Microsoft KB Archive/266767

= How To Set Which Printer Is the System Default Printer =

Article ID: 266767

Article Last Modified on 8/23/2006

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APPLIES TO


 * Microsoft Visual Basic 4.0 Professional Edition
 * Microsoft Visual Basic 5.0 Professional Edition
 * Microsoft Visual Basic 6.0 Professional Edition
 * Microsoft Visual Basic 4.0 Enterprise Edition
 * Microsoft Visual Basic 5.0 Enterprise Edition
 * Microsoft Visual Basic 6.0 Enterprise Edition
 * Microsoft Visual Basic 5.0 Learning Edition
 * Microsoft Visual Basic 6.0 Learning Edition

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This article was previously published under Q266767



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
 Start a new Standard EXE project in Visual Basic. Form1 is created by default.  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 &quot;kernel32&quot; _ Alias &quot;GetProfileStringA&quot; _ (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 &quot;kernel32&quot; _ Alias &quot;WriteProfileStringA&quot; _ (ByVal lpszSection As String, _ ByVal lpszKeyName As String, _ ByVal lpszString As String) As Long

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

Declare Function GetVersionExA Lib &quot;kernel32&quot; _ (lpVersionInformation As OSVERSIONINFO) As Integer

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

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

Public Declare Function GetPrinter Lib &quot;winspool.drv&quot; _ Alias &quot;GetPrinterA&quot; _ (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 &quot;kernel32&quot; _ Alias &quot;lstrcpyA&quot; _ (ByVal lpString1 As String, _ ByVal lpString2 As Any) As Long

Public Declare Function ClosePrinter Lib &quot;winspool.drv&quot; _ (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  Place a ListBox and a CommandButton on Form1.  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 = &quot;&quot; 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 & &quot;,&quot; & DriverName & &quot;,&quot; & PrinterPort ' Store the new printer information in the [WINDOWS] section of   ' the WIN.INI file for the DEVICE= item r = WriteProfileString(&quot;windows&quot;, &quot;Device&quot;, DeviceLine) ' Cause all applications to reload the INI file: l = SendMessage(HWND_BROADCAST, WM_WININICHANGE, 0, &quot;windows&quot;) 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 = &quot;&quot; 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 &quot;SetPrinter Failed. Error code: &quot; & 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 = &quot;&quot; PrinterPort = &quot;&quot;

' The driver name is first in the string terminated by a comma iDriver = InStr(Buffer, &quot;,&quot;) 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, &quot;,&quot;)

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 = &quot;&quot; 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(&quot;PrinterPorts&quot;, PrinterName, &quot;&quot;, _           Buffer, Len(Buffer))

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

If DriverName <> &quot;&quot; And PrinterPort <> &quot;&quot; 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 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(&quot;PrinterPorts&quot;, vbNullString, &quot;&quot;, _      Buffer, Len(Buffer))

' Display the list of printer in the ListBox List1 ParseList List1, Buffer End Sub  Run the project and note that the preceding code populates a ListBox with all available printers. Select one printer in the list and make it the default by clicking the CommandButton. 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.</li></ol>

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