Fetching Immagini dalla scheda SD e visualizzazione in GridView

Question

Sto tentando di recuperare tutte le immagini dalla scheda SD e visualizzarle in una griglia (contenuta in un frammento). Tuttavia, sebbene non vengano lanciate eccezioni, nulla viene visualizzato in Gridview, solo un semplice schermo nero. Non sono sicuro di dove sia il problema, con l'associazione della vista o con il recupero dei dati nel cursore. Questo è il codice corrente per il frammento:

public class PhotoGridFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> {

// member variables for
private static final int PHOTO_LIST_LOADER = 0x01;
private ImageCursorAdapter adapter;
private Cursor c;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getLoaderManager().initLoader(PHOTO_LIST_LOADER, null, this);

    adapter = new ImageCursorAdapter(getActivity().getApplicationContext(), c);
}

/* R.layout.grid_item,
null, new String[] { MediaStore.Images.Thumbnails.DATA }, new int[] {R.id.grid_item},
CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER); */

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    return inflater.inflate(R.layout.photo_item, container, false);     
}


// Loader manager methods
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    String[] projection = { MediaStore.Images.Thumbnails._ID, MediaStore.Images.Thumbnails.DATA };
    CursorLoader cursorLoader = new CursorLoader(getActivity(),
            MediaStore.Images.Media.EXTERNAL_CONTENT_URI, projection,
            null, null, null);
    return cursorLoader;
}

public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
    adapter.swapCursor(cursor);

}

public void onLoaderReset(Loader<Cursor> cursor) {
    adapter.swapCursor(null);
}

private class ImageCursorAdapter extends CursorAdapter {

    private LayoutInflater mLayoutInflater;
    private Context mContext;

    public ImageCursorAdapter(Context context, Cursor c) {
        super(context, c);
        mContext = context;
        mLayoutInflater = LayoutInflater.from(context);
    }

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        ImageView newView = (ImageView) view.findViewById(R.layout.grid_item);
        String imagePath = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Thumbnails._ID));
        if (imagePath != null && imagePath.length() != 0 && newView != null) {
            newView.setVisibility(ImageView.VISIBLE);
        }
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        View v = mLayoutInflater.inflate(R.layout.grid_item, parent, false);
        return v;
    }


}

I file di layout per il progetto sono i seguenti:

photo_item.xml:

<?xml version="1.0" encoding="UTF-8"?>
<GridView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/photo_item"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="24dp"
android:padding="6dp" />

grid_item.xml:

<?xml version="1.0" encoding="utf-8"?>
<ImageView
 xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/grid_item"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="24dp"
android:padding="6dp"

/>

Answer 1

In BindView, in realtà non stai impostando il disegno di ImageView su qualsiasi cosa. Prendi un percorso dell'immagine, verifichi che è un vero percorso e poi ignoralo :) Usa il percorso per ottenere un disegno! Quindi impostare il disegno di ImageView su quell'immagine.

Answer 2

Prova questo codice

sdcard.java

public class Sdcard extends Activity {

//  Cursor used to access the results from querying for images on the SD card.

private Cursor cursor;

 // Column index for the Thumbnails Image IDs.

private int columnIndex;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_sdcard);

    // Set up an array of the Thumbnail Image ID column we want
    String[] projection = {MediaStore.Images.Thumbnails._ID};
    // Create the cursor pointing to the SDCard
    cursor = managedQuery( MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI,
            projection, // Which columns to return
            null,       // Return all rows
            null,
            MediaStore.Images.Thumbnails.IMAGE_ID);
    // Get the column index of the Thumbnails Image ID
    columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Thumbnails._ID);

    GridView sdcardImages = (GridView) findViewById(R.id.gridView1);
    sdcardImages.setAdapter(new ImageAdapter(this));


}

private class ImageAdapter extends BaseAdapter {

    private Context context;

    public ImageAdapter(Context localContext) {
        context = localContext;
    }

    public int getCount() {
        return cursor.getCount();
    }
    public Object getItem(int position) {
        return position;
    }
    public long getItemId(int position) {
        return position;
    }
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView picturesView;
        if (convertView == null) {
            picturesView = new ImageView(context);
            // Move cursor to current position
            cursor.moveToPosition(position);
            // Get the current value for the requested column
            int imageID = cursor.getInt(columnIndex);
            // Set the content of the image based on the provided URI
            picturesView.setImageURI(Uri.withAppendedPath(
                    MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI, "" + imageID));
            picturesView.setScaleType(ImageView.ScaleType.FIT_XY);
            picturesView.setPadding(10, 10, 10, 10);
            picturesView.setLayoutParams(new GridView.LayoutParams(100, 100));
        }
        else {
            picturesView = (ImageView)convertView;
        }
        return picturesView;
    }
}

}