flex-grow
属性定义项目的放大比例,解决的问题是:在空间有多余时把多余空间分配给各个子元素。
flex-grow
的值默认为 0
,也就是说,如果存在剩余空间,也不放大。
flex-grow
取值为非负数(如果取值为负数那么和0的取值效果相同)。
语法
.item {
flex-grow: <number>; /* default 0 */
}
flex-grow
默认为0
flex-grow
默认为 0
时:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
.container {
display: flex;
margin: 0px auto;
width: 900px;
height: 200px;
background-color: #e6e6e6;
}
.item {
width: 50px;
height: 50px;
}
.container div:nth-of-type(1) {background-color:coral;}
.container div:nth-of-type(2) {background-color:lightblue;}
.container div:nth-of-type(3) {background-color:khaki;}
.container div:nth-of-type(4) {background-color:pink;}
.container div:nth-of-type(5) {background-color:lightgrey;}
.container div:nth-of-type(6) {background-color:orange;}
</style>
</head>
<body>
<div class="container">
<div class="item">1</div>
<div class="item">2</div>
<div class="item">3</div>
<div class="item">4</div>
<div class="item">5</div>
<div class="item">6</div>
</div>
</body>
</html>
可以看到,flex-grow
默认值为 0 时,并不会占用剩余的空白间隙扩展自己的宽度,页面效果如下:
flex-grow
值为正整数
如果flex-grow
大于0,则flex
容器剩余空间的分配就会发生。
概念:将所有正整数相加得到分母 sum,每个属性的数值作为分子,然后乘以剩余空间。
公式:分子/分母*剩余空间
平均分配空间
如果所有项目的 flex-grow
属性都为1,则它们将等分剩余空间(如果有的话)。
实例:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
.container {
display: flex;
margin: 0px auto;
width: 900px;
height: 200px;
background-color: #e6e6e6;
}
.item {
height: 50px;
flex:1;
}
.container div:nth-of-type(1) {background-color:coral;}
.container div:nth-of-type(2) {background-color:lightblue;}
.container div:nth-of-type(3) {background-color:khaki;}
.container div:nth-of-type(4) {background-color:pink;}
.container div:nth-of-type(5) {background-color:lightgrey;}
.container div:nth-of-type(6) {background-color:orange;}
</style>
</head>
<body>
<div class="container">
<div class="item">1</div>
<div class="item">2</div>
<div class="item">3</div>
<div class="item">4</div>
<div class="item">5</div>
<div class="item">6</div>
</div>
</body>
</html>
页面效果:
不平均分配空间
如果一个项目的 flex-grow
属性不为1,则按照公式来计算每个元素占有的空间。
实例:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
.container {
display: flex;
margin: 0px auto;
width: 900px;
height: 200px;
background-color: #e6e6e6;
}
.item {
height: 50px;
}
.container div:nth-of-type(1) {flex-grow: 1;background-color:coral;}
.container div:nth-of-type(2) {flex-grow: 3;background-color:lightblue;}
.container div:nth-of-type(3) {flex-grow: 1;background-color:khaki;}
.container div:nth-of-type(4) {flex-grow: 2;background-color:pink;}
.container div:nth-of-type(5) {flex-grow: 4;background-color:lightgrey;}
.container div:nth-of-type(6) {flex-grow: 1;background-color:orange;}
</style>
</head>
<body>
<div class="container">
<div class="item">1</div>
<div class="item">2</div>
<div class="item">3</div>
<div class="item">4</div>
<div class="item">5</div>
<div class="item">6</div>
</div>
</body>
</html>
页面效果:
flex-grow
值为小数
flex-grow
属性值为小数,分两种情况:
1)所有 flex
项的 flex-gorw
属性值之和大于1,仍然按照上面正整数方式进行计算;
2)所有 flex
项的 flex-gorw
属性值之和小于1,基值按照1来进行计算。
例子:项目1为 0.1, 项目2为 0.3,项目3为 0.1, 项目4为 0.2,项目5为 0.1,则它们分配到的剩余空间分别为:
项目1: 900px * (0.1 / 1) = 94.7px;
项目2: 900px * (0.3 / 1) = 265.31px;
项目3: 900px * (0.1 / 1) = 94.7px;
项目4: 900px * (0.2 / 1) = 180px;
项目5: 900px * (0.1 / 1) = 94.7px;
实例:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
.container {
display: flex;
margin: 0px auto;
width: 900px;
height: 200px;
background-color: #e6e6e6;
}
.item {
height: 50px;
}
.container div:nth-of-type(1) {flex-grow: 0.1;background-color:coral;}
.container div:nth-of-type(2) {flex-grow: 0.3;background-color:lightblue;}
.container div:nth-of-type(3) {flex-grow: 0.1;background-color:khaki;}
.container div:nth-of-type(4) {flex-grow: 0.2;background-color:pink;}
.container div:nth-of-type(5) {flex-grow: 0.1;background-color:lightgrey;}
</style>
</head>
<body>
<div class="container">
<div class="item">1</div>
<div class="item">2</div>
<div class="item">3</div>
<div class="item">4</div>
<div class="item">5</div>
</div>
</body>
</html>
页面效果:
flex-grow
值为小数+正整数
flex-grow
值为小数+正整数时,计算方式与正整数一样,如分母取值:sum=1+0.6+0.5+0.2+2=4.3,分子分别为:1/4.3、0.6/4.3、0.5/4.3、0.2/4.3、2/4.3
实例:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
.container {
display: flex;
margin: 0px auto;
width: 900px;
height: 200px;
background-color: #e6e6e6;
}
.item {
height: 50px;
}
.container div:nth-of-type(1) {flex-grow: 1;background-color:coral;}
.container div:nth-of-type(2) {flex-grow: 0.6;background-color:lightblue;}
.container div:nth-of-type(3) {flex-grow: 0.5;background-color:khaki;}
.container div:nth-of-type(4) {flex-grow: 0.2;background-color:pink;}
.container div:nth-of-type(5) {flex-grow: 2;background-color:lightgrey;}
</style>
</head>
<body>
<div class="container">
<div class="item">1</div>
<div class="item">2</div>
<div class="item">3</div>
<div class="item">4</div>
<div class="item">5</div>
</div>
</body>
</html>
页面效果: