Public Class listing14_2
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

    End Sub

    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        components = New System.ComponentModel.Container()
        Me.Text = "listing14_2"
    End Sub

#End Region


Public Interface Shape
  Function IsPtInShape(ByVal Pt As System.Drawing.Point) As Boolean
End Interface

Public Class Rectangle
  Implements Shape

  Private rect As Drawing.Rectangle

  Public Function PtInRect(ByVal Pt As System.Drawing.Point) As Boolean _
      Implements Shape.IsPtInShape
    PtInRect = Pt.Equals(rect)
  End Function
End Class

Public Class Circle
  Implements Shape

  Private rgn As Drawing.Region

  Public Function PtInCircle(ByVal Pt As System.Drawing.Point) As Boolean _
     Implements Shape.IsPtInShape
    PtInCircle = Pt.Equals(rgn)
  End Function
End Class

Sub CheckPoint(ByVal ShapeObject As Shape, ByVal Pt As System.Drawing.Point)
  If (ShapeObject.IsPtInShape(Pt)) Then
    Beep()
  End If
End Sub

Sub Test()
  Dim Pt As System.Drawing.Point
  Dim RectObject As Rectangle
  Dim CircleObject As Circle

  CheckPoint(RectObject, Pt)
  CheckPoint(CircleObject, Pt)
End Sub
End Class