Set terminal font size based on screen DPI

fixfontsizes.pl

#!/usr/bin/perl

use strict;
use warnings;

my $windows = `wmctrl -l -G`;
my $processes = `ps faux`;
my $xrandr = `xrandr | grep " connected"`;

my @displays = ();

while ($xrandr =~ /(\w+) connected (\d+)x(\d+)\+(\d+)\+(\d+).*?(\d+)mm x (\d+)mm/g) {
  my %data = (
      'name', $1,
      'width', $2,
      'height', $3,
      'x', $4,
      'y', $5,
      'fontsize', int(6 + (1.10 * $2 / $6))
    );
  print "Font size on $data{'name'}: $data{'fontsize'}\n";
  push @displays, (\%data);
}

while ($windows =~ /(\w+)\s+\d+\s+(\d+)\s+(\d+).*/g) {
  my ($wid, $x, $y) = ($1, $2, $3, $4, $5);

  my $pid = getpid($wid);
  if ($pid && $processes =~ /$pid.*terminology\n.*(pts\/\d+)/m) {
    my $pts = $1;

    for my $display (@displays) {
      if ($$display{'x'} <= $x && $x < ($$display{'x'} + $$display{'width'})
       && $$display{'y'} <= $y && $y < ($$display{'y'} + $$display{'height'})) {
        setfontsize($pts, $$display{'fontsize'});
      }
    }
  }
}

sub getpid {
  my ($wid) = @_;

  my $wininfo = `xprop -id $wid -notype _NET_WM_PID`;
  if ($wininfo =~ /_NET_WM_PID = (\d+)/) {
    return $1
  }
}

sub setfontsize {
  my ($pts, $fontsize) = @_;
  
  open PTS, ">/dev/$1";
  print PTS "\033[?35h\033]50;#+1 Source Code Pro:size=$fontsize\033\\";
  close PTS
}

Goes well together with borisfaure/terminology#46 :)