flash文本竖排效果实现as3代码

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，为为，服之无。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;
}