在Android中利用viewpager实现一个画廊式效果

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
 }
}

<&#63;xml version="1.0" encoding="utf-8"&#63;>
<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>

<&#63;xml version="1.0" encoding="utf-8"&#63;>
<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);
   }
  });
 }
}