HOW TO ADD A NEW PICTURE OF THE DAY AND HOW TO USE THE ENGINE

- in the data engine "apod"
Add your provider in the Potd class, updateSource( const QString &identifier ) method

- in the applet, you get a QImage and you can call the provider with

    Plasma::DataEngine *engine = dataEngine( "potd" );
    if ( !engine ) {
        return;
    }
    QDate mCurrentDate = QDate::currentDate();
    const QString identifier = QString("apod") + ":" + mCurrentDate.toString( Qt::ISODate );

    engine->disconnectSource( identifier, this );
    engine->connectSource( identifier, this );
    const Plasma::DataEngine::Data data = engine->query( identifier );
    QImage mImage = data[ identifier ].value<QImage>(); 

- TO DEBUG your new provider you need to comment the lines about caching the pic in
potd.cpp at the beginning of the
bool PotdEngine::updateSource( const QString &identifier )
method.