Re: [gtkmm] pack_start and AttachOptions is still confusing

[Michael Babcock <mbabcock la creatureshop henson com>]

Marcelo E. Magallon wrote:
> > > Murray Cumming <murrayc usa net> writes:
>
>  > Are you certain that (false, true) is never used? Can you convince me
>  > or show me something official that says that?
>
>  Ok.  I found a place where (false, true) can be used.
>
>  Picture the following table:
>
>     +-----+-----+-----+
>     | 0,0 | 1,0 | 2,0 |
>     +-----+-----+-----+
>     | 0,1 | 1,1 | 2,1 |
>     +-----+-----+-----+
>     | 0,2 | 1,2 | 2,2 |
>     +-----+-----+-----+
>
>  In GTK+, when you attach a widget to a table you specify three
>  parameters (expand, fill and shrink) for both x and y.
>
>  Let's say (1,0) has only expand set in x and (1,1) has only fill set in
>  x.  The result is that (1,0) expands the whole column and (1,1) has
>  more space to fill.  I don't claim this makes sense, I'm only saying
>  it's possible.
>
>  After thinking about it, the example I mentioned previously now makes
>  sense: a horizontal separator without "fill" set has null size.  But
>  you don't want to set expand on it because you want it to be as large
>  as the largest element in the group, not larger.

Do you mean 0 horizontal size? A separator without "fill" is Gtk::SHRINK 
and it wouldn't make sense to set that horizontally for a hseparator 
because as you say the size would shrink to zero. By group, you mean 
column, right?

>  Now *my* question is what does shrink mean?  Why aren't expand and fill
>  enough for a table?  The documentation really doesn't help here.

Yes, with a Table you have the additional factor of the column width, so 
you can be allocated more space than expected with a Box. So Gtk::SHRINK 
is equivalent to Gtk::EXPAND if another row has a wider column!

I guess I'm basically agreeing with you, just trying to understand the 
issue better. The problem here _seems_ to be an overloading of the 
EXPAND term. In the case of a Table, it both indicates to fill extra 
allocated column space with padding, _and_ possibly to expand the amount 
allocated to that widget within the row, which in turn would increase 
the column size.

So, for x-options:

Gtk::SHRINK expands the column to at least the widget's size request. If 
the column is wider, fill extra space with padding.
Gtk::EXPAND expands the cell based on the other cells in the row. Set 
the colunn width to the maximum of the cell width and existing column 
width, fill extra space with padding.
Gtk::EXPAND|Gtk::FILL as above, but fills space by increasing widget size.

So Gtk::FILL alone would be like Gtk::EXPAND|Gtk::FILL except it would 
not increase the column width? It does seem to be different than 
Gtk::SHRINK, right?


--
Michael Babcock
Jim Henson's Creature Shop