http://www.perlmonks.org?node_id=368213


in reply to Re: using colors with print()
in thread using colors with print()

very nice, here's the same program in perl
use constant RESET     => 0;
use constant BRIGHT    => 1;
use constant DIM       => 2;
use constant UNDERLINE => 3;
use constant BLINK     => 4;
use constant REVERSE   => 7;
use constant HIDDEN    => 8;

use constant BLACK   => 0;
use constant RED     => 1;
use constant GREEN   => 2;
use constant YELLOW  => 3;
use constant BLUE    => 4;
use constant MAGENTA => 5;
use constant CYAN    => 6;
use constant WHITE   => 7;

sub textcolor($$$);

print textcolor( RESET, RED, BLACK ), "In color\n",
  textcolor( RESET, WHITE, BLACK );

sub textcolor($$$) {
    my ( $attr, $fg, $bg ) = @_;
    #Command is the control command to the terminal
    my $command = sprintf( "%c[%d;%d;%dm", 0x1B, $attr, $fg + 30, $bg 
++ 40 );
    return sprintf( "%s", $command );
}

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Re^3: using colors with print()
by pbeckingham (Parson) on Jun 19, 2004 at 23:56 UTC

    I believe there is a need to print the newline character after the reset, not before, or in other words, do not let color attributes span unnecessary lines, and those last lines dealing with $command are redundant. 

    sub textcolor ($$$);

print textcolor (RESET, RED, BLACK),
      'In color',
      textcolor (RESET, WHITE, BLACK),
      "\n";

sub textcolor ($$$) 
{
  my ($attr, $fg, $bg) = @_;
  sprintf "\e[%d;%d;%dm", $attr, $fg + 30, $bg + 40;
}

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      Actually the ANSI escapes span lines so newline position is really immaterial (except from a neatness point of view). In fact AFAIK they remain active until reset, and this status outlives the life of your program as you are effectively manipulating defaults on your term.

        
      $ cat col.pl
#!/usr/bin/perl

# default black background
use constant BLUE => "\e[0;34;40m";
use constant RED  => "\e[0;31;40m";
use constant DEFAULT  => "\e[0;37;40m";

print "The flag is:
", RED, "
red
", DEFAULT, "
white &
", BLUE,"
blue.

ANSI color escapes
will span", DEFAULT, " at least with
putty as the terminal emulation.
", BLUE;

$ ./col.pl
The flag is:

red

white &

blue.

ANSI color escapes
will span at least with
putty as the terminal emulation.
$
$ echo Oops forgot to reset blue mode
Oops forgot to reset blue mode
$ perl -e 'print "\e[0;37;40m"';
$ echo Fixed....
Fixed....

      cheers

      tachyon

[reply]

        Oh, you're absolutely right, the sequences do span lines, and indeed should, but I had problems on Solaris 8/xterm when I relied on this. Perhaps I shouldn't have even mentioned this.

        I will mention though, that the longer those sequences remain active, the greater the chance of the userr hitting Crtl-C and having their terminal in need of an \e[0m.

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