Flutter 系列文章：Flutter Container 控件介绍

时间 2019-12-10

标签 flutter 系列文章 container 控件介绍繁體版

原文原文链接

Container —— 容器类

1、使用方法

若是窗口小部件没有孩子，没有对齐，而是一个height，width或限制提供，则Container试图给出这些限制和家长的约束相结合，以尽量小。bash

Container(
          margin: const EdgeInsets.all(10.0),
          color: const Color(0xFF00FF00),
          width: 48.0,
          height: 48.0,
        )
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若是窗口小部件没有子窗口，没有height，没有width，没有约束，没有对齐，可是父窗口提供了有界约束，那么Container会扩展以适应父窗口提供的约束。app

Container(
          margin: const EdgeInsets.all(10.0),
          color: const Color(0xFF00FF00),
          )
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若是子窗口有宽高、对齐，父窗口没有宽高、对齐，则父窗口会尝试围绕子窗口调整自身大小。less

Container(
          margin: const EdgeInsets.all(10.0),
          color: const Color(0xFFFFFF00),
          child: Container(
            constraints: BoxConstraints.expand(
              height: 50,
              width: 70,
            ),
            margin: const EdgeInsets.all(20.0),
            color: const Color(0xFF00FF00),
          ),
          )
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若是子窗口没有宽高对齐，父窗口提供有有宽高、对齐，则子窗口会尝试展开以适合父窗口，而后根据对齐方式将子项置于其自身内部。ide

Container(
          constraints: BoxConstraints.expand(
            width: 180,
            height: 180,
          ),
          margin: const EdgeInsets.all(10.0),
          color: const Color(0xFF1251F0),
          child: Container(
            margin: const EdgeInsets.all(20.0),
            color: const Color(0xFFee34e5),
          ),
          )
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一个比较完整的container实例ui

Container(
          //BoxConstraints 盒子模型约束 ,设置边框约束
          constraints: BoxConstraints.expand(
            height: 700,
            width: 400
          ),
          //设置padding
          padding: const EdgeInsets.all(8.0),
          color: Colors.teal.shade700,
          //设置子容器的对其方式
          alignment: Alignment.center,
          // Widget 设置子控件
          child: Text('Hello World', style: Theme.of(context).textTheme.display1.copyWith(color: Colors.white)),
          //设置前景盒子装饰
          foregroundDecoration: BoxDecoration(
            color: const Color(0xff7c94b6),
            image: DecorationImage(
              image: NetworkImage('http://c.hiphotos.baidu.com/image/pic/item/a8773912b31bb0516a13ec1d387adab44aede0d4.jpg'),
              fit: BoxFit.cover,
              alignment: Alignment.topCenter
            ),
            border: Border.all(
              color: Colors.black,
              width: 8.0,
            ),
          ),
          //设置变换
          transform: Matrix4.rotationZ(0.2),
        ),
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2、经常使用的属性

alignment ：设置对其方式

alignment：Alignment.center
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child : 设置容器子控件

child: Text('Hello World', style: Theme.of(context).textTheme.display1.copyWith(color: Colors.white))
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constraints ：设置约束

constraints: BoxConstraints.expand(
            height: 700,
            width: 400
          )
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decoration ：设置背景装饰

Container(
      decoration: BoxDecoration(
        color: const Color(0xff7c94b6),
        image: DecorationImage(
          image: ExactAssetImage('images/flowers.jpeg'),
          fit: BoxFit.cover,
        ),
        border: Border.all(
          color: Colors.black,
          width: 8.0,
        ),
      ),
    )
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foregroundDecoration：设置前景装饰

foregroundDecoration: BoxDecoration(
            color: const Color(0xff7c94b6),
            image: DecorationImage(
              image: NetworkImage('http://c.hiphotos.baidu.com/image/pic/item/a8773912b31bb0516a13ec1d387adab44aede0d4.jpg'),
              fit: BoxFit.cover,
              alignment: Alignment.topCenter
            ),
            border: Border.all(
              color: Colors.black,
              width: 8.0,
            ),
          )
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margin 设置外边距

margin: const EdgeInsets.all(20.0)
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padding 设置内边距

padding: const EdgeInsets.all(8.0)
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transform ：设置变换

transform: Matrix4.rotationZ(0.2),
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7.一些经常使用的方法this

build（BuildContext context） → Widget 描述此窗口小部件表示的用户界面部分

@override
Widget build ( BuildContext context){
    
}
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3、一个完整的例子

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.blue,
      ),
      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++;
    });
  }

  //描述此窗口小部件表示的用户界面部分
  @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: Center(
          child:

//          //container 示例1
// 若是窗口小部件没有孩子，没有对齐，而是一个height，width或 限制提供，则集装箱试图给出这些限制和家长的约束相结合，以尽量小。
//        Container(
//          margin: const EdgeInsets.all(10.0),
//          color: const Color(0xFF00FF00),
//          width: 48.0,
//          height: 48.0,
//        )

//          //container 示例2
//          // 若是窗口小部件没有子窗口，没有height，没有width，没有约束，没有对齐，可是父窗口提供了有界约束，那么Container会扩展以适应父窗口提供 的约束。
//          Container(
//          margin: const EdgeInsets.all(10.0),
//          color: const Color(0xFF00FF00),
//          )

          //container 示例3
          // 若是窗口小部件具备对齐，而且父窗口提供无限制约束，则Container会尝试围绕子窗口调整自身大小。
//          Container(
////          margin: const EdgeInsets.all(10.0),
//          color: const Color(0xFFFFFF00),
//          child: Container(
//            constraints: BoxConstraints.expand(
//              height: 50,
//              width: 70,
//            ),
//            margin: const EdgeInsets.all(20.0),
//            color: const Color(0xFF00FF00),
//          ),
//          )

//          //container 示例4
//          // 若是窗口小部件具备对齐，而且父窗口提供有界约束(有宽高)，则Container会尝试展开以适合父窗口，而后根据对齐方式将子项置于其自身内部
//          Container(
//          constraints: BoxConstraints.expand(
//            width: 180,
//            height: 180,
//          ),
//          margin: const EdgeInsets.all(10.0),
//          color: const Color(0xFF1251F0),
//          child: Container(
//            margin: const EdgeInsets.all(20.0),
//            color: const Color(0xFFee34e5),
//          ),
//          )

          //container 示例5 一个比较完整的实例
        Container(
          //BoxConstraints 盒子模型约束 ,设置边框约束
          constraints: BoxConstraints.expand(
            height: 700,
            width: 400
          ),
          margin: const EdgeInsets.all(20.0),
          //设置padding
          padding: const EdgeInsets.all(10.0),
          color: Colors.teal.shade700,
          //设置子容器的对其方式
          alignment: Alignment.center,
          // Widget 设置子控件
          child: Text('Hello World', style: Theme.of(context).textTheme.display1.copyWith(color: Colors.white)),
          //设置前景盒子装饰
          foregroundDecoration: BoxDecoration(
            color: const Color(0xff7c94b6),
            image: DecorationImage(
              image: NetworkImage('http://c.hiphotos.baidu.com/image/pic/item/a8773912b31bb0516a13ec1d387adab44aede0d4.jpg'),
              fit: BoxFit.cover,
              alignment: Alignment.topCenter
            ),
            border: Border.all(
              color: Colors.black,
              width: 8.0,
            ),
          ),
          //设置变换
          transform: Matrix4.rotationZ(0.2),
        ),


          ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

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