MaterialApp构建器错误：未找到叠加窗口小部件

Question

我在构建NavigationDrawer时出现错误，其中tootlip小部件需要materialApp作为祖先。

这是什么意思：

I/flutter ( 5780): _TooltipState#bc79e(ticker inactive)):
I/flutter ( 5780): No Overlay widget found.
I/flutter ( 5780): Tooltip widgets require an Overlay widget ancestor for correct operation.
I/flutter ( 5780): The most common way to add an Overlay to an application is to include a MaterialApp or Navigator
I/flutter ( 5780): widget in the runApp() call.
I/flutter ( 5780): The specific widget that failed to find an overlay was:
I/flutter ( 5780):   Tooltip
I/flutter ( 5780): 
I/flutter ( 5780): The relevant error-causing widget was:
I/flutter ( 5780):   AppBar

我的[[main.dart代码

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      ... //basic info title & theme

      builder: (context, child) => LayoutTemplate(child: child),
      initialRoute:"/home",

      ... //Routing stuff like generate route & navigator key 
    );
  }
}

LayoutTemplate窗口小部件

class LayoutTemplate extends StatelessWidget {
  final Widget child;

  const LayoutTemplate({Key key, this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: Text("home"))
        drawer: NavDrawer()
        body: Column(
          children: <Widget>[
            //NavigationBar(),
            Expanded(
              child: child,
            )
          ],
       ),
    );
  }
}

很抱歉，添加了太多代码。我不确定是什么原因引起的。可能是来自builder的MaterialApp引起的。
感谢您的帮助。

Answer 1

有相同的问题。

leading Material的AppBar属性的文档说明了如何自己实现，我只是删除了tooltip属性，它开始起作用，请参见：https://api.flutter.dev/flutter/material/AppBar/leading.html

AppBar(leading: Builder(builder: (BuildContext context) { 
    return IconButton( 
        icon: const Icon(Icons.menu), 
        onPressed: () { Scaffold.of(context).openDrawer(); } 
    );
}

希望有所帮助。