bug#57962: 29.0.50; Odd font choices

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: luangruo@yahoo.com,  57962@debbugs.gnu.org
> Date: Sun, 16 Oct 2022 14:19:03 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > When we select a suitable font, we generally avoid opening a font,
> > because that's expensive.  So looking at the metrics is not possible,
> > unless we actually open each font.
> 
> Right...  but after opening a font, we could determine that it was
> unsuitable at that point, and then choose another.  That way the happy
> path would still be fast.

If we open the font soon enough after deciding it's what we want, yes.

> > But I don't think I understand what is going on here: these two fonts
> > are of the same size -- 48 -- so how come the glyphs have different
> > sizes?  And how different are they?  Can you look at the character
> > metrics inside gui_produce_glyphs and tell what we get from each font?
> 
> I haven't, but if I emacs -geometry 80x10 -fn "DejaVu Sans Mono-15" -Q,
> I get an Emacs frame that is 2508x762 pixels.  With -fn "Ubuntu Mono-15"
> I get a frame that's 2128x662 pixels, so DejaVu Sans Mono is about 18%
> larger than Ubuntu Mono, which is noticeable, and makes mixing the two
> fonts non-ideal.

Strange.  But I'm not sure I understand the meaning of the 48 think in
the font's XLFD signature.