markNeedsSemanticsUpdate method

Implementation

void markNeedsSemanticsUpdate() {
  assert(!attached || !owner._debugDoingSemantics);
  if (!attached || owner._semanticsOwner == null) {
    _cachedSemanticsConfiguration = null;
    return;
  }

  // Dirty the semantics tree starting at `this` until we have reached a
  // RenderObject that is a semantics boundary. All semantics past this
  // RenderObject are still up-to date. Therefore, we will later only rebuild
  // the semantics subtree starting at the identified semantics boundary.

  final bool wasSemanticsBoundary = _semantics != null && _cachedSemanticsConfiguration?.isSemanticBoundary == true;
  _cachedSemanticsConfiguration = null;
  bool isEffectiveSemanticsBoundary = _semanticsConfiguration.isSemanticBoundary && wasSemanticsBoundary;
  RenderObject node = this;

  while (!isEffectiveSemanticsBoundary && node.parent is RenderObject) {
    if (node != this && node._needsSemanticsUpdate)
      break;
    node._needsSemanticsUpdate = true;

    node = node.parent;
    isEffectiveSemanticsBoundary = node._semanticsConfiguration.isSemanticBoundary;
    if (isEffectiveSemanticsBoundary && node._semantics == null) {
      // We have reached a semantics boundary that doesn't own a semantics node.
      // That means the semantics of this branch are currently blocked and will
      // not appear in the semantics tree. We can abort the walk here.
      return;
    }
  }
  if (node != this && _semantics != null && _needsSemanticsUpdate) {
    // If `this` node has already been added to [owner._nodesNeedingSemantics]
    // remove it as it is no longer guaranteed that its semantics
    // node will continue to be in the tree. If it still is in the tree, the
    // ancestor `node` added to [owner._nodesNeedingSemantics] at the end of
    // this block will ensure that the semantics of `this` node actually gets
    // updated.
    // (See semantics_10_test.dart for an example why this is required).
    owner._nodesNeedingSemantics.remove(this);
  }
  if (!node._needsSemanticsUpdate) {
    node._needsSemanticsUpdate = true;
    if (owner != null) {
      assert(node._semanticsConfiguration.isSemanticBoundary || node.parent is! RenderObject);
      owner._nodesNeedingSemantics.add(node);
      owner.requestVisualUpdate();
    }
  }
}