Reworking the base TextPattern implementation (#7081)

Author: vladimir-krestov

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

@@ -66,9 +66,6 @@ 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,
@@ -555,28 +552,60 @@ internal virtual void Toggle()
 
         internal virtual void Invoke() => DoDefaultAction();
 
-        internal virtual UiaCore.ITextRangeProvider? DocumentRangeInternal => _textProvider?.DocumentRange;
+        internal virtual UiaCore.ITextRangeProvider? DocumentRangeInternal
+        {
+            get
+            {
+                Debug.Fail("Not implemented. DocumentRangeInternal property should be overridden.");
+                return null;
+            }
+        }
 
-        internal virtual UiaCore.ITextRangeProvider[]? GetTextSelection() => _textProvider?.GetSelection();
+        internal virtual UiaCore.ITextRangeProvider[]? GetTextSelection()
+        {
+            Debug.Fail("Not implemented. GetTextSelection method should be overridden.");
+            return null;
+        }
 
-        internal virtual UiaCore.ITextRangeProvider[]? GetTextVisibleRanges() => _textProvider?.GetVisibleRanges();
+        internal virtual UiaCore.ITextRangeProvider[]? GetTextVisibleRanges()
+        {
+            Debug.Fail("Not implemented. GetTextVisibleRanges method should be overridden.");
+            return null;
+        }
 
         internal virtual UiaCore.ITextRangeProvider? GetTextRangeFromChild(UiaCore.IRawElementProviderSimple childElement)
-            => _textProvider?.RangeFromChild(childElement);
+        {
+            Debug.Fail("Not implemented. GetTextRangeFromChild method should be overridden.");
+            return null;
+        }
 
-        internal virtual UiaCore.ITextRangeProvider? GetTextRangeFromPoint(Point screenLocation) => _textProvider?.RangeFromPoint(screenLocation);
+        internal virtual UiaCore.ITextRangeProvider? GetTextRangeFromPoint(Point screenLocation)
+        {
+            Debug.Fail("Not implemented. GetTextRangeFromPoint method should be overridden.");
+            return null;
+        }
 
         internal virtual UiaCore.SupportedTextSelection SupportedTextSelectionInternal
-            => _textProvider?.SupportedTextSelection ?? UiaCore.SupportedTextSelection.None;
+        {
+            get
+            {
+                Debug.Fail("Not implemented. SupportedTextSelectionInternal property should be overridden.");
+                return UiaCore.SupportedTextSelection.None;
+            }
+        }
 
         internal virtual UiaCore.ITextRangeProvider? GetTextCaretRange(out BOOL isActive)
         {
             isActive = BOOL.FALSE;
-            return _textProvider2?.GetCaretRange(out isActive);
+            Debug.Fail("Not implemented. GetTextCaretRange method should be overridden.");
+            return null;
         }
 
-        internal virtual UiaCore.ITextRangeProvider? GetRangeFromAnnotation(UiaCore.IRawElementProviderSimple annotationElement) =>
-            _textProvider2?.RangeFromAnnotation(annotationElement);
+        internal virtual UiaCore.ITextRangeProvider? GetRangeFromAnnotation(UiaCore.IRawElementProviderSimple annotationElement)
+        {
+            Debug.Fail("Not implemented. GetRangeFromAnnotation method should be overridden.");
+            return null;
+        }
 
         internal virtual bool IsReadOnly => false;
 
@@ -1744,12 +1773,6 @@ protected void UseStdAccessibleObjects(IntPtr handle, int objid)
             }
         }
 
-        internal void UseTextProviders(UiaTextProvider textProvider, UiaTextProvider2 textProvider2)
-        {
-            _textProvider = textProvider.OrThrowIfNull();
-            _textProvider2 = textProvider2.OrThrowIfNull();
-        }
-
         /// <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/ComboBox.ComboBoxChildEditUiaProvider.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Drawing;
 using System.Runtime.InteropServices;
 using static Interop;
 
@@ -16,7 +17,7 @@ internal class ComboBoxChildEditUiaProvider : ChildAccessibleObject
         {
             private const string COMBO_BOX_EDIT_AUTOMATION_ID = "1001";
 
-            private readonly ComboBox _owner;
+            private readonly ComboBox _owningComboBox;
             private readonly ComboBoxUiaTextProvider _textProvider;
             private readonly IntPtr _handle;
 
@@ -27,10 +28,9 @@ internal class ComboBoxChildEditUiaProvider : ChildAccessibleObject
             /// <param name="childEditControlhandle">The child edit native window handle.</param>
             public ComboBoxChildEditUiaProvider(ComboBox owner, IntPtr childEditControlhandle) : base(owner, childEditControlhandle)
             {
-                _owner = owner;
+                _owningComboBox = owner;
                 _handle = childEditControlhandle;
                 _textProvider = new ComboBoxUiaTextProvider(owner);
-                UseTextProviders(_textProvider, _textProvider);
             }
 
             /// <summary>
@@ -40,22 +40,22 @@ public ComboBoxChildEditUiaProvider(ComboBox owner, IntPtr childEditControlhandl
             /// <returns>Returns the element in the specified direction.</returns>
             internal override UiaCore.IRawElementProviderFragment? FragmentNavigate(UiaCore.NavigateDirection direction)
             {
-                if (!_owner.IsHandleCreated)
+                if (!_owningComboBox.IsHandleCreated)
                 {
                     return null;
                 }
 
                 switch (direction)
                 {
                     case UiaCore.NavigateDirection.Parent:
-                        return _owner.AccessibilityObject;
+                        return _owningComboBox.AccessibilityObject;
                     case UiaCore.NavigateDirection.PreviousSibling:
-                        return _owner.DroppedDown
-                            ? _owner.ChildListAccessibleObject
+                        return _owningComboBox.DroppedDown
+                            ? _owningComboBox.ChildListAccessibleObject
                             : null;
                     case UiaCore.NavigateDirection.NextSibling:
-                        return _owner.DropDownStyle != ComboBoxStyle.Simple
-                            && _owner.AccessibilityObject is ComboBoxAccessibleObject comboBoxAccessibleObject
+                        return _owningComboBox.DropDownStyle != ComboBoxStyle.Simple
+                            && _owningComboBox.AccessibilityObject is ComboBoxAccessibleObject comboBoxAccessibleObject
                                 ? comboBoxAccessibleObject.DropDownButtonUiaProvider
                                 : null;
                     default:
@@ -67,12 +67,7 @@ public ComboBoxChildEditUiaProvider(ComboBox owner, IntPtr childEditControlhandl
             ///  Gets the top level element.
             /// </summary>
             internal override UiaCore.IRawElementProviderFragmentRoot FragmentRoot
-            {
-                get
-                {
-                    return _owner.AccessibilityObject;
-                }
-            }
+                => _owningComboBox.AccessibilityObject;
 
             public override string Name => base.Name ?? SR.ComboBoxEditDefaultAccessibleName;
 
@@ -88,11 +83,11 @@ internal override UiaCore.IRawElementProviderFragmentRoot FragmentRoot
                     case UiaCore.UIA.ControlTypePropertyId:
                         return UiaCore.UIA.EditControlTypeId;
                     case UiaCore.UIA.HasKeyboardFocusPropertyId:
-                        return _owner.Focused;
+                        return _owningComboBox.Focused;
                     case UiaCore.UIA.IsKeyboardFocusablePropertyId:
                         return (State & AccessibleStates.Focusable) == AccessibleStates.Focusable;
                     case UiaCore.UIA.IsEnabledPropertyId:
-                        return _owner.Enabled;
+                        return _owningComboBox.Enabled;
                     case UiaCore.UIA.AutomationIdPropertyId:
                         return COMBO_BOX_EDIT_AUTOMATION_ID;
                     case UiaCore.UIA.NativeWindowHandlePropertyId:
@@ -128,6 +123,30 @@ internal override bool IsPatternSupported(UiaCore.UIA patternId) =>
             ///  Gets the runtime ID.
             /// </summary>
             internal override int[] RuntimeId => new int[] { RuntimeIDFirstItem, GetHashCode() };
+
+            internal override UiaCore.ITextRangeProvider DocumentRangeInternal
+                => _textProvider.DocumentRange;
+
+            internal override UiaCore.ITextRangeProvider[]? GetTextSelection()
+                => _textProvider.GetSelection();
+
+            internal override UiaCore.ITextRangeProvider[]? GetTextVisibleRanges()
+                => _textProvider.GetVisibleRanges();
+
+            internal override UiaCore.ITextRangeProvider? GetTextRangeFromChild(UiaCore.IRawElementProviderSimple childElement)
+                => _textProvider.RangeFromChild(childElement);
+
+            internal override UiaCore.ITextRangeProvider? GetTextRangeFromPoint(Point screenLocation)
+                => _textProvider.RangeFromPoint(screenLocation);
+
+            internal override UiaCore.SupportedTextSelection SupportedTextSelectionInternal
+                => _textProvider.SupportedTextSelection;
+
+            internal override UiaCore.ITextRangeProvider? GetTextCaretRange(out BOOL isActive)
+                => _textProvider.GetCaretRange(out isActive);
+
+            internal override UiaCore.ITextRangeProvider GetRangeFromAnnotation(UiaCore.IRawElementProviderSimple annotationElement)
+                => _textProvider.RangeFromAnnotation(annotationElement);
         }
     }
 }

src/System.Windows.Forms/src/System/Windows/Forms/DataGridViewTextBoxEditingControl.DataGridViewTextBoxEditingControlAccessibleObject.cs

@@ -11,21 +11,15 @@ partial class DataGridViewTextBoxEditingControl
         /// <summary>
         ///  Defines the DataGridView TextBox EditingControl accessible object.
         /// </summary>
-        internal class DataGridViewTextBoxEditingControlAccessibleObject : ControlAccessibleObject
+        internal class DataGridViewTextBoxEditingControlAccessibleObject : TextBoxBaseAccessibleObject
         {
             /// <summary>
             ///  The parent is changed when the editing control is attached to another editing cell.
             /// </summary>
             private AccessibleObject? _parentAccessibleObject;
-            private readonly TextBoxBase _owningDataGridViewTextBoxEditingControl;
-            private readonly TextBoxBaseUiaTextProvider _textProvider;
 
             public DataGridViewTextBoxEditingControlAccessibleObject(DataGridViewTextBoxEditingControl ownerControl) : base(ownerControl)
-            {
-                _owningDataGridViewTextBoxEditingControl = ownerControl;
-                _textProvider = new TextBoxBaseUiaTextProvider(ownerControl);
-                UseTextProviders(_textProvider, _textProvider);
-            }
+            { }
 
             public override AccessibleObject? Parent => _parentAccessibleObject;
 
@@ -72,13 +66,9 @@ internal override bool IsPatternSupported(UiaCore.UIA patternId)
                 => patternId switch
                 {
                     UiaCore.UIA.ValuePatternId => true,
-                    UiaCore.UIA.TextPatternId => true,
-                    UiaCore.UIA.TextPattern2Id => true,
                     _ => base.IsPatternSupported(patternId)
                 };
 
-            internal override bool IsReadOnly => _owningDataGridViewTextBoxEditingControl.ReadOnly;
-
             /// <summary>
             ///  Sets the parent accessible object for the node which can be added or removed to/from hierarchy nodes.
             /// </summary>

src/System.Windows.Forms/src/System/Windows/Forms/PropertyGridInternal/PropertyGridView.GridViewTextBox.GridViewTextBoxAccessibleObject.cs

@@ -11,16 +11,13 @@ internal partial class PropertyGridView
     {
         private partial class GridViewTextBox
         {
-            private class GridViewTextBoxAccessibleObject : ControlAccessibleObject
+            private class GridViewTextBoxAccessibleObject : TextBoxBaseAccessibleObject
             {
                 private readonly PropertyGridView _owningPropertyGridView;
-                private readonly TextBoxBaseUiaTextProvider _textProvider;
 
                 public GridViewTextBoxAccessibleObject(GridViewTextBox owner) : base(owner)
                 {
                     _owningPropertyGridView = owner.PropertyGridView;
-                    _textProvider = new TextBoxBaseUiaTextProvider(owner);
-                    UseTextProviders(_textProvider, _textProvider);
                 }
 
                 public override AccessibleStates State
@@ -41,8 +38,6 @@ public override AccessibleStates State
                     }
                 }
 
-                internal override bool IsIAccessibleExSupported() => true;
-
                 /// <summary>
                 ///  Returns the element in the specified direction.
                 /// </summary>
@@ -83,8 +78,6 @@ internal override UiaCore.IRawElementProviderFragmentRoot? FragmentRoot
                 internal override bool IsPatternSupported(UiaCore.UIA patternId) => patternId switch
                 {
                     UiaCore.UIA.ValuePatternId => true,
-                    UiaCore.UIA.TextPatternId => true,
-                    UiaCore.UIA.TextPattern2Id => true,
                     _ => base.IsPatternSupported(patternId)
                 };
 

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

@@ -2,36 +2,59 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Drawing;
 using static Interop;
+using static Interop.UiaCore;
 
 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
+            internal override bool IsPatternSupported(UIA patternId)
+                => patternId switch
                 {
-                    UiaCore.UIA.TextPatternId => true,
-                    UiaCore.UIA.TextPattern2Id => true,
+                    UIA.TextPatternId => true,
+                    UIA.TextPattern2Id => true,
                     _ => base.IsPatternSupported(patternId)
                 };
 
-            internal override bool IsReadOnly => _owningTextBoxBase.ReadOnly;
+            internal override bool IsReadOnly
+                => Owner is TextBoxBase textBoxBase && textBoxBase.ReadOnly;
+
+            internal override ITextRangeProvider DocumentRangeInternal
+                => _textProvider.DocumentRange;
+
+            internal override ITextRangeProvider[]? GetTextSelection()
+                => _textProvider.GetSelection();
+
+            internal override ITextRangeProvider[]? GetTextVisibleRanges()
+                => _textProvider.GetVisibleRanges();
+
+            internal override ITextRangeProvider? GetTextRangeFromChild(IRawElementProviderSimple childElement)
+                => _textProvider.RangeFromChild(childElement);
+
+            internal override ITextRangeProvider? GetTextRangeFromPoint(Point screenLocation)
+                => _textProvider.RangeFromPoint(screenLocation);
+
+            internal override SupportedTextSelection SupportedTextSelectionInternal
+                => _textProvider.SupportedTextSelection;
+
+            internal override ITextRangeProvider? GetTextCaretRange(out BOOL isActive)
+                => _textProvider.GetCaretRange(out isActive);
+
+            internal override ITextRangeProvider GetRangeFromAnnotation(IRawElementProviderSimple annotationElement)
+                => _textProvider.RangeFromAnnotation(annotationElement);
         }
     }
 }

src/System.Windows.Forms/src/System/Windows/Forms/ToolStripTextBox.ToolStripTextBoxControl.cs

@@ -218,9 +218,7 @@ protected override void OnVisibleChanged(EventArgs e)
             }
 
             protected override AccessibleObject CreateAccessibilityInstance()
-            {
-                return new ToolStripTextBoxControlAccessibleObject(this, Owner);
-            }
+                => new ToolStripTextBoxControlAccessibleObject(this);
 
             protected override void Dispose(bool disposing)
             {