SherlockFragments在ViewPager中的可見性問題（薑餅）

Question

我已經使用ViewPager滾動片段。

雖然在薑餅測試有一個奇怪的發出─

After scrolling first two tabs, the visibility of all fragments GONE completely 

這樣繼續下去，直到我改變方向。 此問題僅在薑餅設備啓動時發生。它在ICS和其他方面工作正常。

這裏是TabsAdapter

/** 
* This is a helper class that implements the management of tabs and all 
* details of connecting a ViewPager with associated TabHost. It relies on a 
* trick. Normally a tab host has a simple API for supplying a View or 
* Intent that each tab will show. This is not sufficient for switching 
* between pages. So instead we make the content part of the tab host 0dp 
* high (it is not shown) and the TabsAdapter supplies its own dummy view to 
* show as the tab content. It listens to changes in tabs, and takes care of 
* switch to the correct paged in the ViewPager whenever the selected tab 
* changes. 
*/ 
private class TabsAdapter extends FragmentPagerAdapter implements 
     ViewPager.OnPageChangeListener, ActionBar.TabListener { 
    private final Context mContext; 
    private final ActionBar mActionBar; 
    private final ViewPager mViewPager; 
    private final List<String> mTabs = new ArrayList<String>(); 
    private final List<Integer> mTabsId = new ArrayList<Integer>(); 
    private boolean hasClearedDetails = false; 


    private int mCurrentPosition = -1; 
    /** 
    * Used during page migration, to remember the next position 
    * {@link #onPageSelected(int)} specified. 
    */ 
    private int mNextPosition = -1; 

    public TabsAdapter(FragmentActivity activity, ActionBar actionBar, ViewPager pager) { 
     super(activity.getSupportFragmentManager()); 
     mContext = activity; 
     mActionBar = actionBar; 
     mViewPager = pager; 
     mViewPager.setAdapter(this); 
     mViewPager.setOnPageChangeListener(this); 
    } 

    public void addTab(ActionBar.Tab tab, Class<?> clss, int tabId) { 
     mTabs.add(clss.getName()); 
     mTabsId.add(tabId); 
     mActionBar.addTab(tab.setTabListener(this)); 
     notifyDataSetChanged(); 
    } 

    public void removeTabAt(int location) { 
     mTabs.remove(location); 
     mTabsId.remove(location); 
     mActionBar.removeTabAt(location); 
     notifyDataSetChanged(); 
    } 

    public Integer getIdForPosition(int position) { 
     if(position >= 0 && position < mTabsId.size()) { 
      return mTabsId.get(position); 
     } 
     return null; 
    } 

    public Integer getPositionForId(int id) { 
     int fPos = mTabsId.indexOf(id); 
     if(fPos >= 0) { 
      return fPos; 
     } 
     return null; 
    } 

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

    @Override 
    public Fragment getItem(int position) { 
     return Fragment.instantiate(mContext, mTabs.get(position), new Bundle()); 
    } 

    @Override 
    public void onTabSelected(Tab tab, FragmentTransaction ft) { 
     clearDetails(); 
     if (mViewPager.getCurrentItem() != tab.getPosition()) { 
      Log.e(THIS_FILE+"Anurag debugging","ISSUE HERE"); 
      mViewPager.setCurrentItem(tab.getPosition(), true); 
     } 
    } 

    @Override 
    public void onPageSelected(int position) { 
     mActionBar.setSelectedNavigationItem(position); 

     if (mCurrentPosition == position) { 
      Log.w(THIS_FILE, "Previous position and next position became same (" + position 
        + ")"); 
      Log.e(THIS_FILE, "Previous position and next position became same (" + position 
        + ")"); 
     } 

     mNextPosition = position; 
    } 

    @Override 
    public void onTabReselected(Tab tab, FragmentTransaction ft) { 
     // Nothing to do 
    } 
    @Override 
    public int getItemPosition(Object object){ 
     return mCurrentPosition; 
     } 
    @Override 
    public void onTabUnselected(Tab tab, FragmentTransaction ft) { 
     // Nothing to do 
    } 

    @Override 
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { 
     // Nothing to do 
    } 

    @Override 
    public void onPageScrollStateChanged(int state) { 
     switch (state) { 
      case ViewPager.SCROLL_STATE_IDLE: { 
       Log.e(THIS_FILE, "SCROLL_STATE_IDLE"+mCurrentPosition); 
       if (mCurrentPosition >= 0) { 
        sendFragmentVisibilityChange(mCurrentPosition, false); 
       } 
       if (mNextPosition >= 0) { 
        sendFragmentVisibilityChange(mNextPosition, true); 
       } 
       invalidateOptionsMenu(); 

       mCurrentPosition = mNextPosition; 
       break; 
      } 
      case ViewPager.SCROLL_STATE_DRAGGING: 
       Log.e(THIS_FILE, "SCROLL_STATE_DRAGGING"); 
       clearDetails(); 
       hasClearedDetails = true; 
       break; 
      case ViewPager.SCROLL_STATE_SETTLING: 
       Log.e(THIS_FILE, "SCROLL_STATE_SETTLING"); 
       hasClearedDetails = false; 
       break; 
      default: 
       break; 
     } 
    } 

    private void clearDetails() { 
     if (mDualPane && !hasClearedDetails) { 
      Log.e(THIS_FILE, "check in clear detalis"); 
      FragmentTransaction ft = SipHome.this.getSupportFragmentManager() 
        .beginTransaction(); 
      ft.replace(R.id.details, new Fragment(), null); 
      ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE); 
      ft.commit(); 
     } 
    } 
} 

的代碼sendFragmentVisibilityChange的代碼是

private void sendFragmentVisibilityChange(int position, boolean visibility) { 
    try { 
     final Fragment fragment = getFragmentAt(position); 
     if (fragment instanceof ViewPagerVisibilityListener) { 
      ((ViewPagerVisibilityListener) fragment).onVisibilityChanged(visibility); 
     } 
    }catch(IllegalStateException e) { 
     Log.e(THIS_FILE, "Fragment not anymore managed"); 

     e.printStackTrace(); 
    }catch(Exception e) { 
     Log.e(THIS_FILE, "Fragment not anymore managed"); 

     e.printStackTrace(); 
    } 
} 

片段呼籲onVisibilityChanged上滾動執行一些操作。 這些片段擴展了SherlockFragment。

在此先感謝

Answer 1

設置你的ViewPager的OffscreenPageLimit您ViewPager實際持有使用setoffscreenpagelimit（詮釋計數）意見的數量。