บันทึกภาพจาก panel 2 panel ให้อยู่ใน panel เดียวกัน และทำการบันทึกเป็นรูปภาพ

    Dim memoryImage
    Private Declare Auto Function BitBlt Lib "GDI32.DLL" (ByVal hdcDest As IntPtr, ByVal nXDest As Integer, ByVal nYDest As Integer, ByVal nWidth As Integer, ByVal nHeight As Integer, ByVal hdcSrc As IntPtr, ByVal nXSrc As Integer, ByVal nYSrc As Integer, ByVal dwRop As Int32) As Boolean
    Private Sub btnPrintpreview_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPrintpreview.Click
        CaptureScreen()
        PrintPreviewDialog1.Document = PrintDocument1
        PrintPreviewDialog1.ShowDialog()
    End Sub

 Private Sub CaptureScreen()
        Dim mygraphics As Graphics = Panel3.CreateGraphics() 
        Dim s As Size = Panel3.Size

        memoryImage = New Bitmap(s.Width, s.Height, mygraphics)

        Dim memoryGraphics As Graphics = Graphics.FromImage(memoryImage)
        Dim dc1 As IntPtr = mygraphics.GetHdc
        Dim dc2 As IntPtr = memoryGraphics.GetHdc

        BitBlt(dc2, 0, 0, Panel3.ClientRectangle.Width, Panel3.ClientRectangle.Height, dc1, 0, 0, 13369376)
        mygraphics.ReleaseHdc(dc1)
        memoryGraphics.ReleaseHdc(dc2)

    End Sub

    Private Sub PrintDocument1_PrintPage(ByVal sender As System.Object, ByVal e As System.Drawing.Printing.PrintPageEventArgs) Handles PrintDocument1.PrintPage
        e.Graphics.DrawImage(memoryImage, 10, 10)
    End Sub