如何实现PagerAdapter的视图回收机制? [英] How do I implement view recycling mechanism for PagerAdapter?

问题描述

我有一个寻呼机适配器，它想使代表日历的复杂视图膨胀.

I have a pager adapter that suppose to inflate a complex view representing a calendar.

日历的每年充气大约需要350毫秒.

It takes around ~350 ms to inflate each year of the calendar.

为了提高性能，我想实现与ListView回收视图的数组适配器(getView()中的convertView参数)相同的机制.

To improve performance I would like to implement the same mechanism that exists in the ListView array adapter of recycling views (convertView parameter in getView()).

这是适配器当前的getView().

@Override
protected View getView(VerticalViewPager pager, final DateTileGrid currentDataItem, int position)
{
    mInflater = LayoutInflater.from(pager.getContext());

        // This is were i would like to understand weather is should use a recycled view or create a new one.
    View datesGridView = mInflater.inflate(R.layout.fragment_dates_grid_page, pager, false);


    DateTileGridView datesGrid = (DateTileGridView) datesGridView.findViewById(R.id.datesGridMainGrid);
    TextView yearTitle = (TextView) datesGridView.findViewById(R.id.datesGridYearTextView);
    yearTitle.setText(currentDataItem.getCurrentYear() + "");
    DateTileView[] tiles = datesGrid.getTiles();

    for (int i = 0; i < 12; i++)
    {
        String pictureCount = currentDataItem.getTile(i).getPictureCount().toString();
        tiles[i].setCenterLabel(pictureCount);
        final int finalI = i;
        tiles[i].setOnCheckedChangeListener(new DateTileView.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(DateTileView tileChecked, boolean isChecked)
            {
                DateTile tile = currentDataItem.getTile(finalI);
                tile.isSelected(isChecked);
            }
        });
    }

    return datesGridView;
}

是否有实现此类行为的指针或方向? 特别是，我怎么能在适配器中得知DateTileGridViews之一正在被刷出屏幕，所以我可以将其保存在内存中以便下次再次使用.

Any pointers or direction for implementing such a behavior? In particular how can I know in the adapter that one of the DateTileGridViews is being swiped of the screen so I could save it in memory to reuse it next time.

推荐答案

所以我已经弄清楚了.

1. 覆盖destroyItem(ViewGroup container, int position, Object view)并保存您的缓存视图
2. 创建一个单独的方法，以查看是否有机会使用再生视图，或者是否应该为新视图充气.
3. 请记住，一旦使用了回收的视图，就从缓存中删除该视图，以避免相同的视图将相同的视图附加到寻呼机上.

1. overwrite destroyItem(ViewGroup container, int position, Object view) ans save you cached view
2. create a separate method to see if there is any chance to use a recycled view or should you inflate a new one.
3. remember to remove the recycled view from cache once its been used to avoid having same view attaching same view to the pager.

这是代码..我使用了视图堆栈来缓存从寻呼机中删除的所有视图

here is the code.. I used a Stack of view to cache all removed views from my pager

private View inflateOrRecycleView(Context context)
{

    View viewToReturn;
    mInflater = LayoutInflater.from(context);
    if (mRecycledViewsList.isEmpty())
    {
        viewToReturn = mInflater.inflate(R.layout.fragment_dates_grid_page, null, false);
    }
    else
    {
        viewToReturn = mRecycledViewsList.pop();
        Log.i(TAG,"Restored recycled view from cache "+ viewToReturn.hashCode());
    }


    return viewToReturn;
}

@Override
public void destroyItem(ViewGroup container, int position, Object view)
{
    VerticalViewPager pager = (VerticalViewPager) container;
    View recycledView = (View) view;
    pager.removeView(recycledView);
    mRecycledViewsList.push(recycledView);
    Log.i(TAG,"Stored view in cache "+ recycledView.hashCode());
}

不要忘记在适配器构造函数中实例化堆栈.

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