ViewPager单页显示3个item

原文地址：https://github.com/hongyangAndroid/MagicViewPager/wiki

MagicViewPager

单页显示3个Item的ViewPager炫酷切换效果，适用于Banner等。

效果图

• Rotate Y

• Rotate Down

• Rotate Up

• Alpha

• ScaleIn

• ScaleIn + Alpha + Rotate Down

使用

###（1）引入

compile `com.zhy:magic-viewpager:1.0.1`

###（2）示例

• 布局文件

<FrameLayout

    android:layout_width="match_parent"

    android:layout_height="160dp"

    android:clipChildren="false"

    android:layout_centerInParent="true"

    android:background="#aadc71ff"

    >

    <android.support.v4.view.ViewPager

        android:id="@+id/id_viewpager"

        android:layout_width="match_parent"

        android:layout_marginLeft="60dp"

        android:clipChildren="false"

        android:layout_marginRight="60dp"

        android:layout_height="120dp"

        android:layout_gravity="center"

        >

    </android.support.v4.view.ViewPager>

</FrameLayout>

注意外层android:layout_centerInParent="true".（貌似其实没什么影响）

• 编码

mViewPager.setPageMargin(20);//设置page间间距，自行根据需求设置

mViewPager.setOffscreenPageLimit(3);//>=3

mViewPager.setAdapter...//写法不变

//setPageTransformer 决定动画效果

mViewPager.setPageTransformer(true, new RotateDownPageTransformer());

##目前可选动画

• AlphaPageTransformer
• RotateDownPageTransformer
• RotateUpPageTransformer
• RotateYTransformer
• NonPageTransformer
• ScaleInTransformer

动画间可以自由组合，例如：

mViewPager.setPageTransformer(true,new RotateDownPageTransformer(new AlphaPageTransformer(new ScaleInTransformer())));

需求：

1.一个页面显示三个item

2.viewpager无限循环

3.定时滑动

4.长条形小点

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

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

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="wrap_content"

    android:background="#aadc71ff"

    android:clipChildren="false"

    tools:context="com.example.administrator.banner2.MainActivity">

    <android.support.v4.view.ViewPager

        android:id="@+id/viewpager"

        android:layout_width="match_parent"

        android:layout_height="150dp"

        android:layout_gravity="center"

        android:layout_marginBottom="10dp"

        android:layout_marginLeft="30dp"

        android:layout_marginRight="30dp"

        android:layout_marginTop="10dp"

        android:clipChildren="false"></android.support.v4.view.ViewPager>

    <LinearLayout

        android:id="@+id/dotLayout"

        android:layout_width="match_parent"

        android:layout_height="10dp"

        android:layout_gravity="bottom"

        android:layout_marginBottom="10dp"

        android:gravity="center"

        android:orientation="horizontal"></LinearLayout>

</FrameLayout>

import android.os.Bundle;

import android.os.Handler;

import android.support.v4.view.PagerAdapter;

import android.support.v4.view.ViewPager;

import android.support.v7.app.AppCompatActivity;

import android.view.View;

import android.view.ViewGroup;

import android.widget.ImageView;

import android.widget.LinearLayout;

import android.widget.RelativeLayout;

import com.zhy.magicviewpager.transformer.ScaleInTransformer;

import java.util.Timer;

import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {

    private ViewPager mViewPager;

    private PagerAdapter mAdapter;

    private LinearLayout dotLayout;

    private Timer timer;

    private Handler mHandler = new Handler();

    private int prePosition = 0;

    int[] imgRes = {R.drawable.a, R.drawable.b, R.drawable.c, R.drawable.d,

            R.drawable.e, R.drawable.f, R.drawable.g, R.drawable.h, R.drawable.i};

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        mViewPager = (ViewPager) findViewById(R.id.viewpager);

        dotLayout = (LinearLayout) findViewById(R.id.dotLayout);

        initDots();

        mViewPager.setPageMargin(20);

        mViewPager.setOffscreenPageLimit(3);

        mViewPager.setAdapter(mAdapter = new PagerAdapter() {

            @Override

            public Object instantiateItem(ViewGroup container, int position) {

                ImageView view = new ImageView(MainActivity.this);

                view.setScaleType(ImageView.ScaleType.FIT_XY);

                view.setImageResource(imgRes[position % imgRes.length]);

                container.addView(view);

                return view;

            }

            @Override

            public void destroyItem(ViewGroup container, int position, Object object) {

                container.removeView((View) object);

            }

            @Override

            public int getCount() {

                return Integer.MAX_VALUE;

            }

            @Override

            public boolean isViewFromObject(View view, Object o) {

                return view == o;

            }

        });

        mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {

            @Override

            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override

            public void onPageSelected(int position) {

                dotLayout.getChildAt(prePosition).setEnabled(false);

                dotLayout.getChildAt(position % imgRes.length).setEnabled(true);

                prePosition = position % imgRes.length;

            }

            @Override

            public void onPageScrollStateChanged(int state) {

            }

        });

        mViewPager.setPageTransformer(true, new ScaleInTransformer());

        if (null != timer) {

            timer.cancel();

        }

        timer = new Timer();

        timer.schedule(new TimerTask() {

            @Override

            public void run() {

                mHandler.post(new Runnable() {

                    @Override

                    public void run() {

                        mViewPager.setCurrentItem(mViewPager.getCurrentItem() + 1);

                    }

                });

            }

        }, 0, 1000);

    }

    private void initDots() {

        if (null != dotLayout) {

            dotLayout.removeAllViews();

        }

        for (int i = 0; i < imgRes.length; i++) {

            ImageView dot = new ImageView(this);

            dot.setEnabled(false);

            dot.setImageResource(R.drawable.dot);

            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);

            params.leftMargin = 10;

            dot.setLayoutParams(params);

            dotLayout.addView(dot);

        }

        dotLayout.getChildAt(0).setEnabled(true);

    }

}

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

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

    <item android:state_enabled="true">

        <shape android:shape="rectangle">

            <size android:width="15dp" android:height="3dp"></size>

            <corners android:radius="10dp" />

            <solid android:color="#ff0000" />

        </shape>

    </item>

    <item android:state_enabled="false">

        <shape android:shape="rectangle">

            <size android:width="15dp" android:height="3dp"></size>

            <corners android:radius="10dp" />

            <solid android:color="#ffffff" />

        </shape>

    </item>

</selector>