magnifierBuilder property
Signature for a builder that builds a Widget with a MagnifierController.
Consuming MagnifierController or ValueNotifier<MagnifierInfo> is not required, although if a Widget intends to have entry or exit animations, it should take MagnifierController and provide it an AnimationController, so that MagnifierController can wait before removing it from the overlay.
Implementation
MagnifierBuilder get magnifierBuilder => _magnifierBuilder ?? (_, __, ___) => null;