/**
 * @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);