var NumberOfSets = sets.length;
var a = NumberOfSets-1;
var ThisSetNumber = "";
var ThisSet = "";
var b = "";
var c = "";
var d = "";
var e = "";
var f = "";

function enlarge(foo) {
	var url = document.getElementById(foo).src;
	var txt = document.getElementById(foo).alt;
	var desc = document.getElementById(foo).title;
	var code="";
	
	url = url.replace(/_tn/g,'');
	var code = "<img src=\"" + url + "\" alt=\"" + txt + "\"><p>" + desc + "</p>";
	document.getElementById('viewer').innerHTML = code;
}

function setup() {
	document.getElementById('pos').innerHTML = "Set 1 of " + NumberOfSets;
}

function goBack(bar){
	ThisSet = bar;
	for (var ii = 0; ii <= a; ii++){
		if (sets[ii]==ThisSet){
			ThisSetNumber=ii;
		}
	}
	if (ThisSetNumber<=0){
		alert("You are viewing the first available set of pictures now.");
	} else {
		b=sets[ThisSetNumber];
		c=shifts[ThisSetNumber];
		d=sets[ThisSetNumber-1];
		e=shifts[ThisSetNumber-1];
		f = "Set " + parseFloat(ThisSetNumber) + " of " + NumberOfSets;
		document.getElementById('pos').innerHTML = f
		document.getElementById(b).style.display = "none";
		document.getElementById(c).style.display = "none";
		document.getElementById(d).style.display = "block";
		document.getElementById(e).style.display = "block";
	}
}

function goForward(bar){
	ThisSet = bar;
	for (var ii = 0; ii <= a; ii++){
		if (sets[ii]==ThisSet){
			ThisSetNumber=ii;
		}
	}
	if (ThisSetNumber+1>a){
		alert("There are no more pictures available. Please select a previous set.");
	} else {
		b = sets[ThisSetNumber];
		c = shifts[ThisSetNumber];
		d = sets[ThisSetNumber+1];
		e = shifts[ThisSetNumber+1];
		f = "Set " + (parseFloat(ThisSetNumber)+2) + " of " + NumberOfSets;
		document.getElementById('pos').innerHTML = f
		document.getElementById(b).style.display = "none";
		document.getElementById(c).style.display = "none";
		document.getElementById(d).style.display = "block";
		document.getElementById(e).style.display = "block";
	}
}