SVG实现描边动画
Posted 天南有只飞鸟
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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)：
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>super</title> 6 <script src="vivus.js"></script> 7 <style> 8 .super_logo{ 9 position: absolute; 10 opacity: 0; 11 animation:fadeIn 1s ease-in forwards; 12 -webkit-animation:fadeIn 1s ease-in forwards; 13 } 14 #super{ 15 position: absolute; 16 z-index: 1; 17 stroke-dasharray: 800; 18 stroke-dashoffset: 1000; 19 animation: describe 2s forwards; 20 -webkit-animation: describe 2s forwards; 21 } 22 @keyframes fadeIn{ 23 from{opacity: 0;} 24 80%{opacity: 0.5;} 25 to{opacity: 1;} 26 } 27 @-webkit-keyframes fadeIn{ 28 from{opacity: 0;} 29 80%{opacity: 0.5;} 30 to{opacity: 1;} 31 } 32 @keyframes describe{ 33 from{ 34 stroke-dashoffset: 1000; 35 opacity: 1; 36 } 37 to{ 38 stroke-dashoffset: 0; 39 opacity: 0; 40 } 41 } 42 @-webkit-keyframes describe{ 43 from{ 44 stroke-dashoffset: 1000; 45 opacity: 1; 46 } 47 to{ 48 stroke-dashoffset: 0; 49 opacity: 0; 50 } 51 } 52 </style> 53 </head> 54 <body style="background:#0f1a3a;"> 55 <img src="http://images2015.cnblogs.com/blog/754767/201606/754767-20160606165217980-1558570494.gif" alt="super" class="super_logo"> 56 <svg id="super" x="0px" y="0px" width="293px" height="200px" viewBox="0 0 293 200"> 57 <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 58 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 59 s9.334-12.333,15.334-22.333c0,0-21.333-29.333-44-38c0,0-162.001-5.334-163.334-2.667"/> 60 <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 61 s55.333,4.667,60,6.667s32.668,7.254,43.334,31.627L255,93.667C255,93.667,217,59,169.667,50.333z"/> 62 <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 63 S185.333,155,146.5,153.667S75.667,123,75.667,123z"/> 64 <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 65 z"/> 66 <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M174.912,161c0,0-24.745,12.999-24.745,12.333 67 s-15.25-4.249-20.583-10.416"/> 68 <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"/> 69 <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"/> 70 <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 71 C264.875,80.677,249.273,55.266,237.25,52z"/> 72 </svg> 73 </body> 74 </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：
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>super</title> 6 <script src="vivus.js"></script> 7 <style> 8 .super_logo{ 9 position: absolute; 10 } 11 #super{ 12 position: absolute; 13 z-index: 1; 14 } 15 </style> 16 </head> 17 <body style="background:#0f1a3a;"> 18 <img src="super.gif" alt="super" class="super_logo"> 19 <svg id="super" x="0px" y="0px" width="293px" height="200px" viewBox="0 0 293 200"> 20 <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 21 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 22 s9.334-12.333,15.334-22.333c0,0-21.333-29.333-44-38c0,0-162.001-5.334-163.334-2.667"/> 23 <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 24 s55.333,4.667,60,6.667s32.668,7.254,43.334,31.627L255,93.667C255,93.667,217,59,169.667,50.333z"/> 25 <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 26 S185.333,155,146.5,153.667S75.667,123,75.667,123z"/> 27 <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 28 z"/> 29 <path fill="none" data-duration="60" stroke="#ffffff" stroke-width="1" d="M174.912,161c0,0-24.745,12.999-24.745,12.333 30 s-15.25-4.249-20.583-10.416"/> 31 <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"/> 32 <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"/> 33 <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 34 C264.875,80.677,249.273,55.266,237.25,52z"/> 35 </svg> 36 <script> 37 window.onload=function(){ 38 var toPlay= new Vivus(\'super\', { 39 type: \'delayed\', 40 duration: 50, 41 start: \'autostart\', 42 forceRender: false, 43 dashGap: 20} 44 ); 45 var oSuper=document.getElementById(\'super\'); 46 oSuper.addEventListener(\'click\',function(){ 47 toPlay.reset().play(); 48 }); 49 }; 50 </script> 51 </body> 52 </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
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