Efficient Album Cover loading for ListView

Question

I have a list view which display in each view a Album's name, the associated Artist and the album art.

Here is the code of my ListFragment which display this list:

public class AlbumsFragment extends ListFragment implements LoaderManager.LoaderCallbacks<Cursor> {
AlbumsAdapter mAdapter;
 @Override
 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
 View myFragmentView = inflater.inflate(R.layout.albums_fragment_layout, container, false);
 return myFragmentView;
 }
 @Override
 public void onActivityCreated(Bundle savedInstanceState) {
 super.onActivityCreated(savedInstanceState);
 mAdapter = new AlbumsAdapter(getActivity(), null);
 setListAdapter(mAdapter);
 getLoaderManager().initLoader(0, null, this); 
 }
static final String[] ALBUM_SUMMARY_PROJECTION = { MediaStore.Audio.Albums._ID, MediaStore.Audio.Albums.ALBUM, MediaStore.Audio.Albums.ARTIST, MediaStore.Audio.Albums.ALBUM_ART,}; 
 public Loader<Cursor> onCreateLoader(int id, Bundle args) { 
 String select = null; 
 return new CursorLoader(getActivity(), MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI,ALBUM_SUMMARY_PROJECTION, select, null, null); 
 } 
 public void onLoadFinished(Loader<Cursor> loader, Cursor data) { 
 mAdapter.swapCursor(data); 
 } 
 public void onLoaderReset(Loader<Cursor> loader) { 
 mAdapter.swapCursor(null); 
 } 
 }

Here is my custom CursorAdapter's code:

public class AlbumsAdapter extends CursorAdapter {
 private final LayoutInflater mInflater;
 public AlbumsAdapter(Context context, Cursor c) {
 super(context, c);
 mInflater=LayoutInflater.from(context);
 }
 @Override
 public void bindView(View view, Context context, Cursor cursor) {
 ViewHolder holder = (ViewHolder) view.getTag();
 if (holder == null) {
 holder = new ViewHolder();
 holder.albumTitle = (TextView) view.findViewById(R.id.albumTextView);
 holder.artistName = (TextView) view.findViewById(R.id.artistTextView);
 holder.coverAlbum = (ImageView)view.findViewById(R.id.album_cover);
 holder.column1 = cursor.getColumnIndexOrThrow(MediaStore.Audio.Albums.ALBUM);
 holder.column2 = cursor.getColumnIndexOrThrow(MediaStore.Audio.Albums.ARTIST);
 holder.column3 = cursor.getColumnIndexOrThrow(MediaStore.Audio.Albums.ALBUM_ART);
 view.setTag(holder);
 }
 holder.albumTitle.setText(cursor.getString(holder.column1));
 holder.artistName.setText(cursor.getString(holder.column2));
 Bitmap coverBitmap = BitmapFactory.decodeFile(cursor.getString(holder.column3));
 holder.coverAlbum.setImageBitmap(coverBitmap);
 }
 static class ViewHolder {
 TextView albumTitle;
 TextView artistName;
 ImageView coverAlbum;
 int column1; 
 int column2;
 int column3;
 }
 @Override
 public View newView(Context context, Cursor cursor, ViewGroup parent) {
 final View view=mInflater.inflate(R.layout.albums_row,parent,false); 
 return view;
 }
}

As you can see, I use already the trick of the ViewHolder to avoid calling findViewById too often.

But the problem is that my list is still very slow. What can I do to optimize it even more? For instance I could load in priority the Albums' title and Artists' names and display them and then, load in a second time the cover (asynchronously).

I've also tried to scale down the resolution of the Cover's Bitmap before displaying them in the ImageViews, but I saw no improvement :/

Do you have any idea how to make this list less laggy? Any advice is welcome.

Answer 1

Your lag will be coming from this line:

 Bitmap coverBitmap = BitmapFactory.decodeFile(cursor.getString(holder.column3));

Your right about doing it asyncrhonously. You could also scale the image.

What you'll want to do is:

• spawn a new thread
• use a handler for when the bitmap has decoded
• set the bitmap on the imageview in the callback

You could set the image to a spinner whilst it is loading.

An example of something similar is:

http://blog.blundellapps.co.uk/imageview-with-loading-spinner/

And an example of image scaling is:

http://developer.android.com/training/displaying-bitmaps/load-bitmap.html#load-bitmap

• Big T Larrity: stumbled upon this and got some kind of malware popping up from clicking his link
• Blundell: @BigTLarrity thanks for the heads up. I didn't renew my .com domain only my .co.uk, I've updated the link. (some bad person seems to have bought the original then)
• Big T Larrity: lol theres some rascals around aint there :P at least it is sorted now, hope i haven't been pwned haha xD