/*
 * Original from: http://brainerror.net/scripts/javascript/blendtrans/demo.html
 *
 * Edits by ASC:
 *   - Removed unnecessary OO code that caused MSIE to choke
 *   - Added pause between setting bg image and setting opacity to zero to
 *     prevent MSIE image flash
 *   - Increased opacity check argument to 103 for completely smooth fade
 *
 */

//find next image
function nextImage(o) 
{
  do o = o.nextSibling;
  while(o && o.tagName != 'IMG');
  return o;
}

//find first image inside an element
function firstChildImage(o) 
{  
  o = o.firstChild;
      
  while(o && o.tagName != 'IMG') 
  {
      o = o.nextSibling;
  }
  
  return o;
}

//set the opacity of an element to a specified value
function setOpacity(obj, o) 
{
  obj.style.opacity = (o / 100);
  obj.style.MozOpacity = (o / 100);
  obj.style.KhtmlOpacity = (o / 100);
  obj.style.filter = 'alpha(opacity=' + o + ')';
}

//make image invisible and set next one as current image
function getNextImage(image) 
{	
  if (next = nextImage(image)) 
  {
    image.style.display = 'none';
    image.style.zIndex = 0;
  
    next.style.display = 'block';
    next.style.zIndex = 100;  
  } else {
    //if there is not a next image, get the first image again
    next = firstChildImage(image.parentNode);
  }

  return next;
}

//set default values for parameters and starting image
function blendImages(id, speed, pause, caption) 
{
  if(speed == null) 
  {
      speed = 30;
  }  
  if(pause == null) 
  {
      pause = 1500;
  }

  var blend = document.getElementById(id);

  var image = firstChildImage(blend);

  startBlending(image, speed, pause, caption);
}

//make image a block-element and set the caption
function startBlending(image, speed, pause, caption) 
{
  image.style.display = 'block';

  if(caption != null) 
  {
    document.getElementById(caption).innerHTML = image.alt;
  }

  continueFadeImage(image, 0, speed, pause, caption);
}

// ASC: copied from http://www.sean.co.uk/a/webdesign/javascriptdelay.shtm
function pausecomp(millis) 
{
  var date = new Date();
  var curDate = null;

  do 
  { 
    curDate = new Date(); 
  } while(curDate-date < millis);
} 

//set an increased opacity and check if the image is done blending
function continueFadeImage(image, opacity, speed, pause, caption) 
{
  var increment = 5;

  opacity = opacity + increment;

  if (opacity < 100+increment) 
  {
    setTimeout(function() {fadeImage(image, opacity, speed, pause, caption)}, speed);
  } else {
    //if the image is done, set it to the background and make it transparent
    image.parentNode.style.backgroundImage = "url("+image.src+")";

    // ASC: pause 1sec here to prevent MSIE image flash ...
    var paws=pause-1000;
    if (paws < 0 ) 
    {
      paws = 0;
    }
    pausecomp(1000);

    setOpacity(image,0);
    //get the next image and start blending it again
    image = getNextImage(image);
    setTimeout(function() {startBlending(image, speed, pause, caption)}, paws);		
  }
}

//set the opacity to a new value and continue the fading
function fadeImage(image, opacity, speed, pause, caption) 
{
  setOpacity(image,opacity);
  continueFadeImage(image, opacity, speed, pause, caption);
}