Flutter Error: MediaQuery.of() called with a context that does not contain a MediaQuery

Question

I have been trying to get the size of the whole context view in Flutter. But every time I try I\'m getting the above mentioned error. Here\'s my code:

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Answer 1

There is better way. Above solutions would require you to have only one screen widget or inherit all screens from parent class. But there is solution, place the media query initialization into onGenerateRoute callback function

main.dart

import 'package:flutter/material.dart';

class MyApp extends StatefulWidget {
    @override
    State createState() => new MyAppState();
}

class MyAppState extends State {
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        title: 'My Awesome App',
        routes: NavigationUtils.routeList(),
        onGenerateRoute: (routeSettings) =>
          NavigationUtils.onGenerateRoute(routeSettings),
      );
    }
}

NavigationUtils.dart

import 'package:flutter/material.dart';

class NavigationUtils {
    static onGenerateRoute(RouteSettings routeSettings) {   
      return new MaterialPageRoute(
        builder: (context) {
          WidgetUtils.me.init(context);
            return StorageUtils.me.isLogged() ? HomeScreen() : ForkScreen();
        },
        settings: routeSettings,
      );
    }
}

WidgetUtils.dart

import 'package:flutter/material.dart';

class WidgetUtils {
    MediaQueryData _mediaQueryData;
    double _screenWidth;
    double _screenHeight;
    double _blockSizeHorizontal;
    double _blockSizeVertical;

    init(BuildContext context) {
        _mediaQueryData = MediaQuery.of(context);
        screenWidth = _mediaQueryData.size.width;
        screenHeight = _mediaQueryData.size.height;
        blockSizeHorizontal = screenWidth / 100;
        blockSizeVertical = screenHeight / 100;
    }
}

Warning: It is not copy & paste code, there are some singletons etc. but you should get the point ;)