슬리버2

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage(),
    );
  }
}

// Sliver : 찢어진 조각 << 스크롤에 반응 할 수 있다.
class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomScrollView(
        // 요 안에만 슬리버 넣을 수 있다.
        slivers: [
          SliverAppBar(
            title: Text("앱바1"),
            pinned: false,
            floating: true,
            // floating & snap 쌍을 이룬다.
            snap: true,
            expandedHeight: 250,
            flexibleSpace: FlexibleSpaceBar(
              title: Text("플렉시블 스페이스"),
              centerTitle: true,
              background: Image.network(
                "https://picsum.photos/200/300",
                fit: BoxFit.cover,
              ),
            ),
          ),
          SliverToBoxAdapter(
            child: Container(color: Colors.blue, height: 300),
          ),
          SliverPersistentHeader(
            pinned: true,
            floating: false,
            delegate: MySliverPersistentHeaderDelegate(
              minHeight: 50,
              maxHeight: 150,
              child: Container(
                color: Colors.yellow,
              ),
            ),
          ),
          SliverList(
            delegate: SliverChildBuilderDelegate(
              childCount: 30,
              (context, index) {
                return ListTile(
                  title: Text("제목 $index"),
                );
              },
            ),
          ),
          // SliverFillRemaining(
          //   child: Container(
          //     color: Colors.red,
          //   ),
          // )
          //////////////////////
        ],
      ),
    );
  }
}

class MySliverPersistentHeaderDelegate extends SliverPersistentHeaderDelegate {
  MySliverPersistentHeaderDelegate({
    required this.minHeight,
    required this.maxHeight,
    required this.child,
  });

  final double minHeight;
  final double maxHeight;
  final Widget child;

  @override
  Widget build(
      BuildContext context, double shrinkOffset, bool overlapsContent) {
    return child;
  }

  @override
  double get maxExtent => maxHeight; // getter

  @override
  double get minExtent => minHeight;

  @override
  bool shouldRebuild(covariant MySliverPersistentHeaderDelegate oldDelegate) {
    return true;
  }
}