detach method

void detach()

Called when the render object is detached from the render tree.

Subclasses can override to release resources or unregister handlers.

Implementation

void detach() {
  final formerOwner = _pipelineOwner;
  final attachment = _inspectSubtree(this, formerOwner);
  if (attachment.state == _SubtreeState.detached) {
    return;
  }
  if (formerOwner == null) {
    throw StateError('Attached subtree has no root PipelineOwner.');
  }

  final childSnapshot = <RenderObject>[];
  visitChildren(childSnapshot.add);
  formerOwner._forget(this);
  _pipelineOwner = null;
  for (final child in childSnapshot) {
    if (identical(child._pipelineOwner, formerOwner)) {
      child.detach();
    } else if (child._pipelineOwner != null) {
      throw StateError(
        'Render subtree changed owner while it was being detached.',
      );
    }
  }
}