Android开发笔记-Viewpager(2)的双联动效果

为了满足伸手党的需求，先贴上代码

源码

baselinkPageChangeListener.java

public class baselinkPageChangeListener implements ViewPager.OnPageChangeListener {

    private final ViewPager linkViewPager;
    private final ViewPager selfViewPager;

    private int marginX = 0;

    public baselinkPageChangeListener(ViewPager selfViewPager,ViewPager linkViewPager){
        this.linkViewPager = linkViewPager;
        this.selfViewPager = selfViewPager;
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        //计算移动值
        marginX = ((selfViewPager.getWidth() + selfViewPager.getPageMargin()) * position
                + positionOffsetPixels) * (linkViewPager.getWidth() + linkViewPager.getPageMargin()) /
                (selfViewPager.getWidth() + selfViewPager.getPageMargin());

        if (linkViewPager.getScrollX() != marginX) {
            linkViewPager.scrollTo(marginX, 0);
        }
    }

    @Override
    public void onPageSelected(int position) {

    }

    @Override
    public void onPageScrollStateChanged(int state) {
    }
}

Activity.java

public class ViewpagerActivity extends AppCompatActivity {

    private ViewPager mViewpager1;
    private ViewPager mViewpager2;
    private ZoomOutPageTransformer zoomOutPageTransformer;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_viewpage1);
        initView();
    }

    private void initView() {
        mViewpager1 = findViewById(R.id.viewpager1);
        mViewpager2 = findViewById(R.id.viewpager2);
        mViewpager1.setAdapter(new TopViewPgaerAdapter(this));
        mViewpager2.setAdapter(new BottomViewPagerAdapter(this));
        mViewpager1.setOffscreenPageLimit(5);
        mViewpager2.setOffscreenPageLimit(5);

        baselinkPageChangeListener baselinkPageChangeListener = new baselinkPageChangeListener(mViewpager1, mViewpager2);
        mViewpager1.addOnPageChangeListener(baselinkPageChangeListener);

        baselinkPageChangeListener baselinkPageChangeListener1 = new baselinkPageChangeListener(mViewpager2, mViewpager1);
        mViewpager2.addOnPageChangeListener(baselinkPageChangeListener1);
    }

    private static class TopViewPgaerAdapter extends PagerAdapter {

        private Context context;

        public TopViewPgaerAdapter(Context context) {
            this.context = context;
        }

        @Override
        public int getCount() {
            return 5;
        }

        @Override
        public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
            // 判断是不是同一个视图
            return view == object;
        }

        @NonNull
        @Override
        public Object instantiateItem(@NonNull ViewGroup container, int position) {
            View inflate = LayoutInflater.from(context).inflate(R.layout.item_top, container, false);
            container.addView(inflate);
            return inflate;
        }

    }

    private static class BottomViewPagerAdapter extends PagerAdapter {

        private Context context;

        public BottomViewPagerAdapter(Context context) {
            this.context = context;
        }

        @Override
        public int getCount() {
            return 5;
        }

        @Override
        public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
            // 判断是不是同一个视图
            return view == object;
        }

        @NonNull
        @Override
        public Object instantiateItem(@NonNull ViewGroup container, int position) {
            View inflate = LayoutInflater.from(context).inflate(R.layout.item_bottom, container, false);
            container.addView(inflate);
            return inflate;
        }
    }
}

activity_viewpager.xml

item_top.xml

item_bottom.xml

分析

实现思路: 通过ViewPager的OnPageChangeListener监听回调的onPageScrolled(int position, float positionOffset, int positionOffsetPixels)方法来实现联动效果,关键代码如下:

selfViewPager.getWidth() + selfViewPager.getPageMargin() 偏移比例
(selfViewPager.getWidth() + selfViewPager.getPageMargin()) * position + positionOffsetPixels 表示当前手指触摸的ViewPager的总偏移距离
linkViewPager.getWidth() + linkViewPager.getPageMargin() 表示联动的ViewPager的大小

//计算移动值'

// 
marginX = ((selfViewPager.getWidth() + selfViewPager.getPageMargin()) * position
        + positionOffsetPixels) * (linkViewPager.getWidth() + linkViewPager.getPageMargin()) /
        (selfViewPager.getWidth() + selfViewPager.getPageMargin());

if (linkViewPager.getScrollX() != marginX) {
    linkViewPager.scrollTo(marginX, 0);
}

测试


问题


问题产生原因分析
暂未找到原因

解决方案(先上代码)

activity_viewpager.xml

MyLinearLayout.java

public class MyLinearLayout extends LinearLayout {

    private MyLinearLayout otherLinearLayout;

    public MyLinearLayout(Context context) {
        super(context);
    }

    public MyLinearLayout(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public MyLinearLayout(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public MyLinearLayout(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    public LinearLayout getOtherLinearLayout() {
        return otherLinearLayout;
    }

    public void setOtherLinearLayout(MyLinearLayout otherLinearLayout) {
        this.otherLinearLayout = otherLinearLayout;
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        if (otherLinearLayout != null) {
            otherLinearLayout.fakeTouchEvent(ev);
        }
        return super.dispatchTouchEvent(ev);
    }

    public void fakeTouchEvent(MotionEvent ev) {
        super.dispatchTouchEvent(ev);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return super.onTouchEvent(event);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return super.onInterceptTouchEvent(ev);
    }
}

Activity.java

public class ViewPagerActivity extends AppCompatActivity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_viewpage);

        MyLinearLayout  mLinear1 = findViewById(R.id.mLinear1);
        MyLinearLayout  mLinear2 = findViewById(R.id.mLinear2);
        mLinear1.setOtherLinearLayout(mLinear2);
        mLinear2.setOtherLinearLayout(mLinear1);

        ViewPager mViewpager1 = findViewById(R.id.viewpager1);
        ViewPager mViewpager2 = findViewById(R.id.viewpager2);
        mViewpager1.setAdapter(new TopViewPgaerAdapter(this));
        mViewpager2.setAdapter(new BottomViewPagerAdapter(this));
        mViewpager1.setOffscreenPageLimit(5);
        mViewpager2.setOffscreenPageLimit(5);
    }

    private static class TopViewPgaerAdapter extends PagerAdapter {

        private Context context;

        public TopViewPgaerAdapter(Context context) {
            this.context = context;
        }

        @Override
        public int getCount() {
            return 5;
        }

        @Override
        public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
            // 判断是不是同一个视图
            return view == object;
        }

        @NonNull
        @Override
        public Object instantiateItem(@NonNull ViewGroup container, int position) {
            View inflate = LayoutInflater.from(context).inflate(R.layout.item_top, container, false);
            container.addView(inflate);
            return inflate;
        }

    }

    private static class BottomViewPagerAdapter extends PagerAdapter {

        private Context context;

        public BottomViewPagerAdapter(Context context) {
            this.context = context;
        }

        @Override
        public int getCount() {
            return 5;
        }

        @Override
        public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
            // 判断是不是同一个视图
            return view == object;
        }

        @NonNull
        @Override
        public Object instantiateItem(@NonNull ViewGroup container, int position) {
            View inflate = LayoutInflater.from(context).inflate(R.layout.item_parent, container, false);
            container.addView(inflate);
            return inflate;
        }
    }

}

问题: 使用上述代码虽然解决了联动问题，但是在多指滑动时会出现如下问题

解决方案:

禁用多指触控 android:splitMotionEvents="false"

关键代码:

public void setOtherLinearLayout(MyLinearLayout otherLinearLayout) {
    this.otherLinearLayout = otherLinearLayout;
}

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    if (otherLinearLayout != null) {
        otherLinearLayout.fakeTouchEvent(ev);
    }
    return super.dispatchTouchEvent(ev);
}

public void fakeTouchEvent(MotionEvent ev) {
    super.dispatchTouchEvent(ev);
}

可能连你页没有想到，竟然能使用这么少的代码的量解决了联动的问题，而且滑动起来还很丝滑，viewpager2也是使用这种方式来解决的，而且Viewpager2运行起来更加的丝滑，毫无违和感，这一切还得归功于享学课堂的Colin老师，目前网上大部分的教程在viewpager上实现双联动都是使用滑动监听回调和继承viewpager的方式来解决问题。自从加入了享学课堂，才两个多月老板就给涨了两千薪水，之前同事做不出来的功能，我参考享学课堂老师讲的都解决了，哈哈，以后我就要跟着Colin老师学习下去。

废话不多说，viewpager2实现双联动直接上代码

activity_viewpager2.xml

fragment_test.xml

ViewPager2Activity.java

public class ViewPager2Activity extends AppCompatActivity {

    private List fragments = new ArrayList<>();
    private List fragments2 = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ViewPager2 viewPager = findViewById(R.id.viewPager);
        ViewPager2 viewPager2 = findViewById(R.id.viewPager2);

        MyLinearLayout linearLayout1 = findViewById(R.id.linearLayout1);
        MyLinearLayout linearLayout2 = findViewById(R.id.linearLayout2);
        linearLayout1.setOtherLinearLayout(linearLayout2);
        linearLayout2.setOtherLinearLayout(linearLayout1);

        fragments.add( new OneFragment());
        fragments.add( new TwoFragment());
        fragments.add( new ThreeFragment());

        fragments2.add( new OneFragment());
        fragments2.add( new TwoFragment());
        fragments2.add( new ThreeFragment());

        viewPager.setAdapter(new ViewPagerAdapter(this,fragments));
        viewPager2.setAdapter(new ViewPagerAdapter(this,fragments2));
    }
}

ViewPagerAdapter.java

public class ViewPagerAdapter extends FragmentStateAdapter {

    private final List fragments;

    public ViewPagerAdapter(@NonNull FragmentActivity fragmentActivity, List fragments) {
        super(fragmentActivity);
        this.fragments = fragments;
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        return fragments.get(position);
    }

    @Override
    public int getItemCount() {
        return fragments == null ? 0 : fragments.size();
    }
}

OneFragment.java

public class TestFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_test, container, false);
    }
}

TwoFragment.java

public class TwoFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_test, container, false);
    }
}

ThreeFragment.java

public class ThreeFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_test, container, false);
    }
}

效果:

看到没，要多丝滑，就有多丝滑，而且viewpager和viewpager2都是可以通用的，简简单单的代码就实现了，这一切都得感谢享学课堂的Colin老师，他们有着丰富的Android开发经验和前沿的开发技术，此刻都是独一无二的技术，好了，不多说了，我得找老师学习高级技术去了，学到了再分享给大家