class test
    Private r As Rectangle
    Private intXGroesse As Integer = 50 * PB_XFAKTOR
    Private dblFaktor As Double
    Private b As Bitmap
    Private i As Image
    Private tbmp As Bitmap
    Private AlreadyCreated As Boolean
    Private g As Graphics
    Private MausPosi As Point
 
    Private Sub pbAuswahl_MouseEnter(ByVal sender As Object, ByVal e As _
      System.EventArgs) Handles pbAuswahl.MouseEnter
        'Einmaliges Anlegen der fixen Parameter
        If Not AlreadyCreated Then
            r = New Rectangle
            r.Height = pbAuswahl.Height
            r.Width = pbAuswahl.Width
            dblFaktor = pbLupe.Width / pbLupe.Height
            b = New Bitmap(pbLupe.Width, pbLupe.Height)
            i = pbAuswahl.Image
            tbmp = New Bitmap(pbAuswahl.Width, pbAuswahl.Height) 'temporäres 
            ' Bitmap erzeugen
            g = Graphics.FromImage(b)
            AlreadyCreated = True
        End If
 
        pbLupe.Visible = True
        tLupe.Enabled = True
    End Sub
 
    Private Sub pbAuswahl_MouseLeave(ByVal sender As Object, ByVal e As _
      System.EventArgs) Handles pbAuswahl.MouseLeave
        pbLupe.Visible = False
        tLupe.Enabled = False
    End Sub
 
    Private Sub pbAuswahl_MouseMove(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles pbAuswahl.MouseMove
        MausPosi.X = e.X
        MausPosi.Y = e.Y
        tLupe.Stop()
        tLupe.Start()
    End Sub
 
    Private Sub tLupe_Tick(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles tLupe.Tick
        pbAuswahl.DrawToBitmap(tbmp, r) 'Inhalt der Picturebox Hineinzeichnen
        g.DrawImage(tbmp, New Rectangle(0, 0, pbAuswahl.Width, _
          pbAuswahl.Height), _
                            New Rectangle(MausPosi.X - intXGroesse, MausPosi.Y _
                            - CInt(intXGroesse / dblFaktor), _
                            intXGroesse * 2, CInt(intXGroesse / dblFaktor) * _
                            2), GraphicsUnit.Pixel)
        pbLupe.Image = b
    End Sub
end class