flutter appbar not fixed code example
Example: how to make a shrinkable action bar in fluttur
Scaffold(
body: CustomScrollView(
slivers: <Widget>[
SliverAppBar(
expandedHeight : 200.0,
floating : false,
pinned : true,
flexibleSpace : FlexibleSpaceBar(
//This exactly likeyour AppBar
title: "foo",
background: "Whatever you want",
),
),
SliverFillRemaining(
child: //This is exactly like the body which we have for scaffold
Center(),
),
],
),
)