flutter 页面布局 Paddiing Row Column Expanded 组件

Flutter Paddiing 组件

在 html 中常见的布局标签都有 padding 属性，但是 Flutter 中很多 Widget 是没有 padding 属 性。这个时候我们可以用 Padding 组件处理容器与子元素直接的间距。

属性	说明
padding	padding 值, EdgeInsetss 设置填充的值
child	子组件

import 'package:flutter/material.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) {
    return Padding(
      padding: EdgeInsets.fromLTRB(0, 0, 10, 0),
      child: GridView.count(
        crossAxisCount: 2,
        childAspectRatio: 1.7,
        children: <Widget>[
          Padding(
            padding: EdgeInsets.fromLTRB(10, 10, 0, 0),
            child: Image.network('http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg',
                fit: BoxFit.cover),
          ),
          Padding(
            padding: EdgeInsets.fromLTRB(10, 10, 0, 0),
            child: Image.network('http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg',
                fit: BoxFit.cover),
          ),
           Padding(
            padding: EdgeInsets.fromLTRB(10, 10, 0, 0),
            child: Image.network('http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg',
                fit: BoxFit.cover),
          ),
          Padding(
            padding: EdgeInsets.fromLTRB(10, 10, 0, 0),
            child: Image.network('http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg',
                fit: BoxFit.cover),
          ),
           Padding(
            padding: EdgeInsets.fromLTRB(10, 10, 0, 0),
            child: Image.network('http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg',
                fit: BoxFit.cover),
          ),
          Padding(
            padding: EdgeInsets.fromLTRB(10, 10, 0, 0),
            child: Image.network('http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg',
                fit: BoxFit.cover),
          ),
           Padding(
            padding: EdgeInsets.fromLTRB(10, 10, 0, 0),
            child: Image.network('http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg',
                fit: BoxFit.cover),
          ),
          Padding(
            padding: EdgeInsets.fromLTRB(10, 10, 0, 0),
            child: Image.network('http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg',
                fit: BoxFit.cover),
          ),
           Padding(
            padding: EdgeInsets.fromLTRB(10, 10, 0, 0),
            child: Image.network('http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg',
                fit: BoxFit.cover),
          ),
          Padding(
            padding: EdgeInsets.fromLTRB(10, 10, 0, 0),
            child: Image.network('http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg',
                fit: BoxFit.cover),
          ),
        ],
    ));
  }
}

Flutter Row 水平布局组件

属性	说明
mainAxisAlignment	主轴的排序方式
crossAxisAlignment	次轴的排序方式
children	组件子元素

import 'package:flutter/material.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) {
    return Container(
      height: 800.0,
      width: 400.0,
      color: Colors.pink,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        crossAxisAlignment: CrossAxisAlignment.start,     //用的比较少
        children: <Widget>[
          IconContainer(Icons.search,color: Colors.blue),
          IconContainer(Icons.home,color: Colors.orange),
          IconContainer(Icons.select_all,color: Colors.red),
        ],
      ),
    );
  }
}

class IconContainer extends StatelessWidget{
  double size=32.0;
  Color color=Colors.red;
  IconData icon;
  IconContainer(this.icon,{this.color,this.size});
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Container(
      height: 100.0,
      width: 100.0,
      color: this.color,
      child: Center(
        child: Icon(this.icon,size: this.size,color: Colors.white)
      ),
    );
  }
}

Flutter Column 垂直布局组件

属性	说明
mainAxisAlignment	主轴的排序方式
crossAxisAlignment	次轴的排序方式
children	组件子元素

import 'package:flutter/material.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) {
    return Container(
      height: 800.0,
      width: 400.0,
      color: Colors.pink,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        crossAxisAlignment: CrossAxisAlignment.end,
        children: <Widget>[
          IconContainer(Icons.search,color: Colors.blue),
          IconContainer(Icons.home,color: Colors.orange),
          IconContainer(Icons.select_all,color: Colors.red),
        ],
      ),
    );
  }
}

class IconContainer extends StatelessWidget{
  double size=32.0;
  Color color=Colors.red;
  IconData icon;
  IconContainer(this.icon,{this.color,this.size});
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Container(
      height: 100.0,
      width: 100.0,
      color: this.color,
      child: Center(
        child: Icon(this.icon,size: this.size,color: Colors.white)
      ),
    );
  }
}

Flutter Expanded 类似 Web 中的 Flex 布局

Expanded 可以用在 Row 和 Column 布局中

属性	说明
flex	元素站整个父 Row /Column 的比例
child	子元素

import 'package:flutter/material.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) {
    return Row(    

        children: <Widget>[
          Expanded(
            flex: 1,
            child: IconContainer(Icons.search,color: Colors.blue)
          ),
           Expanded(
            flex: 2,
            child: IconContainer(Icons.home,color: Colors.orange),
          ),
           Expanded(
            flex: 1,
            child: IconContainer(Icons.select_all,color: Colors.red),
          ),

        ],
    );
  }
}

class IconContainer extends StatelessWidget{
  double size=32.0;
  Color color=Colors.red;
  IconData icon;
  IconContainer(this.icon,{this.color,this.size});
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Container(
      height: 100.0,
      width: 100.0,
      color: this.color,
      child: Center(
        child: Icon(this.icon,size: this.size,color: Colors.white)
      ),
    );
  }
}

---

import 'package:flutter/material.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) {
    return Row(    

        children: <Widget>[
          Expanded(
            flex: 1,
            child: IconContainer(Icons.home,color: Colors.orange),
          ),
          IconContainer(Icons.search,color: Colors.blue)

        ],
    );
  }
}

class IconContainer extends StatelessWidget{
  double size=32.0;
  Color color=Colors.red;
  IconData icon;
  IconContainer(this.icon,{this.color,this.size});
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Container(
      height: 100.0,
      width: 100.0,
      color: this.color,
      child: Center(
        child: Icon(this.icon,size: this.size,color: Colors.white)
      ),
    );
  }
}

import 'package:flutter/material.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) {
    return Column(
      children: <Widget>[

        Row(
          children: <Widget>[
            Expanded(
              child:   Container(
                height: 180,
                color: Colors.yellow,
                child: Text('你好Flutter'),
              ),
            )
          ],
        ),
        SizedBox(height: 10),
        Row(
          children: <Widget>[
            Expanded(
              flex: 2,
              child: Container(
                height: 180,
                child: Image.network("http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg",fit: BoxFit.cover),
              )
            ),
            SizedBox(width: 10),
            Expanded(
              flex: 1,
              child: Container(
                height: 180,
                child: ListView(
                  children: <Widget>[
                    Container(
                      height: 85,
                      child: Image.network("http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg",fit: BoxFit.cover),

                    ),
                    SizedBox(height: 10),
                    Container(
                      height: 85,
                      child: Image.network("http://pic31.nipic.com/20130801/11604791_100539834000_2.jpg",fit: BoxFit.cover),
                    )
                  ],
                )
              )
            ),

          ],
        )
      ],
    );
  }
}