Re^2: SDL and Cairo segfault

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

use strict;
no warnings;

use SDL v2.3;
use SDL::Video;
use SDL::Surface;

use Cairo;

SDL::init(SDL_INIT_VIDEO);

my $screen = SDL::Video::set_video_mode(400, 300, 32, SDL_SWSURFACE);

SDL::Video::lock_surface($screen) if SDL::Video::MUSTLOCK($screen);

my $surface = Cairo::ImageSurface->create_for_data
(
  $screen->get_pixels_ptr,
  'argb32',
  $screen->w,
  $screen->h,
  $screen->pitch
);

my $cr = Cairo::Context->create($surface);

$cr->rectangle(10, 10, 40, 40);
$cr->set_source_rgb(255, 0, 0);
$cr->fill;

SDL::Video::unlock_surface($screen) if SDL::Video::MUSTLOCK($screen);
  
SDL::Video::flip($screen);
SDL::delay(2000);

SDL::quit();
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#include <SDL.h> 
#include <cairo.h>

int main ()
{
    SDL_Init(SDL_INIT_VIDEO); 
    
    SDL_Surface *screen =
        SDL_SetVideoMode(400, 300, 32, SDL_SWSURFACE); 
    
    if (SDL_MUSTLOCK(screen))
    {
        SDL_LockSurface(screen);
    }
    
    cairo_surface_t *cairosurf = cairo_image_surface_create_for_data
    (
        screen->pixels,
        CAIRO_FORMAT_ARGB32,
        screen->w,
        screen->h,
        screen->pitch
    );
    
    cairo_t *cr = cairo_create(cairosurf);
    
    cairo_rectangle(cr, 10, 10, 40, 40);
    cairo_set_source_rgb(cr, 255, 0, 0);
    cairo_fill(cr);
    
    if (SDL_MUSTLOCK(screen))
    {
        SDL_UnlockSurface(screen);
    }
    
    SDL_Flip(screen); 
    SDL_Delay(2000); 
    
    SDL_Quit(); 
    
    return 0; 
}
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Re^3: SDL and Cairo segfault by Khen1950fx (Canon) on Jan 10, 2011 at 11:23 UTC
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(); [download]	[reply] [d/l]

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Re^3: SDL and Cairo segfault
by Khen1950fx (Canon) on Jan 10, 2011 at 11:23 UTC

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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