ViewPager显示next和前项preVIEW当前页面

问题描述

我想告诉viewpager下一之前页面preVIEW屏幕。前后翻页深秀在深屏幕动画和幻灯片翻页。

I want to show viewpager next and before page preview in screen. Before and next page show deep in screen and slide next page with deep animation.

您可以看一下这个图片

我该怎么办呢？

推荐答案

最后，我做到了:)我修改这个答案Android - 轮播像插件，其显示左和右元素的一部分

Finally, i did it :) I modify this answer Android - Carousel like widget which displays a portion of the left and right elements

您可以看看这个code。

You can look this code.

//pager settings
          pager.setClipToPadding(false);
          pager.setPageMargin(24);
          pager.setPadding(48, 8, 48, 8);
          pager.setOffscreenPageLimit(3);
          pager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

             @Override
             public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
                Log.i("", "onPageScrolled: " + position);

                CampaignPagerFragment sampleFragment = (CampaignPagerFragment) ((CampaignPagerAdapter) pager.getAdapter()).getRegisteredFragment(position);


                float scale = 1 - (positionOffset * RATIO_SCALE);

                // Just a shortcut to findViewById(R.id.image).setScale(scale);
                sampleFragment.scaleImage(scale);


                if (position + 1 < pager.getAdapter().getCount()) {
                   sampleFragment = (CampaignPagerFragment) ((CampaignPagerAdapter) pager.getAdapter()).getRegisteredFragment(position + 1);
                   scale = positionOffset * RATIO_SCALE + (1 - RATIO_SCALE);
                   sampleFragment.scaleImage(scale);
                }
             }

             @Override
             public void onPageSelected(int position) {
                Log.i("", "onPageSelected: " + position);
             }

             @Override
             public void onPageScrollStateChanged(int state) {
                Log.i("", "onPageScrollStateChanged: " + state);
                if (state == ViewPager.SCROLL_STATE_IDLE) {
                   CampaignPagerFragment fragment = (CampaignPagerFragment) ((CampaignPagerAdapter) pager.getAdapter()).getRegisteredFragment(pager.getCurrentItem());
                   fragment.scaleImage(1);
                   if (pager.getCurrentItem() > 0) {
                      fragment = (CampaignPagerFragment) ((CampaignPagerAdapter) pager.getAdapter()).getRegisteredFragment(pager.getCurrentItem() - 1);
                      fragment.scaleImage(1 - RATIO_SCALE);
                   }

                   if (pager.getCurrentItem() + 1 < pager.getAdapter().getCount()) {
                      fragment = (CampaignPagerFragment) ((CampaignPagerAdapter) pager.getAdapter()).getRegisteredFragment(pager.getCurrentItem() + 1);
                      fragment.scaleImage(1 - RATIO_SCALE);
                   }
                }

             }
          });

---

//PagerAdapter

public class CampaignPagerAdapter extends FragmentStatePagerAdapter {
   SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>();

   public CampaignPagerAdapter(FragmentManager fm) {
      super(fm);
   }

   @Override
   public int getCount() {
      return 5;
   }

   @Override
   public Fragment getItem(int position) {
      return new CampaignPagerFragment();
   }

   @Override
   public Object instantiateItem(ViewGroup container, int position) {
      Fragment fragment = (Fragment) super.instantiateItem(container, position);
      registeredFragments.put(position, fragment);
      return fragment;
   }

   @Override
   public void destroyItem(ViewGroup container, int position, Object object) {
      registeredFragments.remove(position);
      super.destroyItem(container, position, object);
   }

   public Fragment getRegisteredFragment(int position) {
      return registeredFragments.get(position);
   }
}

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