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Re^2: using colors with print()

by thunders (Priest)
on Jun 19, 2004 at 22:08 UTC ( #368213=note: print w/ replies, xml ) Need Help??


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 ); }


Comment on Re^2: using colors with print()
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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; }

      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

        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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