Computer Programming Concepts and Visual Basic David I. Schneider

300 Computer Programming Concepts and Visual Basic
[Run and move the thumbs on the scroll bars.]
In Example 5, when you drag the thumb, the face does not move until the dragging is
completed. This can be corrected by adding the following two event procedures.
Private Sub hsbXPos_Scroll() lblFace.Left = hsbXPos.ValueEnd SubPrivate Sub vsbY-
Pos_Scroll() lblFace.Top = vsbYPos.ValueEnd Sub
THE TIMER CONTROL
The timer control, which is invisible during run time, triggers an event after a specified amount
of time. The length of time, measured in milliseconds, is set with the Interval property to be
any number from 0 to 65,535 (about 1 minute and 5 seconds). The event triggered each time
Timer1.Interval milliseconds elapses is called Timer1_Timer( ). In order to begin timing, a timer
must first be turned on by setting its Enabled property to True. A timer is turned off either by
setting its Enabled property to False or by setting its Interval property to 0. The standard prefix
for the name of a timer control is tmr.
EXAMPLE 6
The following program creates a stopwatch that updates the time every tenth of a second.
Object Property Setting
frmWatch Caption Stopwatch
cmdStart Caption Start
lblSeconds Caption Seconds
lblTime Caption (blank)
cmdStop Caption Stop
tmrWatch Interval 100
Enabled False
Private Sub cmdStart_Click()
lblTime.Caption = “ 0” ‘Reset watch
tmrWatch.Enabled = True
End Sub
Private Sub cmdStop_Click()
tmrWatch.Enabled = False
End Sub
Private Sub tmrWatch_Timer()
lblTime.Caption = Str(Val(lblTime.Caption) + .1)
End Sub
[Run, click on the Start button, wait 10.8 seconds, and click on the Stop button.]