Adding a box to a PDF file

add_watermark.pl

#!/usr/bin/perl

use strict;
use PDF::API2::Simple;

my ($input_pdf, $pdf, $api, $page, $width, $height);
my ($box_width, $box_height);

$input_pdf = shift @ARGV;

$pdf = PDF::API2::Simple->new(file => $input_pdf);
$api = $pdf->pdf();

$width = $pdf->width();
$height = $pdf->height();

print "Width:  $width\n";
print "Height: $height\n";

# Make the box 1/2 the document's widest dimension
foreach my $page (1 .. $api->pages()) {
  $api->openpage($page);
  $pdf->current_page($page);

  if ($width > $height) {
    $box_width = $width / 2;
    $box_height = $height;
  } else {
    $box_height = $height / 2;
    $box_width = $width;
    my $half = (($height - $box_height) / 2);
    $pdf->rect( x => 0,
                y => $half,
                to_x => $width,
                to_y => $half + $box_height,
                fill_color => 'white',
                fill => 'on' );
  }
}
$api->saveas('/tmp/out.pdf');