仅第一次下一页的ViewPager部分视图

Question

I want to tell the user that s/he can swipe to change page. So I want to show a partial view of the next page. But that only the very first time. So I figure I would use the code

boolean mFirstTime = true;
@Override
public float getPageWidth(int position) {
  if (position == 0 && mFirstTime) {
    mFirstTime = false;
    return 0.9f;
  }
  return 1f;
}

But my mFirstTime has no apparent effect. Does anyone know a way to achieve my end? I image I could use a listener of sort, but I don't know what would go inside the listener.

Update

Alternatively I tried the snippet below to no avail.

myPager.beginFakeDrag();
myPager.fakeDragBy(Utils.dpToPx(this, 50));
myPager.endFakeDrag();

where the subroutine is

public static int dpToPx(Context context, int dp) {
  return (int) Math.ceil(dp * context.getResources().getDisplayMetrics().density);
}

Answer 1

You need to do the following for it to work.

1. if you're not extending FragmentStatePagerAdapter -> you need to extand that instead of just PagerAdapter

2. You need to override the method

    @Override public int getItemPosition(Object obj){ return POSITION_NONE; //will cause data reload } 

and when you're ready to display the page at full size, call adapter.notifyDataSetChanged()

which will cause the getPageWidth() to be called for each page again, making it grow