merchant_silver_appbar.dart

import 'package:flutter/material.dart';

class MerchantSilverAppbar extends StatefulWidget {
  const MerchantSilverAppbar({Key key}) : super(key: key);

  @override
  _MerchantSilverAppbarState createState() => _MerchantSilverAppbarState();
}

class _MerchantSilverAppbarState extends State<MerchantSilverAppbar> {
  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: Scaffold(
        body: DefaultTabController(
          length: 2,
          child: NestedScrollView(
            headerSliverBuilder:
                (BuildContext context, bool innerBoxIsScrolled) {
              return <Widget>[
                SliverAppBar(
                  expandedHeight: 200,
                  floating: false,
                  pinned: true,
                  snap: false,
                  flexibleSpace: FlexibleSpaceBar(
                    background: Stack(
                      children: [
                        Container(
                          height: 200,
                          width: double.infinity,
                          decoration: BoxDecoration(
                            image: DecorationImage(
                              image: AssetImage('assets/images/test.jpg'),
                              fit: BoxFit.fill,
                            ),
                          ),
                        ),
                        Positioned(top: 10, right: 10, child: Icon(Icons.search)),
                        Align(
                            alignment: Alignment.bottomCenter,
                            child: Container(
                              height: 70,
                              child: Row(
                                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                                crossAxisAlignment: CrossAxisAlignment.start,
                                children: [
                                  Icon(Icons.home,size: 80,),
                                  Column(
                                    crossAxisAlignment: CrossAxisAlignment.center,
                                    children: [Text("Name"), SizedBox(height: 10,), Text("Follow")],
                                  ),
                                  Column(
                                    crossAxisAlignment: CrossAxisAlignment.center,
                                    children: [Text("4.7"), SizedBox(height: 10,),Text("4.8")],
                                  ),
                                  Icon(Icons.question_answer_sharp,size: 80,),
                                ],
                              ),
                            )),
                      ],
                    ),
                  ),
                ),
                SliverPersistentHeader(
                  delegate: _SliverAppBarDelegate(
                    TabBar(
                      labelColor: Colors.black87,
                      unselectedLabelColor: Colors.grey,
                      tabs: [
                        Tab(icon: Icon(Icons.info), text: "Tab 1"),
                        Tab(icon: Icon(Icons.lightbulb_outline), text: "Tab 2"),
                      ],
                    ),
                  ),
                  pinned: true,
                ),
              ];
            },
            body: Center(
              child: Text("Sample text"),
            ),
          ),
        ),
      ),
    );
  }
}

class _SliverAppBarDelegate extends SliverPersistentHeaderDelegate {
  _SliverAppBarDelegate(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 new Container(
      child: _tabBar,
    );
  }

  @override
  bool shouldRebuild(_SliverAppBarDelegate oldDelegate) {
    return false;
  }
}