var interval = 4000;								
var imageNum = 0;

var playing = 0;
playing = "<a href=\"#\" onclick=\"pauseshow()\">Pause slide show</a><br />"; 

var stopped = 0;
stopped = "<a href=\"#\" onclick=\"switchImage(\'slideimg\')\">Play slide show</a><br /><a href=\"#\" onclick=\"prevImage(\'slideimg\'); clearTimeout(timerID)\"> Previous Image</a><br /><a href=\"#\" onclick=\"switchImageOnce(\'slideimg\'); \">Next Image</a><br /> ";

function imageItem(image_location) {
		this.image_item = new Image();
		this.image_item.src = image_location;
}

imageArray = new Array();
for (i=0; i<totalImages; i++)  {
  imageArray[i]=new imageItem(imageDir + (i) + ".jpg");
}

function get_ImageItemLocation(imageObj) {
	return(imageObj.image_item.src)
}

function setImage(place){
	URL = unescape(window.document.location);
	if (URL.indexOf("?") > -1) {   //whether the location contains a "?" or not
		var harvestURL = URL.split("?");  //split at "?";
		imageNum=harvestURL[1]*1;  //need to declare variable type here
		new_image = get_ImageItemLocation(imageArray[imageNum]);
		document.getElementById('imagecaption').innerHTML=(captionArray[imageNum]);
		document.getElementById('slidemenu').innerHTML=(stopped);
		document[place].src = new_image;
		
	}
	else {
		imageNum = -1
		var new_image = getNextImage();
		document[place].src = new_image;
		var recur_call = "switchImage('"+place+"')";
		timerID = setTimeout(recur_call, interval);
		}
}

function pauseshow(){
	clearTimeout(timerID);
	document.getElementById('slidemenu').innerHTML=(stopped);
}
	

function getNextImage() {
			imageNum = (imageNum+1) % totalImages;
			var new_image = get_ImageItemLocation(imageArray[imageNum]);
			document.getElementById('imagecaption').innerHTML=(captionArray[imageNum]);
	return(new_image);
}
		
function getPrevImage() {
	        if (imageNum > 0) {
		imageNum = (imageNum-1) % totalImages;
		}
		else { 
		imageNum = (totalImages-1); 
		}
		var new_image = get_ImageItemLocation(imageArray[imageNum]);
		document.getElementById('imagecaption').innerHTML=captionArray[imageNum];
		return(new_image);
}

function prevImage(place) {
		var new_image = getPrevImage();
		document[place].src = new_image;
}

function switchImage(place) {
		var new_image = getNextImage();
		document[place].src = new_image;
		var recur_call = "switchImage('"+place+"')";
		timerID = setTimeout(recur_call, interval);
		document.getElementById('slidemenu').innerHTML=(playing);
}

function switchImageOnce(place) {
		var new_image = getNextImage();
		document[place].src = new_image;
		var recur_call = "switchImage('"+place+"')";
		timerID = setTimeout(recur_call, interval);
		document.getElementById('slidemenu').innerHTML=(stopped);
		 clearTimeout(timerID);
}