/**
* Timer inacurracy example.
* See: https://bugs.adobe.com/jira/browse/FP-34
*
* Originally by Tox Coxen - http://flashquartermaster.com
* Slight modifications by Dan - http://thewebpageofdan.com
*/
package
{
	import flash.display.MovieClip;
	import flash.events.TimerEvent;
	import flash.utils.Timer;
	import flash.utils.getTimer;
 
	public class TimerTest extends MovieClip
	{
		private var _start:uint;
   		private var _desiredDelay:Number = 1000;
 
		public function TimerTest()
		{
			var timer:Timer = new Timer(_desiredDelay);
			timer.addEventListener(TimerEvent.TIMER, tick);
			_start = getTimer();
			timer.start();
		}
 
		private function tick(evt:TimerEvent):void
		{
			var timer:Timer = Timer(evt.currentTarget);
			var elapsed:Number = (getTimer() - _start);
			var desiredElapsed:Number = (timer.currentCount * _desiredDelay);
			var offset:Number = elapsed - desiredElapsed;
 
			if (offset > 1000)
			{
				trace("MORE THAN A SECOND OFF!");
			}
			trace("Tick | Count: " + timer.currentCount + " / desired Elpased millis " + desiredElapsed + " / getTimer() elapsed millis: " + elapsed + " / offset: " + offset);
		}
	}
}

Tick | Count: 1 / desired elapsed millis 1000 / getTimer() elapsed millis: 1059 / offset: 59
Tick | Count: 2 / desired elapsed millis 2000 / getTimer() elapsed millis: 2112 / offset: 112
Tick | Count: 3 / desired elapsed millis 3000 / getTimer() elapsed millis: 3175 / offset: 175
Tick | Count: 4 / desired elapsed millis 4000 / getTimer() elapsed millis: 4247 / offset: 247
Tick | Count: 5 / desired elapsed millis 5000 / getTimer() elapsed millis: 5311 / offset: 311
Tick | Count: 6 / desired elapsed millis 6000 / getTimer() elapsed millis: 6390 / offset: 390
Tick | Count: 7 / desired elapsed millis 7000 / getTimer() elapsed millis: 7463 / offset: 463
Tick | Count: 8 / desired elapsed millis 8000 / getTimer() elapsed millis: 8511 / offset: 511
Tick | Count: 9 / desired elapsed millis 9000 / getTimer() elapsed millis: 9559 / offset: 559
Tick | Count: 10 / desired elapsed millis 10000 / getTimer() elapsed millis: 10607 / offset: 607
Tick | Count: 11 / desired elapsed millis 11000 / getTimer() elapsed millis: 11671 / offset: 671
Tick | Count: 12 / desired elapsed millis 12000 / getTimer() elapsed millis: 12687 / offset: 687
Tick | Count: 13 / desired elapsed millis 13000 / getTimer() elapsed millis: 13689 / offset: 689
Tick | Count: 14 / desired elapsed millis 14000 / getTimer() elapsed millis: 14759 / offset: 759
Tick | Count: 15 / desired elapsed millis 15000 / getTimer() elapsed millis: 15767 / offset: 767
Tick | Count: 16 / desired elapsed millis 16000 / getTimer() elapsed millis: 16823 / offset: 823
Tick | Count: 17 / desired elapsed millis 17000 / getTimer() elapsed millis: 17871 / offset: 871
Tick | Count: 18 / desired elapsed millis 18000 / getTimer() elapsed millis: 18918 / offset: 918
Tick | Count: 19 / desired elapsed millis 19000 / getTimer() elapsed millis: 19927 / offset: 927
Tick | Count: 20 / desired elapsed millis 20000 / getTimer() elapsed millis: 20983 / offset: 983
MORE THAN A SECOND OFF!
Tick | Count: 21 / desired elapsed millis 21000 / getTimer() elapsed millis: 22038 / offset: 1038
MORE THAN A SECOND OFF!
Tick | Count: 22 / desired elapsed millis 22000 / getTimer() elapsed millis: 23119 / offset: 1119

/**
* Workaround for Timer offsets
* See: https://bugs.adobe.com/jira/browse/FP-34
*
* Originally by Tox Coxen - http://flashquartermaster.com
* Edited by Dan - http://thewebpageofdan.com
*/
package
{
	import flash.utils.Timer;
	import flash.utils.getTimer;
 
	public class TimerReal extends Timer
	{
		private var _desiredDelay:Number;
		private var _initStart:Number;
   		private var _stop:Number;
   		private var _start:Number;
   		private var _pauses:Number;
		private var _offset:Number;
 
		/**
		* Constructs a new RealTimer object with the specified <code>delay</code> and <code>repeatCount</code> states. 
		* 
		* @param delay		The delay between timer events, in milliseconds. 
		* @param repeatCount	Specifies the number of repetitions. If zero, the timer repeats infinitely. If nonzero, the timer runs the specified number of times and then stops. 
		*/
		public function TimerReal(delay:Number, repeatCount:int = 0.0)
		{
			_desiredDelay = delay;
			_initStart = 0;
			_start = 0;
			_stop = 0;
			_pauses = 0;
			super(delay, repeatCount);
		}
 
		/**
		* Manages the timer drift and accounts for pauses caused by stopping and starting the Timer.
		*/
		public function adjustDelay():void
		{
			// Aggregate pauses.
			// When start and stop are called internally in flash.utils.Timer _start will equal _stop
			_pauses += _start - _stop;
 
			var elapsed:Number = (getTimer() - _initStart) - _pauses;
			var desiredElapsed:Number = (currentCount * _desiredDelay);
			_offset = elapsed - desiredElapsed;
			var newDelay:Number = _desiredDelay - _offset;
 
			// Setting negetive values for delay will cause an error
			delay = (newDelay > 0) ? newDelay : _desiredDelay;
		}
 
		/**
		* @private
		*/
		override public function start():void
		{
			// Set _initStart once only otherwise set a value for when Timer.start() is called
			if (_initStart == 0)
			{
				_initStart = getTimer();
			}
			else
			{
				_start = getTimer();
			}
			super.start();
		}
 
		/**
		* @private
		*/
		override public function stop():void
		{
			// Only set the stop value if the Timer has been started and needs to be stopped i.e. is running
			if (_initStart != 0 && running)
			{
				_stop = getTimer();
			}
			super.stop();
		}
 
		/**
		* @private
		*/
		override public function reset():void
		{
			_initStart = 0;
			_start = 0;
			_stop = 0;
			_pauses = 0;
			super.reset();
		}
 
		/**
		* The desired delay.
		*/
		public function set desiredDelay(value:Number):void
		{
			_desiredDelay = value;
		}
 
		/**
		* The current offset.
		*/
		public function get offset():Number
		{
			return _offset;
		}
	}
}

/**
* TimerReal example.
* By Dan - http://thewebpageofdan.com
*/
package
{
	import flash.display.MovieClip;
	import flash.events.TimerEvent;
	import flash.utils.Timer;
	import flash.utils.getTimer;
 
	public class TimerRealExample extends MovieClip
	{
		public function TimerRealExample()
		{
			var timer:TimerReal = new TimerReal(10);
			timer.addEventListener(TimerEvent.TIMER, tick);
			timer.start();
		}
 
		private function tick(evt:TimerEvent):void
		{
			TimerReal(evt.currentTarget).adjustDelay();
			var timeStr:String = millisToTimeStr(evt.target.currentCount + evt.target.offset / 10);
			//trace(timeStr);
		}
 
		/**
		* Converts milliseconds to a time string
		*/
		private function millisToTimeStr(milliseconds:uint):String
		{
			var seconds:uint = Math.floor(milliseconds / 100);
			var minutes:uint = Math.floor(seconds / 60);
			var hours:uint = Math.floor(minutes / 60);
 
			var lminutes:uint = minutes - (hours * 60);
			var lseconds:uint = seconds - (minutes * 60);
			var lmilliseconds:uint = milliseconds - seconds * 100;
 
			var millisecondsStr:String = (lmilliseconds >= 10) ? String(lmilliseconds) : "0" + lmilliseconds;
			var secondsStr:String = (lseconds >= 10) ? String(lseconds) : "0" + lseconds;
			var minutesStr:String = (lminutes >= 10) ? String(lminutes) : "0" + lminutes;
			var hoursStr:String = (hours >= 10) ? String(hours) : "0" + hours;
 
			return String(((hours) ? hoursStr + ":" : "") + minutesStr + ":" + secondsStr + "." + millisecondsStr);
		}
	}
}