Drag and drop over the dragged element

I have a case where I am dragging items and dropping them over an image. 
I am using using the $event parameter passed to ui-on-drop in order to get the exact X/Y location where the item was dropped. 

There is one case where the X/Y are failing which is dragging and dropping the item over itself. The X/Y location returned in $event is relative to the dragged item instead of the drop container. 
