/*
* From: http://www.splintered.co.uk/experiments/archives/javascript_cross_fade/
* 
* Based on: http://slayeroffice.com/code/imageCrossFade/xfade2.html
* 
* Better(?) Image cross fader (C)2004 Patrick H. Lauke aka redux
* 
* Inspired by Steve at Slayeroffice http://slayeroffice.com/code/imageCrossFade/ 
* 
* preInit "Scheduler" idea by Cameron Adams aka The Man in Blue
* http://www.themaninblue.com/writing/perspective/2004/09/29/ 
* 
* Cross-browser event handling for IE5+,  NS6 and Mozilla by Scott Andrew
* Thanks to Steve Clay http://mrclay.org/ a timer fix for Opera
* Tweaked to deal with empty nodes 19 Feb 2006
* 
* AW 28/042009 - Fixed so that correct hyperlink is associated with each image
*                and updated timer for slower (read: better) slideshow.
*/

var galleryId = 'gallery'; /* change this to the ID of the gallery list */
var	gallery; /* this will be the object reference to the list later on */
var galleryImages; /* array that will hold all child elements of the list */
var currentImage; /* keeps track of which image should currently be showing */
var previousImage;
var preInitTimer;
preInit();

/*****/
function preInit()
{
	/*
	* An inspired kludge that - in most cases - manages to initially hide the image
	* gallery list before even onload is triggered (at which point it's normally too
	* late, and the whole list already appeared to the user before being remolded)
	*/
	if ((document.getElementById)&&(gallery=document.getElementById(galleryId)))
	{
		gallery.style.visibility = "hidden";
		if (typeof preInitTimer != 'undefined')
			clearTimeout(preInitTimer);
	}
	else
		preInitTimer = setTimeout("preInit()",2);
}
/****************************************************************************************/


/*****/
function fader(imageNumber,opacity)
{
	/*
	* Helper function to deal specifically with images and the cross-browser
	* differences in opacity handling
	*/
	var obj=galleryImages[imageNumber];
	if (obj.style)
	{
		if (obj.style.MozOpacity!=null)
		{
			/* Mozilla's pre-CSS3 proprietary rule */
			obj.style.MozOpacity = (opacity/100) - .001;
		}
		else if (obj.style.opacity!=null)
		{
			/* CSS3 compatible */
			obj.style.opacity = (opacity/100) - .001;
		}
		else if (obj.style.filter!=null)
		{
			/* IE's proprietary filter */
			obj.style.filter = "alpha(opacity="+opacity+")";
		}
	}
}
/****************************************************************************************/


/*****/
function fadeInit()
{
	if (document.getElementById)
	{
		/*
		* Call preInit again - this shouldn't be necessary, but IE can sometimes get
		* ahead of itself and trigger fadeInit first
		*/
		preInit(); 
		galleryImages = new Array;
		var node = gallery.firstChild;
		
		/*
		* Instead of using childNodes (which also gets empty nodes and messes up the
		* script later) we do it the old-fashioned way and loop through the first
		* child and its siblings
		*/
		while (node)
		{
			if (node.nodeType==1)
			{
				galleryImages.push(node);
			}
			node = node.nextSibling;
		}
		for(i=0;i<galleryImages.length;i++) 
		{
			/* loop through all these child nodes and set up their styles */
			galleryImages[i].style.position='absolute';
			galleryImages[i].style.top=0;
			galleryImages[i].style.zIndex= i == 0 ? 1 : 0;
			
			/* set their opacity to transparent */
			fader(i,0);
		}
		
		/* make the list visible again */
		gallery.style.visibility = 'visible';
		
		/* initialise a few parameters to get the cycle going */
		currentImage=0;
		previousImage=galleryImages.length-1;
		opacity=100;
		fader(currentImage,100);
		
		/* start the whole crossfade process after a second's pause */
		window.setTimeout("crossfade(100)", 1000);
	}
}
/****************************************************************************************/


/*****/
function crossfade(opacity)
{
		/* Make sure the current image is on top */
		galleryImages[currentImage].style.zIndex = 100;
		galleryImages[previousImage].style.zIndex = 0;

		if (opacity < 100)
		{
			/* current image not faded up fully yet...so increase its opacity */
			fader(currentImage,opacity);

			/* fader(previousImage,100-opacity); */
			opacity += 5;
			window.setTimeout("crossfade("+opacity+")", 30);
		}
		else
		{
			/*
			* Make the previous image - which is now covered by
			* the current one - fully transparent
			*/
			fader(previousImage,0);
			
			/* current image is now previous image, as we advance in the list of images */
			previousImage=currentImage;
			currentImage+=1;
			if (currentImage>=galleryImages.length)
			{
				/* Start over from first image if we cycled through all images in the list */
				currentImage=0;
			}
			
			/* and start the crossfade after a second's pause */
			opacity=0;
			window.setTimeout("crossfade("+opacity+")", 5000);
		}
}
/****************************************************************************************/

/* Initialise fader by hiding image object first */
addEvent(window,'load',fadeInit)

/*****/
function addEvent(elm, evType, fn, useCapture) 
{
	/* 3rd party helper functions
	 * addEvent handler for IE and other browsers
	 * cross-browser event handling for IE5+, NS6 and Mozilla
	 * By Scott Andrew
	 */
	if (elm.addEventListener)
	{
		elm.addEventListener(evType, fn, useCapture);
		return true;
	}
	else if (elm.attachEvent)
	{
		var r = elm.attachEvent("on"+evType, fn);
		return r;
	}
} 
/****************************************************************************************/

/***** EOF *****/