public boolean internalCanScrollVertically(int direction) {
        if (mAdapter == null) {
            return false;
        }

        final int height = getClientHeight();
        final int scrollY = getScrollY();
        if (direction < 0) {
            return (scrollY > (int) (height * mFirstOffset));
        } else if (direction > 0) {
            return (scrollY < (int) (height * mLastOffset));
        } else {
            return false;
        }
    }
Returns true if a fake drag is in progress.

@return true if currently in a fake drag, false otherwise.
@see #beginFakeDrag()
@see #fakeDragBy(float)
@see #endFakeDrag()
dkplayer-sample/src/main/java/xyz/doikki/dkplayer/widget/VerticalViewPager.java