(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);