Re: Fwd: Re: PROP_TYPE_LIST declaration [lrclause@cs.uiuc.edu]

[<ashalper cox net>]

> Note that if your list is static, you may want to use PROP_TYPE_ENUM.  I
> think it's prettier and easier to deal with (though I may end up changing
> the PROP_TYPE_LIST widget (or even removing it -- there's not much
> difference between the two, all PROP_TYPE_LIST seems to have going for it
> is that it uses GPtrArray)).

It's dynamic.  Functionally quite similar to attributes in the UML (although I know the UML objects still probably don't make use of StdProp yet).  Should I avoid PROP_TYPE_LIST if you're considering removing it?

> You need to declare the index within your structure as well:
> 
>    GPtrArray *column_list;	/* The list of items */
>    int column_list_index;       /* The currently selected item */
> 
> To declare a ListProp in the PropOffset array, you give it the offset of
> both the list and the index:
> 
>   { "column_list", PROP_TYPE_LIST, offsetof(Independent, column_list),
>                                    offsetof(Independent, column_list_index) },

And there are no name and flags fields?  Looking at chronoline.c and what you have above, the maximalist in me wants to do something like:

   { "column_list", PROP_TYPE_LIST, PROP_FLAG_VISIBLE,
     N_("Column list"), offsetof(Independent, column_list),
     N_("Column index"), offsetof(Independent, column_list_index), NULL },

Also, the quoted example leads to a GCC warning about the column_list_index parameter in offsetof(), which worries me:

independent.c:156: warning: initialization makes pointer from integer without a cast

Thanks,
Andy

---

• From: Lars Clausen <lrclause cs uiuc edu>
• To: dia-list gnome org
• Subject: Re: PROP_TYPE_LIST declaration
• Date: Thu, 10 Apr 2003 21:19:39 -0500

On Thu, 10 Apr 2003, ashalper@cox.net wrote:
> I was wondering if someone could help me out with a PROP_TYPE_LIST
> declaration (I couldn't find any examples in the CVS code). 

There aren't any, in fact.

Note that if your list is static, you may want to use PROP_TYPE_ENUM.  I
think it's prettier and easier to deal with (though I may end up changing
the PROP_TYPE_LIST widget (or even removing it -- there's not much
difference between the two, all PROP_TYPE_LIST seems to have going for it
is that it uses GPtrArray)).

> I think I've got my PropDescription struct correct, but I need help on
> the offsets and the declaration in my object struct.  The PROP_TYPE_LIST
> macro in properties.h is:
> 
> #define PROP_TYPE_LIST "list"  /* ListProperty */
> /* (offset is a GPtrArray of (const gchar *). offset2 is a gint, index of the 
>    active item, -1 if none active.) */
> 
> My object struct looks something like:
> 
> typedef struct _Independent {
>   Element element;
> 
>   GPtrArray *column_list;	/* the ListProperty? */
>      .
>      .
>      .
> 
> } Independent;
> 
> but I'm missing the index, and I'm not at all sure how to declare the
> PropOffset array correctly.

You need to declare the index within your structure as well:

   GPtrArray *column_list;	/* The list of items */
   int column_list_index;       /* The currently selected item */

To declare a ListProp in the PropOffset array, you give it the offset of
both the list and the index:

  { "column_list", PROP_TYPE_LIST, offsetof(Independent, column_list),
                                   offsetof(Independent, column_list_index) },

Remember to create the GPtrArray when you create the array, and set the
index to something reasonable (-1 for no initial selection).  You may also
need to do a deep copy of the list when the object gets copied.

-Lars

-- 
Lars Clausen (http://shasta.cs.uiuc.edu/~lrclause)| HĂ„rdgrim of Numenor
"I do not agree with a word that you say, but I   |----------------------------
will defend to the death your right to say it."   | Where are we going, and
    --Evelyn Beatrice Hall paraphrasing Voltaire  | what's with the handbasket?
_______________________________________________
Dia-list mailing list
Dia-list@gnome.org
http://mail.gnome.org/mailman/listinfo/dia-list
FAQ at http://www.lysator.liu.se/~alla/dia/faq.html
Main page at http://www.lysator.liu.se/~alla/dia

---