(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);

$(document).ready(function() {
	var width = 218;
	var item_width=102;
	var items=2;
	var cur_lic=0;
	var links=new Array("/img/lic/lic1.jpg", "/img/lic/lic2.jpg");

	var $list = $("#licences img");
	$list.css( { backgroundPosition: "7px 7px" } );
//	$("#licences").attr("href", links[0]);
	function move()
	{
		var new_pos = -item_width*cur_lic;
		$list.stop().animate({"backgroundPosition": "("+new_pos+"px 7px)"}, 500);
		$("#licences").attr("href", links[cur_lic]);
	}

	$("#prev_lic").click(function(){
		if (items>cur_lic+1)
		{
			cur_lic++;
			move();
		}
		return false;
	});
	$("#next_lic").click(function(){
		if (cur_lic>0)
		{
			cur_lic--;
			move();
		}
		return false;
	});

});