快速实现SVG动态图标

 

转载自：

作者：阿远Carry
链接：https://juejin.cn/post/6916146797328990216
来源：稀土掘金
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。

 

有些小伙伴看到标题就在想

我做这动态图片肯定不那么麻烦，我随便找几个图贴上去啊！

我只能说：小了，格局小了！

像有些业务场景：比如大屏项目，如果使用png.gif这类，总会失真！

但SVG不会，SVG永远的神！

所以，这篇文章教大家如何快速实现SVG动态图标！

类似这样～

1.寻找图标素材（SVG标签）

我推荐大家去 iconfont 网站，随便找个图标

把鼠标放在图标上，点击下载按钮

会出现如下页面，点击复制SVG代码

你就会得到如下代码

<svg t="1610274780071" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="35827" width="200" height="200">
    <path d="M722.944 501.76h173.568c13.312 0 24.576-10.752 24.576-24.576 0-13.312-10.752-24.576-24.576-24.576h-173.568c-27.136 0-53.76 9.216-75.264 25.088L296.96 734.72c-3.072 2.048-6.144 3.584-9.728 4.096-8.704 1.024-17.408 1.536-26.112 1.536-39.424-1.536-75.776-18.432-102.912-48.128-27.136-30.208-40.448-69.12-37.376-109.056 5.12-69.632 55.808-123.392 121.344-132.608 1.536 29.184 7.68 57.344 18.944 84.48 4.096 9.216 12.8 15.36 22.528 15.36 3.072 0 6.144-0.512 9.216-2.048 12.288-5.12 18.432-19.456 13.312-31.744-10.24-25.088-15.36-51.712-15.36-78.848C290.816 323.584 384 230.4 498.176 230.4c92.672 0 174.592 61.952 199.68 151.04 3.584 12.8 17.408 20.48 30.208 16.896 12.8-3.584 20.48-17.408 16.896-30.208-30.72-110.08-132.096-186.88-246.784-186.88-129.024 0-236.032 95.744-253.44 219.648-93.184 8.192-165.888 82.432-173.056 178.688-3.584 52.736 14.336 105.984 50.176 145.408 35.84 39.936 84.48 62.464 137.728 64.512H266.24c9.728 0 18.944-0.512 28.672-2.048 11.776-1.536 23.04-6.656 32.256-13.312l350.72-257.024c12.288-9.728 28.672-15.36 45.056-15.36zM897.024 740.352h-301.568c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h301.568c13.312 0 24.576-10.752 24.576-24.576 0-13.824-11.264-24.576-24.576-24.576z" fill="#1875F0" p-id="35828"></path>
    <path d="M643.072 598.016c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h141.312c13.312 0 24.576-10.752 24.576-24.576 0-13.312-10.752-24.576-24.576-24.576h-141.312zM928.256 598.016h-62.464c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h62.464c13.312 0 24.576-10.752 24.576-24.576 0-13.312-11.264-24.576-24.576-24.576zM510.464 740.352H448c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h62.464c13.312 0 24.576-10.752 24.576-24.576 0-13.824-11.264-24.576-24.576-24.576z" fill="#1875F0" p-id="35829"></path>
</svg>

 

有的小伙伴就觉得这是啥玩意啊？我看不懂啊！

小伙伴们，先别慌，hold住！

其实这段代码很简单！

就是 svg 标签嵌套了两个 path 标签罢了

svg 标签中 viewBox="0 0 1024 1024" 属性代表是 1024 × 1024 视图

path 标签中的 d 属性定义路径

简单准确理解：就是在 1024 × 1024 的虚拟画布上作画

而 width="200" height="200" 是控制实际svg的大小

也就是等比例缩放，把 1024 × 1024 图片缩放到 200 × 200，还不会失真，真好！

最后一个 path 标签中的 fill="#1875F0" 是填充色

2. 编写动画样式 （CSS）

再编写样式之前，我们还需要对之前svg的内容进行处理

在每个 path 标签中

删除 fill="#1875F0" 原本的填充颜色属性

添加 fill="#fff" 与背景相同的填充颜色

增加 class="icon-path" class类名

增加 stroke="#1875F0" 描绘路径颜色属性

增加 stroke-width="3" 描绘路径的宽度

如下：

<svg t="1610274780071" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="35827" width="200" height="200">
    <path class="icon-path" stroke="#1875F0" stroke-width="3" d="M722.944 501.76h173.568c13.312 0 24.576-10.752 24.576-24.576 0-13.312-10.752-24.576-24.576-24.576h-173.568c-27.136 0-53.76 9.216-75.264 25.088L296.96 734.72c-3.072 2.048-6.144 3.584-9.728 4.096-8.704 1.024-17.408 1.536-26.112 1.536-39.424-1.536-75.776-18.432-102.912-48.128-27.136-30.208-40.448-69.12-37.376-109.056 5.12-69.632 55.808-123.392 121.344-132.608 1.536 29.184 7.68 57.344 18.944 84.48 4.096 9.216 12.8 15.36 22.528 15.36 3.072 0 6.144-0.512 9.216-2.048 12.288-5.12 18.432-19.456 13.312-31.744-10.24-25.088-15.36-51.712-15.36-78.848C290.816 323.584 384 230.4 498.176 230.4c92.672 0 174.592 61.952 199.68 151.04 3.584 12.8 17.408 20.48 30.208 16.896 12.8-3.584 20.48-17.408 16.896-30.208-30.72-110.08-132.096-186.88-246.784-186.88-129.024 0-236.032 95.744-253.44 219.648-93.184 8.192-165.888 82.432-173.056 178.688-3.584 52.736 14.336 105.984 50.176 145.408 35.84 39.936 84.48 62.464 137.728 64.512H266.24c9.728 0 18.944-0.512 28.672-2.048 11.776-1.536 23.04-6.656 32.256-13.312l350.72-257.024c12.288-9.728 28.672-15.36 45.056-15.36zM897.024 740.352h-301.568c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h301.568c13.312 0 24.576-10.752 24.576-24.576 0-13.824-11.264-24.576-24.576-24.576z" fill="#fff" p-id="35828"></path>
    <path class="icon-path" stroke="#1875F0" stroke-width="3" d="M643.072 598.016c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h141.312c13.312 0 24.576-10.752 24.576-24.576 0-13.312-10.752-24.576-24.576-24.576h-141.312zM928.256 598.016h-62.464c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h62.464c13.312 0 24.576-10.752 24.576-24.576 0-13.312-11.264-24.576-24.576-24.576zM510.464 740.352H448c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h62.464c13.312 0 24.576-10.752 24.576-24.576 0-13.824-11.264-24.576-24.576-24.576z" fill="#fff" p-id="35829"></path>
</svg>

 

增加css代码：

.icon-path {
   animation: icon-path-animation 8s ease-in infinite;
}
@keyframes icon-path-animation {
  0% {
    stroke-dasharray: 4917;
    stroke-dashoffset: 4917;
  }

  40% {
    stroke-dasharray: 4917;
    stroke-dashoffset: 0;
    fill: #fff;
  }

  60% {
    stroke-dasharray: 4917;
    stroke-dashoffset: 0;
    fill: #1875F0;
  }

  100% {
    stroke-dasharray: 4917;
    stroke-dashoffset: 0;
    fill: #1875F0;
  }
}

 

大功告成！

哈哈哈，别急

这里有些细节你应该明白！

首先我们用了animation 动画属性：

指定了 icon-path-animation 关键帧的名称

持续时间为 8s

ease-in 由慢到快的 动画过程

infinite 无限次数循环

而，在关键帧中：

小伙伴们比较陌生的应该是 stroke-dasharray 和 stroke-dashoffset 两个属性

stroke-dasharray 表示 路径之间的空白间隙长度

比如将上述 css 替换成这段代码

.icon-path {
    stroke-dasharray: 1000;
}

　　

肉眼可见的他有 1000 的间隙值

还有，细心的小伙伴会发现 有个array的字眼

确实他可以传“数组”进去

例如

.icon-path {
  stroke-dasharray: 60, 50, 60;
}

　

他就会出现

接着就是 stroke-dashoffset 空白间隙的偏移量

.icon-path {
  stroke-dasharray: 1000;
  stroke-dashoffset: 200;
}

　　

其实你可以发现，就是空白间隙就被偏移 200

所以，stroke-dashoffset: 4917; 到 stroke-dashoffset: 0;

应该是 从无到有的过程

这个图标 最长的 path 约为 4917

毕竟，stroke-dashoffset 空白间隙偏移为4917，那就是 4917 - 4917 = 0，此时的 path 应该 0

而当 stroke-dashoffset 空白间隙偏移为 0, 4917 - 0 = 4917，也就是这个图标足够显示的路径长度

或许，有的小伙伴最莫名其妙的是：你怎么知道这个图标路径长度是 4917 啊？胡说八道吗？

其实不是我算的，我用了以下的JS代码获得的

const iconPath = document.getElementsByClassName('icon-path') // 获取 path 标签
for (let i = 0; i < iconPath.length; i++) {
  const item = iconPath[i]
  console.log(item.getTotalLength()) // 获得 path 路径长度
}

　

可以发现，最长度是 4916.69335937， 约为 4917

所以，我们只要选取最长path作为最大间隙就足够！

CSS代码连贯流程应该是：

从 0 到 40% 绘制全部描边路径

从 40% 到 60% 填充颜色

从 60% 100% 保持不变

整个过程从慢到快，持续 8s， 无限循环

所以，看完以上你应该可以快速开发一个动态SVG图标了吧

附上全部代码(html文件)

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>SVG动态图标</title>
    <style>
        .icon-path {
            animation: icon-path-animation 8s ease-in infinite;
        }
        @keyframes icon-path-animation {
            0% {
                stroke-dasharray: 4917;
                stroke-dashoffset: 4917;
                fill: #fff;
            }

            40% {
                stroke-dasharray: 4917;
                stroke-dashoffset: 0;
                fill: #fff;
            }

            60% {
                stroke-dasharray: 4917;
                stroke-dashoffset: 0;
                fill: #1875F0;
            }

            100% {
                stroke-dasharray: 4917;
                stroke-dashoffset: 0;
                fill: #1875F0;
            }
        }
    </style>
</head>
<body>
<svg t="1610274780071" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="35827" width="200" height="200">
    <path class="icon-path" stroke="#1875F0"stroke-width="3" d="M722.944 501.76h173.568c13.312 0 24.576-10.752 24.576-24.576 0-13.312-10.752-24.576-24.576-24.576h-173.568c-27.136 0-53.76 9.216-75.264 25.088L296.96 734.72c-3.072 2.048-6.144 3.584-9.728 4.096-8.704 1.024-17.408 1.536-26.112 1.536-39.424-1.536-75.776-18.432-102.912-48.128-27.136-30.208-40.448-69.12-37.376-109.056 5.12-69.632 55.808-123.392 121.344-132.608 1.536 29.184 7.68 57.344 18.944 84.48 4.096 9.216 12.8 15.36 22.528 15.36 3.072 0 6.144-0.512 9.216-2.048 12.288-5.12 18.432-19.456 13.312-31.744-10.24-25.088-15.36-51.712-15.36-78.848C290.816 323.584 384 230.4 498.176 230.4c92.672 0 174.592 61.952 199.68 151.04 3.584 12.8 17.408 20.48 30.208 16.896 12.8-3.584 20.48-17.408 16.896-30.208-30.72-110.08-132.096-186.88-246.784-186.88-129.024 0-236.032 95.744-253.44 219.648-93.184 8.192-165.888 82.432-173.056 178.688-3.584 52.736 14.336 105.984 50.176 145.408 35.84 39.936 84.48 62.464 137.728 64.512H266.24c9.728 0 18.944-0.512 28.672-2.048 11.776-1.536 23.04-6.656 32.256-13.312l350.72-257.024c12.288-9.728 28.672-15.36 45.056-15.36zM897.024 740.352h-301.568c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h301.568c13.312 0 24.576-10.752 24.576-24.576 0-13.824-11.264-24.576-24.576-24.576z" fill="#fff" p-id="35828"></path>
    <path class="icon-path" stroke="#1875F0" stroke-width="3" d="M643.072 598.016c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h141.312c13.312 0 24.576-10.752 24.576-24.576 0-13.312-10.752-24.576-24.576-24.576h-141.312zM928.256 598.016h-62.464c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h62.464c13.312 0 24.576-10.752 24.576-24.576 0-13.312-11.264-24.576-24.576-24.576zM510.464 740.352H448c-13.312 0-24.576 10.752-24.576 24.576 0 13.312 10.752 24.576 24.576 24.576h62.464c13.312 0 24.576-10.752 24.576-24.576 0-13.824-11.264-24.576-24.576-24.576z" fill="#fff" p-id="35829"></path>
</svg>
<script>
    const iconPath = document.getElementsByClassName('icon-path') // 获取 path 标签
    for (let i = 0; i < iconPath.length; i++) {
        const item = iconPath[i]
        console.log(item.getTotalLength()) // 获得 path 路径长度
    }
</script>
</body>
</html>

　　

最后：

本篇只是实现了简单动画效果

如果想要复杂效果，无非是写好几个不同 animation

如果小伙伴们认真看完明白其中原理，就可以完实现出来的