Flutter AspectRatio、Card 卡片组件

Flutter AspectRatio 组件

AspectRatio 的作用是根据设置调整子元素 child 的宽高比。

AspectRatio 首先会在布局限制条件允许的范围内尽可能的扩展，widget 的高度是由宽 度和比率决定的，类似于 BoxFit 中的 contain，按照固定比率去尽量占满区域。

如果在满足所有限制条件过后无法找到一个可行的尺寸，AspectRatio 最终将会去优先 适应布局限制条件，而忽略所设置的比率。

属性	说明
aspectRatio	宽高比，最终可能不会根据这个值去布局， 具体则要看综合因素，外层是否允许按照这 种比率进行布局，这只是一个参考值
child	子组件

import 'package:flutter/material.dart';
import 'res/listData.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return MaterialApp(
        home: Scaffold(
        appBar: AppBar(title: Text('FlutterDemo')),
        body: LayoutDemo(),
      ));
  }
}
class LayoutDemo extends StatelessWidget {
 @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Container(
      width: 200,
      child: AspectRatio(
        aspectRatio: 2.0/1.0,
        child: Container(
          color: Colors.red,
        ),
      ),

    );
  }
}

import 'package:flutter/material.dart';
import 'res/listData.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return MaterialApp(
        home: Scaffold(
        appBar: AppBar(title: Text('FlutterDemo')),
        body: LayoutDemo(),
      ));
  }
}
class LayoutDemo extends StatelessWidget {
 @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return AspectRatio(
        aspectRatio: 3.0/1.0,
        child: Container(
          color: Colors.red,
        ),     

    );
  }
}

Flutter Card 组件

Card 是卡片组件块，内容可以由大多数类型的 Widget 构成，Card 具有圆角和阴影，这让它 看起来有立体感。

属性	说明
margin	外边距
child	子组件
Shape	Card 的阴影效果，默认的阴影效果为圆角的 长方形边。

import 'package:flutter/material.dart';
import 'package:flutter/painting.dart';
import 'res/listData.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return MaterialApp(
        home: Scaffold(
        appBar: AppBar(title: Text('FlutterDemo')),
        body: LayoutDemo(),
      ));
  }
}
class LayoutDemo extends StatelessWidget {
 @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return ListView(

      children: <Widget>[

          Card(
            margin: EdgeInsets.all(10),
            child: Column(
              children: <Widget>[

                ListTile(
                  title:Text("张三",style: TextStyle(fontSize: 28)) ,
                  subtitle: Text("高级工程师"),
                ),
                 ListTile(
                  title:Text("电话：xxxxx") ,
                ),
                ListTile(
                  title:Text("地址：xxxxxx") ,
                )

              ],
            ),
          ),Card(
            margin: EdgeInsets.all(10),
            child: Column(
              children: <Widget>[

                ListTile(
                  title:Text("李四",style: TextStyle(fontSize: 28)) ,
                  subtitle: Text("高级工程师"),
                ),
                 ListTile(
                  title:Text("电话：xxxxx") ,
                ),
                ListTile(
                  title:Text("地址：xxxxxx") ,
                )

              ],
            ),
          ),
          Card(
            margin: EdgeInsets.all(10),
            child: Column(
              children: <Widget>[

                ListTile(
                  title:Text("王五",style: TextStyle(fontSize: 28)) ,
                  subtitle: Text("高级工程师"),
                ),
                 ListTile(
                  title:Text("电话：xxxxx") ,
                ),
                ListTile(
                  title:Text("地址：xxxxxx") ,
                )

              ],
            ),
          )
      ],
    );
  }
}

demo实现一个图文列表布局

import 'package:flutter/material.dart';
import 'res/listData.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return MaterialApp(
        home: Scaffold(
        appBar: AppBar(title: Text('FlutterDemo')),
        body: LayoutDemo(),
      ));
  }
}
class LayoutDemo extends StatelessWidget {

 @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return ListView(
      children: listData.map((value){
        return Card(
          margin: EdgeInsets.all(10),
          child:Column(
              children: <Widget>[
                  AspectRatio(
                    aspectRatio: 20/9,
                    child: Image.network(value["imageUrl"],fit: BoxFit.cover,),
                  ),
                  ListTile(
                    leading: CircleAvatar(
                      backgroundImage:NetworkImage(value["imageUrl"])
                    ),
                    title: Text(value["title"]),
                    subtitle: Text(value["description"],maxLines: 1,overflow: TextOverflow.ellipsis),
                  )
              ],
          ),

        );

      }).toList(),
    );
  }
}

listdata.drat

  List listData=[
      {
          "title": 'Candy Shop',
          "author": 'Mohamed Chahin',
          "imageUrl": 'http://img.redocn.com/sheji/20141219/zhongguofengdaodeliyizhanbanzhijing_3744115.jpg',
          "description": 'Flutter is Google’s mobile UI framework for crafting high-quality native experiences on iOS and Android in record time. Flutter works with existing',
      },
       {
          "title": 'Childhood in a picture',
          "author": 'Google',
          "imageUrl": 'http://img.redocn.com/sheji/20141219/zhongguofengdaodeliyizhanbanzhijing_3744115.jpg',
          "description": 'Flutter is Google’s mobile UI framework for crafting high-quality native experiences on iOS and Android in record time. Flutter works with existing',
      },
      {
          "title": 'Alibaba Shop',
          "author": 'Alibaba',
          "imageUrl": 'http://img.redocn.com/sheji/20141219/zhongguofengdaodeliyizhanbanzhijing_3744115.jpg',
          "description": 'Dart is a client-optimized language for fast apps on any platform... Dart is a client-optimized language for fast apps on any platform Optimizedfor',
      },
      {
          "title": 'Candy Shop',
          "author": 'Mohamed Chahin',
          "imageUrl": 'http://img.redocn.com/sheji/20141219/zhongguofengdaodeliyizhanbanzhijing_3744115.jpg',
          "description": 'Dart is a client-optimized language for fast apps on any platform... Dart is a client-optimized language for fast apps on any platform Optimizedfor',
      },
       {
          "title": 'Tornado',
          "author": 'Mohamed Chahin',
          "imageUrl": 'http://img.redocn.com/sheji/20141219/zhongguofengdaodeliyizhanbanzhijing_3744115.jpg',
          "description": 'Flutter is Google’s mobile UI framework for crafting high-quality native experiences on iOS and Android in record time. Flutter works with existing',
      },
      {
          "title": 'Undo',
          "author": 'Mohamed Chahin',
          "imageUrl": 'http://img.redocn.com/sheji/20141219/zhongguofengdaodeliyizhanbanzhijing_3744115.jpg',
          "description": 'Flutter is Google’s mobile UI framework for crafting high-quality native experiences on iOS and Android in record time. Flutter works with existing',
      },
      {
          "title": 'white-dragon',
          "author": 'Mohamed Chahin',
          "imageUrl": 'http://img.redocn.com/sheji/20141219/zhongguofengdaodeliyizhanbanzhijing_3744115.jpg',
          "description": 'Dart is a client-optimized language for fast apps on any platform... Dart is a client-optimized language for fast apps on any platform Optimizedfor',
      }      

  ];