examples/howto-add_fd-and-popen.cxx

   1 //
   2 // "$Id: howto-add_fd-and-popen.cxx 8194 2011-01-05 22:28:39Z AlbrechtS $"
   3 //
   4 //     How to use popen() and Fl::add_fd() - erco 10/04/04
   5 //     Originally from erco's cheat sheet, permission by author.
   6 //
   7 //     Shows how the interface can remain "alive" while external
   8 //     command is running and outputing occassional data. For instance,
   9 //     while the command is running, keyboard navigation works,
  10 //     text can be highlighted, and the interface can be resized.
  11 //
  12 // Copyright 2010 Greg Ercolano.
  13 // Copyright 1998-2010 by Bill Spitzak and others.
  14 //
  15 // This library is free software; you can redistribute it and/or
  16 // modify it under the terms of the GNU Library General Public
  17 // License as published by the Free Software Foundation; either
  18 // version 2 of the License, or (at your option) any later version.
  19 //
  20 // This library is distributed in the hope that it will be useful,
  21 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  22 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  23 // Library General Public License for more details.
  24 //
  25 // You should have received a copy of the GNU Library General Public
  26 // License along with this library; if not, write to the Free Software
  27 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  28 // USA.
  29 //
  30 // Please report all bugs and problems on the following page:
  31 //
  32 //     http://www.fltk.org/str.php
  33 //
  34 #include <stdio.h>
  35 #include <FL/Fl.H>
  36 #include <FL/Fl_Window.H>
  37 #include <FL/Fl_Multi_Browser.H>
  38
  39 #ifdef WIN32
  40 #  define PING_CMD "ping -n 10 localhost"       // 'slow command' under windows
  41 #  ifdef _MSC_VER
  42 #    define popen _popen
  43 #    define pclose _pclose
  44 #  else /*_MSC_VER*/
  45 #    include <unistd.h>                         // non-MS win32 compilers (untested)
  46 #  endif /*_MSC_VER*/
  47 #else
  48 #  include <unistd.h>
  49 #  define PING_CMD "ping -i 2 -c 10 localhost"  // 'slow command' under unix
  50 #endif
  51
  52 // GLOBALS
  53 FILE *G_fp = NULL;
  54
  55 // Handler for add_fd() -- called whenever the ping command outputs a new line of data
  56 void HandleFD(int fd, void *data) {
  57   Fl_Multi_Browser *brow = (Fl_Multi_Browser*)data;
  58   char s[1024];
  59   if ( fgets(s, 1023, G_fp) == NULL ) {         // read the line of data
  60     Fl::remove_fd(fileno(G_fp));                // command ended? disconnect callback
  61     pclose(G_fp);                               // close the descriptor
  62     brow->add(""); brow->add("<<DONE>>");       // append msg indicating command finished
  63     return;
  64   }
  65   brow->add(s);                                 // line of data read? append to widget
  66 }
  67
  68 int main(int argc, char *argv[]) {
  69   Fl_Window win(600,600);
  70   Fl_Multi_Browser brow(10,10,580,580);
  71   if ( ( G_fp = popen(PING_CMD, "r") ) == NULL ) {      // start the external unix command
  72     perror("popen failed");
  73     return(1);
  74   }
  75   Fl::add_fd(fileno(G_fp), HandleFD, (void*)&brow);     // setup a callback for the popen()ed descriptor
  76   win.resizable(brow);
  77   win.show(argc, argv);
  78   return(Fl::run());
  79 }
  80
  81 //
  82 // End of "$Id: howto-add_fd-and-popen.cxx 8194 2011-01-05 22:28:39Z AlbrechtS $".
  83 //