dispatchBubbleUp method

Cmd? dispatchBubbleUp(Element startElement, Msg msg, { Set<Element>? visited, })

Dispatches msg by walking UP the element tree from startElement to the root, calling handleUpdate on each StatefulElement's state.

This mirrors Flutter's pointer-event bubbling: the deepest hit element's ancestors get to handle the event, and the first one that produces a Cmd wins.

When visited is provided, elements already in the set are skipped and newly visited elements are added. This prevents a GestureDetector from processing the same event multiple times when several child render objects bubble up to the same ancestor.

Use this for HitTestMouseMsg dispatch so that a GestureDetector (which is a StatefulWidget without its own render object) receives the event even though only its child's render object was hit.

Implementation

Cmd? dispatchBubbleUp(
  Element startElement,
  Msg msg, {
  Set<Element>? visited,
}) {
  Element? current = startElement;
  Cmd? bubbleCmd;
  while (current != null) {
    if (current is StatefulElement) {
      if (visited != null) {
        if (!visited.add(current)) {
          // Already dispatched to this element — skip.
          current = current.parent;
          continue;
        }
      }
      current.rebuild();
      final cmd = current.state.handleUpdate(msg);
      if (cmd != null) {
        bubbleCmd = cmd;
        break;
      }
    }
    current = current.parent;
  }
  _flushDirtyBuilds();
  final mountInit = _owner.drainMountInitCmds();
  return _coalesceCommands([
    if (bubbleCmd != null) bubbleCmd,
    if (mountInit != null) mountInit,
  ]);
}