AS3.0实现图像的扭曲

import flash.display.Sprite;
import flash.display.Loader;
import flash.net.URLRequest;
import flash.events.Event;
import flash.display.Bitmap;
import flash.display.BitmapData;

var pixelsArr : Array;
var loader : Loader;
var url : String;
var bitMap : Bitmap;
var outPut : Bitmap;
var outPutData : BitmapData;

init("imag.jpg");

function draw(source:BitmapData, w:Number, h:Number, topLen:Number ):BitmapData 
{
    outPutData=new BitmapData(1024,768,true, 0x000000);
    var tanA : Number=(h - topLen) / w;
    var tmpHeight:Number;
    for (var i:uint=0; i < w; i++)
    {
        tmpHeight = topLen + i*tanA;
        for (var k:uint=0; k < tmpHeight; k++)
        {
            outPutData.setPixel32(i, k + (h - tmpHeight) / 2, source.getPixel32(i*(source.width/w), k*(source.height / tmpHeight)));
        }
    }
    return outPutData;
}

function init(strURL:String):void
{
    loader = new Loader();
    loader.contentLoaderInfo.addEventListener(Event.COMPLETE, onPicLoaded);
    loader.load(new URLRequest(strURL));
    
}

function onPicLoaded(evt : Event):void 
{
    addChild(loader);
    loader.x = 10
    loader.y = 10
    loader.width=300;
    loader.height=200;
    
    pixelsArr = new Array();
    var $loader : Loader = Loader(evt.target.loader);
    bitMap = Bitmap($loader.content);
    var $bitmapData: BitmapData = bitMap.bitmapData;
    outPut = new Bitmap(draw($bitmapData, 200, 500, 160));
    outPut.y = 100;
    outPut.x = 310
    addChild(outPut);
}