Re: Please fill out the GtkLabel questionnaire

[Benjamin Otte <otte gnome org>]

On Sat, Apr 9, 2011 at 2:14 PM, Tristan Van Berkom
<tristanvb openismus com> wrote:
> What I should have done, as Owen pointed out back in december was to
> leave the label requests very straight-forward and require the program
> author to set an explicit minimum size of the toplevel GtkWindow,
> essentially the difference would only be that instead of having to
> potentially configure a lot of label sizes inside the interface, you
> just configure the desired size of the toplevel and you get a reasonable
> allocation (Havoc also suggested we do some one-shot binary search to
> find a good aspect ratio for the initial size of the toplevel window).
>
So what you are saying is to essentially get rid of the
guess_wrap_width argument to gtk_label_ensure_layout(), right?

> A caveat here is that currently there is no straight-forward way for
> obtaining things like "the size of the largest word in the text" or
> "the size of the widest character".
>
According to Behdad:
pango_layout_set_wrap_mode (layout, mode);
pango_layout_set_width (layout, 0);
pango_layout_get_extents (layout, &extents);
will give you exactly that. It will cause as much wrapping as possible
and then of course the width of the resulting text will be the size of
the widest word/character.

> Labels currently don't wrap and ellipsize both, it would be nice if
> they did however (and it's certainly possible, I would imagine the
> whole text would wrap as much as possible and the text that doesnt
> fit would be ellipsized only on the last line).
>
Oh? Is this a limitation in Pango or is that just missing inside GtkLabel?

> As far as "max-width-chars" and "width-chars" effects go, I dont have
> any strong opinion so far as it's useful, the subtleties are:
>
>  - Do we blatently always request "width-chars" as minimum if set ?
>  - Do we request MIN (text_width, width-chars) ?
>    (I think this is more useful and I think it's how it currently
>     works)
>
> Same for max:
>  - Do we blindly request "max-width-chars" as the natural width ?
>  - Do we request MIN (text_width, max-width-chars) as natural ?
>    (Again I think it's currently the latter and I personally think
>    that is more useful).
>
Paolo and I discussed that, and what we discussed was setting the
minimum/natural size in characters.
There seem to be 4 values that you could want to set:
- minimum value to request for minimum width
- maximum value to request for minimum width
- minimum value to request for natural width
- maximum value to request for natural width
And we have two properties for them:
- width-chars
- max-width-chars

Now I would argue that 2 of the values are kind of useless: the
maximum minimum width and the minimum natural size. If you'd agree
with that premise, you could use width-chars as the minimum minimum
width and max-width-chars as the maximum natural size. (Which is what
I did in my reply.)
The only question that would remain is how you let these properties
interact with the width required by the label's text. I assumed that
the minimum width of the text is bigger than any of those properties,
that size will be used instead, but the natural width of the text is
ignored if the max-width-chars property is set.

Benjamin