Re: Font scaling in CVS Emacs (and Emacs 21.3)

[Christian Schlauer]

Jason Rumney <address@hidden> writes:

> Christian Schlauer <address@hidden> writes:
>
>> 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.
>
> The default font has a height of 13 pixels. The text in question has a
> height of 6 pixels. Perhaps it would be better to round up, but I
> don't think it is a bug.

In my screenshot (the one attached to my original posting), the `T' of
`This is GNU Emacs' has a height of 10 pixels, and the `C' of
`Copyright (C) 2002' has a height of 4 pixels. (To be more precise,
the height of the `C' varies between 4 and 5 pixels, depending which
anti-aliasing is used -- one has three choices in Windows XP: `off'
(height 4), `standard' (height 5), and `ClearType' (height 4), so it
depends on what one uses).

I started CVS Emacs with `-q --no-site-file' and opened a file
containing the following example document:

\documentclass{article}

\begin{document}
  $a_{ij}^2$
\end{document}

Then I measured the height of curly braces:

- Emacs' default font: the height of curly braces in
  `\begin{document}' is 9 pixels, and the height of the curly braces
  in `a_{ij}' is 7 pixels (that is, height 0.78)

- Font `Bitstream Vera Sans Mono': the height of curly braces in
  `\begin{document}' is 12 pixels, and the height of the curly braces
  in `a_{ij}' is 9 pixels (that is, height 0.75)

And the height should be 0.8 (M-x describe-face RET gives `Height:
0.8', everything else `unspecified' or `nil'), so there is nothing
wrong with either of the fonts. Then it isn't a bug, I guess.

I think it is the following screenshot that you can see in
<URL:http://article.gmane.org/gmane.emacs.auc-tex/3706> that made me
think it is a bug (screenshot at the bottom of the message). CVS Emacs
on the left, 21.3 on the right. The lowercase `a' has a height of 6
pixels, the lowercase, subscript `o' has only 4 pixels height (that
is, height is 0.67).

Sorry for suspecting the Emacs developers of writing buggy code ;-)

But I think the font size of the Copyright notice should be increased
somewhat. The height of 0.5 is too low, IMO, see the screenshot in my
original posting (or look at
<URL:http://article.gmane.org/gmane.emacs.pretest.bugs/4202>).

> It would be useful to get more details about the TeX problem,
> particularly the fonts involved, to determine if there is a bug
> there. You can find out what font is used for a character with
> C-u C-x =

With the above example

\documentclass{article}

\begin{document}
  $a_{ij}^2$
\end{document}

and after `M-x global-font-lock-mode RET', C-u C-x = gives:

The character `a'
  character: a (0141, 97, 0x61, U+0061)
    charset: ascii (ASCII (ISO646 IRV))
 code point: 97
     syntax: w  which means: word
   category: a:ASCII   l:Latin  
buffer code: 0x61
  file code: 0x61 (encoded by coding system undecided-dos)
    display: by this font (glyph code)
     -outline-Courier New-normal-r-normal-normal-13-97-96-96-c-80-iso8859-1 
(0x61)

There are text properties here:
  face                 [tex-math-face]
  fontified            t

The character `i'
  character: i (0151, 105, 0x69, U+0069)
    charset: ascii (ASCII (ISO646 IRV))
 code point: 105
     syntax: w  which means: word
   category: a:ASCII   l:Latin  
buffer code: 0x69
  file code: 0x69 (encoded by coding system undecided-dos)
    display: by this font (glyph code)
     -outline-Courier New-normal-r-normal-normal-10-75-96-96-c-60-iso8859-1 
(0x69)

There are text properties here:
  face                 [(tex-math-face subscript)]
  fontified            t
  display              (raise -0.3)

The character `2'
  character: 2 (062, 50, 0x32, U+0032)
    charset: ascii (ASCII (ISO646 IRV))
 code point: 50
     syntax: w  which means: word
   category: a:ASCII   l:Latin  
buffer code: 0x32
  file code: 0x32 (encoded by coding system undecided-dos)
    display: by this font (glyph code)
     -outline-Courier New-normal-r-normal-normal-10-75-96-96-c-60-iso8859-1 
(0x32)

There are text properties here:
  face                 [(tex-math-face superscript)]
  fontified            t
  display              (raise 0.3)

-- 
Christian Schlauer