如何在Flutter中同时使用SliverPersistentHeader和TabBarView？

Question

我有一个主页，其中包含以下代码中的 SliverPersistentHeader 和 TabBarView：

 @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Theme.of(context).backgroundColor,
      body: DefaultTabController(
        length: 3,
        child: NestedScrollView(
          headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
            return <Widget>[
              SliverAppBar(
                expandedHeight: 250.0,
                floating: false,
                pinned: true,
              ),
              SliverPersistentHeader(
                delegate: _SliverAppBarDelegate(
                  TabBar(
                    labelStyle: TextStyle(
                        fontFamily: 'Raleway',
                        fontSize: 17,
                        fontWeight: FontWeight.w400,
                        color: Theme.of(context).backgroundColor),
                    indicatorColor: Theme.of(context).hintColor,
                    labelColor: Theme.of(context).buttonColor,
                    unselectedLabelColor: Theme.of(context).dividerColor,
                    tabs: [
                      Tab(text: "Menu"),
                      Tab(text: "About"),
                      Tab(text: "Contact"),
                    ],
                  ),
                ),
                pinned: true,
              ),
            ];
          },
          body: TabBarView(
            children: <Widget>[MenuTab(), AboutTab(), ContactTab()],
          ),
        ),
      ),
    );
  }
}

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;
  }
}

之后我为每个标签单独创建了类，例如以下代码：

---

class _AboutTabState extends State<AboutTab> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        backgroundColor: Theme.of(context).backgroundColor,
        body: ListView(
      children: <Widget>[
        ListView.builder(
          shrinkWrap: true,
          itemCount: _list.length,
          itemBuilder: (BuildContext context, int index) {
            final _aboutList = _list[index];
            return ExpansionTile(
              title: ListTile(
                title: Padding(
                  padding: const EdgeInsets.fromLTRB(5, 0, 0, 0),
                  child: Text(_aboutList.aboutTitle,
                      style: TextStyle(
                          fontFamily: 'Raleway',
                          fontSize: 16,
                          fontWeight: FontWeight.w500,
                          color: Theme.of(context).buttonColor)),
                ),
              ),
              children: <Widget>[
                ListTile(
                  title: Padding(
                    padding: const EdgeInsets.fromLTRB(10, 0, 0, 0),
                    child: Text(_aboutList.content,
                        style: TextStyle(
                            fontFamily: 'Raleway',
                            fontSize: 16,
                            fontWeight: FontWeight.w400,
                            color: Theme.of(context).toggleableActiveColor)),
                  ),
                )
              ],
            );
          },
        ),
      ],
    ));

问题：当我折叠SliverPersistentHeader时，出现了错误的结果，如下截图所示。谢谢。

- Sana Ebadi

Answer 1

_SliverAppBarDelegate()函数返回一个容器，您可以像以下这样在其中添加颜色：

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(
      color: Colors.white, // ADD THE COLOR YOU WANT AS BACKGROUND.
      child: _tabBar,
    );
  }

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

- A.Rhman Sayes