var imagesOn = new Array();
var imagesOff = new Array();

function preload(on,off) {
  var suffixOn = "-hi"
  if (on != null && on != "") {
    suffixOn = on;
  }
  var suffixOff = ""
  if (off != null && off != "") {
    suffixOff = off;
  }
  var ext = ".gif"

  if (document.images) {
    var n = 0;
    for (var i = 0; i < document.images.length; i++) {
      if (document.images[i].name) {
	var thisImg = document.images[i];
	var name = thisImg.name;
	var path = imgName = thisImg.src;
	path = path.substring(0,path.lastIndexOf('/')+1);
	imgName = imgName.substring(imgName.lastIndexOf('/')+1, imgName.lastIndexOf('.'));
	//alert(name+"\n"+path+"\n"+imgName);

	if (name == imgName || name.indexOf('nav2') != -1) {
	  imagesOn[name] = new Image();
	  imagesOn[name].src = path+name+suffixOn+ext;

	  imagesOff[name] = new Image();
	  imagesOff[name].src = path+name+suffixOff+ext;
	}
      }
    }
  }
  doneLoading = true;
}

function on(imgName) {
  if (!doneLoading) return false;
  swap(imgName, imagesOn[imgName].src);
  return true;
}

function off(imgName) {
  if (!doneLoading) return false;
  swap(imgName, imagesOff[imgName].src);
  return true;
}

function swap(imgName, imgSrc) {
  if (document.images && doneLoading) {
    //alert(name+"\n"+document.images[name].src);
    document.images[imgName].src = imgSrc;
  }
}

onload = function() { preload(); };