// AJAX PRELOAD per immagini e media grandi
    function AJAXPreload() {
        
        var id = '';
        var uri = '';
        var attr = '';
        var clss = '';
        var XMLHttpReqObj = null;    
        
        this.setUri = function(this_uri) {
            uri = this_uri;
        }
        
        this.setElementOnLoad = function(this_id, this_attr) {
            id = this_id;
            attr = this_attr;
        }
        
        this.setClassOnLoad = function(this_class) {
            clss = this_class;
        }
            
        this.initPreload = function() {
            
            if (typeof XMLHttpRequest != "undefined") {
                XMLHttpReqObj = new XMLHttpRequest();
            }
            else {
                try {
                    XMLHttpReqObj = new ActiveXObject("Msxml2.XMLHTTP");
                } catch (e) {
                    try {
                        XMLHttpReqObj = new ActiveXObject("Microsoft.XMLHTTP");
                    } 
                    catch (e) {
                        XMLHttpReqObj = null;
                    }
                }
            }
                
            if (!XMLHttpReqObj) {
                return false;
            }
            else {
                XMLHttpReqObj.open("GET", uri, true);
                
                XMLHttpReqObj.onreadystatechange = function() {
                
                    switch (XMLHttpReqObj.readyState) {
                    case 0: // Uninitialized
                    case 1: // Loading
                    case 2: // Loaded
                    case 3: // Ready
                        break;
                    case 4:
                            
                        switch(XMLHttpReqObj.status) {
                            
                            case 200:
                            case 304:
                                
                                document.getElementById(id).setAttribute(attr, uri); 

                                
                                if (!(clss == '')) {
                                    document.getElementById(id).className = clss;
                                }
                                
                                break;
                                
                            case 0: // wrong protocol
                                
                            default:
                                // Catch exception for IE
                        }
                        
                        break;
                    }
                    
                } // function onreadystatechange   
                
                XMLHttpReqObj.send(null);
                delete XMLHttpReqObj;
            }
        }        
    }
 
 
     function attivaPreload(nomeId, classeLoaded, indirizzo) {
        objpreload1 = new AJAXPreload();
        objpreload1.setElementOnLoad(nomeId, 'src');
        objpreload1.setClassOnLoad(classeLoaded);
        objpreload1.setUri(indirizzo);
        objpreload1.initPreload();    
    }
 // FINE AJAX PRELOAD
 
 
 // preload semplice per immagini
 function preload() {
  if (!document.images) return;
  var wl = new Array();
  var arguments = preload.arguments;
  for (var i = 0; i < arguments.length; i++) {
    wl[i] = new Image();
    wl[i].src = arguments[i];
  }
}
 // fine preload semplice per immagini