android - ViewPager setCurrentItem(pageId, true) does NOT smoothscroll

Question

I am compiling on SDK 4.03, Samsung Infuse Android 2.2, Support Library for Android 4, and using ViewPager in my app, actual swipe works fine, but when I do

viewPager.setCurrentItem(id); // , or
viewPager.setCurrentItem(id, true);  

It does not smooth scroll, but switches views instantly. Although the documentation clearly states that that is the purpose setting the second argument to true. Whats up with this?

Answer 1

I've fixed this by creating a MyViewPager that overrides the ViewPager.mScroller using reflection.

public class MyViewPager extends ViewPager {

    public MyViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
        setMyScroller();
    }

    private void setMyScroller() {
        try {
            Class<?> viewpager = ViewPager.class;
            Field scroller = viewpager.getDeclaredField("mScroller");
            scroller.setAccessible(true);
            scroller.set(this, new MyScroller(getContext()));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public class MyScroller extends Scroller {
        public MyScroller(Context context) {
            super(context, new DecelerateInterpolator());
        }

        @Override
        public void startScroll(int startX, int startY, int dx, int dy, int duration) {
            super.startScroll(startX, startY, dx, dy, 1000 /*1 secs*/);
        }
    }
}