【JavaScript】------- requestAnimationFrame 用法

xiaoxiao2021-03-01  15

如果使用基于 javaScript 的动画,尽量使用 requestAnimationFrame. 避免使用 setTimeout, setInterval.

使用requestAnimationFrame有什么好处?

浏览器可以优化并行的动画动作,更合理的重新排列动作序列,并把能够合并的动作放在一个渲染周期内完成,从而呈现出更流畅的动画效果。比如,通过requestAnimationFrame(),JS动画能够和CSS动画/变换或SVG SMIL动画同步发生。另外,如果在一个浏览器标签页里运行一个动画,当这个标签页不可见时,浏览器会暂停它,这会减少CPU,内存的压力,节省电池电量

各种浏览器对requestAnimationFrame的支持情况

谷歌浏览器,火狐浏览器,IE10+都实现了这个函数,即使你的浏览器很古老,上面的对requestAnimationFrame封装也能让这个方法在IE8/9上不出错。

<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <p id="video" width="12" height="5" ></p> <button id="snap">Snap Photo</button> <script> window.requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame; var start = null; var ele = document.getElementById("video"); var progress = 0; function step(timestamp) { progress += 1; ele.style.width = progress + "%"; ele.innerHTML=progress + "%"; if (progress < 100) { requestAnimationFrame(step); } } requestAnimationFrame(step); document.getElementById("snap").addEventListener("click", function() { ele.style.width = "1px"; progress = 0; requestAnimationFrame(step); }, false); </script> </body> </html> /* 封装性的代码 基于各个浏览器 */ (function() { var lastTime = 0; var vendors = ['webkit', 'moz']; for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) { window.requestAnimationFrame = window[vendors[x]+'RequestAnimationFrame']; window.cancelAnimationFrame = window[vendors[x]+'CancelAnimationFrame'] || window[vendors[x]+'CancelRequestAnimationFrame']; } if (!window.requestAnimationFrame) window.requestAnimationFrame = function(callback, element) { var currTime = new Date().getTime(); var timeToCall = Math.max(0, 16 - (currTime - lastTime)); var id = window.setTimeout(function() { callback(currTime + timeToCall); }, timeToCall); lastTime = currTime + timeToCall; return id; }; if (!window.cancelAnimationFrame) window.cancelAnimationFrame = function(id) { clearTimeout(id); }; }());

 

转载处: http://www.webhek.com/post/requestanimationframe.html

转载处: https://blog.csdn.net/lsy__lsy/article/details/80624563

转载请注明原文地址: https://www.6miu.com/read-4050342.html

最新回复(0)