Greyscale bars/Display: Difference between revisions

=={{header|Perl}}==

<lang perl>sub partition {

my($all, $div) = @_;

my @marks = 0;

push @marks, $_/$div * $all for 1..$div;

my @copy = @marks;

$marks[$_] -= $copy[$_-1] for 1..$#marks;

@marks[1..$#marks];

}

sub bars {

my($h,$w,$p,$rev) = @_;

my (@nums,@vals,$line,$d);

$d = 2**$p;

push @nums, int $_/($d-1) * (2**16-1) for $rev ? reverse 0..$d-1 : 0..$d-1;

push @vals, ($nums[$_]) x (partition($w, $d))[$_] for 0..$#nums;

$line = join(' ', @vals) . "\n";

$line x $h;

}

my($w,$h) = (1280,768);

open my $pgm, '>', 'Greyscale-bars-perl5.pgm' or die "Can't create Greyscale-bars-perl5.pgm: $!";

print $pgm <<"EOH";

P2

# Greyscale-bars-perl5.pgm

$w $h

65535

EOH

my ($h1,$h2,$h3,$h4) = partition($h,4);

print $pgm

bars($h1,$w,3,0),

bars($h2,$w,4,1),

bars($h3,$w,5,0),

bars($h4,$w,6,1);</lang>

[https://github.com/SqrtNegInf/Rosettacode-Perl5-Smoke/blob/master/ref/Greyscale-bars-perl5.png See Greyscale-bars-perl5] (offsite image)