var imageArray = new Array();

function setUpAndStartSlideshow(imageHolderID, imageBaseName, numImages) {
  for (i = 0; i < numImages; i++) {
    imageArray[i] = new Image();
    imageArray[i].src = "images/" + imageBaseName + (i + 1) + ".jpg";
  }
  setTimeout("swapPictures(1, '" + imageHolderID + "')", 5000);
}

/**
 * int currentImage --> index of current image.
 * Will be '1' the first time this is called.
 * string imageHolderID --> ID of img element on page where the slideshow takes
 * place.
 */
function swapPictures(currentImage, imageHolderID) {
  if (currentImage >= imageArray.length) {
    currentImage = 0;
  }
  if (imageArray[currentImage] && imageArray[currentImage].complete) {
    var target = 0;
    if (document.images.imageHolderID) {
      target = document.images.imageHolderID;
    }
    if (document.getElementById(imageHolderID)) {
      target = document.getElementById(imageHolderID);
    }
    if (target) {
      target.src = imageArray[currentImage].src;
      var nextImage = currentImage + 1;
      functionCall = "swapPictures(" + nextImage + ", '" + imageHolderID + "')";
      setTimeout(functionCall, 5000)
    }
  } else {
    setTimeout("swapPictures(" + currentImage + ", '" + imageHolderID + "')",
               500)
  }
}