// Configuration
    //

    // inserta las URL de la imagenes a utilizar
    var loadingImage = 'http://img231.imageshack.us/img231/7171/loadings.gif';      
    var closeButton = 'http://img13.imageshack.us/img13/4240/closel.gif';      


    //
    // getPageScroll()
    // Returns array with x,y page scroll values.
    //
    function getPageScroll(){

       var yScroll;

       if (self.pageYOffset) {
          yScroll = self.pageYOffset;
       } else if (document.documentElement && document.documentElement.scrollTop){    // Explorer 6 Strict
          yScroll = document.documentElement.scrollTop;
       } else if (document.body) {// all other Explorers
          yScroll = document.body.scrollTop;
       }

       arrayPageScroll = new Array('',yScroll)
       return arrayPageScroll;
    }

    //
    // getPageSize()
    // Returns array with page width, height and window width, height
    // Edit for Firefox by pHaez
    //
    function getPageSize(){
       
       var xScroll, yScroll;
       
       if (window.innerHeight && window.scrollMaxY) {   
          xScroll = document.body.scrollWidth;
          yScroll = window.innerHeight + window.scrollMaxY;
       } else if (document.body.scrollHeight > document.body.offsetHeight){ // all but Explorer Mac
          xScroll = document.body.scrollWidth;
          yScroll = document.body.scrollHeight;
       } else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
          xScroll = document.body.offsetWidth;
          yScroll = document.body.offsetHeight;
       }
       
       var windowWidth, windowHeight;
       if (self.innerHeight) {   // all except Explorer
          windowWidth = self.innerWidth;
          windowHeight = self.innerHeight;
       } else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
          windowWidth = document.documentElement.clientWidth;
          windowHeight = document.documentElement.clientHeight;
       } else if (document.body) { // other Explorers
          windowWidth = document.body.clientWidth;
          windowHeight = document.body.clientHeight;
       }   
       
       // for small pages with total height less then height of the viewport
       if(yScroll < windowHeight){
          pageHeight = windowHeight;
       } else {
          pageHeight = yScroll;
       }

       // for small pages with total width less then width of the viewport
       if(xScroll < windowWidth){   
          pageWidth = windowWidth;
       } else {
          pageWidth = xScroll;
       }


       arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight)
       return arrayPageSize;
    }


    //
    // pause(numberMillis)
    // Pauses code execution for specified time. Uses busy code, not good.
    //
    function pause(numberMillis) {
       var now = new Date();
       var exitTime = now.getTime() + numberMillis;
       while (true) {
          now = new Date();
          if (now.getTime() > exitTime)
             return;
       }
    }

    //
    // getKey(key)
    // Gets keycode. If 'x' is pressed then it hides the lightbox.
    //

    function getKey(e){
       if (e == null) { // ie
          keycode = event.keyCode;
       } else { // mozilla
          keycode = e.which;
       }
       key = String.fromCharCode(keycode).toLowerCase();
       
       if(key == 'x'){ hideLightbox(); }
    }


    //
    // listenKey()
    //
    function listenKey () {   document.onkeypress = getKey; }
       

    //
    // showLightbox()
    // Preloads images. Pleaces new image in lightbox then centers and displays.
    //
    function showLightbox(objLink)
    {
       // prep objects
       var objOverlay = document.getElementById('overlay');
       var objLightbox = document.getElementById('lightbox');
       var objCaption = document.getElementById('lightboxCaption');
       var objImage = document.getElementById('lightboxImage');
       var objLoadingImage = document.getElementById('loadingImage');
       var objLightboxDetails = document.getElementById('lightboxDetails');

       
       var arrayPageSize = getPageSize();
       var arrayPageScroll = getPageScroll();

       // center loadingImage if it exists
       if (objLoadingImage) {
          objLoadingImage.style.top = (arrayPageScroll[1] + ((arrayPageSize[3] - 35 - objLoadingImage.height) / 2) + 'px');
          objLoadingImage.style.left = (((arrayPageSize[0] - 20 - objLoadingImage.width) / 2) + 'px');
          objLoadingImage.style.display = 'block';
       }

       // set height of Overlay to take up whole page and show
       objOverlay.style.height = (arrayPageSize[1] + 'px');
       objOverlay.style.display = 'block';

       // preload image
       imgPreload = new Image();

       imgPreload.onload=function(){
          objImage.src = objLink.href;

          // center lightbox and make sure that the top and left values are not negative
          // and the image placed outside the viewport
          var lightboxTop = arrayPageScroll[1] + ((arrayPageSize[3] - 35 - imgPreload.height) / 2);
          var lightboxLeft = ((arrayPageSize[0] - 20 - imgPreload.width) / 2);
          
          objLightbox.style.top = (lightboxTop < 0) ? "0px" : lightboxTop + "px";
          objLightbox.style.left = (lightboxLeft < 0) ? "0px" : lightboxLeft + "px";


          objLightboxDetails.style.width = imgPreload.width + 'px';
          
          if(objLink.getAttribute('title')){
             objCaption.style.display = 'block';
             //objCaption.style.width = imgPreload.width + 'px';
             objCaption.innerHTML = objLink.getAttribute('title');
          } else {
             objCaption.style.display = 'none';
          }
          
          // A small pause between the image loading and displaying is required with IE,
          // this prevents the previous image displaying for a short burst causing flicker.
          if (navigator.appVersion.indexOf("MSIE")!=-1){
             pause(250);
          }

          if (objLoadingImage) {   objLoadingImage.style.display = 'none'; }
          objLightbox.style.display = 'block';

          // After image is loaded, update the overlay height as the new image might have
          // increased the overall page height.
          arrayPageSize = getPageSize();
          objOverlay.style.height = (arrayPageSize[1] + 'px');
          
          // Check for 'x' keypress
          listenKey();

          return false;
       }

       imgPreload.src = objLink.href;
       
    }





    //
    // hideLightbox()
    //
    function hideLightbox()
    {
       // get objects
       objOverlay = document.getElementById('overlay');
       objLightbox = document.getElementById('lightbox');

       // hide lightbox and overlay
       objOverlay.style.display = 'none';
       objLightbox.style.display = 'none';
       
       // disable keypress listener
       document.onkeypress = '';
    }




    //
    // initLightbox()
    // Function runs on window load, going through link tags looking for rel="lightbox".
    // These links receive onclick events that enable the lightbox display for their targets.
    // The function also inserts html markup at the top of the page which will be used as a
    // container for the overlay pattern and the inline image.
    //
    function initLightbox()
    {
       
       if (!document.getElementsByTagName){ return; }
       var anchors = document.getElementsByTagName("a");

       // loop through all anchor tags
       for (var i=0; i<anchors.length; i++){
          var anchor = anchors[i];

          if (anchor.getAttribute("href") && (anchor.getAttribute("rel") == "lightbox")){
             anchor.onclick = function () {showLightbox(this); return false;}
          }
       }

       // the rest of this code inserts html at the top of the page that looks like this:
       //
       // <div id="overlay">
       //      <a href="#" onclick="hideLightbox(); return false;"><img id="loadingImage" /></a>
       //   </div>
       // <div id="lightbox">
       //      <a href="#" onclick="hideLightbox(); return false;" title="Click anywhere to close image">
       //         <img id="closeButton" />      
       //         <img id="lightboxImage" />
       //      </a>
       //      <div id="lightboxDetails">
       //         <div id="lightboxCaption"></div>
       //         <div id="keyboardMsg"></div>
       //      </div>
       // </div>
       
       var objBody = document.getElementsByTagName("body").item(0);
       
       // create overlay div and hardcode some functional styles (aesthetic styles are in CSS file)
       var objOverlay = document.createElement("div");
       objOverlay.setAttribute('id','overlay');
       objOverlay.onclick = function () {hideLightbox(); return false;}
       objOverlay.style.display = 'none';
       objOverlay.style.position = 'absolute';
       objOverlay.style.top = '0';
       objOverlay.style.left = '0';
       objOverlay.style.zIndex = '90';
       objOverlay.style.width = '100%';
       objBody.insertBefore(objOverlay, objBody.firstChild);
       
       var arrayPageSize = getPageSize();
       var arrayPageScroll = getPageScroll();

       // preload and create loader image
       var imgPreloader = new Image();
       
       // if loader image found, create link to hide lightbox and create loadingimage
       imgPreloader.onload=function(){

          var objLoadingImageLink = document.createElement("a");
          objLoadingImageLink.setAttribute('href','#');
          objLoadingImageLink.onclick = function () {hideLightbox(); return false;}
          objOverlay.appendChild(objLoadingImageLink);
          
          var objLoadingImage = document.createElement("img");
          objLoadingImage.src = loadingImage;
          objLoadingImage.setAttribute('id','loadingImage');
          objLoadingImage.style.position = 'absolute';
          objLoadingImage.style.zIndex = '150';
          objLoadingImageLink.appendChild(objLoadingImage);

          imgPreloader.onload=function(){};   //   clear onLoad, as IE will flip out w/animated gifs

          return false;
       }

       imgPreloader.src = loadingImage;

       // create lightbox div, same note about styles as above
       var objLightbox = document.createElement("div");
       objLightbox.setAttribute('id','lightbox');
       objLightbox.style.display = 'none';
       objLightbox.style.position = 'absolute';
       objLightbox.style.zIndex = '100';   
       objBody.insertBefore(objLightbox, objOverlay.nextSibling);
       
       // create link
       var objLink = document.createElement("a");
       objLink.setAttribute('href','#');
       objLink.setAttribute('title','Click to close');
       objLink.onclick = function () {hideLightbox(); return false;}
       objLightbox.appendChild(objLink);

       // preload and create close button image
       var imgPreloadCloseButton = new Image();

       // if close button image found,
       imgPreloadCloseButton.onload=function(){

          var objCloseButton = document.createElement("img");
          objCloseButton.src = closeButton;
          objCloseButton.setAttribute('id','closeButton');
          objCloseButton.style.position = 'absolute';
          objCloseButton.style.zIndex = '200';
          objLink.appendChild(objCloseButton);

          return false;
       }

       imgPreloadCloseButton.src = closeButton;

       // create image
       var objImage = document.createElement("img");
       objImage.setAttribute('id','lightboxImage');
       objLink.appendChild(objImage);
       
       // create details div, a container for the caption and keyboard message
       var objLightboxDetails = document.createElement("div");
       objLightboxDetails.setAttribute('id','lightboxDetails');
       objLightbox.appendChild(objLightboxDetails);

       // create caption
       var objCaption = document.createElement("div");
       objCaption.setAttribute('id','lightboxCaption');
       objCaption.style.display = 'none';
       objLightboxDetails.appendChild(objCaption);

       // create keyboard message
       var objKeyboardMsg = document.createElement("div");
       objKeyboardMsg.setAttribute('id','keyboardMsg');
       objKeyboardMsg.innerHTML = 'press <kbd>x</kbd> to close';
       objLightboxDetails.appendChild(objKeyboardMsg);


    }


    //
    // addLoadEvent()
    // Adds event to window.onload without overwriting currently assigned onload functions.
    //
    function addLoadEvent(func)
    {   
       var oldonload = window.onload;
       if (typeof window.onload != 'function'){
           window.onload = func;
       } else {
          window.onload = function(){
          oldonload();
          func();
          }
       }

    }


    addLoadEvent(initLightbox);   // run initLightbox onLoad