performRebuild method

@override void performRebuild()

Keeps the subtree as it is when the dependents only have to be notified of a change (notifyDependents).

Two halves, because build cannot be skipped: ComponentElement calls it either way. It hands back the widget of the last real build, and this method leaves the child element alone.

The subtree is rebuilt anyway when:

1. autoSelfDependence - the element declared an automatic dependency on itself (used by initializers during the initialization phases).
2. _forceRebuild - the subtree must be rebuilt because the parent is updating the element or the element depends on itself.

Implementation

@override
void performRebuild() {
  // The other way: a `scopeKey` getter that starts returning something else
  // -- a new widget with a different key, or a value read from the element's
  // own state.
  assert(_debugCheckScopeKeyOwnership());
  super.performRebuild();

  // `super.performRebuild()` invokes the common sync [init] inside
  // Flutter's build error boundary. A thrown init is terminal and leaves
  // `_didInit` false for good, so the asynchronous phase of a scope that
  // never synchronously came to be does not start at all -- and the one
  // that did starts it exactly once, on the build that ran the hook.
  if (_didInit && !_didStartAsyncInit) {
    _didStartAsyncInit = true;
    _performAsyncInit(); // ignore: discarded_futures
  }
}