先看效果css
clip 屬性剪裁絕對定位元素。
當一幅圖像的尺寸大於包含它的元素時會發生什麼呢?"clip" 屬性容許您規定一個元素的可見尺寸,這樣此元素就會被修剪並顯示爲這個形狀。html
clip: rect(<top>, <right>, <bottom>, <left>);
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title></title> <style type="text/css"> .box { margin: 100px; display: inline-block; padding: 8px; position: relative; background-color: rgba(255,255,255,0.8); } .box::before { content: ''; position: absolute; left: 0; top: 0; right: 0; bottom: 0; border: 2px solid #E611F1; animation: borderAround 5s infinite linear; background-color: rgba(25,66,25,0.8); } @keyframes borderAround { 0%, 100% { clip: rect(0 148px 2px 0); } 25% { clip: rect(0 148px 116px 146px); } 50% { clip: rect(116px 148px 116px 0); } 75% { clip: rect(0 2px 116px 0); } } </style> </head> <body> <div class="box"> <img src="img/15177108659009550.gif" width="128" height="96" style="background-color: white;"> </div> </body> </html>
附送一張解密圖spa
*借鑑張鑫旭博文3d