android - Differentiating between user scroll and programatic page change in ViewPager -

i have android.support.v4.view.viewpager in application , differentiate between programmatically-initiated smooth scroll , user-initiated touch scroll.

i've had @ viewpager.onpagechangelistener , believe answer may lie in there i'm not sure how.

ok, turns out right answer lying in viewpager.onpagechangelistener. in particular lies in using onpagescrollstatechanged(int state). there 3 states page in viewpager can in:

1. dragging: indicates pager being dragged user.
2. idle: indicates pager in idle, settled state.
3. settling: indicates pager in process of settling final position.

so dragging state occurs when current page being physically dragged user. when user has swiped page states occur in following order: dragging -> settling -> idle. now, onpageselected(int position) method called between "settling" , "idle" states. thus, in order determine whether or not page change caused user scroll 1 needs check previous state "dragging" , current state "settling". can keep boolean variable track whether or not page change user initiated or not , check in onpageselected(int position) method.

here onpagescrollstatechanged method

public void onpagescrollstatechanged(int state)  {     if (previousstate == viewpager.scroll_state_dragging             && state == viewpager.scroll_state_settling)         userscrollchange = true;      else if (previousstate == viewpager.scroll_state_settling             && state == viewpager.scroll_state_idle)         userscrollchange = false;      previousstate = state; } 

the if , else if statements need not explicit did clarity.