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A list-based fallback implementation of `requestAnimationFrame` that reduces the number of `setTimeout`s needed.
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| // http://paulirish.com/2011/requestanimationframe-for-smart-animating/ | |
| // http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating | |
| // requestAnimationFrame polyfill by Erik Möller | |
| // fixes from Paul Irish and Tino Zijdel | |
| // list-based fallback implementation by Jonas Finnemann Jensen | |
| (function() { | |
| var lastTime = 0; | |
| var vendors = ['ms', 'moz', 'webkit', 'o']; | |
| 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){ | |
| var tid = null, cbs = [], nb = 0, ts = 0; | |
| function animate() { | |
| var i, clist = cbs, len = cbs.length; | |
| tid = null; | |
| ts = Date.now(); | |
| cbs = []; | |
| nb += clist.length; | |
| for (i = 0; i < len; i++){ | |
| if(clist[i]) | |
| clist[i](ts); | |
| } | |
| } | |
| window.requestAnimationFrame = function(cb) { | |
| if (tid == null) | |
| tid = window.setTimeout(animate, Math.max(0, 20 + ts - Date.now())); | |
| return cbs.push(cb) + nb; | |
| }; | |
| window.cancelAnimationFrame = function(id) { | |
| delete cbs[id - nb - 1]; | |
| }; | |
| } | |
| }()); |
Hey, interesting idea.
I'm not too good on scoping concepts, but would there be a problem leaving the cbs list in the global scope?
@natb19,
There is only one instance of the cbs variable... so technically it could live in the global scope.
But I would do it because data encapsulation is a good idea :)
https://github.com/kof/animationFrame
a bit optimized version of your shim + some features and ios fix.
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Now a little cleaner than previous revisions, and closer to the specification.
Compared to the original approach, we don't create a new closure for each frame, but just a list and a single timeout.