/**
 * @author Alexander Farkas
 * v. 1.02
 */
(function($) {
	$.extend($.fx.step,{
	    backgroundPosition: function(fx) {
            if (fx.state === 0 && typeof fx.end == 'string') {
                var start = $.curCSS(fx.elem,'backgroundPosition');
                start = toArray(start);
                fx.start = [start[0],start[1]];
                var end = toArray(fx.end);
                fx.end = [end[0],end[1]];
                fx.unit = 'px';
			}
            var nowPosX = [];
            nowPosX[0] = ((fx.end[0] - fx.start[0]) * fx.pos) + fx.start[0] + fx.unit;
            nowPosX[1] = ((fx.end[1] - fx.start[1]) * fx.pos) + fx.start[1] + fx.unit;

            fx.elem.style.backgroundPosition = nowPosX[0]+' '+nowPosX[1];
            
           function toArray(strg){
//               strg = strg.replace(/left|top/g,'0px');
//               strg = strg.replace(/right|bottom/g,'100%');
//               strg = strg.replace(/([0-9\.]+)(\s|\)|$)/g,"$1px$2");
               strg = strg.replace(/[a-z]+/g,'');
               var res = strg.match(/(-?[0-9\.]+)\s(-?[0-9\.]+)/);
               return [parseFloat(res[1],10),parseFloat(res[2],10)];
           }
        }
	});
})(jQuery);