轉載自：
作者：阿遠Carry
連結：https://juejin.cn/post/6916146797328990216
來源：稀土掘金
著作權歸作者所有。商業轉載請聯系作者獲得授權，非商業轉載請注明出處。
有些小夥伴看到标題就在想
我做這動态圖檔肯定不那麼麻煩，我随便找幾個圖貼上去啊！
我隻能說：小了，格局小了！
像有些業務場景：比如大屏項目，如果使用png.gif這類，總會失真！
但SVG不會，SVG永遠的神！
是以，這篇文章教大家如何快速實作SVG動态圖示！
類似這樣～
1.尋找圖示素材（SVG标簽）
我推薦大家去 iconfont 網站，随便找個圖示
把滑鼠放在圖示上，點選
下載下傳按鈕
會出現如下頁面，點選
複制SVG代碼
你就會得到如下代碼
<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>
有的小夥伴就覺得這是啥玩意啊？我看不懂啊！
小夥伴們，先别慌，hold住！
其實這段代碼很簡單！
就是
svg
标簽嵌套了兩個
path
标簽罷了
svg
标簽中
viewBox="0 0 1024 1024"
屬性代表是 1024 × 1024 視圖
path
标簽中的
d
屬性定義路徑
簡單準确了解：就是在 1024 × 1024 的虛拟畫布上作畫
而
width="200" height="200"
是控制實際svg的大小
也就是等比例縮放，把 1024 × 1024 圖檔縮放到 200 × 200，還不會失真，真好！
最後一個
path
fill="#1875F0"
是填充色
2. 編寫動畫樣式 （CSS）
再編寫樣式之前，我們還需要對之前svg的内容進行處理
在每個
path
删除
fill="#1875F0"
原本的填充顔色屬性
添加
fill="#fff"
與背景相同的填充顔色
增加
class="icon-path"
class類名
stroke="#1875F0"
描繪路徑顔色屬性
stroke-width="3"
描繪路徑的寬度
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代碼：
.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
這裡有些細節你應該明白！
首先我們用了
animation
動畫屬性：
指定了
icon-path-animation
關鍵幀的名稱
持續時間為 8s
ease-in
由慢到快的 動畫過程
infinite
無限次數循環
而，在關鍵幀中：
小夥伴們比較陌生的應該是
stroke-dasharray
和
stroke-dashoffset
兩個屬性
stroke-dasharray
表示 路徑之間的空白間隙長度
比如将上述 css 替換成這段代碼
.icon-path {
stroke-dasharray: 1000;
}
肉眼可見的他有 1000 的間隙值
還有，細心的小夥伴會發現 有個array的字眼
确實他可以傳“數組”進去
例如
.icon-path {
stroke-dasharray: 60, 50, 60;
}
他就會出現
接着就是
stroke-dashoffset
空白間隙的偏移量
.icon-path {
stroke-dasharray: 1000;
stroke-dashoffset: 200;
}
其實你可以發現，就是空白間隙就被偏移 200
是以，
stroke-dashoffset: 4917;
到
stroke-dashoffset: 0;
應該是 從無到有的過程
這個圖示 最長的 path 約為 4917
畢竟，
stroke-dashoffset
空白間隙偏移為4917，那就是 4917 - 4917 = 0，此時的 path 應該 0
而當
stroke-dashoffset
空白間隙偏移為 0, 4917 - 0 = 4917，也就是這個圖示足夠顯示的路徑長度
或許，有的小夥伴最莫名其妙的是：你怎麼知道這個圖示路徑長度是 4917 啊？胡說八道嗎？
其實不是我算的，我用了以下的JS代碼獲得的
const iconPath = document.getElementsByClassName('icon-path') // 擷取 path 标簽
for (let i = 0; i < iconPath.length; i++) {
const item = iconPath[i]
console.log(item.getTotalLength()) // 獲得 path 路徑長度
}
可以發現，最長度是 4916.69335937， 約為 4917
是以，我們隻要選取最長path作為最大間隙就足夠！
CSS代碼連貫流程應該是：
從 0 到 40% 繪制全部描邊路徑
從 40% 到 60% 填充顔色
從 60% 100% 保持不變
整個過程從慢到快，持續 8s， 無限循環
是以，看完以上你應該可以快速開發一個動态SVG圖示了吧
附上全部代碼(html檔案)
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>SVG動态圖示</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') // 擷取 path 标簽
for (let i = 0; i < iconPath.length; i++) {
const item = iconPath[i]
console.log(item.getTotalLength()) // 獲得 path 路徑長度
}
</script>
</body>
</html>
最後：
本篇隻是實作了簡單動畫效果
如果想要複雜效果，無非是寫好幾個不同
animation
如果小夥伴們認真看完明白其中原理，就可以完實作出來的