如何查找正在等待打印的打印机的打印任务

* the offset to the "Jobs number" member
* in the PRINTER_INFO_2 structure
#DEFINE CJOBS_OFFSET  77

DO declare

LOCAL hPrinter, cPrinter, cPrnInfo, nBufsize, nResult
cPrinter = GetPrnName()
? "Default printer: ", cPrinter

hPrinter = 0
IF OpenPrinter(cPrinter, @hPrinter, 0) = 0
  ? "Unable to obtain the handle for this printer."
  RETURN
ENDIF

nBufsize = 4096  && allocate sufficient buffer
cPrnInfo = REPLICATE(Chr(0), nBufsize)
nResult = GetPrinterA(hPrinter, 2, @cPrnInfo,;
  nBufsize, @nBufsize)

IF nResult = 0
  ? "Error code:", GetLastError()
ELSE
  ? "Number of print jobs queued:",;
    buf2dword(SUBSTR(cPrnInfo, CJOBS_OFFSET,4))
ENDIF

= ClosePrinter(hPrinter)
* end of main

FUNCTION GetPrnName
* returns default printer name from Windows Registry
  LOCAL cBuffer, cPrinter, cDriver, cPort
  cBuffer = REPLICATE(CHR(0), 120)

  = GetProfileString("Windows", "Device", ",,,",;
    @cBuffer, Len(cBuffer))
  cBuffer = STRTRAN(cBuffer, Chr(0), "")
RETURN SUBSTR(cBuffer, 1, AT(",", cBuffer, 1)-1)

PROCEDURE declare
  DECLARE INTEGER OpenPrinter IN winspool.drv;
    STRING pPrinterName, INTEGER @phPrinter, INTEGER pDefault

  DECLARE INTEGER ClosePrinter IN winspool.drv INTEGER hPrinter

  DECLARE INTEGER GetProfileString IN kernel32;
    STRING lpApp, STRING lpKey, STRING lpDefault,;
    STRING @lpReturnedString, INTEGER nSize

  DECLARE INTEGER GetPrinter IN winspool.drv AS GetPrinterA;
    INTEGER hPrinter, INTEGER Lvl, STRING @pPrinter,;
    INTEGER cbBuf, INTEGER @pcbNeeded

  DECLARE INTEGER GetLastError IN kernel32

FUNCTION buf2dword(cBuffer)
RETURN Asc(SUBSTR(cBuffer, 1,1)) + ;
  BitLShift(Asc(SUBSTR(cBuffer, 2,1)),  8) +;
  BitLShift(Asc(SUBSTR(cBuffer, 3,1)), 16) +;
  BitLShift(Asc(SUBSTR(cBuffer, 4,1)), 24)