Computer Programming Concepts and Visual Basic David I. Schneider

372 Computer Programming Concepts and Visual Basic
‘Set the initial center of the circle to the upper
‘left corner of the form and set its radius to 500.
m_x = 0
m_y = 0
m_r = 500
End Sub
Public Property Get Xcoord() As Integer
Xcoord = m_x
End Property
Public Property Let Xcoord(ByVal vNewValue As Integer)
m_x = vNewValue
End Property
Public Property Get Ycoord() As Integer
Ycoord = m_y
End Property
Public Property Let Ycoord(ByVal vNewValue As Integer)
m_y = vNewValue
End Property
Public Sub Show()
‘Display the circle.
‘See discussion of Circle method in Section 10.4.
frmCircles.Circle (m_x, m_y), m_r
End Sub
Public Sub Move(Dist)
‘Move the center of the circle Dist twips to the right
‘and Dist twips down.
m_x = m_x + Dist
m_y = m_y + Dist
RaiseEvent PositionChanged(m_x, m_y, m_r)
Call Show
End Sub
‘Form code
Private WithEvents round As CCircle
Private Sub Form_Load()
Set round = New CCircle
End Sub
Private Sub cmdMove_Click()
round.Move (500)
End Sub
Private Sub round_PositionChanged(x As Integer, y As Integer, _
r As Integer)
‘This event is triggered when the center of the circle changes.
‘The code determines if part of the circle is off the screen.
If (x + r > frmCircles.Width) Or (y + r ]] frmCircles.Height) Then
lblCaution.Caption = “Circle Off Screen”