SVG实现描边动画

说起SVG，我是恨它又爱它，恨它是因为刚开始接触的时候自己傻B地想用代码去写它，其实在web上我们用它做交互也只是用了几个常用的特性而已，其他的标签知道这么一回事就成了，其实说白了它就是一种图片格式，你得去画它，网站上最长用的SVG交互效果就是描边动画了，今天就来实现它

先上效果图：

思路：要实现这种动画，我们要使用的是SVG的路径path标签，其中然后配合两个属性：stroke-dasharray和stroke-dashoffset，至于用什么方式实现动画效果就八仙过海了，我这里使用的是css3的animation

第一步：了解SVG的path

中文的意思就是路径，描边动画嘛，你得先给个路线我才能描边啊，路径就是这个路线：

先上网找个图片，放进AI里面，然后用钢笔勾勒路径，再把图片删掉，剩下路径，把它另存为svg，然后把它拖进编译器里，就能看到一堆代码，我们只要保留其中的path就好（不会用AI的给你个理由去勾搭设计师美眉）

第二步：了解stroke-dasharray和stroke-dashoffset

理解字面意思就好：

stroke-dasharray：就是把线条断开为虚线，下图就是我把stroke-dasharray设置为10的效果，它就变成虚线了，数值越大，线就越长

stroke-dashoffset：就是设置线条的偏移，设置了这个值后，线段就会偏移相应的值，我们要实现动画只要动态改变这个偏移值就好，那样线条就会动起来了

第三步：利用@keyframes实现动态描边

@keyframes describe{

	from{

		stroke-dashoffset: 1000;

		opacity: 1;

	}

	to{

		stroke-dashoffset: 0;

		opacity: 0;

	}

}

额~~有点快，没关系，明白意思就好，最后，描边完成之后再插入一个动画，让背景图片淡入，最终效果如下：

下班了，不调了，如果再慢点效果估计更好

上终板代码(直接拷贝就能跑)：

 <!DOCTYPE html>

 <html lang="en">

 <head>

     <meta charset="UTF-8">

     <title>super</title>

     <script src="vivus.js"></script>

     <style>

     .super_logo{

         position: absolute;

         opacity: 0;

         animation:fadeIn 1s ease-in  forwards;

             -webkit-animation:fadeIn 1s ease-in  forwards;

     }

     #super{

         position: absolute;

         z-index: 1;

         stroke-dasharray: 800;

           stroke-dashoffset: 1000;

         animation: describe 2s forwards;

             -webkit-animation: describe 2s forwards;

     }

     @keyframes fadeIn{

         from{opacity: 0;}

         80%{opacity: 0.5;}

         to{opacity: 1;}

     }

     @-webkit-keyframes fadeIn{

         from{opacity: 0;}

         80%{opacity: 0.5;}

         to{opacity: 1;}

     }

     @keyframes describe{

         from{

             stroke-dashoffset: 1000;

             opacity: 1;

         }

         to{

             stroke-dashoffset: 0;

             opacity: 0;

         }

     }

     @-webkit-keyframes describe{

         from{

             stroke-dashoffset: 1000;

             opacity: 1;

         }

         to{

             stroke-dashoffset: 0;

             opacity: 0;

         }

     }

     </style>

 </head>

 <body style="background:#0f1a3a;">

 <img src="http://images2015.cnblogs.com/blog/754767/201606/754767-20160606165217980-1558570494.gif" alt="super" class="super_logo">

 <svg id="super" x="0px" y="0px" width="293px" height="200px" viewBox="0 0 293 200">

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M67.667,39.667c0,0-33.334,17.333-46.667,36.667

         c0,0,33.007,40.458,43.331,50.018c19.419,17.982,65.002,55.316,82.169,59.982c0,0,27.834-11.334,49.834-30.667S249,113,261,100

         s9.334-12.333,15.334-22.333c0,0-21.333-29.333-44-38c0,0-162.001-5.334-163.334-2.667"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M169.667,50.333c0,0-71.334-2.667-74.667,8.667s42,14,42,14

         s55.333,4.667,60,6.667s32.668,7.254,43.334,31.627L255,93.667C255,93.667,217,59,169.667,50.333z"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M75.667,123c0,0,42,8,78,8.667s32.667,10.667,32.667,10.667

         S185.333,155,146.5,153.667S75.667,123,75.667,123z"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M45,93c0,0-12.667-24,34-48h-8.667c0,0-35.455,24.559-36,35.677L45,93

         z"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M174.912,161c0,0-24.745,12.999-24.745,12.333

         s-15.25-4.249-20.583-10.416"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M130,162.667c0,0,1.75-3.083,13.667-1.25c0,0,30,0.836,30.75-0.582"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M177.75,43L224,45.5c0,0,7.5,12.125-13,8.625S177.75,43,177.75,43z"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M237.25,52c0,0,2.75,20.375,21.875,35.625l5.75-6.948

         C264.875,80.677,249.273,55.266,237.25,52z"/>

 </svg>

 </body>

 </html>

恩恩~~写到这里我的肚子饿惨了，他们都下班去吃饭了，打字这么开心我干脆再介绍个插件，那就vivus.js

Vivus是一款可以执行SVG路径动画的轻量级Javascript库，github地址：https://github.com/maxwellito/vivus

扔个中文的介绍http://www.htmleaf.com/html5/SVG/201501261279.html

写的还可以，我就不重复码字了，直接上demo：

 <!DOCTYPE html>

 <html lang="en">

 <head>

     <meta charset="UTF-8">

     <title>super</title>

     <script src="vivus.js"></script>

     <style>

     .super_logo{

         position: absolute;

     }

     #super{

         position: absolute;

         z-index: 1;

     }

     </style>

 </head>

 <body style="background:#0f1a3a;">

 <img src="super.gif" alt="super" class="super_logo">

 <svg id="super" x="0px" y="0px" width="293px" height="200px" viewBox="0 0 293 200">

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M67.667,39.667c0,0-33.334,17.333-46.667,36.667

         c0,0,33.007,40.458,43.331,50.018c19.419,17.982,65.002,55.316,82.169,59.982c0,0,27.834-11.334,49.834-30.667S249,113,261,100

         s9.334-12.333,15.334-22.333c0,0-21.333-29.333-44-38c0,0-162.001-5.334-163.334-2.667"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M169.667,50.333c0,0-71.334-2.667-74.667,8.667s42,14,42,14

         s55.333,4.667,60,6.667s32.668,7.254,43.334,31.627L255,93.667C255,93.667,217,59,169.667,50.333z"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M75.667,123c0,0,42,8,78,8.667s32.667,10.667,32.667,10.667

         S185.333,155,146.5,153.667S75.667,123,75.667,123z"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M45,93c0,0-12.667-24,34-48h-8.667c0,0-35.455,24.559-36,35.677L45,93

         z"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M174.912,161c0,0-24.745,12.999-24.745,12.333

         s-15.25-4.249-20.583-10.416"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M130,162.667c0,0,1.75-3.083,13.667-1.25c0,0,30,0.836,30.75-0.582"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M177.75,43L224,45.5c0,0,7.5,12.125-13,8.625S177.75,43,177.75,43z"/>

     <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M237.25,52c0,0,2.75,20.375,21.875,35.625l5.75-6.948

         C264.875,80.677,249.273,55.266,237.25,52z"/>

 </svg>

 <script>

 window.onload=function(){

     var toPlay= new Vivus('super', {

         type: 'delayed',

         duration: 50,

         start: 'autostart',

         forceRender: false,

         dashGap: 20}

     );

     var oSuper=document.getElementById('super');

     oSuper.addEventListener('click',function(){

         toPlay.reset().play();

     });

 };

 </script>

 </body>

 </html>

以上~~如果大家觉得有意思，点个赞呗，关注下也就更好了

他们吃饭都回来了，我也终于要走了，实习狗下班