How to use

getWidth

method

in

androidx.viewpager.widget.ViewPager

private int computeInitialViewPagerScroll(MotionEvent downEvent) {
  // ViewPager can be in intermediate position, we should compute correct initial scroll
  int scroll = viewPager.getScrollX();
  int pageWidth = viewPager.getWidth() + viewPager.getPageMargin();
  // After state restore ViewPager can return negative scroll, let's fix it
  while (scroll < 0) {
    scroll += pageWidth;
  }
  int touchedItem = (int) ((scroll + downEvent.getX()) / pageWidth);
  return pageWidth * touchedItem - scroll;
}

  @Override
  public void run() {
    Activity activity = fragment.getActivity();
    if (fragment.isAdded() && activity != null) {
      fragment.mRecyclerView.startAnimation(AnimationUtils.loadAnimation(
          activity, R.anim.slide_in_bottom));
      int cx = fragment.mViewPager.getWidth();
      SupportAnimator animator = ViewAnimationUtils.createCircularReveal(
          fragment.mViewPager, cx / 2, 0, 0, cx);
      animator.addListener(new SupportAnimator.SimpleAnimatorListener() {
        @Override
        public void onAnimationStart() {
          super.onAnimationStart();
          fragment.mViewPager.setVisibility(View.VISIBLE);
        }
        @Override
        public void onAnimationEnd() {
          super.onAnimationEnd();
          fragment.mViewPagerShadow.setVisibility(View.VISIBLE);
        }
      });
      animator.setDuration(400);
      animator.start();
    }
  }
});