Windows GDI打印机错误StartDocPrinter

Question

Actually I am working with Qt printing and need to send the RAW command (ESCP command) to printer. After did some search and I found that I need to use the Windows API to do it.

Refer to this thread : win32-c-print-string-to-printer

I have created the code like below :

const QString pName = "EPSON LX-300+ /II";
LPBYTE lpData;
BOOL bStatus = FALSE;
HANDLE hPrinter = NULL;
DOC_INFO_1 DocInfo;
DWORD dwPrtJob = 0L;
DWORD dwBytesWritten = 0L;
LPTSTR printerName = new wchar_t[pName.length() + 1];
pName.toWCharArray(printerName);
printerName[pName.length()] = '\0';
QString so = "\x1b@Is it works?";
QByteArray ba = so.toUtf8();
lpData = (unsigned char*)(ba.data());
DWORD dwCount = ba.length();
qDebug() << so;

bStatus = OpenPrinter(printerName, &hPrinter, NULL);
if(bStatus) {
    DocInfo.pDocName = (LPTSTR)_T("My Document");
    DocInfo.pOutputFile = NULL;
    DocInfo.pDatatype = (LPTSTR)_T("RAW");
    dwPrtJob = StartDocPrinter (
                    hPrinter,
                    1,
                    (LPBYTE)&DocInfo);
    qDebug() << GetLastError();
    if (dwPrtJob > 0) {
            qDebug() << "COMMAND";
            // Send the data to the printer.
            bStatus = WritePrinter (
            hPrinter,
            lpData,
            dwCount,
            &dwBytesWritten);
    }
    qDebug() << dwCount;
    qDebug() << dwBytesWritten;

    EndDocPrinter (hPrinter);

    // Close the printer handle.
    bStatus = ClosePrinter(hPrinter);
    qDebug() << bStatus;
}

if (!bStatus || (dwCount != dwBytesWritten)) {
    bStatus = FALSE;
} else {
    bStatus = TRUE;
}

delete printerName;

And the code failed on StartDocPrinter, it returning 0 which mean failed. And using the GetLastError(), the function return 1804. And refer to this , the error is ERROR_INVALID_DATATYPE. I am not sure what error is it. And i try to use different DocInfo.pDatatype to "RAW", "TEXT", and "XPS_PASS", the result is the same.

Is there anything I can do how to fix it?

Answer 1

DOC_INFO_1 DocInfo;
DocInfo.pDocName = (LPTSTR)_T("My Document");
DocInfo.pOutputFile = NULL;
DocInfo.pDatatype = (LPTSTR)_T("RAW");

This casting boils down to

DocInfo.pDocName = (wchar_t*)L"My Document";
...

Where pDocName is declared as wchar_t* This is wrong and the cast simply hides the errors and warnings. Try to avoid Microsoft T macro altogether, these macros are outdated and useless. Use C++ char and wchar_t* instead. To declare UTF16 wide char string in Windows, use the L prefix. The correct usage is as follows:

DOC_INFO_1 DocInfo;
wchar_t docName[100], dataType[100];
wcscpy_s(docName, 100, L"Print Job");
wcscpy_s(dataType, 100, L"RAW");
DocInfo.pDocName = docName;
DocInfo.pOutputFile = NULL;
DocInfo.pDatatype = dataType;

Example:

const QString pName = "EPSON LX-300+ /II";
wchar_t printerName[100];
pName.toWCharArray(printerName);
pName[pName.length()] = '\0';

HANDLE hprinter;
if (OpenPrinter(printerName, &hprinter, NULL))
{
    DOC_INFO_1 DocInfo;
    wchar_t docName[100], dataType[100];
    wcscpy_s(docName, 100, L"Print Job");
    wcscpy_s(dataType, 100, L"RAW");
    DocInfo.pDocName = docName;
    DocInfo.pOutputFile = NULL;
    DocInfo.pDatatype = dataType;

    DWORD printJob = StartDocPrinter(hprinter, 1, (LPBYTE)&DocInfo);
    if (printJob && StartPagePrinter(hprinter))
    {
        MessageBox(0, L"StartPagePrinter OKAY", 0, 0);
        DWORD written = 0;
        int buflen = 100;
        char *buf = new char[buflen];
        strcpy_s(buf, buflen, "123");
        if (WritePrinter(hprinter, buf, 3, &written))
            MessageBox(0, L"OKAY", 0, 0);
        delete[]buf;
        EndPagePrinter(hprinter);
        EndDocPrinter(hprinter);
    }
    ClosePrinter(hprinter);
}