How to create a bounded scrollable TabBarView

问题:

I need to implement the following layout in Flutter.

When the user scrolls, I want the entire layout to scroll (hiding the header and tab bar). However, I can't nest a TabBarView inside a ListView since the TabBarView doesn't have a bounded height and ListViews don't provide a bounded height to their children.

I've already seen these questions, but all of them have unsatisfactory answers for this use case:

• How can I have a TabView with variable height content within a Scrollable View with Flutter? : Exactly what I needed, but the only answer doesn't provide any concrete code on how to implement this, only a reference to a feature (SliverList) that I can't figure out how to implement.
• how to implement a sliverAppBar with a tabBar : The provided code doesn't work since the SliverList doesn't accept a constructor with this shape (and I tried adapting it to use a delegate without success).
• Getting 'Horizontal viewport was given unbounded height.' with TabBarView in flutter : This use case doesn't work for me since I need the entire layout to scroll, and in that answer, the header is fixed to the top.

回答1:

class SliverWithTabBar extends StatefulWidget {
  @override
  _SliverWithTabBarState createState() => _SliverWithTabBarState();
}

class _SliverWithTabBarState extends State<SliverWithTabBar> with SingleTickerProviderStateMixin {
  TabController controller;

  @override
  void initState() {
    super.initState();
    controller = TabController(length: 3, vsync: this);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: NestedScrollView(
        headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
          return [
            SliverAppBar(
              pinned: false,
              backgroundColor: Colors.white,
              flexibleSpace: FlexibleSpaceBar(
                collapseMode: CollapseMode.pin,
                background: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: <Widget>[
                    Container(
                      height: 200.0,
                      width: double.infinity,
                      color: Colors.grey,
                      child: FlutterLogo(),
                    ),
                    Padding(
                      padding: const EdgeInsets.all(10.0),
                      child: Text(
                        'Business Office',
                        style: TextStyle(fontSize: 25.0),
                        textAlign: TextAlign.left,
                      ),
                    ),
                    Padding(
                      padding: const EdgeInsets.all(10.0),
                      child: Text(
                        'Open now\nStreet Address, 299\nCity, State',
                        style: TextStyle(fontSize: 15.0),
                        textAlign: TextAlign.left,
                      ),
                    ),
                    Padding(
                      padding: const EdgeInsets.only(right: 10.0),
                      child: Row(
                        mainAxisAlignment: MainAxisAlignment.end,
                        children: <Widget>[
                          Icon(Icons.share),
                          Padding(
                            padding: const EdgeInsets.only(left: 10.0),
                            child: Icon(Icons.favorite),
                          ),
                        ],
                      ),
                    )
                  ],
                ),
              ),
              expandedHeight: 380.0,
              bottom: TabBar(
                indicatorColor: Colors.black,
                labelColor: Colors.black,
                tabs: [
                  Tab(text: 'POSTS'),
                  Tab(text: 'DETAILS'),
                  Tab(text: 'FOLLOWERS'),
                ],
                controller: controller,
              ),
            )
          ];
        },
        body: ListView.builder(
          itemCount: 100,
          itemBuilder: (BuildContext context, int index) {
            return Card(
              color: index % 2 == 0 ? Colors.blue : Colors.green,
              child: Container(
                alignment: Alignment.center,
                width: double.infinity,
                height: 100.0,
                child: Text(
                  'Flutter is awesome',
                  style: TextStyle(fontSize: 18.0),
                ),
              ),
            );
          },
        ),
      ),
    );
  }
}

You should look for Sliver widgets to achieve NestedScrollView.

That gives you a headerSliverBuilder property where you can actually fit some headers that you might hide or pin on the top of the screen when the body widget is scrolled, in this particular example, a ListView.

You might want to take a look to the RenderSliver documentation.