Re: GtkImageView

[muppet <scott asofyet org>]

On Feb 15, 2008, at 5:47 PM, Jeffrey Ratcliffe wrote:

> On 15/02/2008, muppet <scott asofyet org> wrote:
> > Still another option, more correct but more work, is to register a
> > GBoxed wrapper for the structure.  Then everything will Just Wonk.
>
> OK. I think I have got the GBoxed wrappers working.

Now that you have a GBoxed GType for the struct (that can go upstream  
just like the GEnum GTypes), you can also register the functions to  
marshal the value to and from perl.  See gperl_register_boxed() in  
Glib::xsapi.


> > Torsten recently added to Glib some useful functions for this  
> > purpose,
> > including gperl_sv_is_hash_ref():
>
> That would be excellent, apart from it being too new to be in any
> current distribution.


A primitive replacement that you can use on those older versions would  
be

#ifndef gperl_sv_is_hash_ref
#define gperl_sv_is_hash_ref(sv) \
    ((sv) && SvOK (sv) && SvROK (sv) && SvTYPE (SvRV (sv)) == SVt_PVHV)
#endif

Just put that in the xs file where you want to use it, somewhere  
before you call it.  (The tests are "is it non-null, a valid scalar, a  
reference, and a reference to a hash?")

This doesn't handle magical SVs (which is why Torsten created  
gperl_sv_is_defined()), but it's enough to get you by for what you need.



> > Blessing the hash would help you do even more validation, but is not
> > strictly necessary.  If your user is allowed to supply a plain old
> > hash of his own making, then requiring a blessed hash will be
> > breakage, but if the user is supposed to use one of your methods to
> > create one of these things, then blessing the hash is A Very Good  
> > Idea.
>
> If I wanted to bless the hash, I assume I would have to do it in the
>
> SV *
> newSVGdkPixbufDrawOpts
>
> function, and therefore above the MODULE, which is pure C, and
>
> ST(0) = sv_newmortal();
> sv_setref_pv(ST(0), "Gtk2::Gdk::Pixbuf::Draw::Opts", (void*)RETVAL);
>
> isn't going to work. How do I do it?


    HV * hv;
    hv = newHV ();
    ...

    return sv_bless (newRV_noinc ((SV *) hv), gv_stashpv  
("Gtk2::Gdk::Pixbuf::Draw::Opts", TRUE));

To check it on the other end,

    if (! sv_derived_from (sv, "Gtk2::Gdk::Pixbuf::Draw::Opts"))
        croak ("It ain't a drawopts, yo!");




> Lastly, I am getting
>
> IImageTool.c: In function 'XS_Gtk2__ImageView__Tool_paint_image':
> IImageTool.c:96: warning: initialization makes pointer from integer
> without a cast
>
> which is
>
> GdkPixbufDrawOpts *     opts = SvGdkPixbufDrawOpts (ST(1));
>
> as SvGdkPixbufDrawOpts is defined as a GdkPixbufDrawOpts * in
> DrawCache.xs, I assume it is saying that ST(1) isn't SV *. But I don't
> see how to fix it.

I don't have the code building at the moment, but that usually means  
you don't have a prototype for SvGdkPixbufDrawOpts() in that file.  If  
you refer to a function without a prototype or prior declaration, C is  
defined to assume it returns an int.

I'll guess that this is in the file from which you removed the static  
definition of SvGdkPixbufDrawOpts().  Make sure you're getting the  
prototype from a header.


--
elysse:  You dance better than some.
me:  "Some" what?
elysse:  Some asparagus.