如何在颤动中获得屏幕高度

Question

嗨，我只是想使用 MediaQuery.of(context).size.height 但得到 FlutterError (No MediaQuery widget ancestor found. MyApp widgets require a MediaQuery widget ancestor. The specific widget that could not find a MediaQuery ancestor was: MyApp The ownership chain for the affected widget is: "MyApp ← [root]" No MediaQuery ancestor could be found starting from the context that was passed to MediaQuery.of(). This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget (those widgets introduce a MediaQuery), or it can happen if the context you use comes from a widget above those widgets.)

class BaseLayout extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Container(
          height: MediaQuery.of(context).size.height,
          color: Colors.red,
        ),
      ),
    );
  }
}

Answer 1

已编辑

你必须把它放在 MediaQuery 的上下文之上：

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: BaseLayout()
    );
  }
}

class BaseLayout extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Container(
          height: MediaQuery.of(context).size.height,
          color: Colors.red,
        ),
      ),
    );
  }
}

创建一个自己的 class，您的错误应该消失了。

原回答

你的小部件树中有 MaterialApp 吗？ MaterialApp 提供 MediaQuery.

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      body:WhateverWidget
    );
  }
}

顺便说一下...解决方案在您的错误代码中；)

This can happen because you have not added a WidgetsApp, CupertinoApp, or MaterialApp widget (those widgets introduce a MediaQuery), or it can happen if the context you use comes from a widget above those widgets.)

Answer 2

Hy tony 我找到了你问题的答案您需要为其添加安全区域

class BaseLayout extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: SafeArea(
        child: Scaffold(
          body: Container(
            height: MediaQuery.of(context).size.height,
            color: Colors.red,
          ),
        ),
      ),
    );
  }
}

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