var interval = 4000;

var random_display = 0;

var imageDir = "graphart/";

var imageNum = 0;

imageArray = new Array();
imageArray[imageNum++] = new imageItem(imageDir + "image1.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image2.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image3.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image4.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image5.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image6.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image7.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image8.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image9.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image10.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image11.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image12.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image13.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image14.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image15.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image16.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image17.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image18.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image19.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image20.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image21.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image22.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image23.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image24.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image25.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image26.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image27.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image28.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image29.jpg");
imageArray[imageNum++] = new imageItem(imageDir + "image30.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() {
	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() {
	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 switchImage(place) {
	var new_image = getNextImage();
	document[place].src = new_image;
	var recur_call = "switchImage('"+place+"')";
	timerID = setTimeout(recur_call, interval);
}