AS2 BitmapData ディゾルブによりホワイトアウト

/* ここから */
/* 
ディゾルブによりホワイトアウトする
http://www.fumiononaka.com/Sample/Flash8/PixelDissolve.html
リンケージPenのビットマップデータをロード
*/
import flash.display.BitmapData;
import flash.geom.Point;
var myBitmapData:BitmapData = BitmapData.loadBitmap("Pen");
var _mc:MovieClip = this.createEmptyMovieClip("mc", this.getNextHighestDepth());
_mc.attachBitmap(myBitmapData, _mc.getNextHighestDepth());
var nRandom:Number;
_mc.onPress = function() {
  nRandom = Math.floor(Math.random()*10);
  this.onEnterFrame = xDissolve;
};
var nTotalDissolved:Number = 0;
var nTotalPixels:Number = myBitmapData.width*myBitmapData.height;
var nDissolving:Number = 30;
var zeroPoint:Point = new Point(0, 0);
function xDissolve() {
  nRandom = myBitmapData.pixelDissolve(myBitmapData, myBitmapData.rectangle, zeroPoint, nRandom, nDissolving, 0x00FFFFFF);
  nTotalDissolved += nDissolving;
  if (nTotalDissolved>=nTotalPixels) {
    delete this.onEnterFrame;
  }
  nDissolving = Math.floor(nDissolving*1.1);
}