question: private boolean pageScrolled ( int xPos ) { if ( items . size ( ) == 0 ) { return false ; } final int deltaScroll = xPos - lastScroll ; virtualPos = reversePos ? virtualPos + deltaScroll : virtualPos - deltaScroll ; lastScroll = xPos ; final int width = getClientWidth ( ) ; final float pageOffset = virtualPos / width ; if ( onCardChangeListener != null ) { onCardChangeListener . onCardScrolled ( currentItem , pageOffset , ( int ) virtualPos ) ; } onPageScrolled ( ) ; return true ; }
target:  Called when page is scrolled. Updates virtualPos of page according to scroll position.