import 'package:flutter/material.dart'; class PersistentHeader extends SliverPersistentHeaderDelegate { final double max; final double min; final Widget child; PersistentHeader({this.max = 50.0, this.min = 50.0, @required this.child}); @override Widget build(BuildContext context, double shrinkOffset, bool overlapsContent) { return child; } @override double get maxExtent => max; @override double get minExtent => min; @override bool shouldRebuild(SliverPersistentHeaderDelegate oldDelegate) => oldDelegate != this; }