ACC2000: Enumerating Local and Network Printers

ID: Q200611

The information in this article applies to:

Microsoft Access 2000

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 also those printers on a network that may be connected to your computer.

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.

MORE INFORMATION

Microsoft provides programming examples for illustration only, without warranty either expressed or implied, including, but not limited to, the implied warranties of merchantability and/or fitness for a particular purpose. This article assumes that you are familiar with the programming language being demonstrated and the tools used to create and debug procedures. Microsoft support professionals can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific needs. If you have limited programming experience, you may want to contact a Microsoft Certified Solution Provider or the Microsoft fee-based consulting line at (800) 936-5200. For more information about Microsoft Certified Solution Providers, please see the following page on the World Wide Web:

http://www.microsoft.com/mcsp/

For more information about the support options available from Microsoft, please see the following page on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

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, the code makes it the correct size and calls the API again.

For each entry in the buffer, it 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.

Create a module and type the following lines in the Declarations section:


Option Compare Database
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

Type the following procedures:


Sub EnumeratePrintersWin()

   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 EnumeratePrintersNT()

   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

To test this function, type the following line in the Immediate window, and then press ENTER:


EnumeratePrintersWIN


There are 1 local and connected printers.
8388608      \\NCPRINT\HP5SI@1155,HP LaserJet 5Si MX,HP5SI@1155
\\NCPRINT\HP5SI@1155        \\NCPRINT\HP5SI@1155


EnumeratePrintersNT


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.

Additional query words:

Keywords : kbnetwork kbprg kbprint kbdta
Version : WINDOWS:2000
Platform : WINDOWS
Issue type : kbhowto