flex 数字上标

以A的3次方为例，我们输入以下代码：

/**
* 部分代码参考Adobe文档:
* http://help.adobe.com/zh_CN/AS3LCR/Flash_10.0/flash/text/engine/package-detail.html
* by kingnare.com
*/

package
{
    import __AS3__.vec.Vector;

    import flash.display.Sprite;
    import flash.text.engine.ContentElement;
    import flash.text.engine.ElementFormat;
    import flash.text.engine.FontDescription;
    import flash.text.engine.FontWeight;
    import flash.text.engine.GroupElement;
    import flash.text.engine.TextBaseline;
    import flash.text.engine.TextBlock;
    import flash.text.engine.TextElement;
    import flash.text.engine.TextLine;

    [SWF(width="800", height="600", backgroundColor="#FFFFFF", framerate="24")]

    public class TextEngineTest_TextBaseline extends Sprite
    {
        public function TextEngineTest_TextBaseline()
        {
            //字体属性
            var fd1:FontDescription = new FontDescription("Arial");
            //格式设置
            var ef1:ElementFormat = new ElementFormat(fd1, 16);

            var fd2:FontDescription = new FontDescription("Arial");
            var ef2:ElementFormat = new ElementFormat(fd2, 10);
            //将基线上移8个像素
            ef2.baselineShift = -8;

            //创建已设置格式的文本的字符串
            var te1:TextElement = new TextElement("A",ef1);
            var te2:TextElement = new TextElement("3",ef2);

            var groupVector:Vector.<ContentElement> = new Vector.<ContentElement>();
            groupVector.push(te1, te2);
            //组成ContentElement集合
            var groupElement = new GroupElement(groupVector);
            //创建文本块
            var textBlock:TextBlock = new TextBlock();
            textBlock.content = groupElement;
            //显示文本
            createTextLines(textBlock);
        }

        //显示文本
        private function createTextLines(textBlock:TextBlock):void
        {
            var yPos = 20;
            var line_length:Number = 450;
            var textLine:TextLine = textBlock.createTextLine(null,line_length);
            while (textLine)
            {
                addChild(textLine);
                textLine.x = 15;
                yPos += textLine.height + 8;
                textLine.y=yPos;
                textLine=textBlock.createTextLine(textLine,line_length);
            }
        }
    }
}