/**

 * @author Alexander Farkas

 * v. 1.21

 */





(function($) {

    if(!document.defaultView || !document.defaultView.getComputedStyle){ // IE6-IE8

        var oldCurCSS = jQuery.curCSS;

        jQuery.curCSS = function(elem, name, force){

            if(name === 'background-position'){

                name = 'backgroundPosition';

            }

            if(name !== 'backgroundPosition' || !elem.currentStyle || elem.currentStyle[ name ]){

                return oldCurCSS.apply(this, arguments);

            }

            var style = elem.style;

            if ( !force && style && style[ name ] ){

                return style[ name ];

            }

            return oldCurCSS(elem, 'backgroundPositionX', force) +' '+ oldCurCSS(elem, 'backgroundPositionY', force);

        };

    }

    

    var oldAnim = $.fn.animate;

    $.fn.animate = function(prop){

        if('background-position' in prop){

            prop.backgroundPosition = prop['background-position'];

            delete prop['background-position'];

        }

        if('backgroundPosition' in prop){

            prop.backgroundPosition = '('+ prop.backgroundPosition;

        }

        return oldAnim.apply(this, arguments);

    };

    

    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]];

    }

    

    $.fx.step. backgroundPosition = function(fx) {

        if (!fx.bgPosReady) {

            var start = $.curCSS(fx.elem,'backgroundPosition');

            

            if(!start){//FF2 no inline-style fallback

                start = '0px 0px';

            }

            

            start = toArray(start);

            

            fx.start = [start[0],start[2]];

            

            var end = toArray(fx.options.curAnim.backgroundPosition);

            fx.end = [end[0],end[2]];

            

            fx.unit = [end[1],end[3]];

            fx.bgPosReady = true;

        }

        //return;

        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];



    };

})(jQuery);