Subject: Re: Reorderable tree view
From: Gabriel de Perthuis <Gabriel.de-Perthuis at laPoste.net>
To: pascal.brisset at enac.fr
Cc: lablgtk at math.nagoya-u.ac.jp
In-Reply-To: <20050520.175617.104029881.andrieu at ijm.jussieu.fr>
References: <428D8905.7070008 at recherche.enac.fr>
	 <20050520.175617.104029881.andrieu@ijm.jussieu.fr>
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Date: Fri, 20 May 2005 21:53:03 +0200
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Le vendredi 20 mai 2005 à 17:56 +0200, Olivier Andrieu a écrit :
>  Pascal Brisset [Fri, 20 May 2005]:
>  > Hi,
>  > 
>  > I'm looking for a way to constraint the drag and drop actions in a
>  > GTree.view.  Is it possible to get the "drop" event to check it and
>  > possibly forbid it ?
> 
> What do you want to drag ? rows or columns ?
> 
> - for columns you have gtk_tree_view_set_column_drag_function() (not
> wrapped in lablgtk though)
> 
> - for rows, it's more involved and has to be done in C. You'll have to
> redefine the row_drop_possible method in the GtkTreeDragDest interface
> (which is implemented by GtkTreeStore and GtkListStore). (I think,
> I've never done this before !)

Unless there's a tree view specific quirk (maybe you want to check which
line will be the drop):

method realize () =
	view#drag#dest_set ~flags:[] []
method can_drop () = ...
method update_highlight () =
	if self#can_drop ()
	then view#drag#highlight ()
	else view#drag#unhighlight ()
method drag_motion = fun context ~x ~y ~time ->
	update_highlight ();
	if self#can_drop ()
	then c#status ~time (Some `DEFAULT)
	else c#status None;

The call to dest_set with [] as flags gives you more control than gtk's
target-based (mime types) filtering, but you must control the
highlighting yourself.