Re-apply "Send nextId in addition to previousId for traversal order" (f…

…lutter#14694)

Re-apply "Send nextId in addition to previousId for traversal order (flutter#14676)"

bin/internal/engine.version

@@ -1 +1 @@
-f5a4a9378740c3d5996583a9ed1f7e28ff08ee85
+05c5f817eb731569ddaad6397ee9ce000d37f2f1

packages/flutter/lib/src/semantics/semantics.dart

@@ -92,6 +92,7 @@ class SemanticsData extends Diagnosticable {
  @required this.decreasedValue,
  @required this.hint,
  @required this.textDirection,
+ @required this.nextNodeId,
  @required this.previousNodeId,
  @required this.rect,
  @required this.textSelection,
@@ -151,6 +152,10 @@ class SemanticsData extends Diagnosticable {
  /// [increasedValue], and [decreasedValue].
  final TextDirection textDirection;
 
+ /// The index indicating the ID of the next node in the traversal order after
+ /// this node for the platform's accessibility services.
+ final int nextNodeId;
+
  /// The index indicating the ID of the previous node in the traversal order before
  /// this node for the platform's accessibility services.
  final int previousNodeId;
@@ -237,6 +242,7 @@ class SemanticsData extends Diagnosticable {
  properties.add(new StringProperty('decreasedValue', decreasedValue, defaultValue: ''));
  properties.add(new StringProperty('hint', hint, defaultValue: ''));
  properties.add(new EnumProperty<TextDirection>('textDirection', textDirection, defaultValue: null));
+ properties.add(new IntProperty('nextNodeId', nextNodeId, defaultValue: null));
  properties.add(new IntProperty('previousNodeId', previousNodeId, defaultValue: null));
  if (textSelection?.isValid == true)
  properties.add(new MessageProperty('textSelection', '[${textSelection.start}, ${textSelection.end}]'));
@@ -258,6 +264,7 @@ class SemanticsData extends Diagnosticable {
  && typedOther.decreasedValue == decreasedValue
  && typedOther.hint == hint
  && typedOther.textDirection == textDirection
+ && typedOther.nextNodeId == nextNodeId
  && typedOther.previousNodeId == previousNodeId
  && typedOther.rect == rect
  && setEquals(typedOther.tags, tags)
@@ -269,7 +276,7 @@ class SemanticsData extends Diagnosticable {
  }
 
  @override
- int get hashCode => ui.hashValues(flags, actions, label, value, increasedValue, decreasedValue, hint, textDirection, previousNodeId, rect, tags, textSelection, scrollPosition, scrollExtentMax, scrollExtentMin, transform);
+ int get hashCode => ui.hashValues(flags, actions, label, value, increasedValue, decreasedValue, hint, textDirection, nextNodeId, previousNodeId, rect, tags, textSelection, scrollPosition, scrollExtentMax, scrollExtentMin, transform);
 }
 
 class _SemanticsDiagnosticableNode extends DiagnosticableNode<SemanticsNode> {
@@ -1067,10 +1074,30 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
 
  /// The sort order for ordering the traversal of [SemanticsNode]s by the
  /// platform's accessibility services (e.g. VoiceOver on iOS and TalkBack on
- /// Android). This is used to determine the [previousNodeId] during a semantics update.
+ /// Android). This is used to determine the [nextNodeId] and [previousNodeId]
+ /// during a semantics update.
  SemanticsSortOrder _sortOrder;
  SemanticsSortOrder get sortOrder => _sortOrder;
 
+ /// The ID of the next node in the traversal order after this node.
+ ///
+ /// Only valid after at least one semantics update has been built.
+ ///
+ /// This is the value passed to the engine to tell it what the order
+ /// should be for traversing semantics nodes.
+ ///
+ /// If this is set to -1, it will indicate that there is no next node to
+ /// the engine (i.e. this is the last node in the sort order). When it is
+ /// null, it means that no semantics update has been built yet.
+ int _nextNodeId;
+ void _updateNextNodeId(int value) {
+ if (value == _nextNodeId)
+ return;
+ _nextNodeId = value;
+ _markDirty();
+ }
+ int get nextNodeId => _nextNodeId;
+
  /// The ID of the previous node in the traversal order before this node.
  ///
  /// Only valid after at least one semantics update has been built.
@@ -1194,6 +1221,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
  String increasedValue = _increasedValue;
  String decreasedValue = _decreasedValue;
  TextDirection textDirection = _textDirection;
+ int nextNodeId = _nextNodeId;
  int previousNodeId = _previousNodeId;
  Set<SemanticsTag> mergedTags = tags == null ? null : new Set<SemanticsTag>.from(tags);
  TextSelection textSelection = _textSelection;
@@ -1207,6 +1235,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
  flags |= node._flags;
  actions |= node._actionsAsBits;
  textDirection ??= node._textDirection;
+ nextNodeId ??= node._nextNodeId;
  previousNodeId ??= node._previousNodeId;
  textSelection ??= node._textSelection;
  scrollPosition ??= node._scrollPosition;
@@ -1247,6 +1276,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
  decreasedValue: decreasedValue,
  hint: hint,
  textDirection: textDirection,
+ nextNodeId: nextNodeId,
  previousNodeId: previousNodeId,
  rect: rect,
  transform: transform,
@@ -1289,6 +1319,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
  increasedValue: data.increasedValue,
  hint: data.hint,
  textDirection: data.textDirection,
+ nextNodeId: data.nextNodeId,
  previousNodeId: data.previousNodeId,
  textSelectionBase: data.textSelection != null ? data.textSelection.baseOffset : -1,
  textSelectionExtent: data.textSelection != null ? data.textSelection.extentOffset : -1,
@@ -1363,6 +1394,7 @@ class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
  properties.add(new StringProperty('decreasedValue', _decreasedValue, defaultValue: ''));
  properties.add(new StringProperty('hint', _hint, defaultValue: ''));
  properties.add(new EnumProperty<TextDirection>('textDirection', _textDirection, defaultValue: null));
+ properties.add(new IntProperty('nextNodeId', _nextNodeId, defaultValue: null));
  properties.add(new IntProperty('previousNodeId', _previousNodeId, defaultValue: null));
  properties.add(new DiagnosticsProperty<SemanticsSortOrder>('sortOrder', sortOrder, defaultValue: null));
  if (_textSelection?.isValid == true)
@@ -1539,10 +1571,10 @@ class SemanticsOwner extends ChangeNotifier {
  super.dispose();
  }
 
- // Updates the previousNodeId IDs on the semantics nodes. These IDs are used
- // on the platform side to order the nodes for traversal by the accessibility
- // services. If the previousNodeId for a node changes, the node will be marked as
- // dirty.
+ // Updates the nextNodeId and previousNodeId IDs on the semantics nodes. These
+ // IDs are used on the platform side to order the nodes for traversal by the
+ // accessibility services. If the nextNodeId or previousNodeId for a node
+ // changes, the node will be marked as dirty.
  void _updateTraversalOrder() {
  final List<_TraversalSortNode> nodesInSemanticsTraversalOrder = <_TraversalSortNode>[];
  SemanticsSortOrder currentSortOrder = new SemanticsSortOrder(keys: <SemanticsSortKey>[]);
@@ -1577,12 +1609,20 @@ class SemanticsOwner extends ChangeNotifier {
  return true;
  }
  rootSemanticsNode.visitChildren(visitor);
+
+ if (nodesInSemanticsTraversalOrder.isEmpty)
+ return;
+
  nodesInSemanticsTraversalOrder.sort();
- int previousNodeId = -1;
- for (_TraversalSortNode node in nodesInSemanticsTraversalOrder) {
- node.node._updatePreviousNodeId(previousNodeId);
- previousNodeId = node.node.id;
+ _TraversalSortNode node = nodesInSemanticsTraversalOrder.removeLast();
+ node.node._updateNextNodeId(-1);
+ while (nodesInSemanticsTraversalOrder.isNotEmpty) {
+ final _TraversalSortNode previousNode = nodesInSemanticsTraversalOrder.removeLast();
+ node.node._updatePreviousNodeId(previousNode.node.id);
+ previousNode.node._updateNextNodeId(node.node.id);
+ node = previousNode;
  }
+ node.node._updatePreviousNodeId(-1);
  }
 
  /// Update the semantics using [Window.updateSemantics].

packages/flutter/test/semantics/semantics_test.dart

@@ -348,7 +348,7 @@ void main() {
 
  expect(
  minimalProperties.toStringDeep(minLevel: DiagnosticLevel.hidden),
- 'SemanticsNode#1(owner: null, isMergedIntoParent: false, mergeAllDescendantsIntoThisNode: false, Rect.fromLTRB(0.0, 0.0, 0.0, 0.0), actions: [], isInMutuallyExcusiveGroup: false, isSelected: false, isFocused: false, isButton: false, isTextField: false, invisible, label: "", value: "", increasedValue: "", decreasedValue: "", hint: "", textDirection: null, previousNodeId: null, sortOrder: null, scrollExtentMin: null, scrollPosition: null, scrollExtentMax: null)\n'
+ 'SemanticsNode#1(owner: null, isMergedIntoParent: false, mergeAllDescendantsIntoThisNode: false, Rect.fromLTRB(0.0, 0.0, 0.0, 0.0), actions: [], isInMutuallyExcusiveGroup: false, isSelected: false, isFocused: false, isButton: false, isTextField: false, invisible, label: "", value: "", increasedValue: "", decreasedValue: "", hint: "", textDirection: null, nextNodeId: null, previousNodeId: null, sortOrder: null, scrollExtentMin: null, scrollPosition: null, scrollExtentMax: null)\n'
  );
 
  final SemanticsConfiguration config = new SemanticsConfiguration()

packages/flutter/test/widgets/semantics_test.dart

@@ -417,6 +417,7 @@ void main() {
  rect: TestSemantics.fullScreen,
  actions: allActions.fold(0, (int previous, SemanticsAction action) => previous | action.index),
  previousNodeId: -1,
+ nextNodeId: -1,
  ),
  ],
  );
@@ -613,44 +614,59 @@ void main() {
  expect(semanticsUpdateCount, 1);
  expect(semantics, hasSemantics(
  new TestSemantics(
+ id: 0,
  children: <TestSemantics>[
  new TestSemantics(
+ id: 2,
+ nextNodeId: 5,
  previousNodeId: -1,
  children: <TestSemantics>[
  new TestSemantics(
+ id: 3,
  label: r'Label 1',
  textDirection: TextDirection.ltr,
+ nextNodeId: -1,
  previousNodeId: 4,
  ),
  new TestSemantics(
+ id: 4,
  label: r'Label 2',
  textDirection: TextDirection.ltr,
+ nextNodeId: 3,
  previousNodeId: 6,
  ),
  new TestSemantics(
+ id: 5,
+ nextNodeId: 8,
  previousNodeId: 2,
  children: <TestSemantics>[
  new TestSemantics(
+ id: 6,
  label: r'Label 3',
  textDirection: TextDirection.ltr,
+ nextNodeId: 4,
  previousNodeId: 7,
  ),
  new TestSemantics(
+ id: 7,
  label: r'Label 4',
  textDirection: TextDirection.ltr,
+ nextNodeId: 6,
  previousNodeId: 8,
  ),
  new TestSemantics(
+ id: 8,
  label: r'Label 5',
  textDirection: TextDirection.ltr,
+ nextNodeId: 7,
  previousNodeId: 5,
  ),
  ],
  ),
  ],
  ),
  ],
- ), ignoreTransform: true, ignoreRect: true, ignoreId: true),
+ ), ignoreTransform: true, ignoreRect: true),
  );
  semantics.dispose();
  });
@@ -713,26 +729,31 @@ void main() {
  new TestSemantics(
  label: r'Label 1',
  textDirection: TextDirection.ltr,
+ nextNodeId: -1,
  previousNodeId: 3,
  ),
  new TestSemantics(
  label: r'Label 2',
  textDirection: TextDirection.ltr,
+ nextNodeId: 2,
  previousNodeId: 4,
  ),
  new TestSemantics(
  label: r'Label 3',
  textDirection: TextDirection.ltr,
+ nextNodeId: 3,
  previousNodeId: 5,
  ),
  new TestSemantics(
  label: r'Label 4',
  textDirection: TextDirection.ltr,
+ nextNodeId: 4,
  previousNodeId: 6,
  ),
  new TestSemantics(
  label: r'Label 5',
  textDirection: TextDirection.ltr,
+ nextNodeId: 5,
  previousNodeId: -1,
  ),
  ],
@@ -802,31 +823,37 @@ void main() {
  new TestSemantics(
  children: <TestSemantics>[
  new TestSemantics(
+ nextNodeId: 5,
  previousNodeId: -1,
  children: <TestSemantics>[
  new TestSemantics(
  label: r'Label 1',
  textDirection: TextDirection.ltr,
+ nextNodeId: 7,
  previousNodeId: 5,
  ),
  new TestSemantics(
  label: r'Label 2',
  textDirection: TextDirection.ltr,
+ nextNodeId: -1,
  previousNodeId: 6,
  ),
  new TestSemantics(
  label: r'Label 3',
  textDirection: TextDirection.ltr,
+ nextNodeId: 3,
  previousNodeId: 2,
  ),
  new TestSemantics(
  label: r'Label 4',
  textDirection: TextDirection.ltr,
+ nextNodeId: 4,
  previousNodeId: 7,
  ),
  new TestSemantics(
  label: r'Label 5',
  textDirection: TextDirection.ltr,
+ nextNodeId: 6,
  previousNodeId: 3,
  ),
  ],

packages/flutter/test/widgets/semantics_tester.dart

@@ -43,6 +43,7 @@ class TestSemantics {
  this.decreasedValue: '',
  this.hint: '',
  this.textDirection,
+ this.nextNodeId,
  this.previousNodeId,
  this.rect,
  this.transform,
@@ -71,6 +72,7 @@ class TestSemantics {
  this.hint: '',
  this.textDirection,
  this.previousNodeId,
+ this.nextNodeId,
  this.transform,
  this.textSelection,
  this.children: const <TestSemantics>[],
@@ -106,6 +108,7 @@ class TestSemantics {
  this.increasedValue: '',
  this.decreasedValue: '',
  this.textDirection,
+ this.nextNodeId,
  this.previousNodeId,
  this.rect,
  Matrix4 transform,
@@ -173,6 +176,10 @@ class TestSemantics {
  /// is also set.
  final TextDirection textDirection;
 
+ /// The ID of the node that is next in the semantics traversal order after
+ /// this node.
+ final int nextNodeId;
+
  /// The ID of the node that is previous in the semantics traversal order before
  /// this node.
  final int previousNodeId;
@@ -258,6 +265,8 @@ class TestSemantics {
  return fail('expected node id $id to have hint "$hint" but found hint "${nodeData.hint}".');
  if (textDirection != null && textDirection != nodeData.textDirection)
  return fail('expected node id $id to have textDirection "$textDirection" but found "${nodeData.textDirection}".');
+ if (nextNodeId != null && nextNodeId != nodeData.nextNodeId)
+ return fail('expected node id $id to have nextNodeId "$nextNodeId" but found "${nodeData.nextNodeId}".');
  if (previousNodeId != null && previousNodeId != nodeData.previousNodeId)
  return fail('expected node id $id to have previousNodeId "$previousNodeId" but found "${nodeData.previousNodeId}".');
  if ((nodeData.label != '' || nodeData.value != '' || nodeData.hint != '' || node.increasedValue != '' || node.decreasedValue != '') && nodeData.textDirection == null)
@@ -311,6 +320,8 @@ class TestSemantics {
  buf.writeln('$indent hint: \'$hint\',');
  if (textDirection != null)
  buf.writeln('$indent textDirection: $textDirection,');
+ if (nextNodeId != null)
+ buf.writeln('$indent nextNodeId: $nextNodeId,');
  if (previousNodeId != null)
  buf.writeln('$indent previousNodeId: $previousNodeId,');
  if (textSelection?.isValid == true)
@@ -522,6 +533,8 @@ class SemanticsTester {
  buf.writeln(' hint: r\'${node.hint}\',');
  if (node.textDirection != null)
  buf.writeln(' textDirection: ${node.textDirection},');
+ if (node.nextNodeId != null)
+ buf.writeln(' nextNodeId: ${node.nextNodeId},');
  if (node.previousNodeId != null)
  buf.writeln(' previousNodeId: ${node.previousNodeId},');
 

packages/flutter/test/widgets/semantics_tester_generateTestSemanticsExpressionForCurrentSemanticsTree_test.dart

@@ -105,14 +105,17 @@ void _tests() {
  new TestSemantics(
  children: <TestSemantics>[
  new TestSemantics(
+ nextNodeId: 4,
  previousNodeId: -1,
  children: <TestSemantics>[
  new TestSemantics(
+ nextNodeId: 2,
  previousNodeId: 1,
  children: <TestSemantics>[
  new TestSemantics(
  label: r'Plain text',
  textDirection: TextDirection.ltr,
+ nextNodeId: 3,
  previousNodeId: 4,
  ),
  new TestSemantics(
@@ -124,6 +127,7 @@ void _tests() {
  decreasedValue: r'test-decreasedValue',
  hint: r'test-hint',
  textDirection: TextDirection.rtl,
+ nextNodeId: -1,
  previousNodeId: 2,
  ),
  ],