ViewPager2使用笔记

发表于 更新于 分类于 Changyan：

一.代码位置

XTester-fragment+tab+viewpager2

二.引用

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implementation 'com.google.android.material:material:1.2.1'
implementation "androidx.viewpager2:viewpager2:1.0.0"

三.实现

  • 基本效果

    • xml

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         <?xml version="1.0" encoding="utf-8"?>
      <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:app="http://schemas.android.com/apk/res-auto"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:orientation="vertical">

          <androidx.viewpager.widget.ViewPager
              android:id="@+id/_vp"
              android:layout_width="match_parent"
              android:layout_height="0dp"
              android:layout_weight="1"
              />
      </LinearLayout>

    • java

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      mViewPager = findViewById(R.id.viewpager2);
      mAdapter = new ViewPager2Adapter(this);
      mViewPager.setAdapter(mAdapter);
      mViewPager.setOrientation(ViewPager2.ORIENTATION_HORIZONTAL); //设置ViewPager2滑动方向  ORIENTATION_VERTICAL
      fragments.add(new Fragment1(mViewPager));
      fragments.add(new Fragment2(mViewPager));

    • FragmentStateAdapter

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      class ViewPager2Adapter extends FragmentStateAdapter {
          public ViewPager2Adapter(FragmentActivity fragmentActivity) {
              super(fragmentActivity);
          }

          @Override
          public Fragment createFragment(int position) {
              return fragments.get(position);
          }

          @Override
          public int getItemCount() {
              return fragments.size();
          }
      }

    • 横向效果图

  - 纵向效果图

  • 根据PageTransformer做渐变效果

    • ViewPager2.PageTransformer 
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          public class MyPageTransformer implements ViewPager2.PageTransformer {

          private static final float ROT_MAX = 20.0f;
          private float mRot;
          private static float MIN_SCALE = 0.75f;
          private static float MIN_ALPHA = 0.5f;

          /**
           * @param view     滑动中的那个view
           * @param position
           */
          public void transformPage(View view, float position) {

              int pageWidth = view.getWidth();
              if (position < -1) { // [-Infinity,-1)//This page is way off-screen to the left.
                  view.setAlpha(0);
              } else if (position <= 0) { // [-1,0]Use //the default slide transition when moving to the left page
                  view.setAlpha(1);
                  view.setTranslationX(0);
                  view.setScaleX(1);
                  view.setScaleY(1);
              } else if (position <= 1) { // (0,1]// Fade the page out.
                  view.setAlpha(1 - position);
                  // Counteract the default slide transition
                  view.setTranslationX(pageWidth * -position);
                  // Scale the page down (between MIN_SCALE and 1)
                  float scaleFactor = MIN_SCALE + (1 - MIN_SCALE)
                          * (1 - Math.abs(position));
                  view.setScaleX(scaleFactor);
                  view.setScaleY(scaleFactor);
              } else { // (1,+Infinity]
                  // This page is way off-screen to the right.
                  view.setAlpha(0);
              }
          }
      }
    • activity中设置
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      mViewPager.setPageTransformer(new MyPageTransformer());
    • 横向效果图
    • 纵向效果图

  • 与Tab联动

    • xml
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         <com.google.android.material.tabs.TabLayout
          android:layout_width="match_parent"
          app:tabGravity="fill"
          app:tabMode="fixed"
          android:id="@+id/_tab"
          android:layout_height="wrap_content">
      </com.google.android.material.tabs.TabLayout>
    • abLayoutMediator 
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      private TabLayoutMediator mediator;
      private List<String> mTitle;
      TabLayout mTabLayout;
          ...
              mTitle = new ArrayList<>();
              mTitle.add("播放界面");
              mTitle.add("歌曲界面");
          mTabLayout = (TabLayout)findViewById(R.id._tab);
             mediator = new TabLayoutMediator(mTabLayout, mViewPager, new TabLayoutMediator.TabConfigurationStrategy() {
              @Override
              public void onConfigureTab(TabLayout.Tab tab, int position) {
                  TextView tabView = new TextView(Activity.this);
                  tabView.setText(mTitle.get(position));
                  tabView.setTextColor(getColor(R.color.design_default_color_primary));
                  tab.setCustomView(tabView);
              }
          });
          mediator.attach();
    • 效果图