charbgr

/*
 * Here we want to get the appbar offset changes paired with the direction it's moving and
 * using RxBinding's great `offsetChanges` API to make an rx Observable of this. The first
 * part buffers two while skipping one at a time and emits "scroll direction" enums. Second 
 * part is just a simple map to pair the offset with the resolved scroll direction comparing 
 * to the previous offset. This gives us a nice stream of (offset, direction) emissions.
 *
 * Note that the filter() is important if you manipulate child views of the ABL. If any child
 * view requests layout again, it will trigger an emission from the offset listener with the
 * same value as before, potentially causing measure/layout/draw thrashing if your logic