----------------------------------------main.dart
import 'package:flut_mediaquery/usando_mediaquery.dart';
import 'package:flutter/material.dart';
void main(){
  runApp(  MaterialApp(
    debugShowCheckedModeBanner: false,
    home:   UsandoMediaQuery(),
  ));
}

-------------------------------------usando_mediaquery.dart

import 'package:flutter/material.dart';

class UsandoMediaQuery extends StatefulWidget {
  @override
  _UsandoMediaQueryState createState() => _UsandoMediaQueryState();
}

class _UsandoMediaQueryState extends State<UsandoMediaQuery> {
  @override
  Widget build(BuildContext context) {

    MediaQueryData deviceInfo = MediaQuery.of(context);
	
    print('size: ${deviceInfo.size}');
	  print('padding: ${deviceInfo.padding}');

        return Scaffold(
	        appBar: AppBar(
	          title: Text('Media Query - Exemplo'),
            centerTitle: true,
	        ),
	        body: Padding(
	          padding: const EdgeInsets.all(10.0),
	          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  Text('Tamanho    : ${deviceInfo.size}', style: TextStyle(fontSize: 20.0)),
                  Text('Orientação : ${deviceInfo.orientation}',style: TextStyle(fontSize: 20.0)),
                  Text('Hora(24 h) : ${deviceInfo.alwaysUse24HourFormat}',style: TextStyle(fontSize: 20.0)),
                  Text('Brilho     : ${deviceInfo.platformBrightness}',style: TextStyle(fontSize: 20.0)),
                  Text('Padding    : ${deviceInfo.padding}',style: TextStyle(fontSize: 20.0)),
                ],
            ),
        ),
    );
  }
}