Android使用viewpager实现画廊式效果

public class ZoomOutPageTransformer implements ViewPager.PageTransformer {
 //自由控制缩放比例
 private static final float MAX_SCALE = 1f;
 private static final float MIN_SCALE = 0.8f;//0.85f
 
 @Override
 public void transformPage(View page, float position) {
 
  if (position <= 1) {
 
   float scaleFactor = MIN_SCALE + (1 - Math.abs(position)) * (MAX_SCALE - MIN_SCALE);
 
   page.setScaleX(scaleFactor);
 
   if (position > 0) {
    page.setTranslationX(-scaleFactor * 2);
   } else if (position < 0) {
    page.setTranslationX(scaleFactor * 2);
   }
   page.setScaleY(scaleFactor);
  } else {
 
   page.setScaleX(MIN_SCALE);
   page.setScaleY(MIN_SCALE);
  }
 }
}

public class MyAdapter extends PagerAdapter {
 
 private int[] mData;
 private Context mContext;
 
 public MyAdapter(Context ctx, int[] data) {
  this.mContext = ctx;
  this.mData = data;
 }
 
 @Override
 public int getCount() {
  return mData.length;// 返回数据的个数
 }
 
 @Override
 public Object instantiateItem(final ViewGroup container, final int position) {//子View显示
  View view = View.inflate(container.getContext(), R.layout.item, null);
  ImageView imageView = view.findViewById(R.id.iv_icon);
  imageView.setImageResource(mData[position]);
 
  imageView.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View view) {
    Toast.makeText(mContext, \"当前条目：\" + position, Toast.LENGTH_SHORT).show();
   }
  });
 
  container.addView(view);//添加到父控件
  return view;
 }
 
 @Override
 public boolean isViewFromObject(View view, Object object) {
  return view == object;// 过滤和缓存的作用
 }
 
 @Override
 public void destroyItem(ViewGroup container, int position, Object object) {
  container.removeView((View) object);//从viewpager中移除掉
 }
}

<?xml version=\"1.0\" encoding=\"utf-8\"?>
<LinearLayout xmlns:android=\"http://schemas.android.com/apk/res/android\"
 android:orientation=\"vertical\"
 android:layout_width=\"match_parent\"
 android:layout_height=\"match_parent\">
 <ImageView
  android:id=\"@+id/iv_icon\"
  android:layout_width=\"match_parent\"
  android:scaleType=\"centerCrop\"
  android:src=\"@mipmap/ic_launcher\"
  android:layout_height=\"match_parent\"/>
</LinearLayout>

<?xml version=\"1.0\" encoding=\"utf-8\"?>
<LinearLayout xmlns:android=\"http://schemas.android.com/apk/res/android\"
 android:id=\"@+id/ll_layout\"
 android:layout_width=\"match_parent\"
 android:layout_height=\"match_parent\"
 android:clipChildren=\"false\"
 android:orientation=\"vertical\">
 
 <TextView
  android:layout_width=\"match_parent\"
  android:layout_height=\"wrap_content\"
  android:gravity=\"center\"
  android:padding=\"5dp\"
  android:text=\"viewpager实现画廊效果\"
  android:textColor=\"@color/colorPrimary\"/>
 
 <androidx.viewpager.widget.ViewPager
  android:id=\"@+id/viewPager\"
  android:layout_width=\"200dp\"
  android:layout_height=\"300dp\"
  android:layout_gravity=\"center\"
  android:layout_marginBottom=\"30dp\"
  android:clipChildren=\"false\"
  android:layout_marginTop=\"30dp\"/>
</LinearLayout>

public class MainActivity extends AppCompatActivity {
 private ViewPager mViewPager;
 private LinearLayout ll_layout;
 
 //向导界面的图片
 private int[] mPics = new int[]{R.mipmap.ic_launcher, R.mipmap.ic_launcher, R.mipmap.ic_launcher, R.mipmap.ic_launcher, R.mipmap.ic_launcher};
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  initView();
 }
 
 private void initView() {
  mViewPager = (ViewPager) findViewById(R.id.viewPager);
  ll_layout = (LinearLayout) findViewById(R.id.ll_layout);
 
  //设置适配器
  mViewPager.setAdapter(new MyAdapter(this, mPics));
  mViewPager.setPageMargin(20);
  mViewPager.setOffscreenPageLimit(mPics.length);
  mViewPager.setPageTransformer(true, new ZoomOutPageTransformer());//设置画廊模式
 
  //左右都有图
  mViewPager.setCurrentItem(1);
 
  //viewPager左右两边滑动无效的处理
  ll_layout.setOnTouchListener(new View.OnTouchListener() {
   @Override
   public boolean onTouch(View view, MotionEvent motionEvent) {
    return mViewPager.dispatchTouchEvent(motionEvent);
   }
  });
 }
}