/**
 * @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[2]];
  var end = toArray(fx.end);
  fx.end = [end[0],end[2]];
  fx.unit = [end[1],end[3]];
			}
     var nowPosX = [];
     nowPosX[0] = ((fx.end[0] - fx.start[0]) * fx.pos) + fx.start[0] + fx.unit[0];
     nowPosX[1] = ((fx.end[1] - fx.start[1]) * fx.pos) + fx.start[1] + fx.unit[1];
     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");
        var res = strg.match(/(-?[0-9\.]+)(px|\%|em|pt)\s(-?[0-9\.]+)(px|\%|em|pt)/);
        return [parseFloat(res[1],10),res[2],parseFloat(res[3],10),res[4]];
    }
 }
	});
})(jQuery);