Date: Fri, 04 Mar 2005 10:57:49 +0100 (CET)
Message-Id: <20050304.105749.112609272.andrieu at ijm.jussieu.fr>
To: aubineth at ccs.neu.edu, rich at annexia.org
Cc: lablgtk at kaba.or.jp
Subject: Re: tree view models written in ocaml
From: Olivier Andrieu <andrieu at ijm.jussieu.fr>
In-Reply-To: <cv6jvd$bb8$1 at sea.gmane.org>
	<20050303234255.GA25179@furbychan.cocan.org>
References: <cv6jvd$bb8$1 at sea.gmane.org>
 <20050303234255.GA25179@furbychan.cocan.org>
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

 Ethan Aubin [Sat, 19 Feb 2005]:
 > 
 > Hi, I'm trying to figure out Tree Views but I'm running into some
 > problems.  I've a few objects/records written in ocaml I'd like to
 > use as the model of the tree view, but I'm missing how to setup the
 > column views, so that they pull and format (I can convert what I
 > need into text) the right fields.
 >
 > type gender = Male | Female
 > type person = {name : string; gender : gender; age : int}

You can use the Gobject.Data.caml converter : it has type 'a
Gobject.data_conv, so you can store an arbitrary caml value in it.

Here is how to do it (roughly) :
,----
|  let column_list = new GTree.column_list in
|  let column = column_list#add Gobject.Data.caml in
|  let model = GTree.list_store column_list in
|  List.iter
|    (fun p -> 
|      let row = model#append () in 
|      model#set ~row ~column p)
|    persons ;
|  let viewcol = GTree.view_column () in
|  let renderer = GTree.cell_renderer_text [] in
|  viewcol#pack renderer ;
|  viewcol#set_cell_data_func renderer 
|    (fun m row ->
|       let p = m#get ~row ~column in
|       let text = string_of_person p in
|       renderer#set_properties [`TEXT text]) ;
|  let view = GTree.view ~model () in
|  ignore (view#append_column viewcol) ;
|  view
`----


 Richard Jones [Thu, 3 Mar 2005]:
 > Is it better to write my own tree model?  (And if so, where on
 > earth do I start?  I have no idea how to go about this.)

You can't really write your tree model in caml, you'd need to write it
in C.

 > Or is it better, as was suggested on one of the Gtk lists, to use a
 > Gobject.Data.pointer or Gobject.Data.boxed to "hang" my extra
 > structures on to a row, and just use the ordinary GtkTreeModel?
 > (I'm not exactly sure how to do this one either ...)

Using Gobject.Data.caml is the way to go I'd say : this is the moral
equivalent of G_TYPE_POINTER (or G_TYPE_BOXED), i.e. some data, opaque for
the GtkTreeView, which is displayed using a GtkTreeCellDataFunc.

HTH,
-- 
   Olivier