Android ViewPager上一页和下一页可见？

@Override
public Object instantiateItem(ViewGroup container, int position) {
    View view = getView(position);
    container.addView(view);
    view.setScaleX(getPageScale(position));
    view.setScaleY(getPageScale(position));
    return view;
}

private float getPageScale(int position) {
    if (position == 0 || position == getCount() - 1) {
        return 0.8f; // 上一页和下一页的可见比例
    } else {
        return 1.0f; // 当前页面的可见比例
    }
}

viewPager.setPageTransformer(true, new ViewPager.PageTransformer() {
    @Override
    public void transformPage(View page, float position) {
        if (position < -1 || position > 1) {
            page.setScaleX(0.8f);
            page.setScaleY(0.8f);
        } else if (position == 0) {
            page.setScaleX(1.0f);
            page.setScaleY(1.0f);
        } else {
            page.setScaleX(0.8f + 0.2f * (1 - Math.abs(position)));
            page.setScaleY(0.8f + 0.2f * (1 - Math.abs(position)));
        }
    }
});