Что такое семейство шрифтов по умолчанию для приложения Flutter?

Ответ 1

Шрифтом по умолчанию для MaterialApp является roboto, шрифт Google.

https://fonts.google.com/specimen/Roboto

Ответ 2

Шрифт по умолчанию для MaterialApp описан в

/flutter/packages/flutter/lib/src/material/typography.dart

на iOS стандартная тема TextTheme

  static const TextTheme whiteCupertino = TextTheme(
    display4   : TextStyle(debugLabel: 'whiteCupertino display4',   fontFamily: '.SF UI Display', inherit: true, color: Colors.white70, decoration: TextDecoration.none),
    display3   : TextStyle(debugLabel: 'whiteCupertino display3',   fontFamily: '.SF UI Display', inherit: true, color: Colors.white70, decoration: TextDecoration.none),
    display2   : TextStyle(debugLabel: 'whiteCupertino display2',   fontFamily: '.SF UI Display', inherit: true, color: Colors.white70, decoration: TextDecoration.none),
    display1   : TextStyle(debugLabel: 'whiteCupertino display1',   fontFamily: '.SF UI Display', inherit: true, color: Colors.white70, decoration: TextDecoration.none),
    headline   : TextStyle(debugLabel: 'whiteCupertino headline',   fontFamily: '.SF UI Display', inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    title      : TextStyle(debugLabel: 'whiteCupertino title',      fontFamily: '.SF UI Display', inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    subhead    : TextStyle(debugLabel: 'whiteCupertino subhead',    fontFamily: '.SF UI Text',    inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    body2      : TextStyle(debugLabel: 'whiteCupertino body2',      fontFamily: '.SF UI Text',    inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    body1      : TextStyle(debugLabel: 'whiteCupertino body1',      fontFamily: '.SF UI Text',    inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    caption    : TextStyle(debugLabel: 'whiteCupertino caption',    fontFamily: '.SF UI Text',    inherit: true, color: Colors.white70, decoration: TextDecoration.none),
    button     : TextStyle(debugLabel: 'whiteCupertino button',     fontFamily: '.SF UI Text',    inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    subtitle   : TextStyle(debugLabel: 'whiteCupertino subtitle',   fontFamily: '.SF UI Text',    inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    overline   : TextStyle(debugLabel: 'whiteCupertino overline',   fontFamily: '.SF UI Text',    inherit: true, color: Colors.white,   decoration: TextDecoration.none),
  );

на Android по умолчанию TextTheme

 static const TextTheme whiteMountainView = TextTheme(
    display4   : TextStyle(debugLabel: 'whiteMountainView display4',   fontFamily: 'Roboto', inherit: true, color: Colors.white70, decoration: TextDecoration.none),
    display3   : TextStyle(debugLabel: 'whiteMountainView display3',   fontFamily: 'Roboto', inherit: true, color: Colors.white70, decoration: TextDecoration.none),
    display2   : TextStyle(debugLabel: 'whiteMountainView display2',   fontFamily: 'Roboto', inherit: true, color: Colors.white70, decoration: TextDecoration.none),
    display1   : TextStyle(debugLabel: 'whiteMountainView display1',   fontFamily: 'Roboto', inherit: true, color: Colors.white70, decoration: TextDecoration.none),
    headline   : TextStyle(debugLabel: 'whiteMountainView headline',   fontFamily: 'Roboto', inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    title      : TextStyle(debugLabel: 'whiteMountainView title',      fontFamily: 'Roboto', inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    subhead    : TextStyle(debugLabel: 'whiteMountainView subhead',    fontFamily: 'Roboto', inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    body2      : TextStyle(debugLabel: 'whiteMountainView body2',      fontFamily: 'Roboto', inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    body1      : TextStyle(debugLabel: 'whiteMountainView body1',      fontFamily: 'Roboto', inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    caption    : TextStyle(debugLabel: 'whiteMountainView caption',    fontFamily: 'Roboto', inherit: true, color: Colors.white70, decoration: TextDecoration.none),
    button     : TextStyle(debugLabel: 'whiteMountainView button',     fontFamily: 'Roboto', inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    subtitle   : TextStyle(debugLabel: 'whiteMountainView subtitle',   fontFamily: 'Roboto', inherit: true, color: Colors.white,   decoration: TextDecoration.none),
    overline   : TextStyle(debugLabel: 'whiteMountainView overline',   fontFamily: 'Roboto', inherit: true, color: Colors.white,   decoration: TextDecoration.none),
  );

и вы можете получить семейство шрифтов с помощью следующего кода

DefaultTextStyle.of(context).style.fontFamily

Ответ 3

В Flutter по умолчанию шрифт на Android - Roboto.

Но я использую Android-монитор для запуска своего приложения Flutter. Я нахожу шрифт по умолчанию monospace. Кто подскажет, в чем проблема?

Код выглядит следующим образом:

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        //        primarySwatch: Colors.yellow,
        primaryColor: Colors.teal,

        // default font-family is 'monospace',
        fontFamily: DefaultTextStyle.of(context).style.fontFamily,
        // replace with 'Roboto',but the result is 'monospace'
        // fontFamily: 'Roboto',
        // use 'monospaced',the result is 'monospace'
        // fontFamily: 'monospaced',
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int counter = 0;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      counter++;

      print('defalut font is： ${DefaultTextStyle.of(context).style.fontFamily}');
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(
          widget.title,
        ),
      ),
      body: Text('$counter'),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    ); // This trailing comma makes auto-formatting nicer for build methods.
  }
}