var SwapImage = {
	preload:function(){
		if(!document.images) return false;
		var loadedImg = new Array();
		var arg = arguments;
		for(i=0;i<arg.length;i++){
			loadedImg[i] = new Image();
			loadedImg[i].src = arg[i];
		}
	},
	setswap:function(){
		if(!document.getElementsByTagName) return false;
		var imglist = document.getElementsByTagName("img");
		var swapclass = "swap";
		for(var i=0;i<imglist.length;i++){
			if(imglist[i].className.match(/^swap\s+|\s+swap\s+|\s+swap$|^swap$/i)){
				var state = (imglist[i].src.match(/_on\.(gif|jpg|jpeg|png)$/i)!=null);
				if(state) SwapImage.preload(imglist[i].src.replace(/_on\./,"_ov\."));
				else SwapImage.preload(imglist[i].src.replace(/_off\./,"_ov\."));
				SwapImage.preload(imglist[i].src);
				imglist[i].onmouseover = (state)?function(){
					this.src = this.src.replace(/_on\./,"_ov\.");
					return false;
				}:function(){
					this.src = this.src.replace(/_off\./,"_ov\.");
					return false;
				};
				imglist[i].onmouseout = (state)?function(){
					this.src = this.src.replace(/_ov\./,"_on\.");
					return false;
				}:function(){
					this.src = this.src.replace(/_ov\./,"_off\.");
					return false;
				};
			}
		}
	}
};


if(window.addEventListener){
	window.addEventListener("load",SwapImage.setswap,false);
}else if(window.attachEvent){
	window.attachEvent("onload",SwapImage.setswap);
}else{
	window.onload = SwapImage.setswap;
}