openprinter api

i am working on some code that used the openprinter api to send print code to a generic text printer. the code works fine in windows xp but when i go to run the same app on windows 7 it fails. is there a different api that needs to be used for windows 7 or is this a windows 7 security thing?
thanks

Source, extracts below

Quote:

---

Originally Posted by msdn

If a user does not have permission to open a specified printer or print server with the desired access, the OpenPrinter call will fail with a return value of zero and GetLastError will return the value ERROR_ACCESS_DENIED.

You can call the OpenPrinter function to open a handle to a print server or to determine the access rights that a client has to a print server. To do so, specify the name of the print server in the pPrinterName parameter, set the pDatatype and pDevMode members of the PRINTER_DEFAULTS structure to NULL, and set the DesiredAccess member to specify a server access mask value such as SERVER_ALL_ACCESS. When you are finished with the handle, pass it to the ClosePrinter function to close it.

---

the printer is a network printer that is shared off from another pc. on the windows 7 box the printer is set up to allow user 'EVERYONE' full access to the printer so i would not think it is a permissions issue. i could be wrong though.

I assume OpenPrinter is returning zero? If so, what does Err.LastDllError return? Check that immediately afterwards.

Edited: If you are getting error code 5: Access Denied or any error really. Maybe try setting pDesiredAccess to PRINTER_ACCESS_USE (value of 8)

i will create a test app and check these as what i am running now is compiled code not outputting the error info.

I got my app working and you are correct i am getting error 5 access denied. i tried to change the access level and am not getting an unhandled exception

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

any thoughts?
also this is a service that is doing the printing, not sure if that would make a difference.

Maybe try setting pDesiredAccess to PRINTER_ACCESS_USE (value of 8)

i am sorry but i am a little confused. i tried to set the access level
If OpenPrinter(PrinterName, lhPrinter, 8) = 0 Then

and then i get the Attempted to read or write protected memory. This is often an indication that other memory is corrupt unhandled exception.

can you provide me with a code snippet?
thanks

Did you declare the OpenPrinter API's final parameter as ByRef or ByVal? If not ByVal, try:
OpenPrinter(PrinterName, lhPrinter, ByVal 8&)

this may be an issue with the service somehow. i wrote just a vb forms app with the same basic code that is being used in the service and it prints things fine. the service gives the errors.

Oops, the final parameter in the OpenPrinter API is a structure. The default API declaration appears to be:

Code:

---

Private Declare Function OpenPrinter Lib "winspool.drv" Alias "OpenPrinterA" (ByVal pPrinterName As String, ByRef phPrinter As Long, ByRef pDefault As Any) As Long
Private 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
        dmUnusedPadding As Integer
        dmBitsPerPel As Integer
        dmPelsWidth As Long
        dmPelsHeight As Long
        dmDisplayFlags As Long
        dmDisplayFrequency As Long
End Type
Private Type PRINTER_DEFAULTS
        pDatatype As String
        pDevMode As DEVMODE
        DesiredAccess As Long
End Type
Private Const CCHDEVICENAME As Long = 32
Private Const CCHFORMNAME As Long = 32
Private Const PRINTER_ACCESS_USE AS Long = 8

---

So, using the above info, maybe this will do the trick

Code:

---

Dim PDF As PRINTER_DEFAULTS
PDF.DesiredAccess = PRINTER_ACCESS_USE
lResult = OpenPrinter(PrinterName, lhPrinter, PDF)

---

I modified my test app to use the code you provided(modified to change it to VB.NET) and i get an unhadled exception of value does not fall with the expected range.

i dont think this is an api issue as much as it is an issue with windows 7 security on either the service or the printer.

dougg, did you ever resolve this? I'm having the same problem. The call worked fine under XP, then the user got a Windows 7 machine last week, and it no longer works. The code is VBA in Access 2003. I'm trying LaVolpe's suggestion, passing a PRINTER_DEFAULTS structure with DesiredAccess of 8 (it was previously just passing a NULL third argument), and it's not crashing, but it also still returns FALSE. Err.LastDllError, however, is returning 3012, unlike your case. Some other Google searching indicates this may mean "Printer Not Found".

I'm thinking definitely security issue, not code issue.