Tex -- from fontspec error

2019-09-08 #notes #Tex #fontspec

Starting from a fontspec error: “font-not-found” with xelatex, this post shows how to settle this issue.

The main tex family tree

In short, latex provides a higher-level language to work in than tex, which was developed by Donald Knuth in 1977; pdftex supports PDF output; xetex, which is another modification of the underlying tex engine, supports a wider range of characters beyond just plain English numbers and letters, and includes support for modern font formats; and luatex is extended with the eponymous scripting language, Lua, which is a simple and stable language.

More on XeTex and LuaTex

Both luatex and xetex are UTF-8 engines for processing tex documents. This means that the input (.tex files) can contain characters that with pdftex are difficult to use directly. Both can also use system fonts, again in contrast to pdftex. However, the two are very different in approach.

xetex uses system-specific libraries to work. This means that it is very easy to use ‘out of the box’ for loading system fonts and other UTF-8 tasks. Indeed, it was written for this purpose: supporting languages, etc., that traditional tex struggles with. This makes for an easy to use for end-users, particularly if you use the fontspec package on latex. However, because things between are ‘farmed out’ to the OS, there is a trade-off in flexibility terms.

In contrast, luatex has bigger aims. The idea is to add a scripting language (Lua) to tex and to open up the internals of tex to this language. The result is that a lot is possible, but it has to be programmed in. There is growing latex support for luatex: fontspec v2 supports it, and new packages are being written to use more of the new features.

Why LuaTex?

lua(la)tex has been chosen as the official successor of pdf(la)tex, so you can expect more development effort to go towards it now and in the future. lua(la)tex doesn’t rely on system-specific libraries, so in theory, you’re less prone to encounter platform-specific issues or differences in output. Another advantage of luatex over xetex is that luatex uses the PDF engine of pdftex, while xetex uses its own one. One consequence of this is, that all features of the PGF graphics package (on which TikZ builds) should be available also under luatex, while some features are definitely not available under xetex.

Switching from LaTex to LuaLaTex

For those using LaTex, to produce a document with LuaLaTex, you need to know the following differences:

Don’t load inputenc, just encode your source in UTF-8.
Don’t load fontenc nor textcomp, but load fontspec.
babel works with LuaLaTex but you can load polyglossia instead.
Don’t use any package that changes the fonts, but use fontspec’s commands instead.

So, you only need to get familiar with fontspec, which is easy: select the main (serif) font with \setmainfont, the sans serif font with \setsansfont and the mono-spaced (typewriter) font with \setmonofont.

fontspec

In both luatex and xetex, fonts can be selected either by ‘font name’ or by ‘file name’.

By font name

In luatex, fonts found in the TEXMF tree can also be loaded by name. The simplest example might be something like

    \setmainfont{EB Garamond}[ ... ]

To check if a font is installed,

    fc-list | grep -i 'Garamond'

and show tex filename database

    updmap-sys --listmaps | grep -i 'EBGaramond'

If the font is not installed, the following procedures may be helpful.

Destination texmf-local: your local TeX tree
The new font file must reside in a directory that is part of the tex hierarchy. The best choice is your “local texmf” tree, which can be determined as follows:
```
 kpsewhich --var-value TEXMFLOCAL       # default out on Unix /usr/local/texlive/texmf-local
```
The TeX Directory Structure: unpacking your archive
Navigate to the CTAN fonts directory, choose the desired font and download it as a TDS archive (if possible). If this is the case, you can simply unpack it at the top level of your chosen tree. You can check by inspecting your archive, if it has subdirectories such as fonts/ and tex/, it’s most likely arranged according to the TDS.
```
 unzip yourfile.zip -d /usr/local/texlive/texmf-local  # unpacking into subdirectories of installing tree
```
The TeX filename database
After getting your new files into their proper location, you must update the so-called “TeX filename database”.
```
 sudo -H mktexlsr      # MacTex, -H sets HOME for the sudo environment
 mktexlsr              # TexLive
```
Font map files: telling TeX about the new font
After recording the new files, the last (and most complicated) step is to update various so-called “map” files with the information about your new font. The commands below assume your new font comes with a map file.
```
 sudo -H updmap-sys --force --enable Map=newfont.map    # MacTex
 updmap-sys --force --enable Map=newfont.map            # TexLive
```
Testing and debugging
Once all the above seems to have gone ok, to test if the new font is properly recognized, you can use the standard testfont.tex file, like this
```
 $ pdftex testfont
 ...
 Name of the font to test = tfmname
 ...
 *\table
 *\bye
```
It is imperative to enter the exact name of a .tfm file that was installed, not a system font name or a PostScript font name or anything else. The only thing TeX will recognize is the .tfm filename. Furthermore, leave off the .tfm extension.

By file name

Here is an example of fonts selected by filename,

    \setmonofont{InconsolataN}[
    Path    = \string~/Public/fonts/inconsolata/ ,
    Extension = .otf ,
    UprightFont = *-Regular ,
    BoldFont  = *-bold
    ]