// define the 'getElementById' method for use in older browsers
if (!document.getElementById) {
	if (document.all) {
		document.getElementById = function() {
			if (typeof document.all[arguments[0]]!="undefined") {
				return document.all[arguments[0]];
			} else {
				return null;
			}
		}
	} else if (document.layers) {
		document.getElementById = function() {
			if (typeof document[arguments[0]]!="undefined") {
				return document[arguments[0]];
			} else {
				return null;
			}
		}
	}
}

// define images
images = new Array(10);
images[0] = "<img src='img/header-img-1.jpg' alt='header 1' width='641' height='157'/>";
images[1] = "<img src='img/header-img-2.jpg' alt='header 2' width='641' height='157'/>";
images[2] = "<img src='img/header-img-3.jpg' alt='header 3' width='641' height='157' />";
images[3] = "<img src='img/header-img-4.jpg' alt='header 4' width='641' height='157' />";
images[4] = "<img src='img/header-img-5.jpg' alt='header 5' width='641' height='157' />";
images[5] = "<img src='img/header-img-6.jpg' alt='header 6' width='641' height='157' />";
images[6] = "<img src='img/header-img-7.jpg' alt='header 7' width='641' height='157' />";
images[7] = "<img src='img/header-img-8.jpg' alt='header 8' width='641' height='157' />";
images[8] = "<img src='img/header-img-9.jpg' alt='header 9' width='641' height='157' />";
images[9] = "<img src='img/header-img-10.jpg' alt='header 10' width='641' height='157' />";

// Fade image in and out
fadeStep = 5;
fadeDir = 1;
function fader() {
	if (fadeStep <= 0) { 
		document.getElementById("headerImg").innerHTML = images[index];
		fadeStep = 5;
		fadeDir = 1;
	}
	if (fadeDir == 1 && fadeStep<=100) {
		imageObject = document.getElementById("headerImg");		
		opacValue = fadeStep;
		imageObject.style.opacity = opacValue/100;
		imageObject.style.filter = 'alpha(opacity=' + opacValue + ')';
		fadeStep+=5;
	}
	if (fadeDir == -1 && fadeStep>0) {
		imageObject = document.getElementById("headerImg");		
		opacValue = fadeStep;
		imageObject.style.opacity = opacValue/100;
		imageObject.style.filter = 'alpha(opacity=' + opacValue + ')';
		fadeStep-=5;
	}
}

// rotate message every 10 seconds
function nextMessage() {
	index ++;
	if (index>=images.length) {
		index = 0;
	}
	fadeDir = -1;	
}

// select random starting image
window.onload = function() {
    index = Math.floor(Math.random() * images.length);
    document.getElementById("headerImg").innerHTML = images[index];
    document.getElementById("headerImg").style.opacity = 0;
	document.getElementById("headerImg").style.filter = 'alpha(opacity=0)';
    setInterval ("nextMessage()", 6000);
    setInterval("fader()", 50);
}