flex布局实例
Flex 布局教程：实例篇出处：http://www.ruanyifeng.com/blog/2015/07/flex-examples.html你会看到，不管是什么布局，Flex往往都可以几行命令搞定。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071327.png我只列出代码，详细的语法解释请查阅《Flex布局教程：语法篇》。我的主要参考资料是Landon Schropp的文章和Solved by Flexbox。一、骰子的布局骰子的一面，最多可以放置9个点。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071328.png下面，就来看看Flex如何实现，从1个点到9个点的布局。你可以到codepen查看Demo。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071329.png如果不加说明，本节的HTML模板一律如下。<div class="box"><span class="item"></span></div>上面代码中，div元素（代表骰子的一个面）是Flex容器，span元素（代表一个点）是Flex项目。如果有多个项目，就要添加多个span元素，以此类推。1.1 单项目首先，只有左上角1个点的情况。Flex布局默认就是首行左对齐，所以一行代码就够了。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071301.png.box {display: flex;}设置项目的对齐方式，就能实现居中对齐和右对齐。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071302.png.box {display: flex;justify-content: center;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071303.png.box {display: flex;justify-content: flex-end;}设置交叉轴对齐方式，可以垂直移动主轴。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071304.png.box {display: flex;align-items: center;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071305.png.box {display: flex;justify-content: center;align-items: center;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071306.png.box {display: flex;justify-content: center;align-items: flex-end;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071307.png.box {display: flex;justify-content: flex-end;align-items: flex-end;}1.2 双项目http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071308.png.box {display: flex;justify-content: space-between;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071309.png.box {display: flex;flex-direction: column;justify-content: space-between;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071310.png.box {display: flex;flex-direction: column;justify-content: space-between;align-items: center;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071311.png.box {display: flex;flex-direction: column;justify-content: space-between;align-items: flex-end;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071312.png.box {display: flex;}.item:nth-child(2) {align-self: center;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071313.png.box {display: flex;justify-content: space-between;}.item:nth-child(2) {align-self: flex-end;}1.3 三项目http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071314.png.box {display: flex;}.item:nth-child(2) {align-self: center;}.item:nth-child(3) {align-self: flex-end;}1.4 四项目http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071315.png.box {display: flex;flex-wrap: wrap;justify-content: flex-end;align-content: space-between;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071316.pngHTML代码如下。<div class="box"><div class="column"> <span class="item"></span> <span class="item"></span></div><div class="column"> <span class="item"></span> <span class="item"></span></div></div>CSS代码如下。.box {display: flex;flex-wrap: wrap;align-content: space-between;}.column {flex-basis: 100%;display: flex;justify-content: space-between;}1.5 六项目http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071317.png.box {display: flex;flex-wrap: wrap;align-content: space-between;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071318.png.box {display: flex;flex-direction: column;flex-wrap: wrap;align-content: space-between;}http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071319.pngHTML代码如下。<div class="box"><div class="row"> <span class="item"></span> <span class="item"></span> <span class="item"></span></div><div class="row"> <span class="item"></span></div><div class="row"> <span class="item"></span> <span class="item"></span></div></div>CSS代码如下。.box {display: flex;flex-wrap: wrap;}.row{flex-basis: 100%;display:flex;}.row:nth-child(2){justify-content: center;}.row:nth-child(3){justify-content: space-between;}1.6 九项目http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071320.png.box {display: flex;flex-wrap: wrap;}二、网格布局2.1 基本网格布局最简单的网格布局，就是平均分布。在容器里面平均分配空间，跟上面的骰子布局很像，但是需要设置项目的自动缩放。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071321.pngHTML代码如下。<div class="Grid"><div class="Grid-cell">...</div><div class="Grid-cell">...</div><div class="Grid-cell">...</div></div>CSS代码如下。.Grid {display: flex;}.Grid-cell {flex: 1;}2.2 百分比布局某个网格的宽度为固定的百分比，其余网格平均分配剩余的空间。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071322.pngHTML代码如下。<div class="Grid"><div class="Grid-cell u-1of4">...</div><div class="Grid-cell">...</div><div class="Grid-cell u-1of3">...</div></div>.Grid {display: flex;}.Grid-cell {flex: 1;}.Grid-cell.u-full {flex: 0 0 100%;}.Grid-cell.u-1of2 {flex: 0 0 50%;}.Grid-cell.u-1of3 {flex: 0 0 33.3333%;}.Grid-cell.u-1of4 {flex: 0 0 25%;}三、圣杯布局圣杯布局（Holy Grail Layout）指的是一种最常见的网站布局。页面从上到下，分成三个部分：头部（header），躯干（body），尾部（footer）。其中躯干又水平分成三栏，从左到右为：导航、主栏、副栏。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071323.pngHTML代码如下。<body class="HolyGrail"><header>...</header><div class="HolyGrail-body"> <main class="HolyGrail-content">...</main> <nav class="HolyGrail-nav">...</nav> <aside class="HolyGrail-ads">...</aside></div><footer>...</footer></body>CSS代码如下。.HolyGrail {display: flex;min-height: 100vh;flex-direction: column;}header,footer {flex: 1;}.HolyGrail-body {display: flex;flex: 1;}.HolyGrail-content {flex: 1;}.HolyGrail-nav, .HolyGrail-ads {/* 两个边栏的宽度设为12em */flex: 0 0 12em;}.HolyGrail-nav {/* 导航放到最左边 */order: -1;}如果是小屏幕，躯干的三栏自动变为垂直叠加。@media (max-width: 768px) {.HolyGrail-body { flex-direction: column; flex: 1;}.HolyGrail-nav,.HolyGrail-ads,.HolyGrail-content { flex: auto;}}四、输入框的布局我们常常需要在输入框的前方添加提示，后方添加按钮。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071324.pngHTML代码如下。<div class="InputAddOn"><span class="InputAddOn-item">...</span><input class="InputAddOn-field"><button class="InputAddOn-item">...</button></div>CSS代码如下。.InputAddOn {display: flex;}.InputAddOn-field {flex: 1;}五、悬挂式布局有时，主栏的左侧或右侧，需要添加一个图片栏。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071325.pngHTML代码如下。<div class="Media"><img class="Media-figure" src="" alt=""><p class="Media-body">...</p></div>CSS代码如下。.Media {display: flex;align-items: flex-start;}.Media-figure {margin-right: 1em;}.Media-body {flex: 1;}六、固定的底栏有时，页面内容太少，无法占满一屏的高度，底栏就会抬高到页面的中间。这时可以采用Flex布局，让底栏总是出现在页面的底部。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071326.pngHTML代码如下。<body class="Site"><header>...</header><main class="Site-content">...</main><footer>...</footer></body>CSS代码如下。.Site {display: flex;min-height: 100vh;flex-direction: column;}.Site-content {flex: 1;}七，流式布局每行的项目数固定，会自动分行。http://www.ruanyifeng.com/blogimg/asset/2015/bg2015071330.pngCSS的写法。.parent {width: 200px;height: 150px;background-color: black;display: flex;flex-flow: row wrap;align-content: flex-start;}.child {box-sizing: border-box;background-color: white;flex: 0 0 25%;height: 50px;border: 1px solid red;}
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