The class that raises an event is the event source, and the classes that implement the event are the sinks. An event source can have multiple sinks for the events it generates. When the class raises the event, that event is fired on every class that has elected to sink events for that instance of the object.
The example also uses a form (Form1
) with a button (Command1
), a label (Label1
), and two text boxes (Text1
and Text2
). When you click the button, the first text box displays "From Now" and the second starts to count seconds. When the full time (9.84 seconds) has elapsed, the first text box displays "Until Now" and the second displays "9.84"
The code for Form1
specifies the initial and terminal states of the form. It also contains the code executed when events are raised.
Option Explicit Private WithEvents mText As TimerState Private Sub Command1_Click() Text1.Text = "From Now" Text1.Refresh Text2.Text = "0" Text2.Refresh Call mText.TimerTask(9.84) End Sub Private Sub Form_Load() Command1.Caption = "Click to Start Timer" Text1.Text = "" Text2.Text = "" Label1.Caption = "The fastest 100 meters ever run took this long:" Set mText = New TimerState End Sub Private Sub mText_ChangeText() Text1.Text = "Until Now" Text2.Text = "9.84" End Sub Private Sub mText_UpdateTime(ByVal dblJump As Double) Text2.Text = Str(Format(dblJump, "0")) DoEvents End Sub
The remaining code is in a class module named TimerState. Included among the commands in this module are the Raise Event statements.
Option Explicit Public Event UpdateTime(ByVal dblJump As Double) Public Event ChangeText() Public Sub TimerTask(ByVal Duration As Double) Dim dblStart As Double Dim dblSecond As Double Dim dblSoFar As Double dblStart = Timer dblSoFar = dblStart Do While Timer < dblStart + Duration If Timer - dblSoFar >= 1 Then dblSoFar = dblSoFar + 1RaiseEvent
UpdateTime(Timer - dblStart) End If LoopRaiseEvent
ChangeText End Sub