Dear LyX developers,
State of the art
================
LyX manuals currently use user-preamble code to set the font depending on
the export route and availability:
* Latin Modern (CM-extension) with PDF(luatex), PDF(pdflatex), if lmodern.sty
is installed
* CM-Super (another CM lookalike) with all other export routes, if it is
installed.
* EC (bitmapped CM-extension) with all other export routes if CM-Super
Motivation
==========
The idea was, that
* we wanted to use the default font (Computer Modern (CM)) with the manuals.
* we wanted to use LyX default for the font encoding (T1) instead of the TeX
default (the 7-bit OT1 font encoding).
Using the T1 font encoding is important for non-english languages
using the Latin alphabet, otherwise automatic hyphenation fails and the
output quality of non-ASCII letters is bad.
However, the default font CM does not exist in T1 encoding and TeX
automatically selects a substitution - either CM-Super or EC which both have
problems:
* CM-Super: large (40MB), said to be of inferior quality to LatinModern
* EC: Bitmapped fonts take long with first compilation (must be generated
from MetaFont sources in required resolution), have a fixed resolution and
look bad in old Acrobat readers.
The alternative LatinModern CM-lookalike is not guaranteed to be installed
on each system. To prevent an additional dependency for compiling the
manuals, the following preamble-selection code was chosen:
\usepackage{ifpdf} % part of the hyperref bundle
\ifpdf % if pdflatex or lualatex is used
\@ifpackageloaded{fontspec}{}{% non-tex-fonts default to LModern
% set fonts for nicer pdf view
\IfFileExists{lmodern.sty}{\usepackage{lmodern}}{}
}
\fi % end if pdflatex is used
Problems
========
Besides beeing not a good example for LyX-use, there are specific problems
with the current implementeation:
* Bitmapped EC fonts for PDF(XeTeX), PDF(ps2pdf) and PDF(dvipdfm)
* Bitmapped EC fonts for PS
* LatinModern 8-bit fonts are used with LuaTeX, even if "use-non-TeX-fonts"
is selected. This leads to failures in some of our export tests:
> For the test with non-TeX fonts, the preamble code involving lmodern.sty
> must be changed, otherwise 8-bit fonts are used with wrong font encoding!
> One possibility would be to remove the special casing altogether,
> possibly selecting a better font in the GUI (but this was rejected some
> years ago).
> Another option is the following patch (similar in all places where this
> preamble code is used):
> --- a/lib/doc/fr/UserGuide.lyx
> +++ b/lib/doc/fr/UserGuide.lyx
> @@ -15,11 +15,11 @@
> % email: lyx-d...@lists.lyx.org
> \usepackage{ifpdf} % part of the hyperref bundle
> -\ifpdf % if pdflatex is used
> -
> +\ifpdf % if pdflatex or lualatex is used
> +\@ifpackageloaded{fontspec}{}{% non-tex-fonts default to LModern
> % set fonts for nicer pdf view
> \IfFileExists{lmodern.sty}{\usepackage{lmodern}}{}
> -
> +}
> \fi % end if pdflatex is used
> % for correct jump positions whe clicking on a link to a float
My preferred solution is still to use not only a LyX-recommended non-default
font encoding,
but also a matching LyX-recommended non-default font, set via the GUI.
* Latin Modern is the community-recommended (but not automatically used)
"international" substitution for CM.
+ It comes with optical sizes and mixes well with the default math fonts.
- It is too light for good on-screen reading.
- It is not a required part of TeX.
* The PSNFSS fonts
http://www.ctan.org/tex-archive/macros/latex/required/psnfss/ can be set
via the LyX GUI and support the T1 font encoding.
+ required with every TeX installation
- no optical sizes
- sub-optimal mix with math fonts without additional packages
(acceptable for Palatino (mathpazo) in simple use cases).
Günter
