The source code in this issue is designed for Visual Basic 5.0 and above. It is geared towards the intermediate to advanced programmer. If you have any questions about this issue, please email us at firstname.lastname@example.org
This issue shows how to implement a timer without requiring a Form or the Timer Control. It accomplishes this task by using a couple of API calls, a class and a module. It is useful for situations where your program might not have a form based interface, such as a background task or a data collection module that run indepently from the user interface.
The Timer class contains two routines for starting (StartTimer) and stopping (StopTimer) the timer. It also exposes an event called TimerEvent. This event is raised to the task that created the Timer Class object. This event behaves the same as the the Timer event that the Timer control raises. For more details about this see the sample code.
Public Function StartTimer(ByVal interval As Long) As Boolean Public Sub StopTimer()
StartTimer returns True if it was able to create a timer otherwise it returns False.
This example can be used to gather some information about your system once every lSeconds seconds for lCount times. Some important things to note. The declaration of tmr includes the WithEvents statement. This allows the Timer class to raise an event in the class or form that the class is created in. It is also important to note that the VBTimer.Timer object must be created using the CreateObject function. This is the only way that the event can be defined and will be raised.
Dim WithEvents tmr As VBTimer.Timer Dim mlCount As Long Public Sub LogIt(lCount As Long, lSeconds As Long) If lSeconds > 60 Then lSeconds = 60 ' Only allow 60 seconds between intervals End If Set tmr = CreateObject("VBTimer.Timer") tmr.StartTimer lSeconds * 1000 mlCount = 0 While mlCount <> lCount DoEvents Wend tmr.StopTimer End Sub Private Sub tmr_TimerEvent() Debug.Print "Ticked..." & mlCount ' log something here. Make memory usage or something ' like that. This can be the start of a background ' information logger. mlCount = mlCount + 1 End Sub
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That should be all you need to do to use the formless timer.
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