/**
 * rollImage
 * 
 * @need addOnload()
 * @need getClassAttribute()
 */

function rollImage() {
	var imgs = document.getElementsByTagName("img");
	var overImgs = new Array();
	
	for(var i = 0, l = imgs.length; i < l; i ++) {
		var classes = getClassAttribute(imgs[i]);
		for(j = 0; j < classes.length; j ++) {
			if(classes[j] == "roll") {
				var src = imgs[i].getAttribute("src");
				var type = src.substring(src.lastIndexOf("."), src.length);
				var stackImg = new Image();
				
				imgs[i].baseSrc = src;
				imgs[i].overSrc = src.replace(type, "_roll" + type);
				imgs[i].onmouseover = function() { this.setAttribute("src", this.overSrc); };
				imgs[i].onmouseout  = function() { this.setAttribute("src", this.baseSrc); };
				
				stackImg.setAttribute("src", imgs[i].overSrc);
				overImgs.push(stackImg);
				
				break;
			}
		}
	}
}

addOnload(rollImage);