function ImagePreloader(images, call_back)
{
   // store the call_back
   this.call_back = call_back;

   // initialize internal state.
   this.nLoaded = 0;
   this.nProcessed = 0;
   this.aImages = new Array;

   // record the number of images.
   this.nImages = images.length;

   // for each image, call preload()
   for ( var i = 0; i < images.length; i++ )
      this.preload(images[i]);
}

ImagePreloader.prototype.preload = function(image)
{
   // create new Image object and add to array
   var oImage = new Image;
   this.aImages.push(oImage);

   // set up event handlers for the Image object
   oImage.onload = ImagePreloader.prototype.onload;
   oImage.onerror = ImagePreloader.prototype.onerror;
   oImage.onabort = ImagePreloader.prototype.onabort;

   // assign pointer back to this.
   oImage.oImagePreloader = this;
   oImage.bLoaded = false;

   // assign the .src property of the Image object
   oImage.src = image;
}

ImagePreloader.prototype.onComplete = function()
{
   this.nProcessed++;
   if ( this.nProcessed == this.nImages )
   {
      this.call_back(this.aImages, this.nLoaded);
   }
}

ImagePreloader.prototype.onload = function()
{
   this.bLoaded = true;
   this.oImagePreloader.nLoaded++;
   this.oImagePreloader.onComplete();
}

ImagePreloader.prototype.onerror = function()
{
   this.bError = true;
   this.oImagePreloader.onComplete();
}

ImagePreloader.prototype.onabort = function()
{
   this.bAbort = true;
   this.oImagePreloader.onComplete();
}