ViewPager无法与毕加索懒洋洋地加载图像 [英] ViewPager unable to load images lazily with Picasso

问题描述

我有一个 FragmentActivity 中的第一个标签一个 TabHost 和 FragmentActivity 本身持有 ViewPager 。我们的目标是有可滑动浏览图像的 TabHost 第一个窗格。该的 setAdapter（）方法设置一个 FragmentPagerAdapter ViewPager 用一组片段秒。

I have a FragmentActivity in the first tab of a TabHost, and the FragmentActivity itself holds a ViewPager. The goal is to have swipeable images in the first pane of the TabHost. The ViewPager's setAdapter() method sets a FragmentPagerAdapter with a set of Fragments.

要测试它，我第一次加载大量的图片，我已经在项目的绘制目录本地保存。 精美的一切工作。

To test it, I was first loading a bunch of images that I had kept locally in the project's drawable directory. Everything worked beautifully.

现在我下载了一堆图像的URL的掀起了REST Web服务。我想这些图像在懒洋洋地加载 ViewPager ，和我打过电话毕加索的负荷（）方法在三个地方：

Now I'm downloading a bunch of image URLs' off a REST web service. I want these images to load lazily in the ViewPager, and I tried calling Picasso's load() method in three places:

1. 在的 ViewPager 片段 onCreateView（）方法 S（同一个地方，我是从本地绘制目录更早加载图像）。

1. The onCreateView() method of the ViewPager's Fragments (the same place where I was earlier loading images from the local drawable directory).

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

    View myFragmentView = inflater.inflate(R.layout.layout_fragment, container, false);

    ImageView imageView = (ImageView)getView().findViewById(R.id.fragment_image);
    String url = getArguments().getString(IMAGE_RESOURCE_URL);
    Context context = getActivity();
    Picasso.with(context).load(url).fit().into(imageView);

    return myFragmentView;
}

在的 ViewPager 片段 onViewCreated（）方法秒。

The onViewCreated() method of the ViewPager's Fragments.

@Override
public void onViewCreated(View view, Bundle savedInstanceState){

    Context context = getActivity();
    String url = getArguments().getString(IMAGE_RESOURCE_URL);
    ImageView imageView = (ImageView)view.findViewById(R.id.fragment_image);
    Picasso.with(context).load(url).fit().into(imageView);      

}        

的 onInstantiateItem（）方法 FragmentPagerAdapter 。

@Override
public Object instantiateItem(ViewGroup container, int position) {

    View v = inflater.inflate(R.layout.layout_fragment, container, false);
    Context context = Tab1Activity.this;
    String url = getItem(position).getArguments().getString("IMAGE_RESOURCE_URL");
    ImageView imageView = (ImageView)v.findViewById(R.id.fragment_image);
    Picasso.with(context).load(url).fit().into(imageView);
    return v;
}

这些方法都不奏效。我知道，它不是与毕加索问题，因为有一天，我想在一个使用毕加索的ListView 和它的工作就像一个魅力。我在做什么错了？

None of these methods worked. I know that its not a problem with Picasso because the other day I tried using Picasso in a ListView and it worked like a charm. What am I doing wrong ?

推荐答案

您第一个方法应该可以正常工作......如果你正确地执行它。我希望你的code一起崩溃 NullPointerException异常。

Your first approach should work fine... if you implement it correctly. I would expect your code to crash with a NullPointerException.

替换为：

ImageView imageView = (ImageView)getView().findViewById(R.id.fragment_image);

与

ImageView imageView = (ImageView)myFragmentView.findViewById(R.id.fragment_image);

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