https://note.com/kitoko552/n/n7da7c55ebab6

note_n7da7c55ebab6_5.dart

class _StickyTabBarDelegate extends SliverPersistentHeaderDelegate {
 const _StickyTabBarDelegate(this.tabBar);

 final TabBar tabBar;

 @override
 double get minExtent => tabBar.preferredSize.height;

 @override
 double get maxExtent => tabBar.preferredSize.height;

 @override
 Widget build(BuildContext context, double shrinkOffset, bool overlapsContent) {
   return Container(color: Colors.blue, child: tabBar);
 }

 @override
 bool shouldRebuild(_StickyTabBarDelegate oldDelegate) {
   return tabBar != oldDelegate.tabBar;
 }
}