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C++ Language question

Posted on 1997-09-23
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Last Modified: 2012-06-21
Could someone give me an example using the following API:

OpenPrinter();
FindFirstPrinterChangeNotification();
WaitForSingleObjectEx()
FindNextPrinterChangeNotification();

I'm using MS Visual C++ on Windows NT 4.0
I am trying to log the print jobs that are sent to the printer on an NT 4.0 PrintServer, together with the username and number of pages. I'm able to get a printer handle, then a handle to the notification object. I then use the WaitForObjectEx() function to wait for the change notification (PRINTER_CHANGE_ADD_JOB. The wait functions then returns successfully. When I use the FindNextPrinterChangeNotification() It returns a value of 1 yet the information structure contains no information.I'm declaring a PRINTER_NOTIFY_INFO and I then use a pointer to this structure to pass it to the FindNextPrinterChangeNotification().

Thanks.
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Question by:santamaria
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Author Comment

by:santamaria
ID: 1170334
Edited text of question
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LVL 15

Expert Comment

by:Tommy Hui
ID: 1170335
I'm writing an example right now. Will post when done.
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Accepted Solution

by:
Tommy Hui earned 1000 total points
ID: 1170336
This should get you going:

#include <windows.h>
#include <stdio.h>

int main(int argc, char* argv[])
{
      DWORD needed = 0;
      DWORD returned = 0;
      int i = 0;

      if (!EnumPrinters(PRINTER_ENUM_CONNECTIONS | PRINTER_ENUM_LOCAL, NULL, 4, NULL, 0, &needed, &returned))
      {
            BYTE* buffer = new BYTE[needed];

            if (!EnumPrinters(PRINTER_ENUM_CONNECTIONS | PRINTER_ENUM_LOCAL, NULL, 4, (LPBYTE)buffer, needed, &needed, &returned))
            {
                  printf("Failed\r\n");
                  return 0;
            }

            HANDLE* printerHandles = new HANDLE[returned];
            HANDLE* waitHandles = new HANDLE[returned];
            PRINTER_INFO_4* pInfo = (PRINTER_INFO_4*)buffer;

            for (i = 0; i < returned; i++, pInfo++)
            {
                  printf("Name %s on %s: 0x%08X\r\n",
                        pInfo->pPrinterName, pInfo->pServerName, pInfo->Attributes);

                  if (OpenPrinter(pInfo->pPrinterName, &printerHandles[i], NULL) == 0)
                  {
                        printf("Failed to open printer %s\r\n", pInfo->pPrinterName);
                        printerHandles[i] = NULL;
                        waitHandles[i] = NULL;
                  }
                  else
                  {
                        waitHandles[i] = FindFirstPrinterChangeNotification(
                              printerHandles[i], PRINTER_CHANGE_ALL, 0, NULL);

                        if (waitHandles[i] == INVALID_HANDLE_VALUE)
                              printf("Failed to create printer notification at index %d\r\n", i);
                  }
            }


            do
            {
                  printf("Waiting...\n");
                  DWORD ret = WaitForMultipleObjects(returned, waitHandles, FALSE, INFINITE);

                  if (WAIT_OBJECT_0 <= ret && ret < (WAIT_OBJECT_0 + returned))
                  {
                        int index = ret - WAIT_OBJECT_0;
                        printf("printer %d signaled\n", index);
                        DWORD changed = 0;
                        PRINTER_NOTIFY_INFO* ptr = NULL;
                        PRINTER_NOTIFY_OPTIONS options;
                        PRINTER_NOTIFY_OPTIONS_TYPE      types;
                        WORD fields[] =
                        {
                              PRINTER_NOTIFY_FIELD_PRINTER_NAME,
                        };

                        options.Version      = 2;
                        options.Flags = PRINTER_NOTIFY_OPTIONS_REFRESH;
                        options.Count = 1;
                        options.pTypes = &types;

                        types.Type = PRINTER_NOTIFY_TYPE;
                        types.Count = sizeof fields/sizeof fields[0];
                        types.pFields = fields;

                        if (FindNextPrinterChangeNotification(waitHandles[index], &changed, NULL, (void**)&ptr))
                        {
                              printf("changed = %d\r\n", changed);

                              if (ptr != NULL)
                              {
                                    for (int j = 0; j < ptr->Count; j++)
                                    {
                                          PRINTER_NOTIFY_INFO_DATA* pniData = &(ptr->aData)[j];

                                          printf("Type %d, field %d\n", pniData->Type, pniData->Field);
                                    }
                              }
                              FreePrinterNotifyInfo(ptr);
                        }
                        else
                        {
                              DWORD lastError = GetLastError();
                              printf("FNPCN LastError = %d\r\n", lastError);
                        }
                  }
            }
            while (TRUE);

            // If it theoretically gets here
            //
            for (i = 0; i < returned; i++)
            {
                  if (printerHandles[i] != NULL)
                        ClosePrinter(printerHandles[i]);
                  printerHandles[i] = NULL;

                  if (waitHandles[i] != NULL)
                        FindClosePrinterChangeNotification(waitHandles[i]);
                  waitHandles[i] = NULL;
            }

            delete[] printerHandles;
            delete[] waitHandles;
      }
      else
      {
            DWORD lastError = GetLastError();
            printf("LastError = %d\r\n", lastError);
      }

      return 0;
}


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