弹性盒子基础
弹性盒子(Flexible Box)是css3中盒子模型的弹性布局，在传统的布局方式上增加了很多灵活性。
定义一个弹性盒子
在父盒子上定义display属性：
#box{
display: -webkit-flex; //webkit内核浏览器的兼容设置，下同
display: flex;
}
当然还有行内布局的弹性盒子
#box{
display: -webkit-inline-flex;
display: inline-flex;
}
注意，设为Flex布局以后，子元素的float、clear和vertical-align属性将失效。
弹性盒子兼容情况
- Chrome 29+
- Firefox 28+
- Internet Explorer 11+
- Opera 17+
- Safari 6.1+ (prefixed with -webkit-)
- Android 4.4+
- iOS 7.1+ (prefixed with -webkit-)
弹性盒子概念
弹性盒子两个轴如图：
- 主轴(横轴, main axis)
- 交叉轴(纵轴, cross axis)
弹性盒子属性
在研究具体属性前，先建立一个基本模板，必要时修改一下部分参数：
<!-- html部分 -->
<div id="flex-box">
<div class="flex-item">1</div>
<div class="flex-item">2</div>
<div class="flex-item">3</div>
<div class="flex-item">4</div>
<div class="flex-item">5</div>
</div>
<!-- css部分 -->
#flex-box{
width: 200px;
height: 200px;
border: 1px solid #06f;
display: flex;
display: -webkit-flex;
}
.flex-item{
height: 30px;
width: 30px;
color: #f00;
font-size: 20px;
line-height: 30px;
text-align: center;
background-color: #8f0;
border: 1px solid #f00;
}
- flex-direction
排列方向设置
#flex-box{
flex-direction: row | row-reverse | column | column-reverse;
/* @value row 从左到右(默认)*/
/* @value row-reverse 从右到左*/
/* @value column 从上到下*/
/* @value column-reverse 从下到上*/
}
- flex-wrap
换行设置
.box{
flex-wrap: nowrap | wrap | wrap-reverse;
/* @value nowrap 不换行(默认)*/
/* @value wrap 换行*/
/* @value wrap-reverse 换行 层倒序*/
}
- flex-flow
flex-direction和flex-wrap的缩写属性
.box {
flex-flow: <flex-direction> || <flex-wrap>;
}
- justify-content
水平方向上对齐
.box {
justify-content: flex-start | flex-end | center | space-between | space-around;
}
/* value flex-start 左对齐(默认)*/
/* value flex-end：右对齐*/
/* value center： 居中*/
/* value space-between：两端对齐，项目之间的间隔都相等*/
/* value space-around：每个项目两侧的间隔相等。所以，项目之间的间隔比项目与边框的间隔大一倍*/
- align-items
垂直方向上对齐
.box {
align-items: flex-start | flex-end | center | baseline | stretch;
}
/* value flex-start 交叉轴的起点对齐*/
/* value flex-end 交叉轴的终点对齐*/
/* value center 交叉轴的中点对齐*/
/* value baseline 项目的第一行文字的基线对齐*/
/* value stretch 如果项目未设置高度或设为auto，将占满整个容器的高度(默认)*/
- align-content
多根轴线的对齐方式
.box {
align-content: flex-start | flex-end | center | space-between | space-around | stretch;
}
/* value flex-start 与交叉轴的起点对齐*/
/* value flex-end 与交叉轴的终点对齐*/
/* value center 与交叉轴的中点对齐*/
/* value space-between 与交叉轴两端对齐，轴线之间的间隔平均分布*/
/* value space-around 每根轴线两侧的间隔都相等。所以，轴线之间的间隔比轴线与边框的间隔大一倍*/
/* value stretch 轴线占满整个交叉轴(默认值)*/
子元素属性
- order: 属性定义项目的排列顺序。数值越小，排列越靠前，默认为0
- flex-grow: 属性定义项目的放大比例，默认为0，即如果存在剩余空间，也不放大
- flex-shrink: 属性定义了项目的缩小比例，默认为1，即如果空间不足，该项目将缩小。
- flex-basis: 属性定义了在分配多余空间之前，项目占据的主轴空间它的默认值为auto，即项目的本来大小。
- flex: 属性是flex-grow, flex-shrink和flex-basis的简写。
- align-self: 属性允许单个项目有与其他项目不一样的对齐方式，可覆盖align-items属性。默认值为auto，表示继承父元素的align-items属性，如果没有父元素，则等同于stretch。
多列
- column-count 规定元素应该被分隔的列数
- column-fill 规定如何填充列
- column-gap 规定列之间的间隔
- column-rule 设置所有column-rule-*属性的简写属性
- column-rule-color 规定列之间规则的颜色
- column-rule-style 规定列之间规则的样式
- column-rule-width 规定列之间规则的宽度
- column-span 规定元素应该横跨的列数
- column-width 规定列的宽度
- columns 规定设置column-width和column-count的简写属性
实例
骰子
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>9 faces Dice</title>
</head>
<style>
body{
padding: 0;
margin: 0;
}
#demo{
display: flex;
background-color: #444;
}
.dice{
width: 90px;
height: 90px;
border-radius: 22px;
margin: 20px;
padding: 10px;
box-sizing: border-box;
border: 2px solid #aaa;
background-color: #eee;
display: flex;
flex-direction: column;
justify-content: space-between;
}
.dot{
width: 20px;
height: 20px;
background-color: #222;
border-top: 2px solid #000;
box-sizing: border-box;
/*box-shadow: 0px 0px 2px #000;*/
border-radius: 20px;
}
.line{
display: flex;
justify-content: space-between;
}
#one{
justify-content: center;
align-items: center;
}
#two{
align-items: center;
}
#three .line:nth-of-type(2){
justify-content: center;
}
#three .line:nth-of-type(3){
justify-content: flex-end;
}
#five .line:nth-of-type(2){
justify-content: center;
}
</style>
<body>
<div id="demo">
<div id="one" class="dice">
<div class="line">
<div class="dot"></div>
</div>
</div>
<div id="two" class="dice">
<div class="line">
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
</div>
</div>
<div id="three" class="dice">
<div class="line">
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
</div>
</div>
<div id="four" class="dice">
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
</div>
</div>
<div id="five" class="dice">
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
</div>
</div>
<div id="six" class="dice">
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
</div>
</div>
<div id="seven" class="dice">
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
</div>
</div>
<div id="eight" class="dice">
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
<div class="dot"></div>
</div>
</div>
<div id="nine" class="dice">
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
<div class="dot"></div>
</div>
<div class="line">
<div class="dot"></div>
<div class="dot"></div>
<div class="dot"></div>
</div>
</div>
</div>
</body>
</html>
瀑布流图
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<title>test</title>
<style>
ul{
width: 1000px;
margin: 0 auto;
padding: 0;
columns: 4;
list-style: none;
column-gap: 2px;
column-fill: balance;
}
ul li {
margin: 4px 0;
}
ul li img{
width:240px;
}
</style>
</head>
<body>
<ul>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
</ul>
</body>
</html>
栅格
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<title>test</title>
<style>
#grid-demo{
width: 1000px;
margin: 0 auto;
}
.grid{
display: flex;
margin: 20px 0;
height: 60px;
}
.grid .grid-item{
flex-grow: 1;
background-color: #eee;
height: 60px;
line-height: 60px;
font-size: 26px;
width: 5%;
text-align: center;
margin: 0 10px;
}
.grid .col-10{
flex-basis: 83.3333%
}
.grid .col-8{
flex-basis: 66.6666%;
}
.grid .col-6{
flex-basis: 50%;
}
.grid .col-4{
flex-basis: 33.3333%;
}
.grid .col-3{
flex-basis: 25%;
}
.grid .col-2{
flex-basis: 16.6667%;
}
</style>
</head>
<body>
<div id="grid-demo">
<div class="grid">
<div class="grid-item">1</div>
<div class="grid-item">1</div>
<div class="grid-item">1</div>
<div class="grid-item">1</div>
<div class="grid-item">1</div>
<div class="grid-item">1</div>
<div class="grid-item">1</div>
<div class="grid-item">1</div>
<div class="grid-item">1</div>
<div class="grid-item">1</div>
<div class="grid-item">1</div>
<div class="grid-item">1</div>
</div>
<div class="grid">
<div class="grid-item">2</div>
<div class="grid-item">2</div>
<div class="grid-item">2</div>
<div class="grid-item">2</div>
<div class="grid-item">2</div>
<div class="grid-item">2</div>
</div>
<div class="grid">
<div class="grid-item">3</div>
<div class="grid-item">3</div>
<div class="grid-item">3</div>
<div class="grid-item">3</div>
</div>
<div class="grid">
<div class="grid-item">4</div>
<div class="grid-item">4</div>
<div class="grid-item">4</div>
</div>
<div class="grid">
<div class="grid-item">6</div>
<div class="grid-item">6</div>
</div>
<div class="grid">
<div class="grid-item col-8">8</div>
<div class="grid-item col-4">4</div>
</div>
<div class="grid">
<div class="grid-item">12</div>
</div>
</div>
</body>
</html>
固定底栏
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<title>test</title>
<style>
body{
margin: 0;
padding: 0;
}
#demo{
display: flex;
flex-direction: column;
min-height: 100vh;
}
header, footer{
height: 100px;
background-color: darkblue;
color: white;
text-align: center;
line-height: 100px;
}
.flex-body{
flex-grow: 1;
}
</style>
</head>
<body>
<div id="demo">
<header>I am header!</header>
<div class="flex-body">I am body!</div>
<footer>I am footer!</footer>
</div>
</body>
</html>
