var interval = 3500;
var random_display = 1;
var imageDir = "images/";

var imageNum = 0;
imageArray = new Array(); 
imageArray[imageNum++] = new imageItem(imageDir + "small_units(01).jpg");
imageArray[imageNum++] = new imageItem(imageDir + "small_units(02).jpg");
imageArray[imageNum++] = new imageItem(imageDir + "small_units(03).jpg");
imageArray[imageNum++] = new imageItem(imageDir + "small_units(04).jpg");
imageArray[imageNum++] = new imageItem(imageDir + "small_units(05).jpg");
imageArray[imageNum++] = new imageItem(imageDir + "small_units(06).jpg");
imageArray[imageNum++] = new imageItem(imageDir + "small_units(07).jpg");
var totalImages = imageArray.length;

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

function randNum(x, y) {  
    var range = y - x + 1;  
    return Math.floor(Math.random() * range) + x;  
} 

function getNextImage() {  
imageNum = (imageNum+1) % totalImages;  

var new_image = get_ImageItemLocation(imageArray[imageNum]);  
return(new_image);  
} 

function getSwitchImage() {  
    if (random_display) {  
        imageNum = randNum(0, totalImages-1);  
    }  
    else {  
        imageNum = (imageNum+1) % totalImages;  
    } 

var new_image = get_ImageItemLocation(imageArray[imageNum]);  
return(new_image);  
} 

function getPrevImage() {
	if(imageNum-1 < 0)
		{
			imageNum = totalImages-1;
		}
	else {
		imageNum = (imageNum-1) % totalImages;
		}

var new_image = get_ImageItemLocation(imageArray[imageNum]);
return(new_image);
} 


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

function switchImage02(place) {  
    var new_image = getSwitchImage();  
    document[place].src = new_image;  
    var recur_call = "switchImage02('"+place+"')";  
    timerID = setTimeout(recur_call, interval);  
} 

function nextImage(place) {  
    var new_image = getNextImage();  
    document[place].src = new_image;  
}