var curr = 1;
var tick = 0;
var last = 3;
var slidetick= 1000;
var slidetime = 5 ;
var fadetime = 50;

var unpause = true;
var elapsed = 0;
var clock;

function fadeOn(element,process){	
	process++;
	element.style.opacity = process*0.1;
	element.style.filter= "alpha(opacity="+(process*10)+")";
	if (process<10){
		setTimeout(function(){fadeOn(element,process)},fadetime);
	}
}

function on(element){
	element.style.display="block";
	element.style.opacity = 0;
	element.style.filter= "alpha(opacity=0)";
	setTimeout(function(){fadeOn(element,0)},fadetime);
}

function fadeOff(element,process){	
	process--;
	element.style.opacity = process*0.1;
	element.style.filter= "alpha(opacity="+(process*10)+")";
	if (process>0){
		setTimeout(function(){fadeOff(element,process)},fadetime);
	}
	else
	{
	element.style.display="none";
	}
}
function off(element){
	element.style.opacity = 1;
	element.style.filter= "alpha(opacity=100)";
	setTimeout(function(){fadeOff(element,10)},fadetime);
}

function backward (){
	off(document.getElementById("slide"+curr));
	if(curr==1) {
		curr=last;
	}
	else {
		curr--;
	}
	on(document.getElementById("slide"+curr));
}

function forward (){
	off(document.getElementById("slide"+curr));
	if(curr==last) {
		curr=1;
	}
	else {
		curr++;
	}
	on(document.getElementById("slide"+curr));
}

function playing(){
	if (unpause){
		if (elapsed<slidetime){
			elapsed++;
		}
		else {
			elapsed=0;
			forward();
		}
		clock = setTimeout("playing()",slidetick);
	}
}

function stopInit(){
	document.getElementById("stop").onclick = function() {
		unpause = false;
		clearTimeout(clock);
		elapsed = 0;
	};
}

function playInit(){
	document.getElementById("play").onclick = function(){
		if (!unpause){
			unpause = true;
			clock = setTimeout("playing()",slidetick);
			elapsed = 0;
		}
	};
}

function foreInit(){
	document.getElementById("fore").onclick = function() {
		elapsed = 0;
		forward();
	};
	
}

function backInit(){
	document.getElementById("back").onclick = function() {
		elapsed = 0;
		backward();
	};
}

function slideshow() {
	foreInit();
	backInit();
	stopInit();
	playInit();
	clock = setTimeout("playing()",slidetick);
}