Notification

Notifications are a way to inform users of your app about events, even if the applications has no focus, is minimized, or is only running in the background.

Examples

Update notification

Guidelines

Is this the right control?

Use notifications to inform the user of events that are of interest, even if your app is not in foreground, but don’t spam the user with notifications.

  • Completion of long running tasks that the user has started manually
  • Incoming communication from other users
  • Hardware related events like low battery, lost network connection, running out of disk space

Don’t use a notification for:

  • Operations that don’t require user interaction, such as background processes, syncing, or updates
  • Advertising, rating or feedback requests, or other annoyances
  • If an unexpected or potentially dangerous condition has been reached and the user must make a decision. Use an /components/assistance/message instead.
  • Don’t send notifications if an user has never opened your application

Behavior

Notifications are provided by the system to the user, and foremost the user settings for notification govern the behavior and appearance of notifications. But there are several options to influence and enrich the behavior of your notifications.

Persistence

Making a notification persistent will prevent it from closing after a timeout. Your app must revoke the persistent notification, if the reason for the notification no longer applies, like a power adapter was plugged after a “Laptop battery is almost empty” notification. Use this if the notification requires user interaction, e.g. a device is asking for pairing confirmation.

Urgency

It is recommended that a notification carries an urgency hint:

  • 0 – Low, “Matt is now online”, “You just plugged in your AC adapter”
  • 1 – Normal, “You have new mail”
  • 2 – Critical, “Laptop battery is almost empty”

Actions

You can add up to three action buttons to the notification to enable the user to react to the event without having to go to the app itself.

Preview

You can specify a URL to an image associated with the notification. The image will be displayed as a preview in the notification.

Notification with a preview image

Code

KNotification *notification = new KNotification("contactOnline", widget);
notification->setText(i18n("The contact %1 has gone online", 
contact->name());
notification->setPixmap(contact->pixmap());
notification->setActions(QStringList(i18n("Open chat")));
connect(notification, SIGNAL(activated(unsigned int)), contact , 
                      SLOT(slotOpenChat()));
notification->sendEvent();

Use KNotification to send notifications to the Plasma Workspaces .