Missing glyph in TeXGyreTermes font

Question

For Pinyin (Chinese romanization), I like very much the look of the font TeXGyreTermes-Regular that is installed with my TeX system.

However, it seems to be missing a single Pinyin symbol that I need: ǖ ([U+01d6]). Neither within TeX nor standard word processors does this character appear.

Does anyone know if there is a way to remedy this, other than by using another font?

---

(OP added the following as a suggested edit to Villemoes' answer. I moved it to the question instead. —Caramdir)

Back after a bit of a delay; thanks very much for your help.

First, I've tried your code in LaTeX and it works just fine for ǖ, though it seems some of the other vowels-with-diacritic will also need to be specified the way you have ǖ. As it is, they generate inputenc errors.

Second, as for the difference between ǖ and the other vowels with macron, here is what I show: adding

\DeclareUnicodeCharacter{0101}{\={a}}

to your code, the macron is fine: The problem I originally had, attempting \={ü} in XeLaTex but without your additions, was that the macron looked like this:

Third: More troubling, however, is that your code doesn't seem to work under XeLaTeX, which is what I am using to have fullest support for Chinese script. It may simply be less work to stay with Times New Roman, as nice as Termes looks.

Thanks again for your help.

Answer 1

At first: such missing accented chars can always be constructed if they don't exist, after all what you want is simply an ü with a bar above it.

The main problem is how to construct them. A look in xunicode.sty shows \= and \textdieresisoverline. As default they are mapped to the char U+01D6, but one can undeclare them and test what happens. Actually their result don't look good with your font, so I guess you will have to stick to something like the following \mybar

\documentclass{article}

\makeatletter
\DeclareTextCommand{\mybar}{EU1}[1]
   {\leavevmode\setbox\z@\hbox{#1}\dimen@\ht\z@%
    \rlap{\raise1.1\dimen@\hbox{\kern0.1\wd\z@\rule{0.8\wd\z@}{0.4pt}}}#1}

\makeatother
\usepackage{fontspec}

\UndeclareUTFcomposite[\UTFencname]{x01D6}{\textdieresisoverline}{u}
\UndeclareUTFcomposite[\UTFencname]{x01D6}{\=}{\"u}

\setmainfont{TeX Gyre Termes}
\setsansfont{Times New Roman}
\setmonofont{Linux Libertine O}
\begin{document}
 %Tex Gyre
\noindent
direct: ^^^^01d6\\
mybar: \mybar{ü}\\
textdieresisoverline: \textdieresisoverline{u}\\
\textbackslash=: \={ü}

%Times
\sffamily
\noindent
direct: ^^^^01d6\\
mybar: \mybar{ü}\\
textdieresisoverline: \textdieresisoverline{u}\\
\textbackslash=: \={ü}

\ttfamily %Linux
\noindent
direct: ^^^^01d6\\
mybar: \mybar{ü}\\
textdieresisoverline: \textdieresisoverline{u}\\
\textbackslash=: \={ü}

\end{document}

Answer 2

You could construct it yourself by composing the macron accent with the glyph ü (according to Unicode, this is indeed a legal decomposition, even though the result might be slightly better had the font contained the glyph itself).

You can then use \DeclareUnicodeCharacter to tell LaTeX what to do when it encounters U+01D6.

I think hyphenation will be disabled in words containing this character, but I don't know if one even hyphenates Pinyin. In any case, you can always insert \- to manually allow hyphenations.

\documentclass{article}

\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}

\usepackage{tgtermes}

\DeclareUnicodeCharacter{01D6}{\={ü}}

\begin{document}

% This should give the desired output.
ü  ǖ 

\end{document}