Re: getting the size of a drawing area

[Owen Taylor <otaylor redhat com>]

John C Atkeson <jcatkeson@juno.com> writes:

>   
>   I'm using widget->allocation.width and .height to determine the shape
> of my drawing area at runtime, but am getting funny results.
>   
>   I set allocation.width and .height to 700x500 at startup - and they
> stick there for the entire life of the program, even after the user has
> resized the window/widget many times and the drawing_area is obviously no
> longer those proportions.  
>   
>   How can one not be equal to the other?  

Hrmmm, without sample code, I can't say.

First it is not allowed to touch allocation.width/height yourself.
That is the size that GTK+ gives the widget. Setting it yourself
doesn't make sense, and it will be overwritten. 

Second, when your drawing area gets the new size, the following
code will be called:

=================
static void
gtk_drawing_area_size_allocate (GtkWidget     *widget,
				GtkAllocation *allocation)
{
  g_return_if_fail (widget != NULL);
  g_return_if_fail (GTK_IS_DRAWING_AREA (widget));
  g_return_if_fail (allocation != NULL);

  widget->allocation = *allocation;
  widget->allocation.width = MAX (1, widget->allocation.width);
  widget->allocation.height = MAX (1, widget->allocation.height);

  [...]
}
=================

This looks pretty much guaranteed to change the allocation to
me. My best guesses are that your drawing area is packed in
such a way that the drawing area isn't changing size when
the toplevel changes size or that there is some confusion
between allocation and requisition in your program.

Regards,
                                        Owen