public void setThumbPosition(int x, int y) {
        if (mThumbPosition.x == x && mThumbPosition.y == y) {
            return;
        }
        // do not create new objects here, this is called quite often
        mInvalidateRect.set(mThumbPosition.x + mOffset.x, mOffset.y, mThumbPosition.x + mOffset.x + mWidth, mRecyclerView.getHeight() + mOffset.y);
        mThumbPosition.set(x, y);
        mInvalidateTmpRect.set(mThumbPosition.x + mOffset.x, mOffset.y, mThumbPosition.x + mOffset.x + mWidth, mRecyclerView.getHeight() + mOffset.y);
        mInvalidateRect.union(mInvalidateTmpRect);
        mRecyclerView.invalidate(mInvalidateRect);
    }
Returns whether the specified points are near the scroll bar bounds.
android/third_party/recyclerview-fastscroll/src/main/java/com/simplecityapps/recyclerview_fastscroll/views/FastScroller.java