// IXF1.11 :: Image cross-fade

// *****************************************************

// DOM scripting by brothercake -- http://www.brothercake.com/

// Modified by b!tech berlin (image links will be updated)

//******************************************************

//global object

var ixf = { 'clock' : null, 'count' : 1, 'iCounter' : -1 }

/*****************************************************************************

 Crossfade setup function

*****************************************************************************/

function crossfade()
{
    // Get paths to images
    ixf.imgs    = new Array(0);
    ixf.imgs[0] = arguments[2];

    // Id of the surrounding div
    var surDivId = arguments[3];
    
    // Cache images
    ixf.imgsLen = ixf.imgs[0].length;
    ixf.cache = [];
    for(var i=0; i < ixf.imgsLen; i++)
    {
    	ixf.cache[i] = new Image;
    	ixf.cache[i].src = ixf.imgs[0][i];
    }

	ixf.iCounter++;

	if (ixf.iCounter == ixf.imgsLen) 
	{
		ixf.iCounter = 0;
	}

	//if the timer is not already going
	if(ixf.clock == null)
	{
		//copy the image object
		ixf.obj = document.getElementById(arguments[0]);

		//copy the image src argument
		ixf.src = ixf.imgs[0][ixf.iCounter];

		//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') {
			//weed out win/ie5.0 by testing the length of the filters collection (where filters is an object with no data)
			//then weed out mac/ie5 by testing first the existence of the alpha object (to prevent errors in win/ie5.0)
			//then the returned value type, which should be a number, but in mac/ie5 is an empty string
			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';
		}

		//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'));
			ixf.newimg = document.getElementById(surDivId).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	= getPosition(ixf.obj).x + 'px'; //ixf.getRealPosition(ixf.obj, 'x') + 'px';
			ixf.newimg.style.top	= getPosition(ixf.obj).y + 'px';

			//copy and convert fade duration argument 
			ixf.length = parseInt(arguments[1], 10) * 1000;

			//create fade resolution argument as 20 steps per transition
			ixf.resolution = parseInt(arguments[1], 10) * 20;

			//start the timer
			ixf.clock = setInterval('ixf.crossfade()', ixf.length/ixf.resolution);
		} else {
    		//otherwise if opacity is not supported
			//just do the image swap
			ixf.obj.src = ixf.src;
		}
	}
};



//crossfade timer function
ixf.crossfade = function()
{
	//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 = getPosition(ixf.obj).x + 'px';
	ixf.newimg.style.top = getPosition(ixf.obj).y + 'px'; // ixf.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 x- and y-position of the object
function getPosition(obj) 
{
    mainDiv = document.getElementById('site');
    var pos = { x:0, y:0 };
    do {
        pos.x += obj.offsetLeft;
        pos.y += obj.offsetTop;
        obj = obj.offsetParent
    } while (obj != mainDiv);

    return pos;
}