chapter 6

he following constants are used to give the lights a certain color
Const Off = &H8000000F
Const Red = vbRed
Const Green = vbGreen
Const Orange = &H80C0FF

'a simple traffic junction of two perpendicular crossing streets
'consists of 4 traffic poles. Each traffic pole has a green, orange
'and red light. There is always just one light on per pole.

'The traffic lights control on one of those junctions has just 4
'statusses. The current status is stored in the variable "Status".
Dim Status As Integer

'The time a status lasts, is derived from the following constants, which
'indicate the time in seconds.
Const TimeForStatus1 = 5
Const TimeForStatus2 = 3
Const TimeForStatus3 = 5
Const TimeForStatus4 = 3

Private Sub SetStatus(ByVal intStatus As Integer)
'Set the status variable to the new status
Status = intStatus

'Turn off all the lights
shpLamp1Groen.FillColor = Off
shpLamp1Oranje.FillColor = Off
shpLamp1Rood.FillColor = Off
shpLamp2Groen.FillColor = Off
shpLamp2Oranje.FillColor = Off
shpLamp2Rood.FillColor = Off
shpLamp3Groen.FillColor = Off
shpLamp3Oranje.FillColor = Off
shpLamp3Rood.FillColor = Off
shpLamp4Groen.FillColor = Off
shpLamp4Oranje.FillColor = Off
shpLamp4Rood.FillColor = Off

'Turn on the appropriate lights with the correct color,
'depending on the current status
Select Case intStatus 'or "Select Case Status", won't make any difference
Case 1
shpLamp1Rood.FillColor = Red
shpLamp2Groen.FillColor = Green
shpLamp3Rood.FillColor = Red
shpLamp4Groen.FillColor = Green

Timer1.Interval = TimeForStatus1 * 1000
Case 2
shpLamp1Rood.FillColor = Red
shpLamp2Oranje.FillColor = Orange
shpLamp3Rood.FillColor = Red
shpLamp4Oranje.FillColor = Orange

Timer1.Interval = TimeForStatus2 * 1000
Case 3
shpLamp1Groen.FillColor = Green
shpLamp2Rood.FillColor = Red
shpLamp3Groen.FillColor = Green
shpLamp4Rood.FillColor = Red

Timer1.Interval = TimeForStatus3 * 1000
Case 4
shpLamp1Oranje.FillColor = Orange
shpLamp2Rood.FillColor = Red
shpLamp3Oranje.FillColor = Orange
shpLamp4Rood.FillColor = Red

Timer1.Interval = TimeForStatus4 * 1000
End Select

'We need to call the following subroutine
RefreshLights
End Sub

Private Sub RefreshLights()
'This subroutine makes sure that de data on the screen is
'displayed correctly
shpLamp1Groen.Refresh
shpLamp1Oranje.Refresh
shpLamp1Rood.Refresh
shpLamp2Groen.Refresh
shpLamp2Oranje.Refresh
shpLamp2Rood.Refresh
shpLamp3Groen.Refresh
shpLamp3Oranje.Refresh
shpLamp3Rood.Refresh
shpLamp4Groen.Refresh
shpLamp4Oranje.Refresh
shpLamp4Rood.Refresh
End Sub

Private Sub Form_Load()
'When the programs starts, it starts with status 1
SetStatus 1
'Initializing the timer will start the timer1_timer subroutine after the
'set interval has elapsed (in milliseconds)
Timer1.Interval = TimeForStatus1 * 1000
End Sub
Private Sub Timer1_Timer()
'Change to the next status
Status = Status + 1
'If the next status is 5 then we need to change it back to one
If Status = 5 Then Status = 1

SetStatus Status
End Sub