DOCUMENT:Q266767  04-FEB-2002  [vbwin]
TITLE   :HOWTO: Set Which Printer Is the System Default Printer
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER::4.0,5.0,6.0
OPER/SYS:
KEYWORDS:kbprint kbAPI kbGDI kbPrinting kbSDKWin32 kbSpooler kbVBp kbVBp400 kbVBp500 kbVBp600 kb

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The information in this article applies to:

 - Microsoft Visual Basic Professional Edition for Windows, versions 4.0, 5.0, 6.0 
 - Microsoft Visual Basic Enterprise Edition for Windows, versions 4.0, 5.0, 6.0 
 - Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 
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SUMMARY
=======

This article shows how to programmatically set which printer is the system
default printer. Not all applications or components can select a specific
printer to use. This often makes it necessary to change the default printer for
the system so that the application or component will use the desired printer.

MORE INFORMATION
================

NOTE: This code changes the default printer for the entire system. So all
applications that do not specify a printer, even applications that are currently
running, use this same default. For this reason, you may want to have your code
remember the previous default and then set it back when your print job is
finished.

The following code sample provides a means to determine which printers are
available, and to designate one as the system default printer.

Step-by-Step Example
--------------------

1. Start a new Standard EXE project in Visual Basic. Form1 is created by
   default.

2. Add a new module to the project and insert the following code:

   Public Const HWND_BROADCAST = &HFFFF
   Public Const WM_WININICHANGE = &H1A

   ' constants for DEVMODE structure
   Public Const CCHDEVICENAME = 32
   Public Const CCHFORMNAME = 32

   ' constants for DesiredAccess member of PRINTER_DEFAULTS
   Public Const STANDARD_RIGHTS_REQUIRED = &HF0000
   Public Const PRINTER_ACCESS_ADMINISTER = &H4
   Public Const PRINTER_ACCESS_USE = &H8
   Public Const PRINTER_ALL_ACCESS = (STANDARD_RIGHTS_REQUIRED Or _
   PRINTER_ACCESS_ADMINISTER Or PRINTER_ACCESS_USE)

   ' constant that goes into PRINTER_INFO_5 Attributes member
   ' to set it as default
   Public Const PRINTER_ATTRIBUTE_DEFAULT = 4

   ' Constant for OSVERSIONINFO.dwPlatformId
   Public Const VER_PLATFORM_WIN32_WINDOWS = 1

   Public Type OSVERSIONINFO
       dwOSVersionInfoSize As Long
       dwMajorVersion As Long
       dwMinorVersion As Long
       dwBuildNumber As Long
       dwPlatformId As Long
       szCSDVersion As String * 128
   End Type

   Public Type DEVMODE
        dmDeviceName As String * CCHDEVICENAME
        dmSpecVersion As Integer
        dmDriverVersion As Integer
        dmSize As Integer
        dmDriverExtra As Integer
        dmFields As Long
        dmOrientation As Integer
        dmPaperSize As Integer
        dmPaperLength As Integer
        dmPaperWidth As Integer
        dmScale As Integer
        dmCopies As Integer
        dmDefaultSource As Integer
        dmPrintQuality As Integer
        dmColor As Integer
        dmDuplex As Integer
        dmYResolution As Integer
        dmTTOption As Integer
        dmCollate As Integer
        dmFormName As String * CCHFORMNAME
        dmLogPixels As Integer
        dmBitsPerPel As Long
        dmPelsWidth As Long
        dmPelsHeight As Long
        dmDisplayFlags As Long
        dmDisplayFrequency As Long
        dmICMMethod As Long        ' // Windows 95 only
        dmICMIntent As Long        ' // Windows 95 only
        dmMediaType As Long        ' // Windows 95 only
        dmDitherType As Long       ' // Windows 95 only
        dmReserved1 As Long        ' // Windows 95 only
        dmReserved2 As Long        ' // Windows 95 only
   End Type

   Public Type PRINTER_INFO_5
        pPrinterName As String
        pPortName As String
        Attributes As Long
        DeviceNotSelectedTimeout As Long
        TransmissionRetryTimeout As Long
   End Type

   Public Type PRINTER_DEFAULTS
        pDatatype As Long
        pDevMode As Long
        DesiredAccess As Long
   End Type

   Declare Function GetProfileString Lib "kernel32" _
   Alias "GetProfileStringA" _
   (ByVal lpAppName As String, _
   ByVal lpKeyName As String, _
   ByVal lpDefault As String, _
   ByVal lpReturnedString As String, _
   ByVal nSize As Long) As Long

   Declare Function WriteProfileString Lib "kernel32" _
   Alias "WriteProfileStringA" _
   (ByVal lpszSection As String, _
   ByVal lpszKeyName As String, _
   ByVal lpszString As String) As Long

   Declare Function SendMessage Lib "user32" _
   Alias "SendMessageA" _
   (ByVal hwnd As Long, _
   ByVal wMsg As Long, _
   ByVal wParam As Long, _
   lparam As String) As Long

   Declare Function GetVersionExA Lib "kernel32" _
   (lpVersionInformation As OSVERSIONINFO) As Integer

   Public Declare Function OpenPrinter Lib "winspool.drv" _
   Alias "OpenPrinterA" _
   (ByVal pPrinterName As String, _
   phPrinter As Long, _
   pDefault As PRINTER_DEFAULTS) As Long

   Public Declare Function SetPrinter Lib "winspool.drv" _
   Alias "SetPrinterA" _
   (ByVal hPrinter As Long, _
   ByVal Level As Long, _
   pPrinter As Any, _
   ByVal Command As Long) As Long

   Public Declare Function GetPrinter Lib "winspool.drv" _
   Alias "GetPrinterA" _
   (ByVal hPrinter As Long, _
   ByVal Level As Long, _
   pPrinter As Any, _
   ByVal cbBuf As Long, _
   pcbNeeded As Long) As Long

   Public Declare Function lstrcpy Lib "kernel32" _
   Alias "lstrcpyA" _
   (ByVal lpString1 As String, _
   ByVal lpString2 As Any) As Long

   Public Declare Function ClosePrinter Lib "winspool.drv" _
   (ByVal hPrinter As Long) As Long

       Public Sub SelectPrinter(NewPrinter As String)
           Dim Prt As Printer
           
           For Each Prt In Printers
               If Prt.DeviceName = NewPrinter Then
                   Set Printer = Prt
               Exit For
               End If
           Next
       End Sub

3. Place a ListBox and a CommandButton on Form1.

4. Add the following code to the General Declarations section of Form1:

   Option Explicit

   Private Function PtrCtoVbString(Add As Long) As String
       Dim sTemp As String * 512, x As Long

       x = lstrcpy(sTemp, Add)
       If (InStr(1, sTemp, Chr(0)) = 0) Then
            PtrCtoVbString = ""
       Else
            PtrCtoVbString = Left(sTemp, InStr(1, sTemp, Chr(0)) - 1)
       End If
   End Function

   Private Sub SetDefaultPrinter(ByVal PrinterName As String, _
       ByVal DriverName As String, ByVal PrinterPort As String)
       Dim DeviceLine As String
       Dim r As Long
       Dim l As Long
       DeviceLine = PrinterName & "," & DriverName & "," & PrinterPort
       ' Store the new printer information in the [WINDOWS] section of
       ' the WIN.INI file for the DEVICE= item
       r = WriteProfileString("windows", "Device", DeviceLine)
       ' Cause all applications to reload the INI file:
       l = SendMessage(HWND_BROADCAST, WM_WININICHANGE, 0, "windows")
   End Sub

   Private Sub Win95SetDefaultPrinter()
       Dim Handle As Long          'handle to printer
       Dim PrinterName As String
       Dim pd As PRINTER_DEFAULTS
       Dim x As Long
       Dim need As Long            ' bytes needed
       Dim pi5 As PRINTER_INFO_5   ' your PRINTER_INFO structure
       Dim LastError As Long

       ' determine which printer was selected
       PrinterName = List1.List(List1.ListIndex)
       ' none - exit
       If PrinterName = "" Then
           Exit Sub
       End If

       ' set the PRINTER_DEFAULTS members
       pd.pDatatype = 0&
       pd.DesiredAccess = PRINTER_ALL_ACCESS Or pd.DesiredAccess

       ' Get a handle to the printer
       x = OpenPrinter(PrinterName, Handle, pd)
       ' failed the open
       If x = False Then
           'error handler code goes here
           Exit Sub
       End If

       ' Make an initial call to GetPrinter, requesting Level 5
       ' (PRINTER_INFO_5) information, to determine how many bytes
       ' you need
       x = GetPrinter(Handle, 5, ByVal 0&, 0, need)
       ' don't want to check Err.LastDllError here - it's supposed
       ' to fail
       ' with a 122 - ERROR_INSUFFICIENT_BUFFER
       ' redim t as large as you need
       ReDim t((need \ 4)) As Long

       ' and call GetPrinter for keepers this time
       x = GetPrinter(Handle, 5, t(0), need, need)
       ' failed the GetPrinter
       If x = False Then
           'error handler code goes here
           Exit Sub
       End If

       ' set the members of the pi5 structure for use with SetPrinter.
       ' PtrCtoVbString copies the memory pointed at by the two string
       ' pointers contained in the t() array into a Visual Basic string.
       ' The other three elements are just DWORDS (long integers) and
       ' don't require any conversion
       pi5.pPrinterName = PtrCtoVbString(t(0))
       pi5.pPortName = PtrCtoVbString(t(1))
       pi5.Attributes = t(2)
       pi5.DeviceNotSelectedTimeout = t(3)
       pi5.TransmissionRetryTimeout = t(4)

       ' this is the critical flag that makes it the default printer
       pi5.Attributes = PRINTER_ATTRIBUTE_DEFAULT

          ' call SetPrinter to set it
          X = SetPrinter(Handle, 5, pi5, 0)

          If X = False Then   ' SetPrinter failed
              MsgBox "SetPrinter Failed. Error code: " & Err.LastDllError
              Exit Sub
          Else
              If Printer.DeviceName <> List1.Text Then
              ' Make sure Printer object is set to the new printer
                   SelectPrinter (List1.Text)
              End If
          End If

       ' and close the handle
       ClosePrinter (Handle)
   End Sub

   Private Sub GetDriverAndPort(ByVal Buffer As String, DriverName As _
       String, PrinterPort As String)

       Dim iDriver As Integer
       Dim iPort As Integer
       DriverName = ""
       PrinterPort = ""

       ' The driver name is first in the string terminated by a comma
       iDriver = InStr(Buffer, ",")
       If iDriver > 0 Then

            ' Strip out the driver name
           DriverName = Left(Buffer, iDriver - 1)

           ' The port name is the second entry after the driver name
           ' separated by commas.
           iPort = InStr(iDriver + 1, Buffer, ",")

           If iPort > 0 Then
               ' Strip out the port name
               PrinterPort = Mid(Buffer, iDriver + 1, _
               iPort - iDriver - 1)
           End If
       End If
   End Sub

   Private Sub ParseList(lstCtl As Control, ByVal Buffer As String)
       Dim i As Integer
       Dim s As String

       Do
           i = InStr(Buffer, Chr(0))
           If i > 0 Then
               s = Left(Buffer, i - 1)
               If Len(Trim(s)) Then lstCtl.AddItem s
               Buffer = Mid(Buffer, i + 1)
           Else
               If Len(Trim(Buffer)) Then lstCtl.AddItem Buffer
               Buffer = ""
           End If
       Loop While i > 0
   End Sub

   Private Sub WinNTSetDefaultPrinter()
       Dim Buffer As String
       Dim DeviceName As String
       Dim DriverName As String
       Dim PrinterPort As String
       Dim PrinterName As String
       Dim r As Long
       If List1.ListIndex > -1 Then
           ' Get the printer information for the currently selected
           ' printer in the list. The information is taken from the
           ' WIN.INI file.
           Buffer = Space(1024)
           PrinterName = List1.Text
           r = GetProfileString("PrinterPorts", PrinterName, "", _
               Buffer, Len(Buffer))

           ' Parse the driver name and port name out of the buffer
           GetDriverAndPort Buffer, DriverName, PrinterPort

              If DriverName <> "" And PrinterPort <> "" Then
                  SetDefaultPrinter List1.Text, DriverName, PrinterPort
                  If Printer.DeviceName <> List1.Text Then
                  ' Make sure Printer object is set to the new printer
                     SelectPrinter (List1.Text)
                  End If
              End If
   End Sub

   Private Sub Command1_Click()
       Dim osinfo As OSVERSIONINFO
       Dim retvalue As Integer

       osinfo.dwOSVersionInfoSize = 148
       osinfo.szCSDVersion = Space$(128)
       retvalue = GetVersionExA(osinfo)

       If osinfo.dwPlatformId = VER_PLATFORM_WIN32_WINDOWS Then
           Call Win95SetDefaultPrinter
       Else
       ' This assumes that future versions of Windows use the NT method
           Call WinNTSetDefaultPrinter
       End If
   End Sub

   Private Sub Form_Load()
       Dim r As Long
       Dim Buffer As String

       ' Get the list of available printers from WIN.INI
       Buffer = Space(8192)
       r = GetProfileString("PrinterPorts", vbNullString, "", _
          Buffer, Len(Buffer))

       ' Display the list of printer in the ListBox List1
       ParseList List1, Buffer
   End Sub

5. Run the project and note that the preceding code populates a ListBox with all
   available printers.

6. Select one printer in the list and make it the default by clicking the
   CommandButton.

7. Confirm that the default printer has changed: On the Start button, select
   Settings, select Printers, and then check which printer is marked as the
   default. Alternatively, you can print to the default printer from any
   application on your system.

REFERENCES
==========

For additional information, click the article numbers below to view the articles
in the Microsoft Knowledge Base:

   Q167735 FIX: Setting Printer to Item in the Printers Collection Fails

   Q253612 FIX: Printers Collection May Not Contain All Printers in the Printers
   Folder

   Q246772 HOWTO: Retrieve and Set the Default Printer in Windows

Additional query words: global

======================================================================
Keywords          : kbprint kbAPI kbGDI kbPrinting kbSDKWin32 kbSpooler kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpDSVB kbDSupport kbCodeSnippet 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVB500 kbVB600 kbVB400Search kbVB400
Version           : :4.0,5.0,6.0
Issue type        : kbhowto

=============================================================================

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Copyright Microsoft Corporation 2002.