刷新上恢复活动的FragmentStatePagerAdapter图片 [英] Refresh images on FragmentStatePagerAdapter on resuming activity

问题描述

我已经创建了一个使用 FragmentStatePagerAdapter 来提供小画廊的活动。但是，我不能当活动恢复（即将从其他活动回来后，例如）以刷新。每一次前两个图片将是空白的，只有经过我刷两张图片到一边，他们得到刷新。无我已经找到工作的答案（尤其是覆盖 getItemPosition（））

I have created an activity that uses FragmentStatePagerAdapter to provide small gallery. However, I can't get it to refresh when activity resumes (after coming back from other activity, for example). Every time first two pictures will be blank, and only after i swipe two pictures to the side, they get refreshed. None of the answers I've found work (especially overriding getItemPosition())

我设置它是这样的：

mPagerAdapter = new PhotosPagerAdapter(getSupportFragmentManager());
mPager = (ViewPager) findViewById(R.id.photosViewPager);
mPager.setAdapter(mPagerAdapter);

然后，我有FragmentStatePagerAdapter类：

Then I have FragmentStatePagerAdapter class:

private class PhotosPagerAdapter extends FragmentStatePagerAdapter{

    public PhotosPagerAdapter(FragmentManager fm) {
        super(fm);
    }

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

    @Override
    public Fragment getItem(int position) {
        ImageFragment f = new ImageFragment(position);
        return f;
    }

    @Override
    public int getItemPosition(Object object) {
        throw new RuntimeException();
        //return POSITION_NONE;
    }

}

您可能已经注意到了，我扔的RuntimeException的getItemPosition，因为我想检查，当它被称为。而且它不叫，直到我补充一下，列出包含我的照片。然后ImageFragment类：

As you probably noticed, I throw RuntimeException in getItemPosition, because I wanted to check when it's called. And it isn't called until I add something to list containing my pictures. Then ImageFragment class:

public class ImageFragment extends Fragment{

    int position;
    Bitmap mBitmap;
    int width;
    int height;
    ImageView img;

    public ImageFragment(){
    }

    public ImageFragment(int position){
        this.position = position;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        img = new ImageView(container.getContext());
        img.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
        width = container.getWidth();
        height = container.getHeight();

        loadBitmap();

        return img;
    }       

    public void loadBitmap(){
        if (img == null){
            return;
        }
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(photos.get(position), options);
        options.inSampleSize = calculateInSampleSize(options, width/2, height/2);
        options.inJustDecodeBounds = false;
        mBitmap = BitmapFactory
                .decodeFile(photos.get(position), options);         

        img.setImageBitmap(mBitmap);
    }


    @Override
    public void onDestroyView() {
        mBitmap.recycle();
        super.onDestroyView();
    }       
}

code是有点乱后，我试图修复它。但是：删除 onDestroyView（）不起作用。我已经把 mPagerAdapter.notifyDataSetChanged（）的几个地方，必须叫（如 onResume（）），无结果。我越来越有点绝望了这一点。

Code is kinda messy after I tried to fix it... But: removing onDestroyView() doesn't work. I have put mPagerAdapter.notifyDataSetChanged() in several places that must be called (like onResume()), with no result. I'm getting kinda desperate with that.

推荐答案

与片段寻呼机适配器处理可以皮塔。

Dealing with fragment pager adapters can be a PITA.

下面是一些有用的提示：

Here are a few helpful tips:

<一个href="http://stackoverflow.com/questions/7263291/viewpager-pageradapter-not-updating-the-view">ViewPager PagerAdapter更新不及时的查看

的Andr​​oid ViewPager - 无法更新动态

一般来说这个工作99％的时间......

Generally speaking this one works 99% of the time...

覆盖getItemPosition在PagerAdapter是这样的：

Override getItemPosition in your PagerAdapter like this:

@Override
public int getItemPosition(Object object) {
    return POSITION_NONE;
}

有时候，即使是那些不工作，我必须使用'暴力'的方法，并再次重新创建整个视图（的onCreate起）...

Sometimes even those don't work, I have to use the 'brute force' method and recreate the entire view again (from onCreate onwards)...

这篇关于刷新上恢复活动的FragmentStatePagerAdapter图片的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！