Android: Get SlidingDrawer Handle position

Question

I would like to perform some transparency changes to views which will be hidden when the user drags the handle of a SlidingDrawer manually. The "setOnDrawerScrollListener" only triggers onScrollStarted and onScrollEnded, but I want to slowly fade in/out the view underneath corresponding to the slidingDrawer's position when the user manually drags the SlidingDrawer's Handle open/close.