Android: load app icons in a custom adapter

Question

I'm developing a new Home Launcher that for the moment use a listview to display installed applications. I'm using a custom adapter to provide the applications name and icon. If i leave the app name i got no issues, however, if i add icons the listview becomes really slow and unusable. I also tried with asynctask with no luck. Here is relevant pices of my adapter:

public AppInfoAdapter(Context c, List list, ArrayList<String> appList, PackageManager pm, Resources resources) {
    mContext = c;
    mListAppInfo = list;
    mPackManager = pm;
    mAppList = appList;
    mResources = resources;
    activity = (Activity) c;
}

=====

   @Override

public View getView(int position, View convertView, ViewGroup parent) {

    View v = convertView;

    if(v == null) {
        LayoutInflater inflater = LayoutInflater.from(mContext);
        v = inflater.inflate(R.layout.launcher_adapter_row, null);
    }

    if (v != null) {
        mIcon = (ImageView) v.findViewById(R.id.imageView1);
        tvAppName = (TextView) v.findViewById(R.id.textView1);
    }

    new addItems().execute(tvAppName, mIcon, position);

    return v;
}

====

public class addItems extends AsyncTask<Object, String, Void> {

    private TextView title;
    private ImageView icon;
    private int pos;

    @Override
    protected Void doInBackground(final Object... parameters) {
        activity.runOnUiThread(new Runnable() {
            @Override
            public void run() {
                title = (TextView) parameters[0];
                icon = (ImageView) parameters[1];
                pos = (Integer) parameters[2];

                entry = (ApplicationInfo) mListAppInfo.get(pos);

                icon.setImageDrawable(entry.loadIcon(mPackManager));
                title.setText(entry.loadLabel(mPackManager));
            }
        });

        return null;
    }
}

Tried with listview and also with gridview. The result is the same. It's quite impossible to scroll due to stuttering. Any suggestions? Thanks

Answer 1

You are again loading data in the Ui thread in AsynchTask so change your AsynchTask like this..

public class addItems extends AsyncTask<Object, String, Drawable> {

    private TextView title;
    private ImageView icon;
    private int pos;

    @Override
    protected Drawable doInBackground(final Object... parameters) {
        title = (TextView) parameters[0];
        icon = (ImageView) parameters[1];
        pos = (Integer) parameters[2];

        entry = (ApplicationInfo) mListAppInfo.get(pos);

        Drawable drawable = entry.loadIcon(mPackManager);
        return drawable;
    }

    @Override
    protected void onPostExecute(Drawable result) {
        super.onPostExecute(result);
        icon.setImageDrawable(result);
        title.setText(entry.loadLabel(mPackManager));
    }
}

here i am loading drawable in another thread and passing it to onPostexecute so no overhead on UI thread..setting text is not a difficult task in doInbackGround method.

Answer 2

Problem is with this statement

icon.setImageDrawable(entry.loadIcon(mPackManager));

That is because this method loadIcon() is being called in UI thread. On UI thread if you are trying to decode the Bitmap it will cause hiccups while scrolling.