在 Scaffold 中为 AppBar 添加子标题

Question

在我的 flutter 应用程序中，我有一个具有搜索功能的页面。它通过 bloc 模式实现从 API 服务器给我带来了一些数据。现在我需要添加带有文本“最近搜索”的子标题。在尝试添加它时，它覆盖了我的“输入要搜索的文本”文本。我无法将其添加到屏幕顶部和左侧的应用栏下方这是我现在的阶段：

那就是我要补充的：

AppBar _appBar() {
  return AppBar(
   iconTheme: IconThemeData(
    color: Colors.white.withOpacity(0.8),
  ),
  title: TextField(
    onChanged: _textInputListener.add,
    autofocus: true,
    controller: _textInputController,
    key: Key('searchscreen_input_tf_id'),
    keyboardType: TextInputType.text,
    decoration: InputDecoration(
      hintText: AppTranslations.of(context).text("enter_text_to_search"),
      border: InputBorder.none,
    ),
  ),
  actions: <Widget>[
    IconButton(
      key: Key('searchscreen_clear_ib_id'),
      icon: const Icon(
        Icons.clear,
      ),
      onPressed: () {
        if (_textInputController.text.isNotEmpty) {
          _textInputController.clear();
          _textInputListener.add("");
        }
      },
    )
  ],
);
}


Widget build(BuildContext context) {
 return Container(
  color: Color(0xFF131E42),
  child: SafeArea(
    child: Scaffold(
      resizeToAvoidBottomPadding: false,
      appBar: _appBar(),
      body: BlocBuilder(
        bloc: _searchScreenBloc,
        builder: (_, SearchScreenState state) {
          if (state is InitialSearchScreenState) {
            _searchScreenBloc.add(LoadRecent());
            return _containerWithPaddings(child: CircularProgressIndicator());
          }
          if (state is SearchScreenRecentState) {
            return _recentList(state.securities);
          }
          if (state is SearchScreenLoadingDataState) {
            return _containerWithPaddings(child: CircularProgressIndicator());
          }
          if (state is SearchScreenLoadedDataState) {
            return _loadedList(state.securities);
          }
          if (state is SearchScreenErrorState) {
            _searchScreenBloc.add(LoadSearchResult(securityName: _textInputController.text));
            return _containerWithPaddings(child: CircularProgressIndicator());
          }
          if (state is SearchScreenNoResultsState) {
            return _containerWithPaddings(
                child: Text(
              AppTranslations.of(context).text("no_results"),
              style: TextStyle(
                fontSize: 18.0,
                color: Colors.white,
              ),
            ));
          }

          throw ArgumentError('$state not in cases');
        },
      ),
    ),
  ),
);
}

Answer 1

您可以使用 AppBar 的 bottom 属性。

代码示例

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        appBar: AppBar(
          title: Text('Title'),
          bottom: PreferredSize(
              child: Align(
                alignment: Alignment.centerLeft,
                child: Text('Bottom text'),
              ),
              preferredSize: Size.fromHeight(12.0)),
        ),
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

Try it on DartPad

截图

在 Scaffold 中为 AppBar 添加子标题

Adding Sub Title to AppBar in Scaffold

flutter

flutter-layout

flutter-appbar