Question

I am trying to display images in a grid view within a fragment, and the images are downloaded on the run time within an async task loader and I am using the base adapter within the same fragment.

Now, everything is working fine except that while the images are loaded but no loader animation is shown. My Fragment class is as under which contains a BaseAdapter and AsyncLoader

package friends.appModules.mainClasses;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import friends.appModules.commonClasses.Cheeses;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.AsyncTaskLoader;
import android.support.v4.content.Loader;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.Toast;

public class PeopleNearYou extends Fragment implements     LoaderManager.LoaderCallbacks<List<Images>>{

private GridView pnuGridView;
ImageAdapter myImageAdapter;
boolean isLoadFinished = false;

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    Log.d("Where am I?", "in onActivityCreated PeopleNearYou");

    getLoaderManager().initLoader(1, null, this);
}

/* First Method call after onActivityCreated*/
@Override
public Loader<List<Images>> onCreateLoader(int id, Bundle args) {
    Log.d("Where am I?", "in onCreateLoader PeopleNearYou");
    return new PeopleNearYouLoader(getActivity());
}


@Override
/*Fourth Method Called*/
public void onLoadFinished(Loader<List<Images>> loader,
        List<Images> data) {
    Log.d("Where am I?", "in onLoadFinished PeopleNearYou");

    final Context c = this.getActivity().getApplicationContext();
    myImageAdapter = new ImageAdapter(c);

    myImageAdapter.setData(data);

    pnuGridView.setAdapter(myImageAdapter);
}

@Override
public void onLoaderReset(Loader<List<Images>> loader) {
    Log.d("Where am I?", "in onLoaderReset PeopleNearYou");
    myImageAdapter.setData(null);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    Log.d("Where am I?", "in onCreateView PeopleNearYou");

    View view = inflater.inflate(R.layout.people_near_you, container, false);

    pnuGridView = (GridView) view.findViewById(R.id.gridview);
    //pnuGridView.setBackgroundColor(R.color.dark_gry_txt);
    return view;
}



public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

public class ImageAdapter extends BaseAdapter{
    private Context mContext;
    private List<Images> finallyListCreated;

    public ImageAdapter(Context c) {
        Log.d("Where am I?", "in ImageAdapter Constructor PeopleNearYou");
        mContext = c;

        pnuGridView.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
                Toast.makeText(mContext, "" + position, Toast.LENGTH_SHORT).show();
            }
        });
    }

    public int getCount() {
        Log.d("Where am I?", "in getCount PeopleNearYou");
        return 20;
    }

    public Object getItem(int position) {
        Log.d("Where am I?", "in getItem PeopleNearYou");
        return null;
    }

    public long getItemId(int position) {
        Log.d("Where am I?", "in getItemId PeopleNearYou");
        return 0;
    }

    public void setData(List<Images> data) {
        Log.d("Where am I ??", "in onSetData() PeopleNearYou");
        if (data != null) {
            finallyListCreated = data;
        }
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        Log.d("Where am I?", "in getView PeopleNearYou");
        ImageView imageView;
        if (convertView == null) {  // if it's not recycled, initialize some attributes
            imageView = new ImageView(mContext);
            imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(8, 8, 8, 8);
            imageView.setBackgroundColor(R.color.dark_gry_txt);
        } else {
            imageView = (ImageView) convertView;
        }

        Images item = finallyListCreated.get(position);
        imageView.setImageDrawable(item.getImageUrl());
        return imageView;
    }
}

public static class PeopleNearYouLoader extends AsyncTaskLoader<List<Images>>{

    Context loaderContext;
    List<Images> loaderImageList;

    public PeopleNearYouLoader(Context context) {
        super(context);
        Log.d("Where am I?", "in PeopleNearYouLoader Constructor PeopleNearYou");
        loaderContext = context;
    }

    @Override
    /*Third method called if there are no images in the list else Deliver Result method will be called*/
    public List<Images> loadInBackground() 
    {
        Log.d("Where am I ??", "in loadInBackground() PeopleNearYou");

        List<Images> peopleNearYouImagesList = new ArrayList<Images>(20);

        for (int i=0; i<20; i++) {
            Log.d("Where am I ??", "For loop to set Image objects PeopleNearYou");
            Images peopleNearYouImages = new Images(loadImageFromUrl(Cheeses.imageUrls[i]));
            peopleNearYouImagesList.add(peopleNearYouImages);
        }

        return peopleNearYouImagesList;
    }

    @Override
    public void onCanceled(List<Images> data) {
        super.onCanceled(data);
        onReleaseResources(data);
    }

    @Override
    public void deliverResult(List<Images> images) {
        if (isReset()) {
            if (images != null) {
                onReleaseResources(images);
            }
        }

        List<Images> oldImages = images;
        loaderImageList = images;

        if (isStarted()) {
            super.deliverResult(images);
            Log.d("Where am I ??", "in isStarted = true PeopleNearYou");
        }

        if (oldImages != null) {
            onReleaseResources(oldImages);
            Log.d("Where am I ??", "in oldImages != null PeopleNearYou");
        }
    }

    @Override
    /* Second method called*/
    protected void onStartLoading() {
        if (loaderImageList != null) {
            deliverResult(loaderImageList);
            Log.d("Where am I ??", "in onStartLoading() and list is not null");
        }
        else {
            Log.d("Where am I ??", "in onStartLoading() and list is null");
            forceLoad();
        }
    }

    @Override
    protected void onStopLoading() {
        cancelLoad();
        Log.d("Where am I ??", "in onStopLoading() PeopleNearYou");
    }

    @Override
    protected void onReset() {
        super.onReset();

        onStopLoading();

        if (loaderImageList != null) {
            onReleaseResources(loaderImageList);
            loaderImageList = null;
        }
    }

    protected void onReleaseResources(List<Images> data) {
        Log.d("Where am I ??", "in onReleaseResources() PeopleNearYou");
    }

    public Drawable loadImageFromUrl(String url) {
        InputStream inputStream;
        try {
            inputStream = new URL(url).openStream();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        return Drawable.createFromStream(inputStream, "src");
    }

}
}

and My gridview layout is:

<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/gridview"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:numColumns="auto_fit"
    android:verticalSpacing="10dp"
    android:horizontalSpacing="10dp"
    android:columnWidth="90dp"
    android:stretchMode="columnWidth"
    android:gravity="center"
/>

Also the images class used in my code is:

package friends.appModules.mainClasses;

import android.app.Application;
import android.graphics.drawable.Drawable;

public class Images extends Application{
    private Drawable imageUrl;

    public Images(Drawable imageUrl) {
        this.imageUrl = imageUrl;
    }
    public Drawable getImageUrl() {
        return imageUrl;
    }
}

Thanks in advance.

Answer 1

Take a look at the source code for ListFragment.setListShown(). It does exactly what you’re looking for with the GridView.