var pic = new Array();

pic[0] = '../images/header01.jpg';
pic[1] = '../images/header02.jpg';
pic[2] = '../images/header03.jpg';
pic[3] = '../images/header04.jpg';
pic[4] = '../images/header05.jpg';
pic[5] = '../images/header06.jpg';
pic[6] = '../images/header07.jpg';
pic[7] = '../images/header08.jpg';
pic[8] = '../images/header09.jpg';

// totaal aantal foto's
var totaal = 9;
// random start
var start = randomnumber=Math.floor(Math.random()*totaal);

// alle foto's preloaden
var preLoad = new Array();
for (i = 0; i < totaal; i++) {
	preLoad[i] = new Image();
	preLoad[i].src = pic[i];
}

// aangeven dat dit de eerste keer is dat de loop begint
var eerste_keer = 1;

function wissel(x) {
	t =  start-1;
	
	if (t == -1) {
		t = totaal - 1;
	}
	
	document.getElementById('ani_foto2').style.backgroundImage = "url("+pic[t]+")";
	document.getElementById('ani_foto2').style.opacity = 1.0;
	document.getElementById('ani_foto2').style.filter = 'alpha(opacity=100)';

	document.getElementById('ani_foto1').style.backgroundImage = "url("+pic[start]+")";

	if (eerste_keer == 1) {
		setTimeout("fade('ani_foto2', 100, 0, 1000)", 1000);
		eerste_keer = 0;
	}
	else {
		fade('ani_foto2', 100, 0, 1000);
	}

	start = start + 1;

	if (start > totaal-1) {
		start = 0;
	}

	setTimeout("wissel(start)", 3000);
}

function fade(eID, startOpacity, stopOpacity, duration) {
	var speed = Math.round(duration / 100);
	var timer = 0;
	if (startOpacity < stopOpacity){
		for (var i=startOpacity; i<=stopOpacity; i++) {
			setTimeout("setOpacity('"+eID+"',"+i+")", timer * speed);
			timer++;
		} return;
	}
	for (var i=startOpacity; i>=stopOpacity; i--) {
		setTimeout("setOpacity('"+eID+"',"+i+")", timer * speed);
		timer++;
	}
}

function setOpacity(eID, opacityLevel) {
	var eStyle = document.getElementById(eID).style;
	eStyle.opacity = opacityLevel / 100;
	eStyle.filter = 'alpha(opacity='+opacityLevel+')';
}