ViewPage实现无限轮播画廊效果

1. 效果图

2. 布局文件

主要使用的 android:clipChildren的意思：是否限制子View在其范围内。再父布局和viewpager中设置该属性  ，要显示三个界面 ，还要设置marginleft和marginRight

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent" android:layout_height="match_parent"

    android:clipChildren="false"

    >

    <android.support.v4.view.ViewPager

        android:id="@+id/vp"

        android:layout_width="match_parent"

        android:clipChildren="false"

        android:layout_marginTop="30dp"

        android:layout_marginLeft="60dp"

        android:layout_marginRight="60dp"

        android:layout_height="150dp"></android.support.v4.view.ViewPager>

</RelativeLayout>

3. Adapter

 private class MyAdapter extends PagerAdapter{

        @Override

        public int getCount() {

            return Integer.MAX_VALUE;//无限轮播

        }

        @Override

        public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {

            return view==o;

        }

        @NonNull

        @Override

        public Object instantiateItem(@NonNull ViewGroup container, int position) {

            View view=LayoutInflater.from(Grally2Activity.this).inflate(R.layout.item_vp,null);

            int newwPos=position%(datas.size());//对应数据中的位置

            ImageView img=view.findViewById(R.id.img);

            img.setImageResource(datas.get(newwPos));

            container.addView(view);

            return view;

        }

        @Override

        public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object

                object) {

//            super.destroyItem(container, position, object);

            container.removeView((View) object);

        }

    }

4.关键点PageTransformer

public class Scalltransformer implements ViewPager.PageTransformer {

    private float MINSCALE=0.8f;//最小缩放值

    /**

     * position取值特点：

     * 假设页面从0～1，则：

     * 第一个页面position变化为[0,-1]

     * 第二个页面position变化为[1,0]

     *

     * @param view

     * @param v

     */

    @Override

    public void transformPage(@NonNull View view, float v) {

        float scale;//view  应缩放的值

        if(v>1||v<-1){

            scale=MINSCALE;

        }else if(v<0){

            scale=MINSCALE+(1+v)*(1-MINSCALE);

        }else{

            scale=MINSCALE+(1-v)*(1-MINSCALE);

        }

        view.setScaleY(scale);

        view.setScaleX(scale);

    }

}

5.Activity代码

public class Grally2Activity extends AppCompatActivity {

    @BindView(R.id.vp)

    ViewPager vp;

    private List<Integer> datas=new ArrayList<>();

    @Override

    protected void onCreate(@Nullable Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_grally);

        ButterKnife.bind(this);

        initDatas();

        initVP();

    }

    private void initVP() {

        vp.setPageMargin(20);//设置ViewPager中子布局的间隔

        vp.setOffscreenPageLimit(2);

        vp.setPageTransformer(false,new Scalltransformer());

        vp.setAdapter(new MyAdapter());

        vp.setCurrentItem(Integer.MAX_VALUE/2-(Integer.MAX_VALUE/2%datas.size()));//设置首个轮播显示的位置   实现左右滑动 且首页面对应的是第一个数据

    }

    private void initDatas() {

        datas.add(R.mipmap.p2);

        datas.add(R.mipmap.p3);

        datas.add(R.mipmap.p4);

        datas.add(R.mipmap.p5);

    }

    private class MyAdapter extends PagerAdapter{

        @Override

        public int getCount() {

            return Integer.MAX_VALUE;

        }

        @Override

        public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {

            return view==o;

        }

        @NonNull

        @Override

        public Object instantiateItem(@NonNull ViewGroup container, int position) {

            View view=LayoutInflater.from(Grally2Activity.this).inflate(R.layout.item_vp,null);

            int newwPos=position%(datas.size());

            ImageView img=view.findViewById(R.id.img);

            img.setImageResource(datas.get(newwPos));

            container.addView(view);

            return view;

        }

        @Override

        public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object

                object) {

//            super.destroyItem(container, position, object);

            container.removeView((View) object);

        }

    }

}