Re: custom TreeModel

hi,
on one hand I genuinely feel that there is a real use case for this:
imagine a library that you've written, and you want to show its results
in a gtk treeview, but straight from your result data structure and not
by duplicating the nodes in the treeview itself. What if the input-
output schema of your library is fixed? or suppose that you're porting
it to gtk as an alternative to another gui? People will struggle with
linking their library to the gtk treeview; or in any case I certainly
had a hard time finding out how to get this working. Yes, this way of
adressing the data certainly is complicated, but that makes an example
all the more welcome, no? There is no way around this kind of custom
code, if you want to avoid duplicating your data, or if your data is
constantly changing, for instance.
I also tend to get lost in the documentation for gtk(mm), and for
instance I just did not notice the examples in gtkmm-
documentation/examples/book/custom/custom_treemodel . So an additional
example in the gtkmm/demos does not look superfluous to me.
On the other hand, I don't want to impose, and if you feel there is no
place for my example in the gtkmm demos, then so be it. People really
desperate for an example will now find it in the mailinglist at "Date:
Mon, 16 Dec 2019 23:10:45 +0100", I guess...
happy new year, Danny.
-----Original Message-----
Date: Mon, 23 Dec 2019 13:23:20 +0100Subject: Re: custom TreeModelCc: g
[email protected]: danny <[email protected]>From: Kjell
Ahlstedt <[email protected]>
  
    
  
  
    An alternative would be to add this in a new
        gtkmm-documentation/examples/book/custom/custom_treemodel
        directory  in the gtkmm
          tutorial. And a description in a new section in the Custom
          Widgets chapter (which should then be renamed).

      
    Isn't this kind of custom class that implements
        one or more interfaces quite unusual? And a bit more
complicated
        than most of the demos? There is no corresponding program in
        gtk/demos. All existing C++ demos in gtkmm correspond to C
demos
        in gtk.

      
    Kjell

      
    On 2019-12-22 11:06, danny via
      gtkmm-list wrote:

    
    
>       
>       hello gtkmm,
>       
> 
>       
>       so how do I continue with this? I feel that it would be
>         really handy to add an example such as the one below to the
>         gtkmm demos subdir. 
>       
> 
>       
>       I was struggling with this myself some years ago for a gtk2
>         program where the data were already established (and
> constantly
>         changing) outside the gui in a separate structure.
>       
> 
>       
>       Copying the data into the treeview model, as the existing
>         demo programs do, is obviously not the ideal solution.
>       
> 
>       
>       the other example in gtkmm-documentation
>         keeps is very helpful, but it does not show subdirs...
>       
> 
>       
>       regards, Danny.
>       
> 
>       
>       
>         On Mon, Dec 16, 2019 at 2:10
>           PM danny via gtkmm-list <[email protected]>
>           wrote:
> 
>         
>         
> >           
> >             hi
> >             
> > 
> >             
> >             well, actually, I did not find the example you are
> >               referring to. I probably did when I was working with
> > the
> >               original gtk2 program, though.
> >             
> > 
> >             
> >             so I have come up with this:
> >             (gtkmm-3.22.3/demos)
> >             
> > 
> >             
> >             -------------------------------------------------------
> > -------
> >             /* Tree View/Tree Store
> >              *
> >              * The GtkTreeStore is used to store data in tree form,
> >               to be
> >              * used later on by a GtkTreeView to display it. This
> >               demo builds
> >              * a simple list of nodes in memory and displays it in
> >               the GtkTreeStore. 
> >              *
> >              */
> >             
> > 
> >             
> >             ...
> >             -------------------------------------------------------
> > -------
> >             
> > 
> >             
> >             I'm not sure, though, if I really understand the
> >               purpose of 
> >             
> >               
> >                 
> >                   virtual bool Gtk::TreeModel::iter_parent_vfunc 
> >                   (
> >                   
> > 
> >                   
> >                 
> >               
> >             
> >             
> > 
> >             
> >             this function finds a parent for the given child,
> >               right? but why would that be needed, if a child can
> > only
> >               be arrived at from a parent node in the first place?
> >             
> > 
> >             
> >             regards, Danny.
> >             
> > 
> >             
> >           
> >         
> 
>         
> 
>       
>       
> 
>       
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> 
>

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