Default Printer in Unmanaged C++

2020-07-25 10:15发布

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问题:

I'm looking for a way to find the name of the Windows default printer using unmanaged C++ (found plenty of .NET examples, but no success unmanaged). Thanks.

回答1:

The following works great for printing with the win32api from C++

char szPrinterName[255];
unsigned long lPrinterNameLength;
GetDefaultPrinter( szPrinterName, &lPrinterNameLength );
HDC hPrinterDC;
hPrinterDC = CreateDC("WINSPOOL\0", szPrinterName, NULL, NULL);

In the future instead of googling "unmanaged" try googling "win32 /subject/" or "win32 api /subject/"



回答2:

Here is how to get a list of current printers and the default one if there is one set as the default.

Also note: getting zero for the default printer name length is valid if the user has no printers or has not set one as default.

Also being able to handle long printer names should be supported so calling GetDefaultPrinter with NULL as a buffer pointer first will return the name length and then you can allocate a name buffer big enough to hold the name.

DWORD numprinters;
DWORD defprinter=0;
DWORD               dwSizeNeeded=0;
DWORD               dwItem;
LPPRINTER_INFO_2    printerinfo = NULL;

// Get buffer size

EnumPrinters ( PRINTER_ENUM_LOCAL | PRINTER_ENUM_CONNECTIONS , NULL, 2, NULL, 0, &dwSizeNeeded, &numprinters );

// allocate memory
//printerinfo = (LPPRINTER_INFO_2)HeapAlloc ( GetProcessHeap (), HEAP_ZERO_MEMORY, dwSizeNeeded );
printerinfo = (LPPRINTER_INFO_2)new char[dwSizeNeeded];

if ( EnumPrinters ( PRINTER_ENUM_LOCAL | PRINTER_ENUM_CONNECTIONS,      // what to enumerate
            NULL,           // printer name (NULL for all)
            2,              // level
            (LPBYTE)printerinfo,        // buffer
            dwSizeNeeded,       // size of buffer
            &dwSizeNeeded,      // returns size
            &numprinters            // return num. items
          ) == 0 )
{
    numprinters=0;
}

{
    DWORD size=0;   

    // Get the size of the default printer name.
    GetDefaultPrinter(NULL, &size);
    if(size)
    {
       // Allocate a buffer large enough to hold the printer name.
        TCHAR* buffer = new TCHAR[size];

          // Get the printer name.
        GetDefaultPrinter(buffer, &size);

        for ( dwItem = 0; dwItem < numprinters; dwItem++ )
        {
                          if(!strcmp(buffer,printerinfo[dwItem].pPrinterName))
                defprinter=dwItem;
        }
        delete buffer;
    }
}


回答3:

How to retrieve and set the default printer in Windows:

http://support.microsoft.com/default.aspx?scid=kb;EN-US;246772

Code from now-unavailable article:

// You are explicitly linking to GetDefaultPrinter because linking 
// implicitly on Windows 95/98 or NT4 results in a runtime error.
// This block specifies which text version you explicitly link to.
#ifdef UNICODE
  #define GETDEFAULTPRINTER "GetDefaultPrinterW"
#else
  #define GETDEFAULTPRINTER "GetDefaultPrinterA"
#endif

// Size of internal buffer used to hold "printername,drivername,portname"
// string. You may have to increase this for huge strings.
#define MAXBUFFERSIZE 250

/*----------------------------------------------------------------*/ 
/* DPGetDefaultPrinter                                            */ 
/*                                                                */ 
/* Parameters:                                                    */ 
/*   pPrinterName: Buffer alloc'd by caller to hold printer name. */ 
/*   pdwBufferSize: On input, ptr to size of pPrinterName.        */ 
/*          On output, min required size of pPrinterName.         */ 
/*                                                                */ 
/* NOTE: You must include enough space for the NULL terminator!   */ 
/*                                                                */ 
/* Returns: TRUE for success, FALSE for failure.                  */ 
/*----------------------------------------------------------------*/ 
BOOL DPGetDefaultPrinter(LPTSTR pPrinterName, LPDWORD pdwBufferSize)
{
  BOOL bFlag;
  OSVERSIONINFO osv;
  TCHAR cBuffer[MAXBUFFERSIZE];
  PRINTER_INFO_2 *ppi2 = NULL;
  DWORD dwNeeded = 0;
  DWORD dwReturned = 0;
  HMODULE hWinSpool = NULL;
  PROC fnGetDefaultPrinter = NULL;

  // What version of Windows are you running?
  osv.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
  GetVersionEx(&osv);

  // If Windows 95 or 98, use EnumPrinters.
  if (osv.dwPlatformId == VER_PLATFORM_WIN32_WINDOWS)
  {
    // The first EnumPrinters() tells you how big our buffer must
    // be to hold ALL of PRINTER_INFO_2. Note that this will
    // typically return FALSE. This only means that the buffer (the 4th
    // parameter) was not filled in. You do not want it filled in here.
    SetLastError(0);
    bFlag = EnumPrinters(PRINTER_ENUM_DEFAULT, NULL, 2, NULL, 0, &dwNeeded, &dwReturned);
    {
      if ((GetLastError() != ERROR_INSUFFICIENT_BUFFER) || (dwNeeded == 0))
        return FALSE;
    }

    // Allocate enough space for PRINTER_INFO_2.
    ppi2 = (PRINTER_INFO_2 *)GlobalAlloc(GPTR, dwNeeded);
    if (!ppi2)
      return FALSE;

    // The second EnumPrinters() will fill in all the current information.
    bFlag = EnumPrinters(PRINTER_ENUM_DEFAULT, NULL, 2, (LPBYTE)ppi2, dwNeeded, &dwNeeded, &dwReturned);
    if (!bFlag)
    {
      GlobalFree(ppi2);
      return FALSE;
    }

    // If specified buffer is too small, set required size and fail.
    if ((DWORD)lstrlen(ppi2->pPrinterName) >= *pdwBufferSize)
    {
      *pdwBufferSize = (DWORD)lstrlen(ppi2->pPrinterName) + 1;
      GlobalFree(ppi2);
      return FALSE;
    }

    // Copy printer name into passed-in buffer.
    lstrcpy(pPrinterName, ppi2->pPrinterName);

    // Set buffer size parameter to minimum required buffer size.
    *pdwBufferSize = (DWORD)lstrlen(ppi2->pPrinterName) + 1;
  }

  // If Windows NT, use the GetDefaultPrinter API for Windows 2000,
  // or GetProfileString for version 4.0 and earlier.
  else if (osv.dwPlatformId == VER_PLATFORM_WIN32_NT)
  {
    if (osv.dwMajorVersion >= 5) // Windows 2000 or later (use explicit call)
    {
      hWinSpool = LoadLibrary("winspool.drv");
      if (!hWinSpool)
        return FALSE;
      fnGetDefaultPrinter = GetProcAddress(hWinSpool, GETDEFAULTPRINTER);
      if (!fnGetDefaultPrinter)
      {
        FreeLibrary(hWinSpool);
        return FALSE;
      }

      bFlag = fnGetDefaultPrinter(pPrinterName, pdwBufferSize);
        FreeLibrary(hWinSpool);
      if (!bFlag)
        return FALSE;
    }

    else // NT4.0 or earlier
    {
      // Retrieve the default string from Win.ini (the registry).
      // String will be in form "printername,drivername,portname".
      if (GetProfileString("windows", "device", ",,,", cBuffer, MAXBUFFERSIZE) <= 0)
        return FALSE;

      // Printer name precedes first "," character.
      strtok(cBuffer, ",");

      // If specified buffer is too small, set required size and fail.
      if ((DWORD)lstrlen(cBuffer) >= *pdwBufferSize)
      {
        *pdwBufferSize = (DWORD)lstrlen(cBuffer) + 1;
        return FALSE;
      }

      // Copy printer name into passed-in buffer.
      lstrcpy(pPrinterName, cBuffer);

      // Set buffer size parameter to minimum required buffer size.
      *pdwBufferSize = (DWORD)lstrlen(cBuffer) + 1;
    }
  }

  // Clean up.
  if (ppi2)
    GlobalFree(ppi2);

  return TRUE;
}
#undef MAXBUFFERSIZE
#undef GETDEFAULTPRINTER


// You are explicitly linking to SetDefaultPrinter because implicitly
// linking on Windows 95/98 or NT4 results in a runtime error.
// This block specifies which text version you explicitly link to.
#ifdef UNICODE
  #define SETDEFAULTPRINTER "SetDefaultPrinterW"
#else
  #define SETDEFAULTPRINTER "SetDefaultPrinterA"
#endif

/*-----------------------------------------------------------------*/ 
/* DPSetDefaultPrinter                                             */ 
/*                                                                 */ 
/* Parameters:                                                     */ 
/*   pPrinterName: Valid name of existing printer to make default. */ 
/*                                                                 */ 
/* Returns: TRUE for success, FALSE for failure.                   */ 
/*-----------------------------------------------------------------*/ 
BOOL DPSetDefaultPrinter(LPTSTR pPrinterName)

{
  BOOL bFlag;
  OSVERSIONINFO osv;
  DWORD dwNeeded = 0;
  HANDLE hPrinter = NULL;
  PRINTER_INFO_2 *ppi2 = NULL;
  LPTSTR pBuffer = NULL;
  LONG lResult;
  HMODULE hWinSpool = NULL;
  PROC fnSetDefaultPrinter = NULL;

  // What version of Windows are you running?
  osv.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
  GetVersionEx(&osv);

  if (!pPrinterName)
    return FALSE;

  // If Windows 95 or 98, use SetPrinter.
  if (osv.dwPlatformId == VER_PLATFORM_WIN32_WINDOWS)
  {
    // Open this printer so you can get information about it.
    bFlag = OpenPrinter(pPrinterName, &hPrinter, NULL);
    if (!bFlag || !hPrinter)
      return FALSE;

    // The first GetPrinter() tells you how big our buffer must
    // be to hold ALL of PRINTER_INFO_2. Note that this will
    // typically return FALSE. This only means that the buffer (the 3rd
    // parameter) was not filled in. You do not want it filled in here.
    SetLastError(0);
    bFlag = GetPrinter(hPrinter, 2, 0, 0, &dwNeeded);
    if (!bFlag)
    {
      if ((GetLastError() != ERROR_INSUFFICIENT_BUFFER) || (dwNeeded == 0))
      {
        ClosePrinter(hPrinter);
        return FALSE;
      }
    }

    // Allocate enough space for PRINTER_INFO_2.
    ppi2 = (PRINTER_INFO_2 *)GlobalAlloc(GPTR, dwNeeded);
    if (!ppi2)
    {
      ClosePrinter(hPrinter);
      return FALSE;
    }

    // The second GetPrinter() will fill in all the current information
    // so that all you have to do is modify what you are interested in.
    bFlag = GetPrinter(hPrinter, 2, (LPBYTE)ppi2, dwNeeded, &dwNeeded);
    if (!bFlag)
    {
      ClosePrinter(hPrinter);
      GlobalFree(ppi2);
      return FALSE;
    }

    // Set default printer attribute for this printer.
    ppi2->Attributes |= PRINTER_ATTRIBUTE_DEFAULT;
    bFlag = SetPrinter(hPrinter, 2, (LPBYTE)ppi2, 0);
    if (!bFlag)
    {
      ClosePrinter(hPrinter);
      GlobalFree(ppi2);
      return FALSE;
    }

    // Tell all open programs that this change occurred. 
    // Allow each program 1 second to handle this message.
    lResult = SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, 0L,
      (LPARAM)(LPCTSTR)"windows", SMTO_NORMAL, 1000, NULL);
  }

  // If Windows NT, use the SetDefaultPrinter API for Windows 2000,
  // or WriteProfileString for version 4.0 and earlier.
  else if (osv.dwPlatformId == VER_PLATFORM_WIN32_NT)
  {
    if (osv.dwMajorVersion >= 5) // Windows 2000 or later (use explicit call)
    {
      hWinSpool = LoadLibrary("winspool.drv");
      if (!hWinSpool)
        return FALSE;
      fnSetDefaultPrinter = GetProcAddress(hWinSpool, SETDEFAULTPRINTER);
      if (!fnSetDefaultPrinter)
      {
        FreeLibrary(hWinSpool);
        return FALSE;
      }

      bFlag = fnSetDefaultPrinter(pPrinterName);
      FreeLibrary(hWinSpool);
      if (!bFlag)
        return FALSE;
    }

    else // NT4.0 or earlier
    {
      // Open this printer so you can get information about it.
      bFlag = OpenPrinter(pPrinterName, &hPrinter, NULL);
      if (!bFlag || !hPrinter)
        return FALSE;

      // The first GetPrinter() tells you how big our buffer must
      // be to hold ALL of PRINTER_INFO_2. Note that this will
      // typically return FALSE. This only means that the buffer (the 3rd
      // parameter) was not filled in. You do not want it filled in here.
      SetLastError(0);
      bFlag = GetPrinter(hPrinter, 2, 0, 0, &dwNeeded);
      if (!bFlag)
      {
        if ((GetLastError() != ERROR_INSUFFICIENT_BUFFER) || (dwNeeded == 0))
        {
          ClosePrinter(hPrinter);
          return FALSE;
        }
      }

      // Allocate enough space for PRINTER_INFO_2.
      ppi2 = (PRINTER_INFO_2 *)GlobalAlloc(GPTR, dwNeeded);
      if (!ppi2)
      {
        ClosePrinter(hPrinter);
        return FALSE;
      }

      // The second GetPrinter() fills in all the current<BR/>
      // information.
      bFlag = GetPrinter(hPrinter, 2, (LPBYTE)ppi2, dwNeeded, &dwNeeded);
      if ((!bFlag) || (!ppi2->pDriverName) || (!ppi2->pPortName))
      {
        ClosePrinter(hPrinter);
        GlobalFree(ppi2);
        return FALSE;
      }

      // Allocate buffer big enough for concatenated string.
      // String will be in form "printername,drivername,portname".
      pBuffer = (LPTSTR)GlobalAlloc(GPTR,
        lstrlen(pPrinterName) +
        lstrlen(ppi2->pDriverName) +
        lstrlen(ppi2->pPortName) + 3);
      if (!pBuffer)
      {
        ClosePrinter(hPrinter);
        GlobalFree(ppi2);
        return FALSE;
      }

      // Build string in form "printername,drivername,portname".
      lstrcpy(pBuffer, pPrinterName);  lstrcat(pBuffer, ",");
      lstrcat(pBuffer, ppi2->pDriverName);  lstrcat(pBuffer, ",");
      lstrcat(pBuffer, ppi2->pPortName);

      // Set the default printer in Win.ini and registry.
      bFlag = WriteProfileString("windows", "device", pBuffer);
      if (!bFlag)
      {
        ClosePrinter(hPrinter);
        GlobalFree(ppi2);
        GlobalFree(pBuffer);
        return FALSE;
      }
    }

    // Tell all open programs that this change occurred. 
    // Allow each app 1 second to handle this message.
    lResult = SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, 0L, 0L,
      SMTO_NORMAL, 1000, NULL);
  }

  // Clean up.
  if (hPrinter)
    ClosePrinter(hPrinter);
  if (ppi2)
    GlobalFree(ppi2);
  if (pBuffer)
    GlobalFree(pBuffer);

  return TRUE;
}
#undef SETDEFAULTPRINTER


回答4:

GetDefaultPrinter (MSDN) ought to do the trick. That will get you the name to pass to CreateDC for printing.



回答5:

Unmanaged C++ doesn't exist (and managed C++ is now C++/CLI), if you are referring to C++, using unmanaged as a tag is just sad...



标签： c++ windows unmanaged default printing
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