Web tab selection (#119583)

Correct selection behavior when tabbing into a field on the web.

packages/flutter/lib/src/services/system_navigator.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-
 import 'system_channels.dart';
 
 /// Controls specific aspects of the system navigation stack.

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

@@ -2592,6 +2592,7 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
       _didAutoFocus = true;
       SchedulerBinding.instance.addPostFrameCallback((_) {
         if (mounted && renderEditable.hasSize) {
+          _flagInternalFocus();
           FocusScope.of(context).autofocus(widget.focusNode);
         }
       });
@@ -2714,6 +2715,7 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     clipboardStatus.removeListener(_onChangedClipboardStatus);
     clipboardStatus.dispose();
     _cursorVisibilityNotifier.dispose();
+    FocusManager.instance.removeListener(_unflagInternalFocus);
     super.dispose();
     assert(_batchEditDepth <= 0, 'unfinished batch edits: $_batchEditDepth');
   }
@@ -3236,6 +3238,23 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     }
   }
 
+  // Indicates that a call to _handleFocusChanged originated within
+  // EditableText, allowing it to distinguish between internal and external
+  // focus changes.
+  bool _nextFocusChangeIsInternal = false;
+
+  // Sets _nextFocusChangeIsInternal to true only until any subsequent focus
+  // change happens.
+  void _flagInternalFocus() {
+    _nextFocusChangeIsInternal = true;
+    FocusManager.instance.addListener(_unflagInternalFocus);
+  }
+
+  void _unflagInternalFocus() {
+    _nextFocusChangeIsInternal = false;
+    FocusManager.instance.removeListener(_unflagInternalFocus);
+  }
+
   /// Express interest in interacting with the keyboard.
   ///
   /// If this control is already attached to the keyboard, this function will
@@ -3247,6 +3266,7 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     if (_hasFocus) {
       _openInputConnection();
     } else {
+      _flagInternalFocus();
       widget.focusNode.requestFocus(); // This eventually calls _openInputConnection also, see _handleFocusChanged.
     }
   }
@@ -3677,7 +3697,19 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
       if (!widget.readOnly) {
         _scheduleShowCaretOnScreen(withAnimation: true);
       }
-      if (!_value.selection.isValid) {
+      final bool shouldSelectAll = widget.selectionEnabled && kIsWeb
+          && !_isMultiline && !_nextFocusChangeIsInternal;
+      if (shouldSelectAll) {
+        // On native web, single line <input> tags select all when receiving
+        // focus.
+        _handleSelectionChanged(
+          TextSelection(
+            baseOffset: 0,
+            extentOffset: _value.text.length,
+          ),
+          null,
+        );
+      } else if (!_value.selection.isValid) {
         // Place cursor at the end if the selection is invalid when we receive focus.
         _handleSelectionChanged(TextSelection.collapsed(offset: _value.text.length), null);
       }
@@ -3834,6 +3866,7 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
     // unfocused field that previously had a selection in the same spot.
     if (value == textEditingValue) {
       if (!widget.focusNode.hasFocus) {
+        _flagInternalFocus();
         widget.focusNode.requestFocus();
         _selectionOverlay = _createSelectionOverlay();
       }

packages/flutter/test/widgets/editable_text_show_on_screen_test.dart

@@ -553,7 +553,14 @@ void main() {
         focusNode.requestFocus();
         await tester.pumpAndSettle();
 
-        expect(isCaretOnScreen(tester), !readOnly);
+        if (kIsWeb) {
+          await tester.sendKeyEvent(LogicalKeyboardKey.arrowRight);
+          await tester.pump();
+        }
+
+        // On web, the entire field is selected, and only part of that selection
+        // is visible on the screen.
+        expect(isCaretOnScreen(tester), !readOnly && !kIsWeb);
         expect(scrollController.offset, readOnly ? 0.0 : greaterThan(0.0));
         expect(editableScrollController.offset, readOnly ? 0.0 : greaterThan(0.0));
       });

packages/flutter/test/widgets/editable_text_test.dart

@@ -780,13 +780,28 @@ void main() {
     focusNode.requestFocus();
     await tester.pump();
 
-    expect(controller.value, value);
+    // On web, focusing a single-line input selects the entire field.
+    final TextEditingValue webValue = value.copyWith(
+      selection: TextSelection(
+        baseOffset: 0,
+        extentOffset: controller.value.text.length,
+      ),
+    );
+    if (kIsWeb) {
+      expect(controller.value, webValue);
+    } else {
+      expect(controller.value, value);
+    }
     expect(focusNode.hasFocus, isTrue);
 
     focusNode.unfocus();
     await tester.pump();
 
-    expect(controller.value, value);
+    if (kIsWeb) {
+      expect(controller.value, webValue);
+    } else {
+      expect(controller.value, value);
+    }
     expect(focusNode.hasFocus, isFalse);
   });
 
@@ -4349,7 +4364,10 @@ void main() {
                           ],
                           value: expectedValue,
                           textDirection: TextDirection.ltr,
-                          textSelection: const TextSelection.collapsed(offset: 24),
+                          // Focusing a single-line field on web selects it.
+                          textSelection: kIsWeb
+                              ? const TextSelection(baseOffset: 0, extentOffset: 24)
+                              : const TextSelection.collapsed(offset: 24),
                         ),
                       ],
                     ),
@@ -15062,7 +15080,7 @@ testWidgets('Floating cursor ending with selection', (WidgetTester tester) async
                 ),
               ),
             );
-          }
+          },
         ),
       ),
     );
@@ -15088,6 +15106,217 @@ testWidgets('Floating cursor ending with selection', (WidgetTester tester) async
 
     EditableText.debugDeterministicCursor = false;
   });
+
+  group('selection behavior when receiving focus', () {
+    testWidgets('tabbing between fields', (WidgetTester tester) async {
+      final TextEditingController controller1 = TextEditingController();
+      final TextEditingController controller2 = TextEditingController();
+      controller1.text = 'Text1';
+      controller2.text = 'Text2\nLine2';
+      final FocusNode focusNode1 = FocusNode();
+      final FocusNode focusNode2 = FocusNode();
+
+      await tester.pumpWidget(
+        MaterialApp(
+          home: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children:  <Widget>[
+              EditableText(
+                key: ValueKey<String>(controller1.text),
+                controller: controller1,
+                focusNode: focusNode1,
+                style: Typography.material2018().black.titleMedium!,
+                cursorColor: Colors.blue,
+                backgroundCursorColor: Colors.grey,
+              ),
+              const SizedBox(height: 200.0),
+              EditableText(
+                key: ValueKey<String>(controller2.text),
+                controller: controller2,
+                focusNode: focusNode2,
+                style: Typography.material2018().black.titleMedium!,
+                cursorColor: Colors.blue,
+                backgroundCursorColor: Colors.grey,
+                minLines: 10,
+                maxLines: 20,
+              ),
+              const SizedBox(height: 100.0),
+            ],
+          ),
+        ),
+      );
+
+      expect(focusNode1.hasFocus, isFalse);
+      expect(focusNode2.hasFocus, isFalse);
+      expect(
+        controller1.selection,
+        const TextSelection.collapsed(offset: -1),
+      );
+      expect(
+        controller2.selection,
+        const TextSelection.collapsed(offset: -1),
+      );
+
+      // Tab to the first field (single line).
+      await tester.sendKeyEvent(LogicalKeyboardKey.tab);
+      await tester.pumpAndSettle();
+      expect(focusNode1.hasFocus, isTrue);
+      expect(focusNode2.hasFocus, isFalse);
+      expect(
+        controller1.selection,
+        kIsWeb
+          ? TextSelection(
+              baseOffset: 0,
+              extentOffset: controller1.text.length,
+            )
+          : TextSelection.collapsed(
+              offset: controller1.text.length,
+            ),
+      );
+
+      // Move the cursor to another position in the first field.
+      await tester.tapAt(textOffsetToPosition(tester, controller1.text.length - 1));
+      await tester.pumpAndSettle();
+      expect(
+        controller1.selection,
+        TextSelection.collapsed(
+          offset: controller1.text.length - 1,
+        ),
+      );
+
+      // Tab to the second field (multiline).
+      await tester.sendKeyEvent(LogicalKeyboardKey.tab);
+      await tester.pumpAndSettle();
+      expect(focusNode1.hasFocus, isFalse);
+      expect(focusNode2.hasFocus, isTrue);
+      expect(
+        controller2.selection,
+        TextSelection.collapsed(
+          offset: controller2.text.length,
+        ),
+      );
+
+      // Move the cursor to another position in the second field.
+      await tester.tapAt(textOffsetToPosition(tester, controller2.text.length - 1, index: 1));
+      await tester.pumpAndSettle();
+      expect(
+        controller2.selection,
+        TextSelection.collapsed(
+          offset: controller2.text.length - 1,
+        ),
+      );
+
+      // On web, the document root is also focusable.
+      if (kIsWeb) {
+        await tester.sendKeyEvent(LogicalKeyboardKey.tab);
+        await tester.pumpAndSettle();
+        expect(focusNode1.hasFocus, isFalse);
+        expect(focusNode2.hasFocus, isFalse);
+      }
+
+      // Tabbing again goes back to the first field and reselects the field.
+      await tester.sendKeyEvent(LogicalKeyboardKey.tab);
+      await tester.pumpAndSettle();
+      expect(focusNode1.hasFocus, isTrue);
+      expect(focusNode2.hasFocus, isFalse);
+      expect(
+        controller1.selection,
+        kIsWeb
+          ? TextSelection(
+              baseOffset: 0,
+              extentOffset: controller1.text.length,
+            )
+          : TextSelection.collapsed(
+              offset: controller1.text.length - 1,
+            ),
+      );
+
+      // Tabbing to the second field again retains the moved selection.
+      await tester.sendKeyEvent(LogicalKeyboardKey.tab);
+      await tester.pumpAndSettle();
+      expect(focusNode1.hasFocus, isFalse);
+      expect(focusNode2.hasFocus, isTrue);
+      expect(
+        controller2.selection,
+        TextSelection.collapsed(
+          offset: controller2.text.length - 1,
+        ),
+      );
+    });
+
+    testWidgets('when having focus stolen between frames on web', (WidgetTester tester) async {
+      final TextEditingController controller1 = TextEditingController();
+      controller1.text = 'Text1';
+      final FocusNode focusNode1 = FocusNode();
+      final FocusNode focusNode2 = FocusNode();
+
+      await tester.pumpWidget(
+        MaterialApp(
+          home: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children:  <Widget>[
+              EditableText(
+                key: ValueKey<String>(controller1.text),
+                controller: controller1,
+                focusNode: focusNode1,
+                style: Typography.material2018().black.titleMedium!,
+                cursorColor: Colors.blue,
+                backgroundCursorColor: Colors.grey,
+              ),
+              const SizedBox(height: 200.0),
+              Focus(
+                focusNode: focusNode2,
+                child: const SizedBox.shrink(),
+              ),
+              const SizedBox(height: 100.0),
+            ],
+          ),
+        ),
+      );
+
+      expect(focusNode1.hasFocus, isFalse);
+      expect(focusNode2.hasFocus, isFalse);
+      expect(
+        controller1.selection,
+        const TextSelection.collapsed(offset: -1),
+      );
+
+      final EditableTextState state = tester.state<EditableTextState>(find.byType(EditableText).first);
+
+      // Set the text editing value in order to trigger an internal call to
+      // requestFocus.
+      state.userUpdateTextEditingValue(
+        controller1.value,
+        SelectionChangedCause.keyboard,
+      );
+      // Focus takes a frame to update, so it hasn't changed yet.
+      expect(focusNode1.hasFocus, isFalse);
+      expect(focusNode2.hasFocus, isFalse);
+
+      // Before EditableText's listener on widget.focusNode can be called, change
+      // the focus again
+      focusNode2.requestFocus();
+      await tester.pump();
+      expect(focusNode1.hasFocus, isFalse);
+      expect(focusNode2.hasFocus, isTrue);
+
+      // Focus the EditableText again, which should cause the field to be selected
+      // on web.
+      focusNode1.requestFocus();
+      await tester.pumpAndSettle();
+      expect(focusNode1.hasFocus, isTrue);
+      expect(focusNode2.hasFocus, isFalse);
+      expect(
+        controller1.selection,
+        TextSelection(
+          baseOffset: 0,
+          extentOffset: controller1.text.length,
+        ),
+      );
+    },
+      skip: !kIsWeb, // [intended]
+    );
+  });
 }
 
 class UnsettableController extends TextEditingController {

packages/flutter/test/widgets/editable_text_utils.dart

@@ -10,9 +10,9 @@ import 'package:flutter_test/flutter_test.dart';
 /// On web, the context menu (aka toolbar) is provided by the browser.
 const bool isContextMenuProvidedByPlatform = isBrowser;
 
-// Returns the first RenderEditable.
-RenderEditable findRenderEditable(WidgetTester tester) {
-  final RenderObject root = tester.renderObject(find.byType(EditableText));
+// Returns the RenderEditable at the given index, or the first if not given.
+RenderEditable findRenderEditable(WidgetTester tester, {int index = 0}) {
+  final RenderObject root = tester.renderObject(find.byType(EditableText).at(index));
   expect(root, isNotNull);
 
   late RenderEditable renderEditable;
@@ -37,8 +37,8 @@ List<TextSelectionPoint> globalize(Iterable<TextSelectionPoint> points, RenderBo
   }).toList();
 }
 
-Offset textOffsetToPosition(WidgetTester tester, int offset) {
-  final RenderEditable renderEditable = findRenderEditable(tester);
+Offset textOffsetToPosition(WidgetTester tester, int offset, {int index = 0}) {
+  final RenderEditable renderEditable = findRenderEditable(tester, index: index);
   final List<TextSelectionPoint> endpoints = globalize(
     renderEditable.getEndpointsForSelection(
       TextSelection.collapsed(offset: offset),