function showPic (whichpic) {
  if (!document.getElementById) return true;
	
	// swap displayed image	
	var url = whichpic.href
	document.getElementById('displayedimage').src = url;
	
	// change subnav link to active
	var nav = document.getElementById("nav");
	var links = nav.getElementsByTagName("a");
	for ( var i=0; i < links.length; i++) {
		links[i].className = '';
	}
	whichpic.className = 'current';
		
	// hide text for old image
	var hidedivs = document.getElementById("displaytext").getElementsByTagName("div");
	for ( var i=0; i < hidedivs.length; i++) {
		hidedivs[i].className = "hide";
	}
	
	// show text for new displayed image
	var displayid = url.substring(url.lastIndexOf("_")+1,url.lastIndexOf(".jpg"));
	document.getElementById(displayid).className = "show";
	return false;
	
}

function checkIfImage(url) {
	var v_switch = url.substring(url.length-3,url.length).toLowerCase();
	switch (v_switch) {
	// If the v_switch var equals any of the following...
	case 'gif':
	case 'jpg':
	case 'png':
	case 'bmp':
		// Then yes, it is an image...
		return true;
	default:
		// Otherwise, it's not an image.
		return false;
	}
}

function prepareGallery() {
  if (!document.getElementsByTagName) return false;
  if (!document.getElementById) return false;
  if (!document.getElementById("nav")) return false;
  var gallery = document.getElementById("nav");
  var links = gallery.getElementsByTagName("a");
  for ( var i=0; i < links.length; i++) {
		if (checkIfImage(links[i].href)) {
			links[i].onclick = function() {
				return showPic(this);
			}
		}
  }
}

window.onload=function(){prepareGallery();};