package  
{
	import flash.events.Event;
	import flash.events.KeyboardEvent;
	import flash.text.TextField;
	import flash.text.TextFormat;
 
	/**
	 *  @author Jankees.van.Woezik
	 */
	public class AutomaticFonSizeBehavior 
	{
 
		private var _textField:TextField;
		private var _startSize:Number;
		private var _currentSize:Number;
		private var _prevText:String;
		private var _maxHeight:Number;
		private var _minimalFontSize:uint;
 
		/**
		 * Usage:
		 * 
		 * _updater = new AutomaticFonSizeBehavior(textField);
		 * 
		 * // this is enough for input fields, if you set text using code you should call the update function after you have set the text like this:
		 * 
		 * _updater.update();
		 * 
		 */
		public function AutomaticFonSizeBehavior(inTextField:TextField,inStartSize:Number = 40,inMinimalFontSize:uint = 9, willUpdateOnInput = true) 
		{
			_minimalFontSize = inMinimalFontSize;
			_startSize = inStartSize;
			_currentSize = inStartSize;
			_textField = inTextField;
			_prevText = "";
 
			_maxHeight = _textField.height;
 
			_textField.addEventListener(Event.REMOVED_FROM_STAGE,dispose);
 
			if(willUpdateOnInput) addEventListeners();
 
			setFontSize(_startSize);
 
			update();
		}
 
		public function update(event:Event = null):void 
		{
			_textField.scrollV = 0;
 
			if(_prevText.length > _textField.length)
                setFontSize(_startSize);
 
			while (_maxHeight < _textField.textHeight + (4 * _textField.numLines)) 
			{ 
				if(_currentSize <= _minimalFontSize) break;
				setFontSize(_currentSize - 0.5);
			}
 
			if(_currentSize <= _minimalFontSize) 
			{
				_textField.text = _prevText;
			} 
			else 
			{
				_prevText = _textField.text;
			}
		}
 
		private function addEventListeners():void 
		{
			_textField.addEventListener(Event.CHANGE,update);
			_textField.addEventListener(KeyboardEvent.KEY_UP,update);
		}
 
		private function setFontSize(inSize:Number):void 
		{
			_currentSize = inSize;
 
			var currentTextFormat:TextFormat = _textField.getTextFormat();
			currentTextFormat.size = _currentSize;
 
			_textField.setTextFormat(currentTextFormat);
			_textField.defaultTextFormat = currentTextFormat;
		}
 
		/**
		 * Dispose everything
		 */
		private function dispose(event:Event):void 
		{
			_textField.removeEventListener(KeyboardEvent.KEY_UP,update);
			_textField.removeEventListener(Event.CHANGE,update);
			_textField.removeEventListener(Event.REMOVED_FROM_STAGE,dispose);
 
			_textField = null;
		}
	}
}