mbond has asked for the wisdom of the Perl Monks concerning the following question:

My current task is to create a text based form that will be placed on older laptops in our building. The only requirement of the form that i am currently stuck on is that the user must be able to move between fields using the arrow keys.

My question is how do i catch the signal fromt he arrow keys (^[[A, etc ...)? Once i can catch it moving the cursor will be trival.

The OS is a X-less install of Linux.

Thanks in advance

mbond

Replies are listed 'Best First'.
Re: Arrow Keys
by blakem (Monsignor) on Aug 28, 2001 at 04:50 UTC
[reply]
Re: Arrow Keys
by stefan k (Curate) on Aug 28, 2001 at 12:22 UTC
    A while back I rewrote a perl script which I took from a form where such a task was performed. I can't remember the details exactly but this seems to be the relevant code section: 
    while ( $_=getc(STDIN) ) {
  last if /[q\r\003\032]/;# break on q,Return,Ctrl-C,Ctrl-Z
  $Index-- if /[8A]/;     # up
  $Index++ if /[2B]/;     # down
  $Index=0 if /[9H1]/;    # home
  $Index=$LineCount if /[3F4]/; # end
}

    [download]
    It all takes place in a terminal which has been set to raw device (?): 
    $oldtty = `stty --save`;
system('stty raw -echo');

    [download]

    Regards... Stefan

[reply]
[d/l]
[select]
      After cobbling some stuff together, I got this working. Hope it helps someone else. Bill 
      #!/usr/bin/perl -w

use strict;
use warnings;

use IO::Handle;

eval {
    my $stdin = new IO::Handle;
       $stdin->fdopen( fileno( STDIN ), "r" ) || die "Cannot open STDIN";

    system "stty -icanon -isig -echo min 1 time 0";

    while ( my $char = $stdin->getc() ) {
        print "Up\n"     if ( ord( $char ) == 65 );  # up
        print "Down\n"   if ( ord( $char ) == 66 );  # down
        print "Right\n"  if ( ord( $char ) == 67 );  # right arrow
        print "Left\n"   if ( ord( $char ) == 68 );  # left arrow
        print "Return\n" if ( ord( $char ) == 10 );  # return key
        print "Delete\n" if ( ord( $char ) == 127 ); # delete key
        print "Esc\n"    if ( ord( $char ) == 27 );  # escape key
        print "Tab\n"    if ( ord( $char ) == 9 );   # tab key
        next             if ( ord( $char ) == 32 );  # skip on space key
        last             if ( $char =~ /q/ );        # break on q
        last             if ( $char =~ /\003/ );     # break on Ctrl-C
        last             if ( $char =~ /\032/ );     # break on Ctrl-Z
        print "ord: " . ord($char) . "\n";
    }
    system "stty icanon echo isig";
    exit(0);
};

if ( $@ ) {
    print "$@\n";
    system "stty icanon echo isig";
    exit(1);
}
[reply]
        heh... I posted the last bit of code, but wanted to mention that I have not found a good source for the escape codes (\###). Bill
[reply]

Back to Seekers of Perl Wisdom