/*
 * 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) {
	if (o != null) {
		do { o = o.nextSibling; }
		while (o && o.tagName != 'IMG');
		return o;
	}
}

//find first image inside an element
function firstChildImage(o){
	if (o != null) {
		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) {
	if (obj != null && o != null) {
		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 = 1;
	}
	
	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, memberID) {
	//change image style here
	if (image != null) {
		image.style.display = 'block';
	}
	
	if(caption != null) {
		document.getElementById(caption).innerHTML = image.alt;
	}
	
	if (image != null) {
		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) {
	opacity = opacity + 3;

	if (opacity < 103) {

		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(0);
		
		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);
}