Question

我有一个 ViewPager为4个标签的片段，在第四个标签中我有另一个带有3个标签的Viewpager，以便每当我切换我的topviewPagerTab时（一个有4个选项卡）然后子视图中的片段的setUserVisiblehint（带有3个选项卡）不被称为。

所以实际上，第4个/最后一个标签的sub viewPager中的片段对于用户是不可见的，但是 setUserVisibleHint（）没有被调用，因此我的布尔值 isMyPageVisible被设置为除非我在subviewPager

中切换标签，否则访问该片段对他们来说总是如此

boolean isPageVisible = false;

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    isPageVisible = isVisibleToUser;
}

Answer 1

public class UserAdapter extends FragmentPagerAdapter
{
    private ArrayList<Fragment> fragments;

    public UserAdapter(FragmentManager fm, ArrayList<Fragment> fragments)
    {
        super(fm);
        this.fragments = fragments;
    }

    public void clearFragment()
    {
        fragments.clear();
    }

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

    @Override
    public int getCount() {
        return fragments.size();
    }


    public void setUserVisibleHint(boolean isUserVisibleHint)
    {
        if(viewPagerPojos != null && viewPagerPojos.size() > 0)
        {
            for(ViewPagerPojo viewPagerPojo : viewPagerPojos)
            {
                viewPagerPojo.getFragment().setUserVisibleHint(isUserVisibleHint);
            }
        }
    }

}

并在每个片段中

@Override
public void setUserVisibleHint(boolean isVisible) {
    super.setUserVisibleHint(isVisible);
    if (mAdaptor != null) {
     mAdaptor.setUserVisibleHint(isVisible);
    }
}

和子片段

boolean isPageVisible;

@Override
public void setUserVisibleHint(boolean isVisibleHint) 
{
    isPageVisible = this.isVisible() && isVisibleHint;
    super.setUserVisibleHint(isPageVisible);
}

Answer 2

问题在于，当您在外部片段之间移动时，不会调用内部viewpager中显示的当前片段的setUserVisibleHint。扩展FragmentStatePagerAdaptor

public class CustomPagerAdaptor extends FragmentStatePagerAdaptor {
    private Fragment primary;

    @Override
    public void setPrimaryItem(ViewGroup container, int position, Object object) {
        super.setPrimaryItem(container, position, object);
        primary = (Fragment)object;
    }

    public void setUserVisibleHint(boolean isVisible) {
        if (primary != null){
            primary.setUserVisibleHint(isVisible);
        }
    }
}

在外部片段中通过setUserVisibleHint传递：

@Override
public void setUserVisibleHint(boolean isVisible) {
    super.setUserVisibleHint(isVisible);
    if (mAdaptor != null) mAdaptor.setUserVisibleHint(isVisible);
}

片段setUserVisibleHint未在另一个ViewPager内的Viewpager中调用

2 个答案: