Would you would expect timers in ActionScript 3.0 to be accurate??
“yes, of course!” But there’s a problem:
If you set a Timer to go off indefinitely (i.e., with a repeatCount of 0), it appears that the timer doesn’t start the next interval until the listener function returns. So if you don’t correct for this, then your timer function will creep by the duration of the listener function. If your listener function does something that’s potentially lengthy, you might want to execute it with a callLater() so that the timer isn’t affected. But the timer will still creep unless you apply a correction. Here’s some sample code that demonstrates the effect, side-by-side with a correction.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 | < ?xml version="1.0" encoding="utf-8"?> <mx :Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" creationComplete="{onCreationComplete(event)}"> </mx><mx :Script> < ![CDATA[ import mx.utils.StringUtil; import mx.events.FlexEvent; private const BASE_INTERVAL:Number = 1000; private var _creepingTimer:Timer = new Timer(BASE_INTERVAL); private var _steadyTimer:Timer = new Timer(BASE_INTERVAL); private var _startTime:Date; private function onCreationComplete(e:FlexEvent) : void { _creepingTimer.addEventListener(TimerEvent.TIMER, onCreepingTimer); _creepingTimer.start(); _steadyTimer.addEventListener(TimerEvent.TIMER, onSteadyTimer); _steadyTimer.start(); _startTime = new Date(); } private function onCreepingTimer(e:TimerEvent) : void { var now:Date = new Date(); var deltaMS:int = now.time - _startTime.time; uiCreepingLog.text += StringUtil.substitute("\r{0}", deltaMS); } private function onSteadyTimer(e:TimerEvent) : void { var now:Date = new Date(); var deltaMS:int = now.time - _startTime.time; uiSteadyLog.text += StringUtil.substitute("\r{0}", deltaMS); var offset:int = deltaMS % BASE_INTERVAL; _steadyTimer.delay = offset < 500 ? BASE_INTERVAL - offset : BASE_INTERVAL; } ]]> </mx> <mx :HBox width="100%" height="100%"> <mx :TextArea id="uiCreepingLog" width="50%" height="100%" text="Creeping timer:"/> <mx :TextArea id="uiSteadyLog" width="50%" height="100%" text="Steady timer:"/> </mx> |
read the orignal post at : joy of flex
