If there is no default printer configured, you are basically out of luck, as you can't even set the TPrinter::PrinterIndex property to a value >= 0 since it will first call SetToDefaultPrinter() before checking if the new value matches the current value. TPrinter::GetPrinter() reads the TPrinter::PrinterIndex property, so if there is no currently selected printer and no default printer, the exception is thrown. TPrintDialog::Execute() (which uses the Win32 API PrintDlg() function) first calls TPrinter::GetPrinter() to get a handle to the DEVMODE of the currently selected printer, which it then uses to initialize the dialog (via the PRINTDLG::hDevMode field). The TPrinter::PrinterIndex setter if the FPrinterIndex member is currently -1, or the property is being set to -1. The TPrinter::PrinterIndex getter if the FPrinterIndex member is currently -1. TPrinter::SetToDefaultPrinter() is called only by:
If EnumPrinters() above does not report a default device, the default is then queried from the Win32 API GetDefaultPrinter() function (Delphi/C++Builder 2009 and later), or the device value of the section of %windir%\win.ini (Delphi/C++Builder 2007 and earlier). The TPrinter::Printers list does not contain the default printer.
WINDOWS API ENUMPRINTERSW CODE
The Win32 API EnumPrinters() function fails with an ERROR_INVALID_NAME error code when enumerating with the (undocumented) PRINTER_ENUM_DEFAULT flag. Thanks.The exception "There is no default printer currently selected" is thrown only by the TPrinter::SetToDefaultPrinter() method, when either: I see what you're saying, I can't receive a value when there is no memory to store it in. That means if the function expects LPTYPE, you should be declaring TYPE var and passing &var as the parameter.Oh, that clears it up Salem. That means if the function expects LPTYPE, you should be declaring TYPE var and passing &var as the parameter. Unless the documentation specifically states that NULL is an acceptable value for an out parameters, you need to be passing a pointer to valid memory in all cases. ReturnValue = EnumPrinters(PRINTER_ENUM_LOCAL, NULL, 4, printerInfo, sizeof(PRINTER_INFO_4), &bytesNeeded, &bytesCopied ) So what you should really be doing is something like It means that the function is expecting to WRITE data to some variable of yours to deliver information you need. You can't just go around declaring variables which match the function prototype, you have to think about how those parameters are going to be used.ĭo you know what the annotation _Out_ even means? > "A null reference was passed to the stub" Can someone help me understand what's wrong with this code? I have no idea what that is talking about, since I don't understand what it refers to when it says "stub". "A null reference was passed to the stub" My problem is EnumPrinters fails with error 1780 : I've written some code to create a temporary text file( I haven't gotten to the actual printing yet, so I'm leaving it empty) also. }I decided to try to make my own code for printing a text document on the local printer. If ( remove(FILE_NAME) ) perror("Deleting file") ReturnValue = EnumPrinters(PRINTER_ENUM_LOCAL, NULL, 4, printerInfo, sizeof(PRINTER_INFO_4), bytesNeeded, bytesCopied ) PrinterInfo = malloc(sizeof(PRINTER_INFO_4))
MessageBox(NULL, (LPCTSTR)lpDisplayBuf, TEXT("Error"), MB_OK) (lstrlen((LPCTSTR)lpMsgBuf) + lstrlen((LPCTSTR)lpszFunction) + 40) * sizeof(TCHAR)) LpDisplayBuf = (LPVOID)LocalAlloc(LMEM_ZEROINIT, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), * Retrieve the system error message for the last-error code */
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