base on the bit101's TextArea Component

base on the bit101s TextArea Component

package {

import flash.display.MovieClip;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.text.TextField;
import flash.display.Stage;

public class TextScroll {
	
	private var txt:TextField;
	private var thumb:MovieClip;
	private var dragBar:MovieClip;
	private var group:MovieClip;
	
	/**
	 * TODO
	 * base on the bit101's TextArea Component
	 * 
	 * @param	t 
	 * @param	g contain a dragThumb and a dragBarBackGround
	 * 
	 * @example
	 * new TextScroll(txt, scrollGroup);
	 */
	public function TextScroll(t:TextField, g:MovieClip):void {
		this.txt = t;
		this.group = g;
		this.thumb = this.group.getChildByName("scrollThumb") as MovieClip; //the dragThumb
		this.dragBar = this.group.getChildByName("scrollBar") as MovieClip; //the scrollBar 
		this.txt.background = true;
		this.txt.backgroundColor = 0xFFFFFF;
		addTxtChange(this.txt);
		attachThumbBar(this.txt, this.group);
		thumbSizeUpdate(this.txt);
		this.thumb.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);	
	}
	
	private var downMouseY:Number = 0;
	
	private function mouseDownHandler(evt:MouseEvent):void{
		var yRatio:Number = thumb.transform.matrix.d;
		downMouseY = thumb.mouseY * yRatio;
		thumb.stage.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);
		thumb.stage.addEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
	}
	
	private  function mouseUpHandler(evt:MouseEvent):void{
		thumb.stage.removeEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);
		thumb.stage.removeEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
	}

	private  function mouseMoveHandler(evt:MouseEvent):void{
		var yRatio:Number = this.dragBar.transform.matrix.d;
		var r:Number = this.dragBar.mouseY * yRatio - downMouseY;
		thumb.y = Math.max(0, Math.min(r, this.dragBar.height - thumb.height));
		var dr:Number = thumb.y / (this.dragBar.height - thumb.height);
		txt.scrollV = Math.round(dr * (txt.maxScrollV - 1) + 1);
	}
	
	private function attachThumbBar(t:TextField, thumbBarGroup:MovieClip):void{
		thumbBarGroup.x = t.x + t.width;
		thumbBarGroup.y = t.y;
		this.dragBar.height = t.height;
	}
	
	private function thumbSizeUpdate(t:TextField):void{
		var max:int = t.numLines;
		var maxSv:int = t.maxScrollV;
		var ratio:Number = (max - maxSv + 1) / max;
		thumb.height = this.dragBar.height * ratio;
		if(txt.scrollV > txt.maxScrollV){
			txt.scrollV = txt.maxScrollV;
		}
		if (txt.scrollV < 1) {
			txt.scrollV = 1;
		}
		thumb.y = ((txt.scrollV - 1) / (txt.maxScrollV - 1)) * (this.dragBar.height - thumb.height);
	}

	private function addTxtChange(t:TextField):void{
		t.addEventListener(Event.CHANGE, function(evt:Event):void{
			thumbSizeUpdate(t);
		});
		/*
		t.addEventListener(Event.SCROLL, function(evt:Event):void{
			//thumbSizeUpdate(t);
			//evt.preventDefault();// unable prevent textField's scroll
		});
		/*/
		t.addEventListener(MouseEvent.MOUSE_WHEEL, function(evt:MouseEvent):void {
			t.scrollV -= evt.delta; //important
			thumbSizeUpdate(t);
		});
		//*/
	}
}	
}

TextScroll.as

package {

import flash.display.MovieClip;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.text.TextField;
import flash.display.Stage;

public class TextScroll {
	
	private var txt:TextField;
	private var thumb:MovieClip;
	private var dragBar:MovieClip;
	private var group:MovieClip;
	
	/**
	 * TODO
	 * base on the bit101's TextArea Component
	 * 
	 * @param	t 
	 * @param	g contain a dragThumb and a dragBarBackGround
	 * 
	 * @example
	 * new TextScroll(txt, scrollGroup);
	 */
	public function TextScroll(t:TextField, g:MovieClip):void {
		this.txt = t;
		this.group = g;
		this.thumb = this.group.getChildByName("scrollThumb") as MovieClip; //the dragThumb
		this.dragBar = this.group.getChildByName("scrollBar") as MovieClip; //the scrollBar 
		this.txt.background = true;
		this.txt.backgroundColor = 0xFFFFFF;
		addTxtChange(this.txt);
		attachThumbBar(this.txt, this.group);
		thumbSizeUpdate(this.txt);
		this.thumb.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);	
	}
	
	private var downMouseY:Number = 0;
	
	private function mouseDownHandler(evt:MouseEvent):void{
		var yRatio:Number = thumb.transform.matrix.d;
		downMouseY = thumb.mouseY * yRatio;
		thumb.stage.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);
		thumb.stage.addEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
	}
	
	private  function mouseUpHandler(evt:MouseEvent):void{
		thumb.stage.removeEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);
		thumb.stage.removeEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
	}

	private  function mouseMoveHandler(evt:MouseEvent):void{
		var yRatio:Number = this.dragBar.transform.matrix.d;
		var r:Number = this.dragBar.mouseY * yRatio - downMouseY;
		thumb.y = Math.max(0, Math.min(r, this.dragBar.height - thumb.height));
		var dr:Number = thumb.y / (this.dragBar.height - thumb.height);
		txt.scrollV = Math.round(dr * (txt.maxScrollV - 1) + 1);
	}
	
	private function attachThumbBar(t:TextField, thumbBarGroup:MovieClip):void{
		thumbBarGroup.x = t.x + t.width;
		thumbBarGroup.y = t.y;
		this.dragBar.height = t.height;
	}
	
	private function thumbSizeUpdate(t:TextField):void{
		var max:int = t.numLines;
		var maxSv:int = t.maxScrollV;
		var ratio:Number = (max - maxSv + 1) / max;
		thumb.height = this.dragBar.height * ratio;
		if(txt.scrollV > txt.maxScrollV){
			txt.scrollV = txt.maxScrollV;
		}
		if (txt.scrollV < 1) {
			txt.scrollV = 1;
		}
		thumb.y = ((txt.scrollV - 1) / (txt.maxScrollV - 1)) * (this.dragBar.height - thumb.height);
	}

	private function addTxtChange(t:TextField):void{
		t.addEventListener(Event.CHANGE, function(evt:Event):void{
			thumbSizeUpdate(t);
		});
		t.addEventListener(Event.SCROLL, function(evt:Event):void{
			thumbSizeUpdate(t);
		});
	}
}	
}