Re: [Vala] all available ccodes

[Frederik <scumm_fredo gmx net>]

aaron andersen wrote:
> Is there a list of all the available tags for the vala parser? Like
> [array_length], [array_null_terminated], [NoArrayLength], etc...

Unfortunately, there is no such list. [NoArrayLength] is deprecated in favor
of [CCode (array_length=false)].

> I'm trying to figure out how to get the function SDL_ListModes to bind
> properly but am at a bit of a loss.
>
> struct SDL_Rect is defined in the vapi as a struct (Rect) and
> SDL_ListModes returns a null terminated array of pointers to SDL_Rect
> structs...
>
> SDL_Rect **modes = SDL_ListModes(params...);
> int i = 0;
> while ((SDL_Rect *iterator = modes[i]) != NULL) {
> i++
> }
>
> Given that the current bindings for SDL just returns a void * I'm not
> even sure this is possible with vala?
>
> Any help greatly appreciated!

This is the correct binding:

[CCode (cname="SDL_ListModes", array_length=false, array_null_terminated=true)]
public static unowned Rect*[]? list_modes(PixelFormat? format, uint32 flags);

Explanation:

http://sdl.beuc.net/sdl.wiki/SDL_ListModes
"Return Value: The pointer to the array of SDL_Rect
On success. The pointer to the video dimensions array is managed by SDL
itself. The caller must not free the returned pointer."

* The last sentence means 'unowned'
* '[]' because it is an array
* '?' because it can return 'null'
* The function doesn't have a length out parameter, this means no array length
* The code example 'for (i=0; modes[i]; ++i)' indicates that it is 'null'
  terminated instead

Unfortunately, the returned array is somewhat odd because it is an array of
pointers to structs instead of a simple array of structs. Vala expects that
only for arrays of heap-allocated objects but not for struct arrays. That's
why you need to add a '*' and have to access the 'w' and 'h' fields of the
'Rect's with '->' in this example program:

----------------------------------------------------------------------------
using SDL;

int main () {
        SDL.init (InitFlag.VIDEO);

        var modes = Video.list_modes (null, SurfaceFlag.FULLSCREEN
                                          | SurfaceFlag.HWSURFACE);
        if (modes == null) {
                stderr.printf ("No modes available!\n");
                return 1;
        }
        if ((int) modes == -1) {
                stderr.printf ("All resolutions available.\n");
                return 1;
        }

        foreach (var mode in modes) {
                stdout.printf ("%d x %d\n", mode->w, mode->h);
        }

        SDL.quit ();

        return 0;
}
----------------------------------------------------------------------------


Best regards,

Frederik