I used "no warnings" after I finished the script. Always "use warnings" is always the right thing, but, with SDL, it likes to keep sending out little messsages that aren't useful. That's why I used "no warnings".

I adjusted your script a little. It produces a red rectangle png. Give it a test drive.

#!/usr/bin/perl

use strict;
use Cairo;
use SDL;
use SDL::Video;
use SDL::Surface;
use SDL::Rect;

use constant WIDTH  => 400;
use constant HEIGHT => 300;

SDL::init(SDL_INIT_VIDEO);

my $screen = SDL::Video::set_video_mode(WIDTH, 
                     HEIGHT, 32, SDL_SWSURFACE);

my $surface = Cairo::ImageSurface->create(
              'rgb24', WIDTH, HEIGHT);
my $cr = Cairo::Context->create($surface);

$0 =~ /(.*)\.pl/;
my $out = "$1.png";

$cr->rectangle (0, 0, WIDTH, HEIGHT);
$cr->set_source_rgb (255, 0, 0);
$cr->fill;
$cr->show_page;

$surface->write_to_png ($out);

SDL::quit();
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