How to use DrvDeviceCapabilities in winddiui.h (WITH winspool.lib added but LNK2019 unresolved external symbol STILL occured )

Question

Function DrvDeviceCapabilities(winddiui.h) should be used if I want to identify a printer's color capability according to this link. But there is always a link error (LNK2019 unresolved external symbol ) though I added winspool.lib to Library Directories in VC++ Directories and Additional Dependencies in Linker-Input.

I used dumpbin tool to find related symbol in ALL lib files but found nothing. As a contrast to DrvDeviceCapabilities, some other symbols can be easily found like OpenPrinter and StartDoc.

It seems that DeviceCapabilitiesA function can also retrieves the capabilities of a printer driver but it isn't be mentioned in this link . What is the difference between these functions or structures? And how to get the printer capabilities in a correct way?

Any replies would be appreciated!

Answer 1

The DrvDeviceCapabilities function is not exported from winspool.drv but can be obtained as follows -

Minimal example tested on Win10 22H2

#include <Windows.h>
#include <winddiui.h>

#include <stdio.h>
#include <tchar.h>
#include <memory>

typedef decltype(DrvDeviceCapabilities)* DDC;

int main()
{
    HANDLE hPrinter{};
    DWORD cbNeeded{};
    if (OpenPrinter((LPTSTR)_T("Microsoft Print to PDF"), &hPrinter, NULL))
    {
        if (!GetPrinterDriver(hPrinter, NULL, 2, NULL, 0, &cbNeeded) && GetLastError() == ERROR_INSUFFICIENT_BUFFER)
        {
            std::unique_ptr<BYTE[]> buf = std::make_unique<BYTE[]>(cbNeeded);
            if (GetPrinterDriver(hPrinter, NULL, 2, buf.get(), cbNeeded, &cbNeeded))
            {
                PDRIVER_INFO_2 pdrv2 = (PDRIVER_INFO_2) buf.get();
                _tprintf_s(_T("DLL to load: %s\n"), pdrv2->pConfigFile);

                HMODULE hMod = LoadLibrary(pdrv2->pConfigFile);
                if (hMod)
                {
                    DDC pfDrvDeviceCapabilities = (DDC)GetProcAddress(hMod, "DrvDeviceCapabilities");
                    if (pfDrvDeviceCapabilities)
                        _tprintf_s(_T("GetProcAddress succeeeded!\n"));
                    else
                        _tprintf_s(_T("GetProcAddress error ws %d\n"), GetLastError());

                    FreeLibrary(hMod);
                }
                else
                    _tprintf_s(_T("LoadLibrary error ws %d\n"), GetLastError());
            }
            else
                _tprintf_s(_T("GetPrinterDriver error was %d\n"), GetLastError());
        }
        else
            _tprintf_s(_T("GetPrinterDriver error was %d\n"), GetLastError());

        ClosePrinter(hPrinter);
    }

    return 0;
}