ACC: Enumerating Local and Network Printers

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Summary

Advanced: Requires expert coding, interoperability, and multiuser skills.


This article shows you two procedures that use the EnumPrinters API function to retrieve a list of printers available locally and that your computer is connected to on the network.


The procedures demonstrate returning data to both the PRINTER_INFO_1 structure and the PRINTER_INFO_4 structure, each of which provides slightly different information about the printer. If you are using Microsoft Windows 95 or later, you can return data to the PRINTER_INFO_1 structure; if you are using Microsoft Windows NT, you can return data to either structure.


This article assumes that you are familiar with Visual Basic for Applications and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Visual Basic for Applications, please refer to your version of the "Building Applications with Microsoft Access" manual.

More Information

WARNING: ANY USE BY YOU OF THE CODE PROVIDED IN THIS ARTICLE IS AT YOUR OWN RISK. Microsoft provides this code "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose.


Use the Sub routine EnumeratePrinters1 if you are running Microsoft Windows 95 or later. You can use either Sub routine if you are running Microsoft Windows NT.


The code in each of the two examples performs these steps:


  • Calls the EnumPrinters API, which returns a buffer of data, a success flag, and a flag indicating whether the buffer is too small.
  • If the buffer is too small, makes it the correct size and calls the API again.
  • For each entry in the buffer, extracts the data and prints it.
NOTE: When using these functions in your own applications, you may want to return an array of data that can be displayed in a list box or grid rather than print the values.


The buffer is in the following format:

|rec1|rec2|...|recn|...garbage...|strn|...|str2|str1|
INFO records containing string pointers and numeric values are added from the left, and the string text for each record is added from the right. The area between the end of the last record and the start of the last string text contains garbage.


The buffer is declared as type Long, which makes extracting data from the records easier - all fields are either Long or pointers (pointers map to Long).


The StrLen() and PtrToStr() functions are used to set up the receiving string variable and to copy the text from the buffer to the variable.


  1. Create a module and type the following lines in the Declarations section:
          Option Explicit

    Const PRINTER_ENUM_CONNECTIONS = &H4
    Const PRINTER_ENUM_LOCAL = &H2

    Type PRINTER_INFO_1
    flags As Long
    pDescription As String
    PName As String
    PComment As String
    End Type

    Type PRINTER_INFO_4
    pPrinterName As String
    pServerName As String
    Attributes As Long
    End Type

    Declare Function EnumPrinters Lib "winspool.drv" Alias _
    "EnumPrintersA" (ByVal flags As Long, ByVal name As String, _
    ByVal Level As Long, pPrinterEnum As Long, ByVal cdBuf As Long, _
    pcbNeeded As Long, pcReturned As Long) As Long
    Declare Function PtrToStr Lib "Kernel32" Alias "lstrcpyA" _
    (ByVal RetVal As String, ByVal Ptr As Long) As Long
    Declare Function StrLen Lib "Kernel32" Alias "lstrlenA" _
    (ByVal Ptr As Long) As Long
  2. Type the following procedures:
          Sub EnumeratePrinters1()
    Dim Success As Boolean, cbRequired As Long, cbBuffer As Long
    Dim Buffer() As Long, nEntries As Long
    Dim I As Long, PFlags As Long, PDesc As String, PName As String
    Dim PComment As String, Temp As Long
    cbBuffer = 3072
    ReDim Buffer((cbBuffer \ 4) - 1) As Long
    Success = EnumPrinters(PRINTER_ENUM_CONNECTIONS Or _
    PRINTER_ENUM_LOCAL, _
    vbNullString, _
    1, _
    Buffer(0), _
    cbBuffer, _
    cbRequired, _
    nEntries)
    If Success Then
    If cbRequired > cbBuffer Then
    cbBuffer = cbRequired
    Debug.Print "Buffer too small. Trying again with " & _
    cbBuffer & " bytes."
    ReDim Buffer(cbBuffer \ 4) As Long
    Success = EnumPrinters(PRINTER_ENUM_CONNECTIONS Or _
    PRINTER_ENUM_LOCAL, _
    vbNullString, _
    1, _
    Buffer(0), _
    cbBuffer, _
    cbRequired, _
    nEntries)
    If Not Success Then
    Debug.Print "Error enumerating printers."
    Exit Sub
    End If
    End If
    Debug.Print "There are " & nEntries & _
    " local and connected printers."
    For I = 0 To nEntries - 1
    PFlags = Buffer(4 * I)
    PDesc = Space$(StrLen(Buffer(I * 4 + 1)))
    Temp = PtrToStr(PDesc, Buffer(I * 4 + 1))
    PName = Space$(StrLen(Buffer(I * 4 + 2)))
    Temp = PtrToStr(PName, Buffer(I * 4 + 2))
    PComment = Space$(StrLen(Buffer(I * 4 + 2)))
    Temp = PtrToStr(PComment, Buffer(I * 4 + 2))
    Debug.Print PFlags, PDesc, PName, PComment
    Next I
    Else
    Debug.Print "Error enumerating printers."
    End If
    End Sub

    Sub EnumeratePrinters4()
    Dim Success As Boolean, cbRequired As Long, cbBuffer As Long
    Dim Buffer() As Long, nEntries As Long
    Dim I As Long, PName As String, SName As String
    Dim Attrib As Long, Temp As Long
    cbBuffer = 3072
    ReDim Buffer((cbBuffer \ 4) - 1) As Long
    Success = EnumPrinters(PRINTER_ENUM_CONNECTIONS Or _
    PRINTER_ENUM_LOCAL, _
    vbNullString, _
    4, _
    Buffer(0), _
    cbBuffer, _
    cbRequired, _
    nEntries)
    If Success Then
    If cbRequired > cbBuffer Then
    cbBuffer = cbRequired
    Debug.Print "Buffer too small. Trying again with " & _
    cbBuffer & " bytes."
    ReDim Buffer(cbBuffer \ 4) As Long
    Success = EnumPrinters(PRINTER_ENUM_CONNECTIONS Or _
    PRINTER_ENUM_LOCAL, _
    vbNullString, _
    4, _
    Buffer(0), _
    cbBuffer, _
    cbRequired, _
    nEntries)
    If Not Success Then
    Debug.Print "Error enumerating printers."
    Exit Sub
    End If
    End If
    Debug.Print "There are " & nEntries & _
    " local and connected printers."
    For I = 0 To nEntries - 1
    PName = Space$(StrLen(Buffer(I * 3)))
    Temp = PtrToStr(PName, Buffer(I * 3))
    SName = Space$(StrLen(Buffer(I * 3 + 1)))
    Temp = PtrToStr(SName, Buffer(I * 3 + 1))
    Attrib = Buffer(I * 3 + 2)
    Debug.Print "Printer: " & PName, "Server: " & SName, _
    "Attributes: " & Hex$(Attrib)
    Next I
    Else
    Debug.Print "Error enumerating printers."
    End If
    End Sub
  3. To test this function, type the following line in the Debug window, and then press ENTER:
    EnumeratePrinters1
    The output should be similar to the following:


    There are 1 local and connected printers.
    8388608 \\NCPRINT\HP5SI@1155,HP LaserJet 5Si MX,HP5SI@1155
    \\NCPRINT\HP5SI@1155 \\NCPRINT\HP5SI@1155
    If you are using Microsoft Windows NT, type:

    EnumeratePrinters4
    The output should be similar to the following:

    There are 1 local and connected printers.
    Printer: \\NCPRINT\HP5SI@1155 Server: \\NCPRINT
    Attributes: 10

References

For more information about the EnumPrinters function, please refer to the Win32 SDK.
Propiedades

Id. de artículo: 166008 - Última revisión: 01/19/2007 - Revisión: 1

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