Because I began to use many Unicode characters (Japanese, some unusual diacritics, etc.) I switched from LaTeX to XeLaTeX to render my documents. Unfortunately, if a font is missing, the letters are simply left out (for example, when I had forgotten to specify the font for Japanese) without any error (and I can't seem to spot a warning either). I will read the result, but I prefer to get some early warning if some character isn't available. Is there any way to get a warning about characters that have not been rendered? An error would be even better.
[Tex/LaTex] Check for missing fonts/characters in XeLaTeX
fontsxetex
Related Solutions
As Andrey points out, the key is the concept of "interchar tokens". Suppose you have some CJK characters that doesn't appear in the normal font and you want to use another for them; say that the characters are U+4E01 and U+4E02.
Then the following will do:
\usepackage{fontspec}
\setmainfont[Ligatures=TeX]{<a font>}
\newfontfamily{\JapSubstFont}{<another font with the missing chars>}
\XeTeXinterchartokenstate=1
\newXeTeXintercharclass\JapSubst
\XeTeXcharclass"4E01=\JapSubst
\XeTeXcharclass"4E02=\JapSubst
\XeTeXinterchartoks 0 \JapSubst = {\begingroup\JapSubstFont}
\XeTeXinterchartoks 255 \JapSubst = {\begingroup\JapSubstFont}
\XeTeXinterchartoks \JapSubst 0 = {\endgroup}
\XeTeXinterchartoks \JapSubst 255 = {\endgroup}
Each time that a character in the \JapSubst charclass will be at the start or end of a "word" or be preceded or followed by a "normal" character, it will be typeset in the \JapSubstFont.
One can also specify a range:
\count255="4E01
\loop\ifnum\count255<"5000
\XeTeXcharclass\count255=\JapSubst
\advance\count255 by 1
\repeat
The following fonts are all in TeX Live 2013:
\documentclass{article}
\usepackage{fontspec}
\defaultfontfeatures{Ligatures=TeX}
\newcommand\test[1]{%
#1\\{\fontspec{#1}Βίβλος γενέσεως Ἰησοῦ Χριστοῦ υἱοῦ Δαυὶδ υἱοῦ Ἀβραάμ.}
\par\medskip}
\setlength{\parindent}{0pt}
\begin{document}
\test{CMU Serif}
\test{EB Garamond}
\test{GFS Artemisia}
\test{GFS Baskerville}
\test{GFS Bodoni}
\test{GFS Complutum}
\test{GFS Didot}
\test{GFS Olga}
\test{GFS Porson}
\test{GFS Solomos}
\test{Junicode}
\test{Linux Libertine O}
\test{Old Standard}
\end{document}
Best Answer
The log should list all missing characters in the form of:
Where
<char>and<font>is real character and TeX font name respectively. I usually use a simplegrepcall to check for such messages in the log.