import 'package:flutter/material.dart'; class LoadingWidget extends StatelessWidget { final bool visible; const LoadingWidget({Key key, this.visible}) : super(key: key); @override Widget build(BuildContext context) { return AnimatedOpacity( duration: const Duration(milliseconds: 300), opacity: visible ? 1.0 : 0.0, child: Container( alignment: FractionalOffset.center, child: const CircularProgressIndicator(), ), ); } }