Sharing Event Procedures

[sukishan]

Sharing Event Procedures
Event procedures related to items in a control array are easily recognizable because they have an extra Index parameter, which precedes all other parameters. This extra parameter receives the index of the element that's raising the event, as you can see in this example:

Private Sub Text1_KeyPress(Index As Integer, KeyAscii As Integer)
MsgBox "A key has been pressed on Text1(" & Index & ") control"
End Sub

The fact that multiple controls can share the same set of event procedures is often in itself a good reason to create a control array. For example, say that you want to change the background color of each of your TextBox controls to yellow when it receives the input focus and restore its background color to white when the user clicks on another field:

Private Sub Text1_GotFocus(Index As Integer)
Text1(Index).BackColor = vbYellow
End Sub
Private Sub Text1_LostFocus(Index As Integer)
Text1(Index).BackColor = vbWhite
End Sub

Control arrays are especially useful with groups of OptionButton controls because you can remember which element in the group has been activated by adding one line of code to their shared Click event. This saves code when the program needs to determine which button is the active one:

' A module-level variable
Dim optFrequencyIndex As Integer

Private Sub optFrequency_Click(Index As Integer)
' Remember the last button selected.
optFrequencyIndex = Index
End Sub