' Mr. Minich
' Period 1
' Ch4Demo1
' 11/2/2000
' Purpose - to illustrate the use of the KeyPress event and an If/ElseIf statement

Option Explicit

Private Sub Form_Activate()
    ' displaying appropriate messages & setting visibility
    
    lblMessage.AutoSize = True  ' allows message to fit into labels without being
    lblWarning.AutoSize = True  '   cut off
    
                                ' setting various captions
    lblMessage.Caption = "Press a to add 1" & vbCrLf & "Press s to subtract 1"
    lblRunningTotal.Caption = "0"
    lblWarning.Caption = "Press 'a' to add one and 's' to subtract one"
    cmdExit.Caption = "Exit"
    cmdClear.Caption = "&Clear"
    
    lblWarning.Visible = False  ' warning should be invisible at first
    
    frmMain.KeyPreview = True   ' necessary for KeyPress to work with
                                '   command buttons on the form
    
End Sub

Private Sub Form_KeyPress(KeyAscii As Integer)
    ' adds or subtracts one depending on the user's keypress
    
    '   KeyAscii is the parameter used to store the ASCII value of the key
    '   that was pressed by the user.

    lblWarning.Visible = False  ' make warning invisible in case it was visible
    
    If (KeyAscii = 97) Then                     ' if a is pressed add one
        lblRunningTotal.Caption = Val(lblRunningTotal.Caption) + 1
    ElseIf (KeyAscii = 115) Then                ' if s is pressed subtract one
        lblRunningTotal.Caption = Val(lblRunningTotal.Caption) - 1
    Else                                        ' show warning if wrong key pressed
        lblWarning.Visible = True
    End If
    
End Sub


Private Sub cmdClear_Click()
    ' clear running total label
    
    lblRunningTotal.Caption = "0"
End Sub

Private Sub cmdExit_Click()
    ' unload form and exit project
    
    Unload Me
    End
End Sub

' Notes:

' vbCrLf is the Visual Basic "Carriage Return/Line Feed constant" that allows you to 
'	break up Caption settings over two or more lines.

' KeyAscii is the default name for the parameter of the KeyPress event. It is not 
'	recommended that you change this parameter name for any reason but do realize
'	that is simply the numerical ASCII value of the key which was pressed by the user.

' In effect, the statement

'		lblRunningTotal.Caption = Val(lblRunningTotal.Caption) + 1

'	is a counter statement. It allows for the running total to be stored and displayed in the caption
'	of the label lblRunningTotal. Each time it is executed, one is added to the existing value stored
'	in the caption.