WinprintPrintDocumentOnPrintProcessor Function

Uses of the different forms of the gdiPlaySpoolStream and ReadPrinter functions are shown in the following pseudo code version of the WinprintPrintDocumentOnPrintProcessor function.

The WinprintPrintDocumentOnPrintProcessor function is supplied two parameters:

A handle to the print processor which the caller has obtained with a previous call to WinprintOpenPrintProcessor
A pointer to a PRINTPROCESSORDOCUMENTDATA structure, which is defined below.

Data Structure Definitions

The WinprintPrintDocumentOnPrintProcessor function uses two data structures: PRINTPROCESSORDOCUMENTDATA, a pointer to which is given as a parameter, and the global PRINTPROCESSORDATA structure.

typedef struct _PRINTPROCESSORDOCUMENTDATA
{
   LPDEVMODE pDevMode;       // printer device init and status info
   LPTSTR    pDatatype;      // datatype of document
   LPTSTR    pParameters;    // print processor parameters
   LPTSTR    pDocumentName;  // 
   DWORD     JobId;          // print job assoc w/ document
   LPTSTR    pOutputFile;    // document spool file
   LPTSTR    pSpoolFileName; // full path to document spool file
   LPTSTR    pSepFile;       // file printed between jobs
}PRINTPROCESSORDOCUMENTDATA

The global PRINTPROCESSORDATA structure is defined below:

typedef struct _PRINTPROCESSORDATA 
{
    DWORD   signature;
    DWORD   cb;
    struct _PRINTPROCESSORDATA FAR *pNext;
    DWORD   fsStatus;
    HANDLE  semPaused;
    DWORD   uDatatype;
    HANDLE  hPrinter;
    LPTSTR  pPrinterName;
} PRINTPROCESSORDATA, *PPRINTPROCESSORDATA;

Function Pseudo code

The logic of the WinprintPrintDocumentOnPrintProcessor function is shown in the following pseudo code. Notice that the ReadPrinter function is used to read the spool file, rather than reading status data from the printer. When the WinprintPrintDocumentOnPrintProcessor function is called, the print processor already has a printer associated with it (has a handle to a printer). However, this handle, which was established in a prior OpenPrintProcessor function call, is used to write to printer.

if not called with a handle this print processor has open then
   set last error to ERROR_INVALID_HANDLE
   return FALSE
endif
if capable of using document datatype passed in
   move datatype into PRINTPROCESSORDATA structure
endif
if capable of using separator file type passed in
   print out the banner that separates this job from previous job
endif
move information about the document from PPRINTPROCESSORDATA structure to local DOC_INFO_2 structure, specifically:
(1) document name
(2) spool file filename
(3) spool file data type
(4) print job ID

call local print provider OpenPrinter function to open the printer that is already associated with the print processor for reading (the spool file).

call local print provider StartDocPrinter function with DI_READ_SPOOL_JOB flag set in JOB_INFO_2 structure to initiate reading of spool file.

if the spool file datatype is raw then
    call the local print processor StartDocPrinter with DI_CHANNEL_WRITE
    flag set in JOB_INFO_2 structure to enable sending spool file
    contents directly to printer through the local print provider. 
    (If the spool file datatype is EMF, the print processor will send
    the spool file data through GDI32.)
endif

/* start of loop: 
while there is still data to be read in the spool file, call the local print provider ReadPrinter function to read a block of data from the spool file. if the spool file data type is raw, the block of data is then sent directly to the printer by this print processor code; if the spool file data type is EMF, then this print processor code will use the gdiPlaySpoolStream function call to get GDI32 to manage the rendering and sending of the print data to the printer. */

                  while there is still data to be read in the spool file, call the 
                  local print provider ReadPrinter function to read a block of data from
                  the spool file.

   trap special case of Print Processor paused between print out of 
   pages (one page = one EMF file) and wait until unpaused

   trap special case of Print Processor aborted and document datatype is
   EMF and call GDI32 gdiPlaySpoolStream function to delete metafiles 
   and DC
   /* Note the parameter list for this gdiPlaySpoolStream function call.
      This parameter list structure instructs gdiPlaySpoolStream to
      delete the spool file(s) and close the printer DC, etc.

      gdiPlaySpoolStream(
                         NULL, 
                         NULL, 
                         lpDoc->pSpoolFileName, 
                         0, 
                         0, 
                         hDC);
      break;
   */

   if document datatype is raw, call the print provider WritePrinter 
   function to send the spool file data directly to the printer.

   if document datatype is EMF then call GDI32 gdiPlaySpoolStream
   function to playback the EMF file. 
   /* Note the structure of the parameter list in the gdiPlaySpoolStream
      function call used to actually render and send data to the printer
      from the EMF spool file. The hDC parameter is NULL the first
      time this function is called.

      hDC = gdiPlaySpoolStream(
                               pData->pPrinterName,
                               lpDoc->pOutputFile,
                               Buffer, 
                               lpDoc->JobId, 
                               &NoRead, 
                               hDC
                               );
   */

      if gdiPlaySpoolStream does not return a DC handle and process the
      first block of spool file data OK, then call the GDI32 
      gdiPlaySpoolStream function to delete metafiles. 

/* end of loop */

if spool file data type is raw, call the local print provider EndDocPrinter function to end the document printing session.