void _handleOnLongPress(Activity activity) {
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return SimpleDialog(
          title: Text(
            activity.title.toString(),
            style: TextStyle(color: colorTheme['dark']),
          ),
          children: [
            Container(
              child: Padding(
                padding: const EdgeInsets.all(20.0),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Container(
                      child: Row(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: [
                          ClipRRect(
                            borderRadius: BorderRadius.circular(20.0),
                            child: Image(
                              height: 150.0,
                              width: 150.0,
                              image: AssetImage(activity.imagePath),
                              // fit espande un immagine su tutto l'area disegnabile
                              fit: BoxFit.cover,
                            ),
                          ),
                        ],
                      ),
                    ),
                    SizedBox(
                      height: 30,
                    ),
                    Text(
                      'Descrizione',
                      style: TextStyle(
                          color: colorTheme['dark'],
                          fontSize: 15,
                          fontWeight: FontWeight.w700),
                    ),