window.addEventListener?window.addEventListener('load',xfade,false):window.attachEvent('onload',xfade);

var d=document, imgs = new Array("img/fondo1.jpg", "img/fondo2.jpg", "img/fondo3.jpg", "img/fondo4.jpg", "img/fondo5.jpg", "img/fondo6.jpg", "img/fondo7.jpg");
var zInterval = 15000, cImageIndex = 0, cOpacity = 1, opacityInc = 0.05, sign = 1;

/*var img0 = new Image(imgs[0]);
var img1 = new Image(imgs[1]);
var img2 = new Image(imgs[2]);
var img3 = new Image(imgs[3]);
*/
function xfade() {

	if(!d.getElementById || !d.createElement)return;
	bg = d.getElementById('background-img');

	if (cOpacity < 0) {
		cOpacity = 0;
		sign = 1;
		cImageIndex = imgs[cImageIndex+1]?cImageIndex+1:0;
		bg.style.backgroundImage = 'url(/wp-content/themes/opera/'+ imgs[cImageIndex] +')';
	}
	if (cOpacity > 1) {
		cOpacity = 1;
		sign = -1;
	}
	
	if (cOpacity == 1) {
		setTimeout(xfade,zInterval);
	} else {
		setTimeout(xfade,50);
	}
	setOpacity(bg, cOpacity); 
	cOpacity += sign*opacityInc;
}

function setOpacity(obj, opacity) { //alert(opacity);
	obj.xOpacity = opacity;
	obj.style.opacity = obj.xOpacity;
	obj.style.MozOpacity = obj.xOpacity;
	obj.style.filter = 'alpha(opacity=' + (obj.xOpacity*100) + ')';
}