/*
 Add rollovers to nav:
 1. add a call to this javascript file to the page head
 2. add class "subnav" to the links to enable rollovers
 
 <a href="" class="subnav"><img src="nav.gif"></a><a class="subnav" href=""><img src="nav2.gif"></a>
*/

var preloaded = [];

function initRollovers() { 
 var links = document.getElementsByTagName('a');
 for (var a = 0; a < links.length; a++) {
  var link = links[a];
  if (link.className == 'subnav') {
   var images = link.getElementsByTagName('img');
   if (images.length > 0) {
    var img = images[0];
    
    // Calculate rollover src and preload image
    var src = img.src;
    var extIndex = src.lastIndexOf('.');
    var ext = src.substring(extIndex);
    var root = src.substring(0, extIndex);
    var rolloverSrc = root + '_over' + ext;
    
    var image = new Image();
    image.src = rolloverSrc;
    preloaded[preloaded.length] = image;
    
    // Reset mouseover/mouseout to perform rollover
    var mouseover = 'this.src = "' + rolloverSrc + '";';
    img.onmouseover = new Function(mouseover);
    
    var mouseout = 'this.src = "' + src + '"';
    img.onmouseout = new Function(mouseout);
   }
  }
 }
}

// Called by gallery preview photos to set rollover state
function setRollover(img, rolloverSrc, src) {
    
    var image = new Image();
    image.src = rolloverSrc;
    preloaded[preloaded.length] = image;
    
    // Reset mouseover/mouseout to perform rollover
    var mouseover = 'this.src = "' + rolloverSrc + '";';
    img.onmouseover = new Function(mouseover);
    
    var mouseout = 'this.src = "' + src + '"';
    img.onmouseout = new Function(mouseout);
    
}


// Initialize rollovers and image preload on page load
if (window.addEventListener){
  window.addEventListener("load", initRollovers, false);
} else if (window.attachEvent){
  window.attachEvent("onload", initRollovers);
}