _textProvider2;
+
         // The support for the UIA Notification event begins in RS3.
         // Assume the UIA Notification event is available until we learn otherwise.
         // If we learn that the UIA Notification event is not available,
@@ -350,15 +355,13 @@ internal virtual int ProviderOptions
 
         internal virtual UiaCore.IRawElementProviderSimple? HostRawElementProvider => null;
 
-        internal virtual object? GetPropertyValue(UiaCore.UIA propertyID)
-        {
-            if (propertyID == UiaCore.UIA.IsInvokePatternAvailablePropertyId)
+        internal virtual object? GetPropertyValue(UiaCore.UIA propertyID) =>
+            propertyID switch
             {
-                return IsInvokePatternAvailable;
-            }
-
-            return null;
-        }
+                UiaCore.UIA.IsInvokePatternAvailablePropertyId => IsInvokePatternAvailable,
+                UiaCore.UIA.BoundingRectanglePropertyId => Bounds,
+                _ => null
+            };
 
         private bool IsInvokePatternAvailable
         {
@@ -474,6 +477,29 @@ internal virtual void Toggle()
 
         internal virtual void Invoke() => DoDefaultAction();
 
+        internal virtual UiaCore.ITextRangeProvider? DocumentRangeInternal => _textProvider?.DocumentRange;
+
+        internal virtual UiaCore.ITextRangeProvider[]? GetTextSelection() => _textProvider?.GetSelection();
+
+        internal virtual UiaCore.ITextRangeProvider[]? GetTextVisibleRanges() => _textProvider?.GetVisibleRanges();
+
+        internal virtual UiaCore.ITextRangeProvider? GetTextRangeFromChild(UiaCore.IRawElementProviderSimple childElement)
+            => _textProvider?.RangeFromChild(childElement);
+
+        internal virtual UiaCore.ITextRangeProvider? GetTextRangeFromPoint(Point screenLocation) => _textProvider?.RangeFromPoint(screenLocation);
+
+        internal virtual UiaCore.SupportedTextSelection SupportedTextSelectionInternal
+            => _textProvider?.SupportedTextSelection ?? UiaCore.SupportedTextSelection.None;
+
+        internal virtual UiaCore.ITextRangeProvider? GetTextCaretRange(out BOOL isActive)
+        {
+            isActive = BOOL.FALSE;
+            return _textProvider2?.GetCaretRange(out isActive);
+        }
+
+        internal virtual UiaCore.ITextRangeProvider? GetRangeFromAnnotation(UiaCore.IRawElementProviderSimple annotationElement) =>
+            _textProvider2?.RangeFromAnnotation(annotationElement);
+
         internal virtual bool IsReadOnly => false;
 
         internal virtual void SetValue(string? newValue)
@@ -673,6 +699,37 @@ UiaCore.IRawElementProviderSimple[] UiaCore.ILegacyIAccessibleProvider.GetSelect
 
         void UiaCore.IInvokeProvider.Invoke() => Invoke();
 
+        UiaCore.ITextRangeProvider? UiaCore.ITextProvider.DocumentRange => DocumentRangeInternal;
+
+        UiaCore.ITextRangeProvider[]? UiaCore.ITextProvider.GetSelection() => GetTextSelection();
+
+        UiaCore.ITextRangeProvider[]? UiaCore.ITextProvider.GetVisibleRanges() => GetTextVisibleRanges();
+
+        UiaCore.ITextRangeProvider? UiaCore.ITextProvider.RangeFromChild(UiaCore.IRawElementProviderSimple childElement) =>
+            GetTextRangeFromChild(childElement);
+
+        UiaCore.ITextRangeProvider? UiaCore.ITextProvider.RangeFromPoint(Point screenLocation) => GetTextRangeFromPoint(screenLocation);
+
+        UiaCore.SupportedTextSelection UiaCore.ITextProvider.SupportedTextSelection => SupportedTextSelectionInternal;
+
+        UiaCore.ITextRangeProvider? UiaCore.ITextProvider2.DocumentRange => DocumentRangeInternal;
+
+        UiaCore.ITextRangeProvider[]? UiaCore.ITextProvider2.GetSelection() => GetTextSelection();
+
+        UiaCore.ITextRangeProvider[]? UiaCore.ITextProvider2.GetVisibleRanges() => GetTextVisibleRanges();
+
+        UiaCore.ITextRangeProvider? UiaCore.ITextProvider2.RangeFromChild(UiaCore.IRawElementProviderSimple childElement) =>
+            GetTextRangeFromChild(childElement);
+
+        UiaCore.ITextRangeProvider? UiaCore.ITextProvider2.RangeFromPoint(Point screenLocation) => GetTextRangeFromPoint(screenLocation);
+
+        UiaCore.SupportedTextSelection UiaCore.ITextProvider2.SupportedTextSelection => SupportedTextSelectionInternal;
+
+        UiaCore.ITextRangeProvider? UiaCore.ITextProvider2.GetCaretRange(out BOOL isActive) => GetTextCaretRange(out isActive);
+
+        UiaCore.ITextRangeProvider? UiaCore.ITextProvider2.RangeFromAnnotation(UiaCore.IRawElementProviderSimple annotationElement) =>
+            GetRangeFromAnnotation(annotationElement);
+
         BOOL UiaCore.IValueProvider.IsReadOnly => IsReadOnly ? BOOL.TRUE : BOOL.FALSE;
 
         string? UiaCore.IValueProvider.Value => Value;
@@ -1595,6 +1652,12 @@ protected void UseStdAccessibleObjects(IntPtr handle, int objid)
             }
         }
 
+        internal void UseTextProviders(UiaTextProvider textProvider, UiaTextProvider2 textProvider2)
+        {
+            _textProvider = textProvider ?? throw new ArgumentNullException(nameof(textProvider));
+            _textProvider2 = textProvider2 ?? throw new ArgumentNullException(nameof(textProvider2));
+        }
+
         /// <summary>
         ///  Performs custom navigation between parent/child/sibling accessible
         ///  objects. This is basically just a wrapper for GetSysChild(), that

src/System.Windows.Forms/src/System/Windows/Forms/InternalAccessibleObject.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Diagnostics.CodeAnalysis;
+using System.Drawing;
 using System.Globalization;
 using System.Reflection;
 using System.Runtime.InteropServices;
@@ -40,7 +41,9 @@ internal sealed class InternalAccessibleObject :
         ISelectionItemProvider,
         IScrollItemProvider,
         IRawElementProviderHwndOverride,
-        IMultipleViewProvider
+        IMultipleViewProvider,
+        ITextProvider,
+        ITextProvider2
     {
         private IAccessible publicIAccessible;                      // AccessibleObject as IAccessible
         private readonly Oleaut32.IEnumVariant publicIEnumVariant;  // AccessibleObject as Oleaut32.IEnumVariant
@@ -69,6 +72,8 @@ internal sealed class InternalAccessibleObject :
         private readonly IScrollItemProvider publicIScrollItemProvider;                            // AccessibleObject as IScrollItemProvider
         private readonly IRawElementProviderHwndOverride publicIRawElementProviderHwndOverride;    // AccessibleObject as IRawElementProviderHwndOverride
         private readonly IMultipleViewProvider publicIMultiViewProvider;                           // AccessibleObject as IMultipleViewProvider
+        private readonly ITextProvider publicITextProvider;                                        // AccessibleObject as ITextProvider
+        private readonly ITextProvider2 publicITextProvider2;                                      // AccessibleObject as ITextProvider2
 
         /// <summary>
         ///  Create a new wrapper.
@@ -100,6 +105,8 @@ internal InternalAccessibleObject(AccessibleObject accessibleImplemention)
             publicIScrollItemProvider = (IScrollItemProvider)accessibleImplemention;
             publicIRawElementProviderHwndOverride = (IRawElementProviderHwndOverride)accessibleImplemention;
             publicIMultiViewProvider = (IMultipleViewProvider)accessibleImplemention;
+            publicITextProvider = (ITextProvider)accessibleImplemention;
+            publicITextProvider2 = (ITextProvider2)accessibleImplemention;
             // Note: Deliberately not holding onto AccessibleObject to enforce all access through the interfaces
         }
 
@@ -314,6 +321,8 @@ ProviderOptions IRawElementProviderSimple.ProviderOptions
                 UIA.SelectionItemPatternId => (ISelectionItemProvider)this,
                 UIA.ScrollItemPatternId => (IScrollItemProvider)this,
                 UIA.MultipleViewPatternId => (IMultipleViewProvider)this,
+                UIA.TextPatternId => (ITextProvider)this,
+                UIA.TextPattern2Id => (ITextProvider2)this,
                 _ => null
             };
         }
@@ -365,8 +374,7 @@ UiaRect IRawElementProviderFragment.BoundingRectangle
 
         void ILegacyIAccessibleProvider.DoDefaultAction() => publicILegacyIAccessibleProvider.DoDefaultAction();
 
-        IAccessible? ILegacyIAccessibleProvider.GetIAccessible()
-            => publicILegacyIAccessibleProvider.GetIAccessible();
+        IAccessible? ILegacyIAccessibleProvider.GetIAccessible() => publicILegacyIAccessibleProvider.GetIAccessible();
 
         IRawElementProviderSimple[] ILegacyIAccessibleProvider.GetSelection() => publicILegacyIAccessibleProvider.GetSelection();
 
@@ -376,6 +384,40 @@ UiaRect IRawElementProviderFragment.BoundingRectangle
 
         void IInvokeProvider.Invoke() => publicIInvokeProvider.Invoke();
 
+        ITextRangeProvider[]? ITextProvider.GetSelection() => publicITextProvider.GetSelection();
+
+        ITextRangeProvider[]? ITextProvider.GetVisibleRanges() => publicITextProvider.GetVisibleRanges();
+
+        ITextRangeProvider? ITextProvider.RangeFromChild(IRawElementProviderSimple childElement)
+            => publicITextProvider.RangeFromChild(childElement);
+
+        ITextRangeProvider? ITextProvider.RangeFromPoint(Point screenLocation)
+            => publicITextProvider.RangeFromPoint(screenLocation);
+
+        SupportedTextSelection ITextProvider.SupportedTextSelection => publicITextProvider.SupportedTextSelection;
+
+        ITextRangeProvider? ITextProvider.DocumentRange => publicITextProvider.DocumentRange;
+
+        ITextRangeProvider[]? ITextProvider2.GetSelection() => publicITextProvider2.GetSelection();
+
+        ITextRangeProvider[]? ITextProvider2.GetVisibleRanges() => publicITextProvider2.GetVisibleRanges();
+
+        ITextRangeProvider? ITextProvider2.RangeFromChild(IRawElementProviderSimple childElement)
+            => publicITextProvider2.RangeFromChild(childElement);
+
+        ITextRangeProvider? ITextProvider2.RangeFromPoint(Point screenLocation)
+            => publicITextProvider2.RangeFromPoint(screenLocation);
+
+        SupportedTextSelection ITextProvider2.SupportedTextSelection => publicITextProvider2.SupportedTextSelection;
+
+        ITextRangeProvider? ITextProvider2.DocumentRange => publicITextProvider2.DocumentRange;
+
+        ITextRangeProvider? ITextProvider2.GetCaretRange(out BOOL isActive)
+            => publicITextProvider2.GetCaretRange(out isActive);
+
+        ITextRangeProvider? ITextProvider2.RangeFromAnnotation(IRawElementProviderSimple annotationElement)
+            => publicITextProvider2.RangeFromAnnotation(annotationElement);
+
         BOOL IValueProvider.IsReadOnly => publicIValueProvider.IsReadOnly;
 
         string? IValueProvider.Value => publicIValueProvider.Value;

src/System.Windows.Forms/src/System/Windows/Forms/RichTextBox.cs

@@ -2257,7 +2257,7 @@ private RichTextBoxSelectionAttribute GetCharFormat(CFM mask, CFE effect)
             return charFormat;
         }
 
-        Font GetCharFormatFont(bool selectionOnly)
+        private Font GetCharFormatFont(bool selectionOnly)
         {
             ForceHandleCreate();
 
@@ -3237,6 +3237,8 @@ private void UserPreferenceChangedHandler(object o, UserPreferenceChangedEventAr
             }
         }
 
+        protected override AccessibleObject CreateAccessibilityInstance() => new ControlAccessibleObject(this);
+
         /// <summary>
         ///  Creates the IRichEditOleCallback compatible object for handling RichEdit callbacks. For more
         ///  information look up the MSDN info on this interface. This is designed to be a back door of

src/System.Windows.Forms/src/System/Windows/Forms/TextBox.cs

@@ -647,6 +647,48 @@ protected override void OnHandleDestroyed(EventArgs e)
             base.OnHandleDestroyed(e);
         }
 
+        protected override void OnKeyUp(KeyEventArgs e)
+        {
+            base.OnKeyUp(e);
+
+            if (IsHandleCreated && ContainsNavigationKeyCode(e.KeyCode))
+            {
+                AccessibilityObject?.RaiseAutomationEvent(UiaCore.UIA.Text_TextSelectionChangedEventId);
+            }
+        }
+
+        private bool ContainsNavigationKeyCode(Keys keyCode)
+        {
+            switch (keyCode)
+            {
+                case Keys.Up:
+                case Keys.Down:
+                case Keys.PageUp:
+                case Keys.PageDown:
+                case Keys.Home:
+                case Keys.End:
+                case Keys.Left:
+                case Keys.Right:
+                    return true;
+                default:
+                    return false;
+            }
+        }
+
+        protected override void OnMouseDown(MouseEventArgs e)
+        {
+            base.OnMouseDown(e);
+
+            if (IsHandleCreated)
+            {
+                // As there is no corresponding windows notification
+                // about text selection changed for TextBox assuming
+                // that any mouse down on textbox leads to change of
+                // the caret position and thereby change the selection.
+                AccessibilityObject?.RaiseAutomationEvent(UiaCore.UIA.Text_TextSelectionChangedEventId);
+            }
+        }
+
         protected virtual void OnTextAlignChanged(EventArgs e)
         {
             if (Events[EVENT_TEXTALIGNCHANGED] is EventHandler eh)

src/System.Windows.Forms/src/System/Windows/Forms/TextBoxBase.TextBoxBaseAccessibleObject.cs

@@ -0,0 +1,46 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using static Interop;
+
+namespace System.Windows.Forms
+{
+    public abstract partial class TextBoxBase
+    {
+        internal class TextBoxBaseAccessibleObject : ControlAccessibleObject
+        {
+            private readonly TextBoxBase _owningTextBoxBase;
+            private readonly TextBoxBaseUiaTextProvider _textProvider;
+
+            public TextBoxBaseAccessibleObject(TextBoxBase owner) : base(owner)
+            {
+                _owningTextBoxBase = owner;
+                _textProvider = new TextBoxBaseUiaTextProvider(owner);
+
+                UseTextProviders(_textProvider, _textProvider);
+            }
+
+            internal override bool IsIAccessibleExSupported() => true;
+
+            internal override bool IsPatternSupported(UiaCore.UIA patternId) =>
+                patternId switch
+                {
+                    UiaCore.UIA.TextPatternId => true,
+                    UiaCore.UIA.TextPattern2Id => true,
+                    _ => base.IsPatternSupported(patternId)
+                };
+
+            internal override object? GetPropertyValue(UiaCore.UIA propertyID) =>
+                propertyID switch
+                {
+                    UiaCore.UIA.IsTextPatternAvailablePropertyId => IsPatternSupported(UiaCore.UIA.TextPatternId),
+                    UiaCore.UIA.IsTextPattern2AvailablePropertyId => IsPatternSupported(UiaCore.UIA.TextPattern2Id),
+                    UiaCore.UIA.IsValuePatternAvailablePropertyId => IsPatternSupported(UiaCore.UIA.ValuePatternId),
+                    _ => base.GetPropertyValue(propertyID)
+                };
+
+            internal override bool IsReadOnly => _owningTextBoxBase.ReadOnly;
+        }
+    }
+}