A notification is a UI area that is displayed for a period of time and then closes automatically even if no user interaction occurs. Systems that implement notifications typically have them display in a fixed, particular area of the UI. An alternative colloquial term for notifications that is used by some programmers is toast.

Notifications are exclusively for use in an out-of-browser application scenario for Silverlight 4. The out-of-browser installation or startup experience indicate to a user that an application is now running in the context of the local client computer, rather than as a Web site with Silverlight content. For more information about out-of-browser installation or startup, see Out-of-Browser Support.

Similar to Popup, content of a notification window is not part of the primary Silverlight visual tree, it effectively is described by a separate visual tree that is rendered and added to the content area. For purposes of XAML namescope resolution, a notification window's objects exists in a separate XAML namescope.

Using Popup within a notification window is not supported.

You must set Height and Width on a notification window before Show is called and the notification displays. Attempting to set the height/width of a displayed notification throws an exception. You may want to check Visibility first to avoid the exception.

User Interaction with a Notification Window

Notification Positioning and Dimensions

Multiple Notifications

The following example code illustrates the various aspects of creating and displaying a notification window.

This code illustrates creating a new NotificationWindow and setting properties as part of its containing page's initialization, then calling Show from a helper method.

• The reference to nwContent refers to a constructor call to a custom UserControl "page" that is defined in the same project as a Page build action. The UserControl defines the root of UI content that the notification displays.

• Note how the NotificationWindow Height and Width are based on the nwContent UserControl dimensions. This is a good technique for maintaining code-design separation, but make sure that the UI design does not exceed the 400-width, 100-height limits imposed by the NotificationWindow API.

• Note the check against IsRunningOutOfBrowser wrapping all NotificationWindow API calls.

• The NextNotify method is invoked one time for the initial application load, mainly for illustration. Otherwise, it would be invoked whenever application logic determines an additional notification should display.

• Note how NextNotify uses a simple technique to close the visible window before it tries to display again, in order to avoid exceptions from multiple notifications trying to show.

• This particular design keeps reusing the same NotificationWindow instance nw. This is appropriate because there can only be one NotificationWindow displayed at a time. An alternative technique is to create different NotificationWindow instances with different content, but to keep track of them in a list to make sure you do not show more than one at a time.

• Note the call to DataContext. This particular notification design uses a single Content definition by the nwContent UserControl, and that design incorporates two TextBlock areas with data-bound Text. By changing the data context prior to each Show call to point to new business objects, you have a lightweight technique for changing the text in each notification shown, which is based on the data binding feature of Silverlight.

public MainPage()
{
...
  if (App.Current.IsRunningOutOfBrowser) {
      nw = new NotificationWindow();
      nw.Content = nwContent;
      nw.Height = nwContent.Height;
      nw.Width = nwContent.Width;
      NextNotify();
  }
...
}

private void NextNotify()
{
    if (nw.Visible)
        nw.Close();
    nw.Content.DataContext = list[count];
    nw.Show(5000);
    App.Current.MainWindow.Activate();
}

Silverlight

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Reference

Other Resources