打印控制：监测打印状态

 void CControlPrinterDlg::OnSelchangePrinters()
{
 // TODO: Add your control notiflication handler code here
 m_listBox2.ResetContent();
 int nIndex=m_listBox.GetCurSel();
 CString strPrinterName;
 if (nIndex!=CB_ERR) {
  m_listBox.GetText(nIndex,strPrinterName);
  if (!strPrinterName.IsEmpty()) {
   ListJobs((LPTSTR)(LPCSTR)strPrinterName);
  }
 }
}

BOOL CControlPrinterDlg::ListJobs(LPSTR szPrinterName)
{
 HANDLE hPrinter;
 DWORD dwNeeded,dwReturned,i;
 JOB_INFO_1 *pJobInfo;
 if (!OpenPrinter(szPrinterName,&hPrinter,NULL)) {
  return false;
 }
 if (!EnumJobs(hPrinter,0,0xFFFFFFFF,1,NULL,0,&dwNeeded,&dwReturned)) {
  if (GetLastError()!=ERROR_INSUFFICIENT_BUFFER) {
   ClosePrinter(hPrinter);
   return false;
  }
 }
 if ((pJobInfo=(JOB_INFO_1*)malloc(dwNeeded))==NULL) {
  ClosePrinter(hPrinter);
  return false;
 }
 if (!EnumJobs(hPrinter,0,0xFFFFFFFF,1,(LPBYTE)pJobInfo,
  dwNeeded,&dwNeeded,&dwReturned)) {
  ClosePrinter(hPrinter);
  free(pJobInfo);
  return false;
 }
 ClosePrinter(hPrinter);
 for(i=0;i<dwReturned;i++)
 {
  m_listBox2.AddString(pJobInfo[i].pDocument);
 }
 free(pJobInfo);
 return true;
}