//ロールオーバークラス名
var ROCLS = 'rollover';

//ロールオーバー用画像接尾語
var SUFFIX = '_on';

//////////////////////////////////////////////////////////////////////////////////////////////////
function RollOverImages(className){
	if(!document.ROI) document.ROI = this;
	this.className = className;
	this.imgArray = new Array();
	var imgNum = 0;
	if(className){
		var objImg = base.getElementsByClassName(className);
		for(var i = 0; i < objImg.length; i++){
			var temp = objImg[i];
			temp.id = (temp.id)? temp.id : (this.className + '_' + i);
			var src = temp.src;
			var type = src.substring(src.lastIndexOf('.'));
			var name = src.substring(0,src.length - type.length);
			var overSrc = name + SUFFIX + type;
			this.setRollOver(temp, src, overSrc);
			
			this.imgArray[imgNum] = overSrc;
			imgNum = imgNum + 1;
		}
	}
	this.preloadImg(this.imgArray);
}

RollOverImages.prototype.preloadImg = function(srcs){
	var ret = new Array();
	if(!document.images || !srcs) return;
	for(var i = 0; i < srcs.length; i++){
		(new Image()).src = srcs[i];
		ret.push(srcs[i]);
	}
}

RollOverImages.prototype.setRollOver = function(obj, img, overImg){
	if(!obj.onmouseover) obj.onmouseover = function(){
		obj.src = overImg;
	};
	if(!obj.onmouseout) obj.onmouseout = function(){
		obj.src = img;
	};
}