/* This javascript file contains the variables and functions used to 
 manage the banner display at the top of each of the st. james's montefiore site's pages */
var advertCounter = 0;
var advertOpacity = 0;
var fadeOrSwap = "swap";
var advertToFade;
var advertToSwap;

function addEvent(elm, evType, fn, useCapture) {
    // cross browser event handling for IE5+, NS6+ and Mozilla/Gecko
    // by Scott Andrew
    if (elm.addEventListener) {
        elm.addEventListener(evType, fn, useCapture);
        return true;
    }     else if (elm.attachEvent) {
        var r = elm.attachEvent('on' + evType, fn);
        return r;
    }    else {
        elm['on' + evType] = fn;
    }
}    


    
function swapFadeAdvert() {
    if (advertOpacity <= 0) {
        fadeOrSwap = "swap";
        advertOpacity = 100;
        var advertBox1 = document.getElementById('advertLink1');
        var advertBox2 = document.getElementById('advertLink2');
        if (advertBox1.style.zIndex >= advertBox2.style.zIndex) {
            advertToFade = 1;
            advertToSwap = 2;
        }
        else {
            advertToFade = 2;
            advertToSwap = 1;            
        }
        advertCounter=advertCounter+1;
        if (advertCounter > 11) {
            advertCounter = 0;
            }
        getASponsor(document.getElementById('advertLink' + advertToSwap), advertCounter);     
    }
    else {
        fadeOrSwap = "fade";
        var fadeAdvert = document.getElementById('advertLink' + advertToFade);
        var swapAdvert = document.getElementById('advertLink' + advertToSwap);
        advertOpacity-=1;
        setOpacity(fadeAdvert, advertOpacity);
        if (advertOpacity <= 0) {
            fadeAdvert.style.zIndex = 1;
            swapAdvert.style.zIndex = 2;
            setOpacity(fadeAdvert, 100);
            }            
    }
    
    if (fadeOrSwap == "swap") {
        setTimeout("swapFadeAdvert()",7000);
    }
    else
    {
        setTimeout("swapFadeAdvert()",10); 
    }    
    }    

  // Function by Simon Willison from sitepoint.com
  function setOpacity(obj, opacity)
  {
      opacity = (opacity == 100)?99.999:opacity;

      // IE/Win
      obj.style.filter = "alpha(opacity:"+opacity+")";

      // Safari<1.2, Konqueror
      obj.style.KHTMLOpacity = opacity/100;

      // Older Mozilla and Firefox
      obj.style.MozOpacity = opacity/100;

      // Safari 1.2, newer Firefox and Mozilla, CSS3
      obj.style.opacity = opacity/100;
  }