//units label format callback
static char *_progress_format_cb(double val) {
	static char buffer[15];
	int items = val * 100;
	if (snprintf(buffer, 15, "%i items sent", items) > 0) {
		return strdup(buffer);
	}
	return NULL;
}

//free unit format string
static void _progress_format_free(char *str) {
	free(str);
}

// update progressbar, 1% for each call (for demo purposes)
static Eina_Bool progressbar_value_set(void *data) {
	Evas_Object *progressbar = data;
	double progress = elm_progressbar_value_get(progressbar);
	if (progress < 1.0) {
		progress += 0.01;
		elm_progressbar_value_set(progressbar, progress);
		return ECORE_CALLBACK_RENEW;
	}
	return ECORE_CALLBACK_CANCEL;
}

static void progressbar_test(Evas_Object *parent) {
	// create a progressbar
	Evas_Object *progressbar = elm_progressbar_add(parent);
	elm_win_resize_object_add(parent, progressbar);

	//progressbar setup
	elm_progressbar_horizontal_set(progressbar, EINA_FALSE);
	elm_object_style_set(progressbar, "progressbar");

	//set units label function
	elm_progressbar_unit_format_function_set(progressbar, _progress_format_cb, _progress_format_free);

	evas_object_show(progressbar);

	// add a timer to change progressbar values (demo)
	ecore_timer_add(0.1, progressbar_value_set, progressbar);
}