Como definir qual impressora é a impressora padrão de sistema

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ID do artigo: 266767 - Exibir os produtos aos quais esse artigo se aplica.
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Sumário

Este artigo mostra como programaticamente definir qual impressora é a impressora padrão de sistema. Nem todos os aplicativos ou componentes podem selecionar uma impressora específica para usar. Isso torna necessário para alterar a impressora padrão para o sistema para que o aplicativo ou componente usarão a impressora desejada.

Mais Informações

Observação : este código altera a impressora padrão para todo o sistema. Portanto, todos os aplicativos que não especificam uma impressora, até mesmo aplicativos que atualmente estão sendo executados, usam esse mesmo padrão. Por esse motivo, convém ter seu código, lembre-se o padrão anterior e, em seguida, defina-o novamente quando terminar o trabalho de impressão.

O exemplo de código a seguir fornece um meio para determinar quais impressoras estão disponíveis e designar um como a impressora padrão de sistema.

Exemplo passo a passo

  1. Inicie um novo projeto Standard EXE no Visual Basic. O Form1 é criado por padrão.
  2. Adicione um novo módulo para o projeto e insira o código a seguir:
    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. Coloque um controle ListBox e um CommandButton no Form1.
  4. Adicione o seguinte código à seção General Declarations do 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 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. Executar o projeto e observe que o código anterior preenche uma ListBox com todas as impressoras disponíveis.
  6. Selecione uma impressora na lista e torne-o padrão clicando no CommandButton .
  7. Confirmar que a impressora padrão foi alterado: no botão Iniciar , selecione configurações , selecione Printers e verificar qual impressora está marcada como o padrão. Como alternativa, você pode imprimir na impressora padrão de qualquer aplicativo em seu sistema.

Referências

Para obter informações adicionais, clique nos números abaixo para ler os artigos na Base de dados de Conhecimento da Microsoft:
167735CORRECÇÃO: Falha de configuração de impressora para item na coleção impressoras
253612CORRECÇÃO: Printers Collection pode não conter todas as impressoras na pasta Impressoras
246772Como recuperar e definir a impressora padrão no Windows

Propriedades

ID do artigo: 266767 - Última revisão: quarta-feira, 23 de agosto de 2006 - Revisão: 3.3
A informação contida neste artigo aplica-se a:
  • 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 Enterprise Edition for Windows 6.0
  • Microsoft Visual Basic 5.0 Learning Edition
  • Microsoft Visual Basic 6.0 Learning Edition
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kbmt kbapi kbcodesnippet kbgdi kbhowto kbprint kbspooler KB266767 KbMtpt
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