#!/usr/bin/perl
use strict;
use warnings;
use Cairo;
use constant
{
WIDTH => 600,
HEIGHT => 600,
};
{
my $surf = Cairo::ImageSurface->create ('argb32', WIDTH, HEIGHT);
my $cr = Cairo::Context->create ($surf);
$0 =~ /(.*)\.pl/;
my $out = "$1.png";
$cr->rectangle (0, 0, WIDTH, HEIGHT);
$cr->set_source_rgb (1, 1, 1);
$cr->fill;
draw_spiral ($cr, WIDTH, HEIGHT);
$cr->show_page;
$surf->write_to_png ($out);
}
sub draw_spiral
{
my ($cr, $width, $height) = @_;
my $wd = .02 * $width;
my $hd = .02 * $height;
$width -= 2;
$height -= 2;
$cr->move_to ($width + 1, 1 - $hd);
for (my $i=0; $i < 9; $i++)
{
$cr->rel_line_to (0, $height - $hd * (2 * $i - 1));
$cr->rel_line_to (- ($width - $wd * (2 * $i)), 0);
$cr->rel_line_to (0, - ($height - $hd * (2 * $i)));
$cr->rel_line_to ($width - $wd * (2 * $i + 1), 0);
}
$cr->set_source_rgb (0, 0, 1);
$cr->stroke;
}