as3 文本竖排效果实现

import flash.text.engine.TextBlock;
import flash.text.engine.ElementFormat;
import flash.text.engine.ContentElement;
import flash.text.engine.TextElement;

var linePosition:Number = this.stage.stageWidth - 45;
var tb:TextBlock=new TextBlock();
var shijingText:String = "葛之覃兮，施于中谷，维叶萋萋。黄鸟于飞，集于灌木，其鸣喈喈。葛之覃兮，施于中谷，维叶莫莫。是刈是濩，为絺为绤，服之无斁。言告师氏，言告言归。薄污我私，薄浣我衣。害浣害否，归宁父母。";

var format:ElementFormat = new ElementFormat();
format.fontSize = 12;
format.color = 0xCC0000;
format.textRotation = TextRotation.AUTO;

tb.lineRotation = TextRotation.ROTATE_90;
tb.baselineZero = TextBaseline.IDEOGRAPHIC_CENTER;

tb.content = new TextElement(shijingText,format);

var previousLine:TextLine = null;
while (true)
{
	var textLine:TextLine = tb.createTextLine(previousLine,180);
	if (textLine == null)
	{
		break;
	}

	textLine.y = 20;
	textLine.x = linePosition;
	linePosition -=  25;
	addChild(textLine);
	previousLine = textLine;
}