var totimages = 0;
var currimage = 0;
var previmage = 0;

function countProducts() {
    images = document.getElementsByTagName('img');
    for (i=0; i<images.length; i++) {
        if ((images[i].className == 'foto_prodotto') || (images[i].getAttribute('class') == 'foto_prodotto')) {
            totimages++;
        }
    }
   
    currimage = 1;
    previmage = totimages;
}

function previmg() {
    previmage = currimage;
    currimage = (currimage == 1)? totimages : --currimage;        
    show_foto(previmage, currimage);
}

function nextimg() {
    previmage = currimage;
    currimage = (currimage == totimages)? 1 : ++currimage;
    show_foto(previmage, currimage);
}

function show_foto(p, c) {
    document.getElementById('prod' + p).style.display = 'none';
    document.getElementById('prod' + c).style.display = 'block';
}


function openzoom(w, h) {
   window.open('zoom.html?idprod='+ currimage, '', 'left=100,top=100,width=' + w +',height='+ h +',resizable=no,scrollbars=no,location=no,toolbar=no');
}

function openpopup(page, h, w) {
   // Apre popup centrato nello schermo
   h = (h || 580);
   w = (w || 626);
   var l = Math.floor((screen.width-w)/2);
   var t = Math.floor((screen.height-h)/2);
   window.open(page,"","width=" + w + ",height=" + h + ",top=" + t + ",left=" + l);
}