47 lines
1.6 KiB
JavaScript
47 lines
1.6 KiB
JavaScript
let lastTime = 0
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const prefixes = 'webkit moz ms o'.split(' ') // 各浏览器前缀
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let requestAnimationFrame
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let cancelAnimationFrame
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const isServer = typeof window === 'undefined'
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if (isServer) {
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requestAnimationFrame = function() {
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return
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}
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cancelAnimationFrame = function() {
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return
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}
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} else {
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requestAnimationFrame = window.requestAnimationFrame
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cancelAnimationFrame = window.cancelAnimationFrame
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let prefix
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// 通过遍历各浏览器前缀，来得到requestAnimationFrame和cancelAnimationFrame在当前浏览器的实现形式
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for (let i = 0; i < prefixes.length; i++) {
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if (requestAnimationFrame && cancelAnimationFrame) { break }
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prefix = prefixes[i]
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requestAnimationFrame = requestAnimationFrame || window[prefix + 'RequestAnimationFrame']
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cancelAnimationFrame = cancelAnimationFrame || window[prefix + 'CancelAnimationFrame'] || window[prefix + 'CancelRequestAnimationFrame']
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}
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// 如果当前浏览器不支持requestAnimationFrame和cancelAnimationFrame，则会退到setTimeout
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if (!requestAnimationFrame || !cancelAnimationFrame) {
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requestAnimationFrame = function(callback) {
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const currTime = new Date().getTime()
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// 为了使setTimteout的尽可能的接近每秒60帧的效果
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const timeToCall = Math.max(0, 16 - (currTime - lastTime))
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const id = window.setTimeout(() => {
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callback(currTime + timeToCall)
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}, timeToCall)
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lastTime = currTime + timeToCall
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return id
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}
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cancelAnimationFrame = function(id) {
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window.clearTimeout(id)
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}
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}
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}
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export { requestAnimationFrame, cancelAnimationFrame }
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