/**
 * @author Alexander Farkas
 * v. 1.22
 */


(function($) {
	$(document).ready(function () {
		if(!document.defaultView || !document.defaultView.getComputedStyle){ // IE6-IE8
			var oldCurCSS = $.curCSS;
			$.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.end);
				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);