build method
AnimatorWidget calls build to retrieve the animated Widget. The extracted Animator from the getDefinition phase is injected to supply a controller and the Animation objects. Example: @override Widget build(BuildContext context, Animator animator, Widget child) { return FadeTransition( opacity: animation.get('opacity'), child: child, ); }
Implementation
@override
Widget build(BuildContext context, Animator animator, Widget child) {
  return FadeTransition(
    opacity: animator.get("opacity") as Animation<double>,
    child: AnimatedBuilder(
      animation: animator.controller!,
      child: child,
      builder: (BuildContext context, Widget? child) => Transform.translate(
        child: child,
        offset: Offset(animator.get("translateX")!.value, 0.0),
      ),
    ),
  );
}