Prompt TextInput with ignore text

There are cases in which we need more than text input, which should let the user to notify with some custom text  in text input whenever it is empty. i.e. prompt text input. But there are special cases in which we should even treat some text as empty and should show the prompt text in text input. I went through this need when my client asked me to show a prompt text in text input whenever it is zero. We could restrict zero in text input by using conditional expression in text property, provided we must ensure wherever we are setting the text input.

So i have decided to extend the text input component so that i could restrict zero in one place called set text(value : String) method. when i wanted to implement, i needed prompt text input and i asked myself why should not i do that too. I went ahead did at last.

You can find the implemented component code below which allows you to set ignore text (the text you want to treat as empty text) and you can also enable/disable the prompt text input. If it is disabled, it would function as normal text input.

Click here to download sample application

package
{
	import flash.display.DisplayObject;
	import flash.events.Event;
	import flash.events.FocusEvent;

	import mx.controls.TextInput;
	import mx.utils.StringUtil;
	[Style(name="promptStyleName", type="String")]
	public class PromptIgnoreTextInput extends TextInput
	{
		[Bindable] private var textEmpty : Boolean;
		public function PromptIgnoreTextInput()
		{
			super();
			this.addEventListener(FocusEvent.FOCUS_IN, handleFocusIn);
			this.addEventListener(FocusEvent.FOCUS_OUT, handleFocusOut);
			this.addEventListener(Event.CHANGE, handleChange);
		}
		[Bindable] private var _prompt : String;
		public function set prompt(value : String):void
		{
			_prompt = value;
		}
		public function get prompt():String
		{
			return _prompt;
		}
		[Bindable] private var _ignoreText : String;
		public function set ignoreText(value : String):void
		{
			_ignoreText = value;
		}
		public function get ignoreText():String
		{
			return _ignoreText;
		}
		[Bindable] private var _enablePrompt : Boolean;
		public function set enablePrompt(value : Boolean):void
		{
			_enablePrompt = value;
		}
		public function get enablePrompt():Boolean
		{
			return _enablePrompt;
		}
		override public function set text(value:String):void
		{
			value = StringUtil.trim(value);
			if(value != null && value != "")
			{
				if(value == ignoreText)
				{
					textEmpty = true;
				}
				else
				{
					textEmpty = false;
				}
			}
			else
			{
				textEmpty = true;
			}

			super.text = value;
			invalidateDisplayList();
		}
		override public function get text():String
		{
			return super.text;
		}
		override protected function updateDisplayList(unscaledWidth:Number,
		unscaledHeight:Number):void
		{
			if(_enablePrompt)
			{
				if(textEmpty && !isCurrentlyFocussed())
				{
					super.text = prompt;
					this.styleName = getStyle("promptStyleName");
				}
				else if(textEmpty && isCurrentlyFocussed())
				{
					super.text = "";
					this.styleName = "";
				}
				else
				{
					this.styleName = "";
				}
			}
			super.updateDisplayList(unscaledWidth, unscaledHeight);
		}
		protected function isCurrentlyFocussed():Boolean
		{
			var focussedComponent : DisplayObject;
			focussedComponent = focusManager.getFocus() as DisplayObject;
			if(focussedComponent)
			{
				if(focussedComponent == this || this.contains(focussedComponent))
					return true;
			}
			return false;
		}
		protected function handleFocusIn(event : FocusEvent):void
		{
			invalidateDisplayList();
		}
		protected function handleFocusOut(event : FocusEvent):void
		{
			text = super.text;
			invalidateDisplayList();
		}
		protected function handleChange(event : Event):void
		{
			textEmpty = (super.text.length == 0 || super.text == _ignoreText) ?
			            true : false;
		}

	}
}

Please let me know if you find any problem or have any suggestion about this component so that i could refine this code when i find time. Thank you for reading this post.