var isf = { 'clock' : null, 'fade' : true, 'count' : 1 }

isf.imgs = [
'/images/gallery/gallery01.jpg',
'/images/gallery/gallery02.jpg',
'/images/gallery/gallery03.jpg',
'/images/gallery/gallery04.jpg',
'/images/gallery/gallery05.jpg',
'/images/gallery/gallery06.jpg',
'/images/gallery/gallery07.jpg',
'/images/gallery/gallery08.jpg',
'/images/gallery/gallery09.jpg',
'/images/gallery/gallery10.jpg',
'/images/gallery/gallery11.jpg',
'/images/gallery/gallery12.jpg',
'/images/gallery/gallery13.jpg',
'/images/gallery/gallery14.jpg',
'/images/gallery/gallery15.jpg',
'/images/gallery/gallery16.jpg',
'/images/gallery/gallery17.jpg',
'/images/gallery/gallery18.jpg',
'/images/gallery/gallery19.jpg',
'/images/gallery/gallery20.jpg',
'/images/gallery/gallery21.jpg',
'/images/gallery/gallery22.jpg',
'/images/gallery/gallery23.jpg',
'/images/gallery/gallery24.jpg',
'/images/gallery/gallery25.jpg',
'/images/gallery/gallery26.jpg',
'/images/gallery/gallery27.jpg',
'/images/gallery/gallery28.jpg',
'/images/gallery/gallery29.jpg',
'/images/gallery/gallery30.jpg',
'/images/gallery/gallery31.jpg',
'/images/gallery/gallery32.jpg',
'/images/gallery/gallery33.jpg',
'/images/gallery/gallery34.jpg',
'/images/gallery/gallery35.jpg'
];

isf.imgsLen = isf.imgs.length;
isf.cache = [];
for(var i=0; i<isf.imgsLen; i++)
{
	isf.cache[i] = new Image;
	isf.cache[i].src = isf.imgs[i];
}


//swapfade setup function
function swapfade()
{
	if(isf.clock == null)
	{
		//copy the image object
		isf.obj = arguments[0];

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

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

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

	//if any kind of opacity is supported
	if(isf.type != 'none')
	{

		//copy and convert fade duration argument
		//the duration specifies the whole transition
		//but the swapfade is two distinct transitions
		isf.length = parseInt(arguments[2], 10) * 500;
		
		//create fade resolution argument as 20 steps per transition
		//again, split for the two distrinct transitions
		isf.resolution = parseInt(arguments[2], 10) * 10;
		
		//start the timer

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

};

//swapfade timer function
isf.swapfade = function()
{

	//increase or reduce the counter on an exponential scale
	isf.count = (isf.fade) ? isf.count * 0.5 : (isf.count * (1/0.5));


	//if the counter has reached the bottom
	if(isf.count < (1 / isf.resolution))
	{

		//clear the timer
		clearInterval(isf.clock);
		isf.clock = null;
		
		//do the image swap
		isf.obj.src = isf.src;
		
		//reverse the fade direction flag
		isf.fade = false;
		
		//restart the timer

		isf.clock = setInterval('isf.swapfade()', isf.length/isf.resolution);
	
	}
	
	//if the counter has reached the top
	if(isf.count > (1 - (1 / isf.resolution)))
	{
		//clear the timer
		clearInterval(isf.clock);
		isf.clock = null;
		
		//reset the fade direction flag
		isf.fade = true;
		
		//reset the counter
		isf.count = 1;
	}
	
	//set new opacity value on element
	//using whatever method is supported
	switch(isf.type)
	{
	case 'ie' :
	isf.obj.filters.alpha.opacity = isf.count * 100;
	break;
	
	case 'khtml' :
	isf.obj.style.KhtmlOpacity = isf.count;
	break;
	
	case 'moz' :
	//restrict max opacity to prevent a visual popping effect in firefox
	isf.obj.style.MozOpacity = (isf.count == 1 ? 0.9999999 : isf.count);
	break;
	
	default :
	//restrict max opacity to prevent a visual popping effect in firefox
	isf.obj.style.opacity = (isf.count == 1 ? 0.9999999 : isf.count);
	}
};