- curTop = parseInt( jQuery.curCSS( elem, 'top', true ), 10 ) || 0,
- curLeft = parseInt( jQuery.curCSS( elem, 'left', true ), 10) || 0,
- props = {
- top: (options.top - curOffset.top) + curTop,
- left: (options.left - curOffset.left) + curLeft
- };
-
- if ( 'using' in options ) {
+ curCSSTop = jQuery.css( elem, "top" ),
+ curCSSLeft = jQuery.css( elem, "left" ),
+ calculatePosition = (position === "absolute" && jQuery.inArray('auto', [curCSSTop, curCSSLeft]) > -1),
+ props = {}, curPosition = {}, curTop, curLeft;
+
+ // need to be able to calculate position if either top or left is auto and position is absolute
+ if ( calculatePosition ) {
+ curPosition = curElem.position();
+ }
+
+ curTop = calculatePosition ? curPosition.top : parseInt( curCSSTop, 10 ) || 0;
+ curLeft = calculatePosition ? curPosition.left : parseInt( curCSSLeft, 10 ) || 0;
+
+ if ( jQuery.isFunction( options ) ) {
+ options = options.call( elem, i, curOffset );
+ }
+
+ if (options.top != null) {
+ props.top = (options.top - curOffset.top) + curTop;
+ }
+ if (options.left != null) {
+ props.left = (options.left - curOffset.left) + curLeft;
+ }
+
+ if ( "using" in options ) {