import 'package:flutter/material.dart'; class TabTransitionWidget extends StatefulWidget { final Widget child; const TabTransitionWidget(this.child, {Key key}) : assert(child != null), super(key: key); @override _TabTransitionWidgetState createState() => _TabTransitionWidgetState(); } class _TabTransitionWidgetState extends State { var _show = false; @override void initState() { super.initState(); Future.delayed(Duration(microseconds: 10)).then((value) { if (mounted) setState(() => _show = true); }); } @override Widget build(BuildContext context) { if (!_show) return Center(child: CircularProgressIndicator()); else return widget.child; } }