StartDocPrinter WinAPI call fails in VBA - vba

Question

Objective: Print from string or rich text box to any printer desired, using the Win API functions specified.
Problem: Calling StartDocPrinter in VBA Access always returns 0.
Info: The code below runs through, without breaking. OpenPrinter appears to get a good handle. When StartDocPrinter is called, it returns 0.
Using the following code I have tried,
Saving different info to dDocInfo and per #David_Heffernan recommendation, declared DOCINFO properties as Long and set values to 0.
When .pDatatype = vbNullstring, GetLastError returns,
Error 124 (invalid level) when StartDocPrinter parameter Level = 1
Error 6 (invalid handle) when StarDocPrinter parameter Level = ByVal 1, though an apparent valid handle shows in hPrinter
When .pDatatype = "RAW", GetLastError returns 0 regardless.
When .pDatatype = 'vbNullString and either DOCINFO property is set to a string, GetLastError returns 0 regardless.
Changing the parameters of the WinAPI functions (ByRef DOCINFO)
Checking into access privilege issues. It appears, from other's code, that setting the last OpenPrinter parameter to 0 should set the requested access to the printer to be PRINTER_ACCESS_USE. Is it possible GetLastError is not returning access denial errors?
Converting multiple references' code from C++ to VBA, but converting or not including pointers is confusing. Am I not converting StartDocPrinter(printer, 1, (LPBYTE) &docInfo); correctly?
Code:
Declarations:
Type DOCINFO
pDocName As String
pOutputFile As String
pDatatype As String
End Type
Public Declare Function OpenPrinter Lib "winspool.drv" Alias "OpenPrinterA" (ByVal pPrinterName As String, hPrinter As Long, ByVal pDefault As Long) As Long
Public Declare Function StartDocPrinter Lib "winspool.drv" Alias "StartDocPrinterA" (hPrinter As Long, Level As Long, dDocInfo As DOCINFO) As Long
Function:
Public Function printRawData(sPrinterName As String, lData As String) As Boolean
Dim bStatus As Boolean, hPrinter As Long, dDocInfo As DOCINFO, lJob As Long, nWritten As Integer
' Open a handle to the printer.
bStatus = OpenPrinter(sPrinterName, hPrinter, 0)
If bStatus Then
' Fill in the structure with info about this "document."
dDocInfo.pDocName = vbNullString
dDocInfo.pOutputFile = vbNullString
dDocInfo.pDatatype = "RAW"
' Inform the spooler the document is beginning.
lJob = StartDocPrinter(hPrinter, 1, dDocInfo) 'Returns 0 :(
Debug.Print hPrinter, sPrinterName, lJob, GetLastError()
If lJob > 0 Then
' Start a page.
bStatus = StartPagePrinter(hPrinter)
If bStatus Then
' Send the data to the printer.
bStatus = WritePrinter(hPrinter, lData, Len(lData), nWritten)
EndPagePrinter (hPrinter)
End If
' Inform the spooler that the document is ending.
EndDocPrinter (hPrinter)
End If
' Close the printer handle.
ClosePrinter (hPrinter)
End If
' Check to see if correct number of bytes were written.
If Not bStatus Or (nWritten <> Len(lData)) Then
printRawData = False
Else
printRawData = True
End If
End Function
References/Relevant Questions:
- http://support.microsoft.com/kb/154078 Basis document for this code. Edit: Found where ByVal was missed on a few declarations here.
- Send Raw Data to ZPL Printer using Visual Basic (MS Access 2000) This person seems to use nearly identical code effectively, so why can't I? The answer to this question is written in C++.
- http://www.cplusplus.com/forum/general/26184/ The code here is also written in C++ and I am unsure how to convert.
- http://codingdomain.com/visualbasic/win32api/datatypes/ Guidance I'm using on converting datatypes and pointers, which I don't fully understand.
- StartDocPrinter(hPrinter, 1, di) returns false Some code was provided here but no answer. This is where I got idea to give errors provided.
- excel bva code to send command to usb printer I tried this and do not have the required access privileges. I would still like to know how to use the above code correctly, even if this is what I would end up doing.

Answer 1

With #HansPassant's link to the MS KB, I discovered the error in my code. The declaration of the StartDocPrinter function was missing ByVal for the hPrinter and Level parameters.
Public Declare Function StartDocPrinter Lib "winspool.drv" Alias "StartDocPrinterA" (ByVal hPrinter As Long, ByVal Level As Long, dDocInfo As DOCINFO) As Long

Answer 2

Your declaration for the DOCINFO structure does not look correct. It should be declared as:
Type DOCINFO
cbSize As Integer
lpszDocName As String
lpszOutput As String
lpszDatatype As String
fwType As Integer
End Type
The cbSize should be initialized to the size of the structure in bytes, and fwType should be set to 0.