1 | module.exports = raf
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2 |
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3 | var EE = require('events').EventEmitter
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4 | , _raf = require('./polyfill.js')
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5 | , now = global.performance && global.performance.now ? function() {
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6 | return performance.now()
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7 | } : Date.now || function () {
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8 | return +new Date()
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9 | }
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10 |
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11 |
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12 | function raf(el, tick) {
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13 | var now = raf.now()
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14 | , ee = new EE
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15 |
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16 | if(typeof el === 'function') {
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17 | tick = el
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18 | el = undefined
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19 | }
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20 |
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21 | ee.pause = function() { ee.paused = true }
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22 | ee.resume = function() { ee.paused = false }
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23 |
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24 | _raf.call(window, iter, el)
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25 |
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26 | if(tick) {
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27 | ee.on('data', function(dt) {
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28 | tick(dt)
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29 | })
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30 | }
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31 |
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32 | return ee
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33 |
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34 | function iter(timestamp) {
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35 | var _now = raf.now()
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36 | , dt = _now - now
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37 |
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38 | now = _now
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39 |
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40 | if(!ee.paused) {
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41 | ee.emit('data', dt)
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42 | }
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43 |
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44 | _raf.call(window, iter, el)
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45 | }
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46 | }
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47 |
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48 | raf.polyfill = _raf
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49 | raf.now = now
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50 |
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