PRODUCT  :  Borland C++                           NUMBER  :  1717
  VERSION  :  All
       OS  :  WIN
     DATE  :  October 25, 1993                         PAGE  :  1/3

    TITLE  :  Printing from an EasyWin Application




  /* ---------------------------------------------------------- *\
  This is an example program that demonstrates a technique to echo
  output to the printer from within an EasyWin application. This
  is accomplished by chaining to a function pointer used
  internally by EasyWin. EasyWin uses the function, _WriteBuf, to
  handle text output. This function is pointed to by
  __WriteBufFPtr so, by hooking the current setting for this
  pointer, it is possible to add functionality ( such as printing
  ) when outputting via EasyWin.

  To run the TEST program place the modules, TESTECHO.CPP and
  ECHOPRNT.C in a project. To add echo printing to other EasyWin
  applications, include "echoprnt.h" and make calls to
  StartEchoPrint() and EndEchoPrint() at appropriate locations. It
  is also necessary to add ECHOPRNT.C to the project.  A second
  method would be to define ECHOALWAYS and add the file ECHOPRNT.C
  to the project. When ECHOALWAYS is defined ECHOPRNT uses a
  #pragma startup and #pragma exit to invoke the ECHOPRNT
  functions, thereby avoiding code modifications to the existing
  EasyWin application.

  \* ---------------------------------------------------------- */

  // File: TESTECHO.CPP

  #include <stdio.h>
  #include <iostream.h>
  #include "echoprnt.h"

  int main()
  {
      StartEchoPrint();

      printf("send a test string to the printer\n");
      puts("another test string\r\n");
      cout << "print from C++ program" << endl;

      EndEchoPrint();

      return 0;
  }















  PRODUCT  :  Borland C++                           NUMBER  :  1717
  VERSION  :  All
       OS  :  WIN
     DATE  :  October 25, 1993                         PAGE  :  2/3

    TITLE  :  Printing from an EasyWin Application




  //===================================================================
  // File: ECHOPRNT.H

  #ifndef __ECHOPRNT_H
  #define __ECHOPRNT_H

  #ifdef __cplusplus
  extern "C"{
  #endif

  void StartEchoPrint();
  void EndEchoPrint();

  #ifdef __cplusplus
  }
  #endif
  #endif



  //===============================================================
  // File: ECHOPRNT.C


  #include <io.h>
  #include <stdio.h>
  #include "echoprnt.h"


  typedef void(*WRITEFUNC)(char*, unsigned);

  FILE      *fprn = NULL;
  WRITEFUNC _SaveBufFPtr;
  extern WRITEFUNC  __WriteBufFPtr;   //Function pointer used by
                                      //EasyWin

  /////////////////////////////////////////////////////////////
  // EchoPrint: Called by EasyWin. Sends data to printer (PRN)
  //            and then calls original __WriteBufFPtr.
  void EchoPrint( char* Buffer, unsigned Count )
  {
      // first write the buffer to the printer
      __WriteBufFPtr =0;













  PRODUCT  :  Borland C++                           NUMBER  :  1717
  VERSION  :  All
       OS  :  WIN
     DATE  :  October 25, 1993                         PAGE  :  3/3

    TITLE  :  Printing from an EasyWin Application




      fwrite( Buffer, Count, 1, fprn );

      __WriteBufFPtr = EchoPrint;
      // now print it to the screen
      if( _SaveBufFPtr )
          _SaveBufFPtr( Buffer, Count );
  }

  /////////////////////////////////////////////////////////////
  // StartEchoPrint: Called by our program to hook the EasyWin
  //                 function pointer.
  void StartEchoPrint()
  {
      fprn = fopen( "PRN", "w+t" );
      _SaveBufFPtr = __WriteBufFPtr;
      __WriteBufFPtr = EchoPrint;
  }
  #ifdef ECHOALWAYS
  #pragma startup StartEchoPrint 64
  #endif

  /////////////////////////////////////////////////////////////
  // EndEchoPrint: Called by our program to restore the EasyWin
  //               function pointer
  void EndEchoPrint()
  {
      __WriteBufFPtr = _SaveBufFPtr;
      if ( fprn )
      {
          fclose( fprn );
          fprn = NULL;
      }
  }
  #ifdef ECHOALWAYS
  #pragma exit EndEchoPrint 64
  #endif

  DISCLAIMER: You have the right to use this technical information
  subject to the terms of the No-Nonsense License Statement that
  you received with the Borland product to which this information
  pertains.