ViewPager 在屏幕上显示下一个和之前的项目预览

Question

我想在屏幕中的页面预览之前和之前显示 viewpager。前一页和下一页显示在屏幕深处，并用深度动画滑动下一页。

你可以看看这张图

我该怎么做？

Answer 1

您可以将 PagerTransformer 用于 ViewPager :-

mViewPager.setPageTransformer(false, new ViewPager.PageTransformer() {
     @Override
     public void transformPage(View page, float position) {
             // do transformation here
      }
     });

使用此 link 获得完整教程：-

http://andraskindler.com/blog/2013/create-viewpager-transitions-a-pagertransformer-example/

希望对您有所帮助:)

Answer 2

终于，我做到了:)我修改了这个答案Android - Carousel like widget which displays a portion of the left and right elements

你可以看看这段代码。

//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);
   }
}

例如：https://github.com/mrleolink/SimpleInfiniteCarousel..

您好，少了一件东西 sampleFragment.scaleImage（规模）；它是在 CampaignPagerFragment 中创建的一种方法，它缩放片段 rootView..

例如public void scaleImage(float scaleX) { rootView.setScaleY(scaleX); rootView.invalidate(); }

Answer 3

viewPager.setPageMargin(100);
viewPager.setPageTransformer(false, new ViewPager.PageTransformer()
{
    @Override
    public void transformPage(View page, float position)
    {
        int pageWidth = viewPager.getMeasuredWidth() -
            viewPager.getPaddingLeft() - viewPager.getPaddingRight();
        int pageHeight = viewPager.getHeight();
        int paddingLeft = viewPager.getPaddingLeft();
        float transformPos = (float) (page.getLeft() -
            (viewPager.getScrollX() + paddingLeft)) / pageWidth;
        int max = pageHeight / 10;
        if (transformPos < -1)
        {
            // [-Infinity,-1)
            // This page is way off-screen to the left.
            page.setAlpha(0.5f);// to make left transparent
            page.setScaleY(0.7f);
        }
        else if (transformPos <= 1)
        {
            // [-1,1]
            page.setScaleY(1f);
        }
        else
        {
            // (1,+Infinity]
            // This page is way off-screen to the right.
            page.setAlpha(0.5f);// to make right transparent
            page.setScaleY(0.7f);
        }
    }
});

Answer 4

I did this by changing my viewpager's padding based on the position.

carouselViewHolder.carouselViewPager.setPadding(Utils.dpToPixels(context, 12), 0, Utils.dpToPixels(context, paddingRequired - 12), 0); // initial padding for position 0
carouselViewHolder.carouselViewPager.setPageMargin(Utils.dpToPixels(context, 12)); // margin between pages
carouselViewHolder.carouselViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    }
    @Override
    public void onPageSelected(int position) {
        if (position != 0) {
            if (position == playCardData.getPlayCards().size() - 1) {
                carouselViewHolder.carouselViewPager.setPadding(Utils.dpToPixels(context, finalPaddingRequired - 12), 0, Utils.dpToPixels(context, 12), 0);
            } else
                carouselViewHolder.carouselViewPager.setPadding(Utils.dpToPixels(context, finalPaddingRequired / 2), 0, Utils.dpToPixels(context, finalPaddingRequired / 2), 0);
        } else {
            carouselViewHolder.carouselViewPager.setPadding(Utils.dpToPixels(context, 12), 0, Utils.dpToPixels(context, finalPaddingRequired - 12), 0);
        }
    }
    @Override
    public void onPageScrollStateChanged(int state) {
    }
});

Answer 5

我认为这是最简单、最干净的解决方案。

float scaleFactor = 0.85f;
viewPager.setPageMargin(-35);
viewPager.setOffscreenPageLimit(2);
viewPager.setPageTransformer(false, new ViewPager.PageTransformer() {
    @Override
    public void transformPage(@NonNull View page, float position) {
        page.setScaleY((1 - Math.abs(position) * (1 - scaleFactor)));
        page.setScaleX(scaleFactor + Math.abs(position) * (1 - scaleFactor));
    }
});

ViewPager 在屏幕上显示下一个和之前的项目预览

ViewPager show next and before item preview on screen

android

pager

android-viewpager