SliverAppBar で minHeight みたいなことしたい場合

main.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        body: CustomScrollView(
          slivers: <Widget>[
            SliverAppBar(
              pinned: true,
              expandedHeight: 200,
              flexibleSpace: Image.asset('assets/cover.jpg', fit: BoxFit.cover),
              bottom: PreferredSize(child: Text(''), preferredSize: Size.fromHeight(60),),  // これが minHeight の役割をする感じ
            ),
            SliverList(
              delegate: SliverChildBuilderDelegate((BuildContext context, int index) {
                return Container(padding: EdgeInsets.all(16.0), child: Text('Row_$index'));
              }),
            )
          ],
        ),
      ),
    );
  }
}