Creating an Alarm Clock in the System Tray

Ever since the earliest versions of Windows, it has always surprised me that there is no built-in alarm clock. For people with Outlook, reminders fill this void; however, you don't always want an event in your calendar. Others could use the system Task Scheduler, but it's really overkill for a simple alarm, not to mention difficult to use for this purpose! Ideally, the system clock should just have a tab for setting an alarm, but of course this isn't available.

For this column I decided to see what it would take to use Visual Studio 2005 to create a simple alarm clock that would hide to the system tray, display a notification, and optionally play a sound. Once an alarm is passed, it should roll over to the same time/next day, and have a checkbox for enabling and disabling the alarm. The user interface should be easy-to-grasp with as few controls as possible. I'm a firm believer in "less is more" in user interface design.

Creating the alarm clock enabled me to work with both new and improved features in Visual Studio 2005. The highlighted code samples use Visual Basic 2005 Express Edition; however, any of the Visual Studio Express Editions can be used to create a similar sample. Beta 2 of the Express editions can be downloaded from http://msdn.microsoft.com/express.

From a design point of view, I knew that I wanted an icon to appear in the system tray (the row of icons by the system clock). I knew that I wanted the alarm to show as a system notification, not as a message box. System notifications are a great feature in Windows XP which allow you to alert a user without stealing focus and without requiring immediate action. .NET 2.0 makes notifications a snap. I also wanted to play a sound when the alarm fired. This is trivial with Visual Basic, and only requires a few lines of code in C#. Altogether, the project went smoothly and I was able to implement exactly what I had imagined.

The first step is to create a Windows Forms project in Visual Studio. This creates a mostly empty project, containing a single blank form. This form will become the settings dialog, so start by highlighting the form in the Solution Explorer and pressing F2. This makes the filename editable. A good name is simply "AlarmSettingsForm". Drag two textbox controls for the sound filename and the alarm message respectively. Drag a checkbox to enable and disable the alarm, a DateTimePicker for the actual time entry, buttons for OK, Cancel, file browse, and corresponding labels.

Once the UI layout is complete, the next step is to add the system tray icon. This requires no Win32 calls, as all of the features are completely available in managed code. From the Toolbox, drag a NotifyIcon control to the design surface. Because it is essentially a non-visual control, it will actually snap to the surface beneath the form itself. Set the three BalloonTip properties for a message to appear when notification is triggered.

In order for the notify icon to always be displayed visually at runtime, you will need to create an icon file. From the Solution Explorer, add a new item of type Icon File. From here you are on your own! As you can see, I don't really consider myself an artist, but I can throw something together in a pinch (it's a bell in case you're wondering).

(click image to zoom)

You'll need to associate the icon file with the NotifyIcon control. You will also need to create a context menu. This is the menu to appear when you right-click the icon in the tray. If you right-click the system clock you see a menu for Toolbars, Adjust Date/Time, Customize Notifications, and more. To create a similar menu, drag a ContextMenuStrip from the Toolbox, and then select it to start editing. Add options for Settings, Enabled, and Exit.

In order to allow your application to sound an alarm, you need to know when the specified time has been reached. You can't directly be notified at a given time, but you can determine this yourself without incurring much overhead. Drag a Timer control to the design surface and set an interval of 1000. The timer interval is measured in milliseconds, so when enabled, the control will fire once each second. In the Tick event handler of the timer control add the following code:

Visual C#

if( DateTime.Now.CompareTo(alarmTime) >= 0 )
{
    // Add a day to the alarm to reset it for the next day
    RolloverTime();

    // Show the notification for up to a minute.
    // After that, no one must be paying attention!
    AlarmNotifyIcon.BalloonTipText = 
        (alarmMessage.Length > 0?alarmMessage:"Attention!");
    AlarmNotifyIcon.ShowBalloonTip(60000);

    // Play the alarm sound
    if( alarmSound.Length > 0 )
    {
        player.PlayLooping();
    }
}

Visual Basic

If DateTime.Now.CompareTo(alarmTime) >= 0 Then
    ' Add a day to the alarm to reset it for the next day
    RolloverTime()
    ' Show the notification for up to a minute.
    ' After that, no one must be paying attention!
    AlarmNotifyIcon.BalloonTipText = _
        IIf(alarmMessage.Length > 0, alarmMessage, "Attention!")
    AlarmNotifyIcon.ShowBalloonTip(60000)

     ' Play the alarm sound
    If alarmSound.Length > 0 Then
        My.Computer.Audio.Play(alarmSound, AudioPlayMode.BackgroundLoop)
    End If
End If

Notice the first call is to the RolloverTime method. This has not been defined yet, but is very important for simulating a real-world alarm clock. If you set the alarm for 3:00 P.M., internally the DateTime object will reflect 3:00 P.M. of a certain day. Once the alarm time is reached, it must be changed to 3:00 P.M. of the next day. Using the constructor to create a new instance of DateTime rather than calling the AddDays method removes any worry about the current date portion when a new time is selected. Here is the code to accomplish that:

Visual C#

private void RolloverTime()
{
    // If the user selects a time already passed, it must be for tomorrow
    if( DateTime.Now.TimeOfDay.CompareTo(alarmTime.TimeOfDay) > 0 )
    {
        alarmTime = new DateTime(DateTime.Now.Year, 
            DateTime.Now.Month, DateTime.Now.Day + 1, 
            alarmTime.Hour, alarmTime.Minute, alarmTime.Second);
    }
    // Otherwise, set it for today
    else
    {
        alarmTime = new DateTime(DateTime.Now.Year, 
            DateTime.Now.Month, DateTime.Now.Day, 
            alarmTime.Hour, alarmTime.Minute, alarmTime.Second);
    }
}

Visual Basic

Private Sub RolloverTime()
' If the user selects a time already passed, it must be for tomorrow
If DateTime.Now.TimeOfDay.CompareTo(alarmTime.TimeOfDay) > 0 Then
       alarmTime = New DateTime(DateTime.Now.Year, _
          DateTime.Now.Month, DateTime.Now.Day + 1, _
          alarmTime.Hour, alarmTime.Minute, alarmTime.Second)
   ' Otherwise, set it for today
   Else
      alarmTime = New DateTime(DateTime.Now.Year, _
          DateTime.Now.Month, DateTime.Now.Day, _
          alarmTime.Hour, alarmTime.Minute, alarmTime.Second)
   End If
End Sub

Conclusion

Visual Studio 2005 makes it easy to work with notifications, timers, tray icons, and sound. A next step might be to add "snooze" functionality. Perhaps clicking the notification elsewhere than the close button would delay the alarm for several minutes. Changing the tray icon based on the alarm being enabled, disabled, or ringing would also be a nice touch. If you haven't already, download Visual C# 2005 Express Edition and try this out. Get started at http://msdn.microsoft.com/express.