bug#65803: 29.1; Noto Sans Mono CJK JP has doubled-width on Windows

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: shingo.fg8@gmail.com,  65803@debbugs.gnu.org
> Date: Sun, 10 Sep 2023 15:31:36 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > See above: other backends only calculate the average width for
> > proportional fonts.  So what you say doesn't fit my reading of the
> > code.
> 
> Because if spacing is not FC_PROPORTIONAL or FC_DUAL, we know in advance
> that max_advance_width or max_advance are identical to the average of
> all ASCII glyphs.  Such special treatment is an optimization, nothing
> more.  max_advance_width is the advance width (in em space) of the
> widest glyph when the font is scalable, and max_advance is that in pixel
> space if not.

So you think it's okay to do the same in the w32 font backend,
i.e. take the average width from the font when the font is known to be
fixed-pitch?  If not, please elaborate, because that's what I
understand from what you wrote above.