// object definition for piece
function piece(name, src, medium, dimensions, year)
{ 
	this.name = name;
	this.src = src;
	this.medium = medium;
	this.dimensions = dimensions;
	this.year = year;
} 

// add an item to a collection
function addItem(collection, newitem)
{
	collection[collection.length] = newitem;
}

// define constants
var img_blank = new Image();
img_blank.src = "images/blank.gif";

// initialize counter
var currItem = getParameter("itemid");
if (currItem == null)
	currItem = 0;

function getPageItem(itemid)
{
	if (document.all)
		return document.all[itemid];
	else
		return document.getElementById(itemid);
}

function update()
{
	if (!document.all)
	{
		location.href = location.pathname + "?itemid=" + currItem;
	}
	else
	{
		var fields = new Array("name", "medium", "dimensions", "year");
		for (var i = 0; i < fields.length; i++)
		{
			getPageItem("item_" + fields[i]).innerHTML = currColl[currItem][fields[i]];
		}
		getPageItem("item_num").innerHTML = eval(currItem) + 1;
		getPageItem("item_img").src = img_blank.src;
		getPageItem("item_img").src = "images/items/" + currColl[currItem]["src"];
	}
}

function next()
{
	if (currItem < currColl.length - 1)
		currItem++;
	else
		currItem = 0;

	update();
}

function prev()
{
	if (currItem > 0)
		currItem--;
	else
		currItem = currColl.length - 1;

	update();
}