Font scaling in CVS Emacs (and Emacs 21.3)

[Christian Schlauer]

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[ Summary: There is a problem with the scaling of the /default/
font(s) that Emacs uses (on Windows). It is visible on the splash screen
and in TeX/LaTeX mode. It depends on the font. Maybe it exists on
GNU/Linux, too, depending on the font you use. ]

There might be a bug in the font scaling of Emacs. You can see that on
the startup screen when you look at the font size in the line
`Copyright (C) 2002 Free Software Foundation', which should have the
height 0.5. A screenshot on a GNU/Linux system can be found here
<URL:http://theotp1.physik.uni-ulm.de/~ste/comp/emacs/misc/emacs-splash.png>.

Now, while this looks still reasonably, something is wrong on Windows,
using the default font of Emacs on Windows. I attach a screenshot to
this message that shows that the height of that line is less than 0.5
on Windows.

Why is this important? Emacs' built-in TeX/LaTeX mode (and AUCTeX,
too) changes the size of sub- and superscripts (i.e., things like
$a_{ij}^2$) to the height 0.8, and this looks still reasonable on the
same GNU/Linux system, see
<URL:http://theotp1.physik.uni-ulm.de/~ste/comp/emacs/auctex/script-display.png>,
but on Windows, with the default font that Emacs uses on Windows, it
doesn't look good at all, see
<URL:http://article.gmane.org/gmane.emacs.auc-tex/4451>. The size of
the sub- and superscripts seems to be 0.5 or something, but should be
0.8. (It is only legible as CVS Emacs on Windows does anti-aliasing of
the text font, but the user has to activate the anti-aliasing on her
system (called ClearType and only available on Windows XP), and I have
only seen it on LCD screens, I don't know if it makes sense on CRTs.)

How it looks on Windows depends also on the font that one uses: I
changed the font in both CVS Emacs and Emacs 21.3 to `Bitstream Vera
Sans Mono' (must have come with OpenOffice), and then it looks similar
to the screenshots taken on the GNU/Linux system, that is, the height
of the sub- and superscripts seems to be 0.8 -- I can send you such a
screenshot, if you need it.

(This bug report is a result of a discussion between Reiner Steib and
me on gmane.emacs.auc-tex. It starts about here:
<URL:http://article.gmane.org/gmane.emacs.auc-tex/4384>.)

In GNU Emacs 21.3.50.1 (i386-mingw-nt5.1.2600)
 of 2004-07-26 on BERATUNG4
configured using `configure --with-gcc (3.3) --cflags 
-I../../jpeg-6b-1/include -I../../libpng-1.2.4-1/include 
-I../../tiff-3.5.7/include -I../../xpm-nox-4.2.0/include 
-I../../zlib-1.1.4-1/include'

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: DEU
  locale-coding-system: cp1252
  default-enable-multibyte-characters: t

Major mode: LaTeX

Minor modes in effect:
  tool-bar-mode: t
  encoded-kbd-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  line-number-mode: t

Recent input:
C-x C-f k : SPC t p SPC u s SPC t e s t . t e x <return>
\ d o c u m e n t c l a s s { a r t i c l e } <return>
<return> C-c C-o d o u <backspace> c u SPC <return>
M-x g l o b a l SPC f o n SPC SPC SPC <return> $ a
_ { i j } ^ 2 $ M-x r e p o r t SPC e m SPC SPC <r
eturn>

Recent messages:
Loading image...done
Loading tooltip...done
(New file)
Loading tex-mode...
Loading regexp-opt...done
Loading tex-mode...done
Loading skeleton...done
Loading font-lock...done
Loading jit-lock...done
Loading emacsbug...done