如何在 Flutter 中设置主屏幕的背景颜色？

Question

我正在学习 Flutter，而且我是从最基础的开始。我没有使用 MaterialApp。设置全屏背景色有什么好方法？

这是我目前所拥有的：

import 'package:flutter/material.dart';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new Center(child: new Text("Hello, World!"));
  }
}

我的一些问题是：

• 设置背景颜色的基本方法是什么？
• 我到底在看什么，在屏幕上？哪个代码“是”背景？有什么东西可以设置背景颜色吗？如果没有，什么是简单且合适的“简单背景”（为了绘制背景颜色）。

感谢您的帮助！

上面的代码生成一个带有白色文本的黑屏：

Answer 1

按照 sirelon 的建议，像这样在主题中添加脚手架颜色，

theme: new ThemeData(scaffoldBackgroundColor: const Color(0xFFEFEFEF)),

或者可以像这样为单个脚手架上色

Scaffold(
    backgroundColor: Color(0xFFF1F1F1),
    ...
);

Answer 2

你可以把六位十六进制放在 (0xFF**......**) 之后：

return Scaffold( 
    backgroundColor: const Color(0xFFE9ECEF),
.....) } )

Answer 3

示例代码：

import 'package:flutter/material.dart';

void main() {
  runApp(
    MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Sample App'),
          backgroundColor: Colors.amber,  // changing Appbar back color
        ),
        backgroundColor: Colors.blue,     // changing body back color
      ),
    ),
  );
}

Answer 4

home: Scaffold(
            backgroundColor:  Color(
                0xBF453F3F),

完成了:)

Answer 5

您应该返回 Scaffold 小部件并将您的小部件添加到 Scaffold

就像这段代码一样：

import 'package:flutter/material.dart';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return Scaffold(
          backgroundColor: Colors.white,
          body: Center(child: new Text("Hello, World!"));
    );
  }
}

Answer 6

Scaffold(
      backgroundColor: Constants.defaulBackground,
      body: new Container(
      child: Center(yourtext)

      )
)

Answer 7

有很多方法，我在这里列出几个。

1. 使用backgroundColor

   Scaffold(
     backgroundColor: Colors.black,
     body: Center(...),
   )
   

2. 在SizedBox.expand 中使用Container

   Scaffold(
     body: SizedBox.expand(
       child: Container(
         color: Colors.black,
         child: Center(...)
       ),
     ),
   )
   

3. 使用Theme

   Theme(
     data: Theme.of(context).copyWith(scaffoldBackgroundColor: Colors.black),
     child: Scaffold(
       body: Center(...),
     ),
   )
   

Answer 8

您可以一次将背景颜色设置为应用程序中的所有脚手架。

只需在 ThemeData 中设置 scaffoldBackgroundColor:

 MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(scaffoldBackgroundColor: const Color(0xFFEFEFEF)),
      home: new MyHomePage(title: 'Flutter Demo Home Page'),
    );

Answer 9

关于 Flutter 的基本示例，您可以使用 Scaffold 的backgroundColor: Colors.X 进行设置

  @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(
  backgroundColor: Colors.blue,
  body: Center(
    // Center is a layout widget. It takes a single child and positions it
    // in the middle of the parent.
    child: Column(
      // Column is also layout widget. It takes a list of children and
      // arranges them vertically. By default, it sizes itself to fit its
      // children horizontally, and tries to be as tall as its parent.
      //
      // Invoke "debug painting" (press "p" in the console, choose the
      // "Toggle Debug Paint" action from the Flutter Inspector in Android
      // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
      // to see the wireframe for each widget.
      //
      // Column has various properties to control how it sizes itself and
      // how it positions its children. Here we use mainAxisAlignment to
      // center the children vertically; the main axis here is the vertical
      // axis because Columns are vertical (the cross axis would be
      // horizontal).
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        Text(
          'You have pushed the button this many times:',
        ),
        Text(
          '$_counter',
          style: Theme.of(context).textTheme.display1,
        ),
      ],
    ),
  ),
  floatingActionButton: FloatingActionButton(
    onPressed: _incrementCounter,
    tooltip: 'Increment',
    child: Icon(Icons.add_circle),
  ), // This trailing comma makes auto-formatting nicer for build methods.
);
}

Answer 10

这是改变背景颜色的另一种方法：

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(home: Scaffold(backgroundColor: Colors.pink,),);
  }
}

Answer 11

我认为您也可以使用脚手架来制作白色背景。下面是一些可能有帮助的代码。

import 'package:flutter/material.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
  @override
    Widget build(BuildContext context) {

      return new MaterialApp(
        title: 'Testing',
        home: new Scaffold(
        //Here you can set what ever background color you need.
          backgroundColor: Colors.white,
        ),
      );
    }
}

希望这会有所帮助?。

Answer 12

我认为您需要使用MaterialApp 小部件并使用theme 并将primarySwatch 设置为您想要的颜色。如下代码，

import 'package:flutter/material.dart';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

Answer 13

这是我发现的一种方法。我不知道是否有更好的方法，或者取舍是什么。

Container“尽量做大”，根据https://flutter.io/layout/。此外，Container 可以采用decoration，可以是BoxDecoration，也可以是color（即背景色）。

这是一个确实用红色填充屏幕并显示“Hello, World!”的示例进入中心：

import 'package:flutter/material.dart';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new Container(
      decoration: new BoxDecoration(color: Colors.red),
      child: new Center(
        child: new Text("Hello, World!"),
      ),
    );
  }
}

注意，容器由 MyApp build() 返回。 Container 有一个装饰和一个子元素，即居中的文本。

在这里查看它的实际效果：