// JavaScript Document
var fps = 30;
var time =5;
steps = time * fps;
// NB maxImg is set in navElement "header" so that unused image divs can be hidden before they are rendered.  IE can't find it, so define it again here:
function fade() { //  called from onLoad, gives delay before fading first slide
    setTimeout(function() { startFade() }, 2000 )
}
var maxImg=0; // number of images
function startFade() { 
// find out how many images exist on page 
   for(var i = 1; i < 7; i++) {
      if(document.getElementById('fade'+i)) {
          if(document.getElementById('fade'+i).complete) {
             maxImg++;
          }
      }
   }
   if(maxImg == 1) {
      // single image
      document.getElementById('box1').style.background = 
      document.getElementById('fade1');
   }
   else if(maxImg == 0) {
      // no images - replace background colour
      document.getElementById('imgscroll').style.background = '#1f60a9';
   } 
   else {
      // fade process
      // determines browser type
      var img = document.getElementById('fade1');
      if (typeof img.style.opacity != 'undefined') {
         var otype = 'w3c';
      }
      else if  (typeof img.style.MozOpacity  != 'undefined') {
         otype = 'moz';
      }
      else if (typeof img.style.KhtmlOpacity  != 'undefined') {
         otype = 'khtml';
      }
      else if (typeof img.filters == 'object') {
         otype = (img.filters.length > 0
         && typeof img.filters.alpha == 'object'
         && typeof img.filters.alpha.opacity == 'number')
         ? 'ie' : 'none';
      }
      else { otype = 'none';}
      // initiates fading process if browser capable
      if (otype != 'none' ) {
               dofade(1, 0, otype);
      }
   }
}
function dofade(imgNum, value, otype) {
   value += 1 / steps;
   if (value > 1) {
      value = 1;
   }
   
   // define the IDs of the 2 images changing opacity
   var imgOut = document.getElementById('fade'+imgNum);
   var imgIn  = document.getElementById('fade'+((imgNum % maxImg) + 1));
   setfade(imgOut, 1-value, otype);
   setfade(imgIn, value, otype);
// positive and negative fading to be included into following
// using value and 1-value
   if (value < 1) {
      setTimeout(function() {
         dofade(imgNum, value, otype);
      }, 1000 / fps);
   } 
   else { 
      // time delay and followimg image fade
	  setTimeout(function() {
		dofade((imgNum % maxImg) + 1, 0, otype)
	  }, 3000);
   }
}
function setfade(img, value, otype) {
   switch(otype)
   {
   case 'ie':
   img.filters.alpha.opacity = value * 100;
   break;
   case 'khtml':
   img.style.KhtmlOpacity = value;
   break;
   case 'moz':
   img.style.MozOpacity = (value == 1 ? 0.9999999 : value);
   break;
   default:
   img.style.opacity = (value == 1 ? 0.9999999 : value);
   }
}