// www.brothercake.com

var ixfs = new Array( );

//crossfade setup function
function crossfade()
{
  ixf = { 'clock' : null, 'count' : 1 };

  //copy the image object
  ixf.obj = arguments[0];

  //copy the image src argument
  ixf.src = arguments[1];

  //store the supported form of opacity
  if(typeof ixf.obj.style.opacity != 'undefined')
    ixf.type = 'w3c';
  else if(typeof ixf.obj.style.MozOpacity != 'undefined')
    ixf.type = 'moz';
  else if(typeof ixf.obj.style.KhtmlOpacity != 'undefined')
    ixf.type = 'khtml';
  else if(typeof ixf.obj.filters == 'object')
    ixf.type = (ixf.obj.filters.length > 0 && typeof ixf.obj.filters.alpha == 'object' && typeof ixf.obj.filters.alpha.opacity == 'number') ? 'ie' : 'none';
  else
    ixf.type = 'none';

  //change the image alt text if defined
  if(typeof arguments[3] != 'undefined' && arguments[3] != '')
    ixf.obj.alt = arguments[3];

  //if any kind of opacity is supported
  if(ixf.type != 'none')
  {
    //create a new image object and append it to body
    //detecting support for namespaced element creation, in case we're in the XML DOM
    ixf.newimg = document.getElementsByTagName('body')[0].appendChild((typeof document.createElementNS != 'undefined') ? document.createElementNS('http://www.w3.org/1999/xhtml', 'img') : document.createElement('img'));

    //set positioning classname
    ixf.newimg.className = 'idupe';

    //set src to new image src
    ixf.newimg.src = ixf.src

    //move it to superimpose original image
    ixf.newimg.style.left = getRealPosition(ixf.obj, 'x') + 'px';
    ixf.newimg.style.top = getRealPosition(ixf.obj, 'y') + 'px';

    // TODO: do we need these two lines?  -- added 05-10-22 JNB
    ixf.newimg.width = ixf.obj.width;
    ixf.newimg.height = ixf.obj.height;

    //copy and convert fade duration argument
    ixf.length = parseInt(arguments[2], 10) * 1000;

    //create fade resolution argument as 20 steps per transition
    ixf.resolution = parseInt(arguments[2], 10) * 20;

    //start the timer
    ixf.clock = setInterval('step(' + ixfs.length + ')', ixf.length/ixf.resolution);

    ixfs.push( ixf );
  }
  //otherwise if opacity is not supported
  else
  {
    //just do the image swap
    ixf.obj.src = ixf.src;
  }
};

//crossfade timer function
step = function()
{
  ixf = ixfs[ arguments[ 0 ]];

  //decrease the counter on a linear scale
  ixf.count -= (1 / ixf.resolution);

  //if the counter has reached the bottom
  if(ixf.count < (1 / ixf.resolution))
  {
    //clear the timer
    clearInterval(ixf.clock);
    ixf.clock = null;

    //reset the counter
    ixf.count = 1;

    //set the original image to the src of the new image
    ixf.obj.src = ixf.src;
  }

  //set new opacity value on both elements
  //using whatever method is supported
  switch(ixf.type)
  {
    case 'ie':
      ixf.obj.filters.alpha.opacity = ixf.count * 100;
      ixf.newimg.filters.alpha.opacity = (1 - ixf.count) * 100;
      break;

    case 'khtml':
      ixf.obj.style.KhtmlOpacity = ixf.count;
      ixf.newimg.style.KhtmlOpacity = (1 - ixf.count);
      break;

    case 'moz':
      //restrict max opacity to prevent a visual popping effect in firefox
      ixf.obj.style.MozOpacity = (ixf.count == 1 ? 0.9999999 : ixf.count);
      ixf.newimg.style.MozOpacity = (1 - ixf.count);
      break;

    default:
      //restrict max opacity to prevent a visual popping effect in firefox
      ixf.obj.style.opacity = (ixf.count == 1 ? 0.9999999 : ixf.count);
      ixf.newimg.style.opacity = (1 - ixf.count);
  }

  //now that we've gone through one fade iteration
  //we can show the image that's fading in
  ixf.newimg.style.visibility = 'visible';

  //keep new image in position with original image
  //in case text size changes mid transition or something
  ixf.newimg.style.left = getRealPosition(ixf.obj, 'x') + 'px';
  ixf.newimg.style.top = getRealPosition(ixf.obj, 'y') + 'px';

  //if the counter is at the top, which is just after the timer has finished
  if(ixf.count == 1)
  {
    //remove the duplicate image
    ixf.newimg.parentNode.removeChild(ixf.newimg);
  }
};

//get real position method
getRealPosition = function()
{
  this.pos = (arguments[1] == 'x') ? arguments[0].offsetLeft : arguments[0].offsetTop;
  this.tmp = arguments[0].offsetParent;
  while(this.tmp != null)
  {
    this.pos += (arguments[1] == 'x') ? this.tmp.offsetLeft : this.tmp.offsetTop;
    this.tmp = this.tmp.offsetParent;
  }

  return this.pos;
};