Convertendo um Form em uma Imagem para Impressão

Imports System.Drawing.Printing

Module Imprimir

    Dim memoryImage As Bitmap
    Private WithEvents printDocument1 As New PrintDocument

    'Private Sub printDocument1_PrintPage(ByVal sender As System.Object, ByVal e As System.Drawing.Printing.PrintPageEventArgs) Handles printDocument1.PrintPage
    ' e.Graphics.DrawImage(memoryImage, 0, 0)
    'End Sub

    ''' <summary>
    ''' esta rotina transforma o form em uma imagem e imprime a imagem em um doc pdf
    ''' </summary>
    Public Sub ImprimirFormComoImagemPDF()
        'Dim myGraphics As Graphics = Me.CreateGraphics()
        Dim myGraphics As Graphics = frmPrincipal.CreateGraphics()
        'Dim s As Size = Me.Size
        Dim s As Size = frmPrincipal.Size
        memoryImage = New Bitmap(s.Width, s.Height, myGraphics)
        Dim memoryGraphics As Graphics = Graphics.FromImage(memoryImage)
        'memoryGraphics.CopyFromScreen(Me.Location.X, Me.Location.Y, 0, 0, s)
        memoryGraphics.CopyFromScreen(frmPrincipal.Location.X, frmPrincipal.Location.Y, 0, 0, s)

        'memoryGraphics.CopyFromScreen(Me.Location.X, Me.Location.Y, Me.Location.X + s.Width - 500, Me.Location.Y + s.Height, s)
        memoryGraphics.CopyFromScreen(frmPrincipal.Location.X, frmPrincipal.Location.Y, frmPrincipal.Location.X + s.Width - 500, frmPrincipal.Location.Y + s.Height, s)

        printDocument1.Print()
    End Sub

    ''' <summary>
    ''' Exibindo impressoras instaladas
    ''' </summary>
    Public Function ImpressorasInstaladas() As ArrayList
        Dim a As New ArrayList
        Dim v_total
        Dim pd As PrintDocument = New PrintDocument
        Dim pkInstalledPrinters As String

        a.Clear()

        Try

            'retornar o numero total de impressoras instaladas
            v_total = PrinterSettings.InstalledPrinters.Count

            For i = 0 To PrinterSettings.InstalledPrinters.Count - 1
                pkInstalledPrinters = PrinterSettings.InstalledPrinters.Item(i)
                a.Add(pkInstalledPrinters)
            Next

            Return a
            'seleciona o primeiro item
            'Me.Cmb_Impressoras.SelectedIndex = (v_item)
        Catch ex As Exception
            'exibe mensagem de erro cajo aconteça ao inesperado
            MessageBox.Show("Erro da função ImpressorasInstaladas : " + ex.Message)
            Return Nothing
        Finally
s
            'libera da memória
            pd.Dispose()
        End Try
    End Function

End Module