in reply to SDL and Cairo segfault

Why use Cairo? SDL::Video can produce a beautiful red rectangle all by itself.

The segmentation fault was happening because the video mode wasn't being set right, and you were missing SDL::Rect. Here's a script that works for me: 

#!/usr/bin/perl

use strict;
no warnings;
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 $mcolor = SDL::Video::map_RGB($screen->format(),
                                 255, 0, 0);
SDL::Video::fill_rect($screen,
    SDL::Rect->new( 
        WIDTH / 4, HEIGHT / 4,
        WIDTH / 2, HEIGHT / 2), $mcolor);
        
SDL::Video::update_rect( $screen, 0, 0, WIDTH, HEIGHT );
sleep 10;
SDL::quit();

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If that works, then you can add whatever you need to add. If you run into problems, post another question. Good luck.

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Re^2: SDL and Cairo segfault
by Atacama (Sexton) on Jan 09, 2011 at 20:46 UTC

    Thank you for reply.

    The main reasons for cairo were to draw more interesting stuff than a red rectangle (which was used to make example code short) and to do it fast enough for a simple game.

    Your code worked perfectly, but would you like to explain what is the reason for "no warnings", please? Everybody seems to be advocating for "use warnings".

    I suddenly discovered SDL::GFX::Primitives namespace which looks suitable

    Just in case, here are two pieces of code: Perl version segfaults and C one works. Either they are not equivalent or perl-cairo and perl-sdl are not compatible

    Read more... (2 kB)
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      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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