ViewPager2使用笔记

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

  <?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>

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));

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();
    }
}

 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);
        }
    }
}

mViewPager.setPageTransformer(new MyPageTransformer());

 <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>

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();