Support for disabling interactive TextField caret and selection (#22924)

Make it possible to disable TextField's default handlers for tap and long press. If enableInteractiveSelection is false then taps no longer move the text caret and long-press no longer selects text and shows the cut/copy/paste menu. Accessibility is similarly limited.

packages/flutter/lib/src/material/text_field.dart

@@ -88,8 +88,9 @@ class TextField extends StatefulWidget {
   /// characters may be entered, and the error counter and divider will
   /// switch to the [decoration.errorStyle] when the limit is exceeded.
   ///
-  /// The [textAlign], [autofocus], [obscureText], and [autocorrect] arguments
-  /// must not be null.
+  /// The [textAlign], [autofocus], [obscureText], [autocorrect],
+  /// [maxLengthEnforced], [scrollPadding], [maxLines], [maxLength],
+  /// and [enableInteractiveSelection] arguments must not be null.
   ///
   /// See also:
   ///
@@ -121,6 +122,7 @@ class TextField extends StatefulWidget {
     this.cursorColor,
     this.keyboardAppearance,
     this.scrollPadding = const EdgeInsets.all(20.0),
+    this.enableInteractiveSelection = true,
   }) : assert(textAlign != null),
        assert(autofocus != null),
        assert(obscureText != null),
@@ -130,6 +132,7 @@ class TextField extends StatefulWidget {
        assert(maxLines == null || maxLines > 0),
        assert(maxLength == null || maxLength > 0),
        keyboardType = keyboardType ?? (maxLines == 1 ? TextInputType.text : TextInputType.multiline),
+       assert(enableInteractiveSelection != null),
        super(key: key);
 
   /// Controls the text being edited.
@@ -343,6 +346,9 @@ class TextField extends StatefulWidget {
   /// Defaults to EdgeInserts.all(20.0).
   final EdgeInsets scrollPadding;
 
+  /// {@macro flutter.widgets.editableText.enableInteractiveSelection}
+  final bool enableInteractiveSelection;
+
   @override
   _TextFieldState createState() => _TextFieldState();
 
@@ -487,7 +493,8 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
   }
 
   void _handleTap() {
-    _renderEditable.handleTap();
+    if (widget.enableInteractiveSelection)
+      _renderEditable.handleTap();
     _requestKeyboard();
     _confirmCurrentSplash();
   }
@@ -497,7 +504,8 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
   }
 
   void _handleLongPress() {
-    _renderEditable.handleLongPress();
+    if (widget.enableInteractiveSelection)
+      _renderEditable.handleLongPress();
     _confirmCurrentSplash();
   }
 
@@ -567,9 +575,11 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
         autocorrect: widget.autocorrect,
         maxLines: widget.maxLines,
         selectionColor: themeData.textSelectionColor,
-        selectionControls: themeData.platform == TargetPlatform.iOS
-            ? cupertinoTextSelectionControls
-            : materialTextSelectionControls,
+        selectionControls: widget.enableInteractiveSelection
+          ? (themeData.platform == TargetPlatform.iOS
+             ? cupertinoTextSelectionControls
+             : materialTextSelectionControls)
+          : null,
         onChanged: widget.onChanged,
         onEditingComplete: widget.onEditingComplete,
         onSubmitted: widget.onSubmitted,
@@ -581,6 +591,7 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
         cursorColor: widget.cursorColor ?? Theme.of(context).cursorColor,
         scrollPadding: widget.scrollPadding,
         keyboardAppearance: keyboardAppearance,
+        enableInteractiveSelection: widget.enableInteractiveSelection,
       ),
     );
 

packages/flutter/lib/src/material/text_form_field.dart

@@ -74,6 +74,7 @@ class TextFormField extends FormField<String> {
     bool enabled = true,
     Brightness keyboardAppearance,
     EdgeInsets scrollPadding = const EdgeInsets.all(20.0),
+    bool enableInteractiveSelection = true,
   }) : assert(initialValue == null || controller == null),
        assert(textAlign != null),
        assert(autofocus != null),
@@ -84,6 +85,7 @@ class TextFormField extends FormField<String> {
        assert(scrollPadding != null),
        assert(maxLines == null || maxLines > 0),
        assert(maxLength == null || maxLength > 0),
+       assert(enableInteractiveSelection != null),
        super(
     key: key,
     initialValue: controller != null ? controller.text : (initialValue ?? ''),
@@ -117,6 +119,7 @@ class TextFormField extends FormField<String> {
         enabled: enabled,
         scrollPadding: scrollPadding,
         keyboardAppearance: keyboardAppearance,
+        enableInteractiveSelection: enableInteractiveSelection,
       );
     },
   );

packages/flutter/lib/src/rendering/editable.dart

@@ -118,6 +118,8 @@ class RenderEditable extends RenderBox {
   ///
   /// The [offset] is required and must not be null. You can use [new
   /// ViewportOffset.zero] if you have no need for scrolling.
+  ///
+  /// The [enableInteractiveSelection] argument must not be null.
   RenderEditable({
     TextSpan text,
     @required TextDirection textDirection,
@@ -137,6 +139,7 @@ class RenderEditable extends RenderBox {
     Locale locale,
     double cursorWidth = 1.0,
     Radius cursorRadius,
+    bool enableInteractiveSelection = true,
     @required this.textSelectionDelegate,
   }) : assert(textAlign != null),
        assert(textDirection != null, 'RenderEditable created without a textDirection.'),
@@ -145,8 +148,9 @@ class RenderEditable extends RenderBox {
        assert(offset != null),
        assert(ignorePointer != null),
        assert(obscureText != null),
+       assert(enableInteractiveSelection != null),
        assert(textSelectionDelegate != null),
-  _textPainter = TextPainter(
+       _textPainter = TextPainter(
          text: text,
          textAlign: textAlign,
          textDirection: textDirection,
@@ -162,6 +166,7 @@ class RenderEditable extends RenderBox {
        _offset = offset,
        _cursorWidth = cursorWidth,
        _cursorRadius = cursorRadius,
+       _enableInteractiveSelection = enableInteractiveSelection,
        _obscureText = obscureText {
     assert(_showCursor != null);
     assert(!_showCursor.value || cursorColor != null);
@@ -692,6 +697,20 @@ class RenderEditable extends RenderBox {
     markNeedsPaint();
   }
 
+  /// If false, [describeSemanticsConfiguration] will not set the
+  /// configuration's cursor motion or set selection callbacks.
+  ///
+  /// True by default.
+  bool get enableInteractiveSelection => _enableInteractiveSelection;
+  bool _enableInteractiveSelection;
+  set enableInteractiveSelection(bool value) {
+    if (_enableInteractiveSelection == value)
+      return;
+    _enableInteractiveSelection = value;
+    markNeedsTextLayout();
+    markNeedsSemanticsUpdate();
+  }
+
   @override
   void describeSemanticsConfiguration(SemanticsConfiguration config) {
     super.describeSemanticsConfiguration(config);
@@ -705,10 +724,10 @@ class RenderEditable extends RenderBox {
       ..isFocused = hasFocus
       ..isTextField = true;
 
-    if (hasFocus)
+    if (hasFocus && enableInteractiveSelection)
       config.onSetSelection = _handleSetSelection;
 
-    if (_selection?.isValid == true) {
+    if (enableInteractiveSelection && _selection?.isValid == true) {
       config.textSelection = _selection;
       if (_textPainter.getOffsetBefore(_selection.extentOffset) != null) {
         config

packages/flutter/lib/src/widgets/editable_text.dart

@@ -183,7 +183,8 @@ class EditableText extends StatefulWidget {
   /// default to [TextInputType.multiline].
   ///
   /// The [controller], [focusNode], [style], [cursorColor], [textAlign],
-  /// and [rendererIgnoresPointer], arguments must not be null.
+  /// [rendererIgnoresPointer], and [enableInteractiveSelection] arguments must
+  /// not be null.
   EditableText({
     Key key,
     @required this.controller,
@@ -213,6 +214,7 @@ class EditableText extends StatefulWidget {
     this.cursorRadius,
     this.scrollPadding = const EdgeInsets.all(20.0),
     this.keyboardAppearance = Brightness.light,
+    this.enableInteractiveSelection = true,
   }) : assert(controller != null),
        assert(focusNode != null),
        assert(obscureText != null),
@@ -224,6 +226,7 @@ class EditableText extends StatefulWidget {
        assert(autofocus != null),
        assert(rendererIgnoresPointer != null),
        assert(scrollPadding != null),
+       assert(enableInteractiveSelection != null),
        keyboardType = keyboardType ?? (maxLines == 1 ? TextInputType.text : TextInputType.multiline),
        inputFormatters = maxLines == 1
            ? (
@@ -399,6 +402,17 @@ class EditableText extends StatefulWidget {
   /// Defaults to EdgeInserts.all(20.0).
   final EdgeInsets scrollPadding;
 
+  /// {@template flutter.widgets.editableText.enableInteractiveSelection}
+  /// If true, then long-pressing this TextField will select text and show the
+  /// cut/copy/paste menu, and tapping will move the text caret.
+  ///
+  /// True by default.
+  ///
+  /// If false, most of the accessibility support for selecting text, copy
+  /// and paste, and moving the caret will be disabled.
+  /// {@endtemplate}
+  final bool enableInteractiveSelection;
+
   /// Setting this property to true makes the cursor stop blinking and stay visible on the screen continually.
   /// This property is most useful for testing purposes.
   ///
@@ -864,12 +878,30 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     _selectionOverlay?.hide();
   }
 
+  VoidCallback _semanticsOnCopy(TextSelectionControls controls) {
+    return widget.enableInteractiveSelection && _hasFocus && controls?.canCopy(this) == true
+      ? () => controls.handleCopy(this)
+      : null;
+  }
+
+  VoidCallback _semanticsOnCut(TextSelectionControls controls) {
+    return widget.enableInteractiveSelection && _hasFocus && controls?.canCut(this) == true
+      ? () => controls.handleCut(this)
+      : null;
+  }
+
+  VoidCallback _semanticsOnPaste(TextSelectionControls controls) {
+    return widget.enableInteractiveSelection &&_hasFocus && controls?.canPaste(this) == true
+      ? () => controls.handlePaste(this)
+      : null;
+  }
+
   @override
   Widget build(BuildContext context) {
     FocusScope.of(context).reparentIfNeeded(widget.focusNode);
     super.build(context); // See AutomaticKeepAliveClientMixin.
-    final TextSelectionControls controls = widget.selectionControls;
 
+    final TextSelectionControls controls = widget.selectionControls;
     return Scrollable(
       excludeFromSemantics: true,
       axisDirection: _isMultiline ? AxisDirection.down : AxisDirection.right,
@@ -879,9 +911,9 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
         return CompositedTransformTarget(
           link: _layerLink,
           child: Semantics(
-            onCopy: _hasFocus && controls?.canCopy(this) == true ? () => controls.handleCopy(this) : null,
-            onCut: _hasFocus && controls?.canCut(this) == true ? () => controls.handleCut(this) : null,
-            onPaste: _hasFocus && controls?.canPaste(this) == true ? () => controls.handlePaste(this) : null,
+            onCopy: _semanticsOnCopy(controls),
+            onCut: _semanticsOnCut(controls),
+            onPaste: _semanticsOnPaste(controls),
             child: _Editable(
               key: _editableKey,
               textSpan: buildTextSpan(),
@@ -903,6 +935,7 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
               rendererIgnoresPointer: widget.rendererIgnoresPointer,
               cursorWidth: widget.cursorWidth,
               cursorRadius: widget.cursorRadius,
+              enableInteractiveSelection: widget.enableInteractiveSelection,
               textSelectionDelegate: this,
             ),
           ),
@@ -967,9 +1000,11 @@ class _Editable extends LeafRenderObjectWidget {
     this.rendererIgnoresPointer = false,
     this.cursorWidth,
     this.cursorRadius,
+    this.enableInteractiveSelection = true,
     this.textSelectionDelegate,
   }) : assert(textDirection != null),
        assert(rendererIgnoresPointer != null),
+       assert(enableInteractiveSelection != null),
        super(key: key);
 
   final TextSpan textSpan;
@@ -991,6 +1026,7 @@ class _Editable extends LeafRenderObjectWidget {
   final bool rendererIgnoresPointer;
   final double cursorWidth;
   final Radius cursorRadius;
+  final bool enableInteractiveSelection;
   final TextSelectionDelegate textSelectionDelegate;
 
   @override
@@ -1014,6 +1050,7 @@ class _Editable extends LeafRenderObjectWidget {
       obscureText: obscureText,
       cursorWidth: cursorWidth,
       cursorRadius: cursorRadius,
+      enableInteractiveSelection: enableInteractiveSelection,
       textSelectionDelegate: textSelectionDelegate,
     );
   }

packages/flutter/test/material/text_field_test.dart

@@ -404,6 +404,34 @@ void main() {
     expect(controller.selection.extentOffset, tapIndex);
   });
 
+  testWidgets('enableInteractiveSelection = false, tap', (WidgetTester tester) async {
+    final TextEditingController controller = TextEditingController();
+
+    await tester.pumpWidget(
+      overlay(
+        child: TextField(
+          controller: controller,
+          enableInteractiveSelection: false,
+        ),
+      )
+    );
+    expect(controller.selection.baseOffset, -1);
+    expect(controller.selection.extentOffset, -1);
+
+    const String testValue = 'abc def ghi';
+    await tester.enterText(find.byType(TextField), testValue);
+    await skipPastScrollingAnimation(tester);
+
+    // Tap would ordinarily reposition the caret.
+    final int tapIndex = testValue.indexOf('e');
+    final Offset ePos = textOffsetToPosition(tester, tapIndex);
+    await tester.tapAt(ePos);
+    await tester.pump();
+
+    expect(controller.selection.baseOffset, -1);
+    expect(controller.selection.extentOffset, -1);
+  });
+
   testWidgets('Can long press to select', (WidgetTester tester) async {
     final TextEditingController controller = TextEditingController();
 
@@ -434,6 +462,37 @@ void main() {
     expect(controller.selection.extentOffset, testValue.indexOf('f')+1);
   });
 
+  testWidgets('enableInteractiveSelection = false, long-press', (WidgetTester tester) async {
+    final TextEditingController controller = TextEditingController();
+
+    await tester.pumpWidget(
+      overlay(
+        child: TextField(
+          controller: controller,
+          enableInteractiveSelection: false,
+        ),
+      )
+    );
+
+    const String testValue = 'abc def ghi';
+    await tester.enterText(find.byType(TextField), testValue);
+    expect(controller.value.text, testValue);
+    await skipPastScrollingAnimation(tester);
+
+    expect(controller.selection.isCollapsed, true);
+
+    // Long press the 'e' to select 'def'.
+    final Offset ePos = textOffsetToPosition(tester, testValue.indexOf('e'));
+    final TestGesture gesture = await tester.startGesture(ePos, pointer: 7);
+    await tester.pump(const Duration(seconds: 2));
+    await gesture.up();
+    await tester.pump();
+
+    expect(controller.selection.isCollapsed, true);
+    expect(controller.selection.baseOffset, -1);
+    expect(controller.selection.extentOffset, -1);
+  });
+
   testWidgets('Can drag handles to change selection', (WidgetTester tester) async {
     final TextEditingController controller = TextEditingController();
 
@@ -2530,6 +2589,48 @@ void main() {
     semantics.dispose();
   });
 
+  testWidgets('TextField semantics, enableInteractiveSelection = false', (WidgetTester tester) async {
+    final SemanticsTester semantics = SemanticsTester(tester);
+    final TextEditingController controller = TextEditingController();
+    final Key key = UniqueKey();
+
+    await tester.pumpWidget(
+      overlay(
+        child: TextField(
+          key: key,
+          controller: controller,
+          enableInteractiveSelection: false,
+        ),
+      ),
+    );
+
+    await tester.tap(find.byKey(key));
+    await tester.pump();
+
+    expect(semantics, hasSemantics(TestSemantics.root(
+      children: <TestSemantics>[
+        TestSemantics.rootChild(
+          id: 1,
+          textDirection: TextDirection.ltr,
+          actions: <SemanticsAction>[
+            SemanticsAction.tap,
+            // Absent the following because enableInteractiveSelection: false
+            // SemanticsAction.moveCursorBackwardByCharacter,
+            // SemanticsAction.moveCursorBackwardByWord,
+            // SemanticsAction.setSelection,
+            // SemanticsAction.paste,
+          ],
+          flags: <SemanticsFlag>[
+            SemanticsFlag.isTextField,
+            SemanticsFlag.isFocused,
+          ],
+        ),
+      ],
+    ), ignoreTransform: true, ignoreRect: true));
+
+    semantics.dispose();
+  });
+
   testWidgets('TextField semantics for selections', (WidgetTester tester) async {
     final SemanticsTester semantics = SemanticsTester(tester);
     final TextEditingController controller = TextEditingController()