Re: getting the natural size of a widget

This is perfect - thank you so much.  I'll see if I can get this rigged into
our code base.

-David


On 2/7/08, Julien Moutinho <[email protected]> wrote:
>
> On Wed, Feb 06, 2008 at 08:34:04PM +0000, David Powers wrote:
> > I am attempting to use the GnoCanvas to build what is essentially a
> custom
> > container.  Placing widgets on the canvas works like a charm, but I
> can't
> > seem to find where the normal containers are reading their sizing hints
> > from.  I can read the height/width_request properties, but they seem to
> be
> > minimal sizes (e.g. for a text entry box I get a height and width of 1).
> > Does anyone have any hints on where I could go hunting - or maybe I
> should
> > be taking a different approach?
>
> According to the following links, gtk_widget_size_request() is the way
> containers read their sizing hints:
>
>
> http://library.gnome.org/devel/gtk/stable/GtkContainer.html#size-requisition
>
>   "The size requisition phase of the widget layout process operates
> top-down.
>   It starts at a top-level widget, typically a GtkWindow.
>   The top-level widget asks its child for its size requisition by calling
>   gtk_widget_size_request(). To determine its requisition, the child asks
>   its own children for their requisitions and so on.
>   Finally, the top-level widget will get a requisition back from its
> child."
>
>
> http://library.gnome.org/devel/gtk/stable/GtkWidget.html#gtk-widget-size-request
>
>   "This function is typically used when implementing a GtkContainer
> subclass.
>   Obtains the preferred size of a widget. The container uses this
> information
>   to arrange its child widgets and decide what size allocations to give
> them
>   with gtk_widget_size_allocate()."
>
> Unfortunately, gtk_widget_size_request() has not been wrapped inside
> LablGTK yet.
> However, I'm joining a little patch which wraps it plus an example that
> may help you.
> I've also applied the patch to:
>   svn://[email protected]/svn/lablgtk/branches/moutinho
>
> NOTE: my lablgtk2 top-loop fails to run the example:
> % lablgtk2 lablgtk_example__size_request.ml
> Fatal error: exception Failure("float_of_string")
> 2%
> (This bug may be related to ~x ~y ~width ~height parameters,
> because without them it does not fail)
>
> So you may have to run the example with this command:
>
> % ocamlc -g -I +lablgtk2 lablgtk.cma lablgnomecanvas.cma gtkInit.cmo \
>     lablgtk_example__size_request.ml && ./a.out
> root_group#get_bounds: 0. 0. 0. 0.
> widget#get_bounds: 0. 0. 23. 12.
> widget#get_bounds: 25. 14. 52. 26.
> List.length root_group#get_items = 2
> root_group#get_bounds: 0. 0. 52. 26.
> found a widget item:
>   requested_width  = 23
>   requested_height = 12
> found a widget item:
>   requested_width  = 27
>   requested_height = 12
>
> HTH.
>
>
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>
>
>

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