/**
The JavaScript functions below will gradually enlarge or shrink an image
on the current page. I use this for mouseover effects, but there might be
some other interesting applications of it as well.

You can use these scripts in any way you'd like, just don't pretend like
you wrote them yourself.

version 1.0
March 17, 2005
Julian Robichaux, http://www.nsftools.com
*/

/**** adjust these two parameters to control how fast or slow
 **** the images grow/shrink ****/
// how many milliseconds we should wait between resizing events
var resizeDelay = 10;
// how many pixels we should grow or shrink by each time we resize
var resizeIncrement = 5;

// this will hold information about the images we're dealing with
var imgCache = new Object();



function getCacheTag (imgElement) {
	return imgElement.src + "~" + imgElement.offsetLeft + "~" + imgElement.offsetTop;
}



function cachedImg (imgElement, increment) {
	this.img = imgElement;
	this.cacheTag = getCacheTag(imgElement);
	this.originalSrc = imgElement.src;
	
	var h = imgElement.height;
	var w = imgElement.width;
	this.originalHeight = h;
	this.originalWidth = w;
	
	increment = (!increment) ? resizeIncrement : increment;
	this.heightIncrement = Math.ceil(Math.min(1, (h / w)) * increment);
	this.widthIncrement = Math.ceil(Math.min(1, (w / h)) * increment);
}



function resizeImg (imgElement, percentChange, newImageURL) {
	
	var pct = (percentChange) ? percentChange / 100 : 1;
	var cacheTag = imgElement.getAttribute("cacheTag");
	if (!cacheTag) {
		cacheTag = getCacheTag(imgElement);
		imgElement.setAttribute("cacheTag", cacheTag);
	}
	
	var cacheVal = imgCache[cacheTag];
	if (!cacheVal) {
		imgCache[cacheTag] = new Array(new cachedImg(imgElement), pct);
	} else {
		cacheVal[1] = pct;
	}
	
	
	if (newImageURL)
		imgElement.src = newImageURL;
	
	
	resizeImgLoop(cacheTag);
	return true;
}



function resizeImgLoop (cacheTag) {
	
	var cacheVal = imgCache[cacheTag];
	if (!cacheVal)
		return false;
	
	var cachedImageObj = cacheVal[0];
	var imgElement = cachedImageObj.img;
	var pct = cacheVal[1];
	var plusMinus = (pct > 1) ? 1 : -1;
	var hinc = plusMinus * cachedImageObj.heightIncrement;
	var vinc = plusMinus * cachedImageObj.widthIncrement;
	var startHeight = cachedImageObj.originalHeight;
	var startWidth = cachedImageObj.originalWidth;
	
	var currentHeight = imgElement.height;
	var currentWidth = imgElement.width;
	var endHeight = Math.round(startHeight * pct);
	var endWidth = Math.round(startWidth * pct);
	
	
	if ( (currentHeight == endHeight) || (currentWidth == endWidth) )
		return true;
	
	
	var newHeight = currentHeight + hinc;
	var newWidth = currentWidth + vinc;
	if (pct > 1) {
		if ((newHeight >= endHeight) || (newWidth >= endWidth)) {
			newHeight = endHeight;
			newWidth = endWidth;
		}
	} else {
		if ((newHeight <= endHeight) || (newWidth <= endWidth)) {
			newHeight = endHeight;
			newWidth = endWidth;
		}
	}
	
	
	imgElement.height = newHeight;
	imgElement.width = newWidth;
	
	
	if ((newHeight == cachedImageObj.originalHeight) || (newWidth == cachedImageObj.originalwidth)) {
		imgElement.src = cachedImageObj.originalSrc;
	}
	
	
	setTimeout("resizeImgLoop('" + cacheTag + "')", resizeDelay);
}