#!/usr/bin/perl
use strict;
use warnings;

use Tk;

my $scale_faktor = 1.5;

my $window = MainWindow->new();


my $c1 = $window->Canvas(-width  => 958 * $scale_faktor,
                         -height => 150 * $scale_faktor,
                        )
                  ->pack();

...
my $oval = $c1->createOval($x1, $y1, $x2, $y2, -fill => 'gray');
...