Most of the problems that occur during the translation of a given
LATEX file (say trouble.tex) can be detected and solved at
the macro-level. That is, most problems induce a macro-related warning
and can be solved by writing a few
macros. The best place for these macros is an user style file (say
trouble.hva) given as
argument to HEVEA.
# hevea trouble.hva trouble.tex
By doing so, the macros written specially for HEVEA are not
seen by LATEX. Even better, trouble.tex is not changed
at all.
A worth-mentiong alternative is inserting \usepackage{trouble}
in the document preamble. Then, given HEVEA semantics for
\usepackage (see Section B.5.2),
HEVEA-specific commands should be placed in
the file “trouble.hva” file, while LATEX-specific commands
should be placed in the file “trouble.sty”.
Of course, adapting a document to HEVEA processing will be easier if the LATEX source is written in a generic style, using macros. Note that this style is recommended anyway, since it facilitates document maintenance.
This section has been outdated by the implementation of
\raisebox by C. Spiel. Nevertheless, the method illustrated here is still highly valuable. This method can be summarised as “if HEVEA does not know about a macro, you may solve the problem a simple one yourself” and “do not ignore warnings”.
Consider the following LATEX source excerpt:
You can \raisebox{.6ex}{\em raise} text.
LATEX typesets this as follows:
Since HEVEA does not know about \raisebox,
it incorrectly processes this input. More precisely,
it first prints a warning message:
trouble.tex:34: Unknown macro: \raisebox
Then, it goes on by translating the arguments of \raisebox as if
they were normal text. As a
consequence some .6ex is finally found in the html output:
You can .6exraise text.
To correct this, you should provide a macro that has more or less the effect of
\raisebox. It is impossible to write a generic
\raisebox macro for HEVEA, because of html limitations.1
However, in this case, the effect of \raisebox is to raise the box a little.
Thus, the first, numerical, argument to \raisebox can be
ignored in a private \raisebox macro defined in trouble.hva:
\newcommand{\raisebox}[2]{$^{\mbox{#2}}$}
Now, translating the document yields:
You can raise text a little.
Of course, this will work only when all \raisebox commands in
the document raise text a little. Consider, the following
example, where text
is both raised a lowered a little:
You can \raisebox{.6ex}{\em raise}
or \raisebox{-.6ex}{\em lower} text.
Which LATEX renders as follows:
Whereas, with the above definition of \raisebox, HEVEA produces:
You can raise or lower text.
A solution is to add a new macro definition in the trouble.hva file:
\newcommand{\lowerbox}[2]{$_{\mbox{#2}}$}
Then, trouble.tex itself has to be modified a little.
You can \raisebox{.6ex}{\em raise}
or \lowerbox{-.6ex}{\em lower} text.
HEVEA now produces a satisfying output:
You can raise or lower text.
Note that, for the document to remain LATEX-processable,
it should also contain the following definition for
\lowerbox:
\newcommand{\lowerbox}[2]{\raisebox{#1}{#2}}
This definition can safely be placed anywhere in trouble.tex,
since by HEVEA semantics for \newcommand (see
section B.8.1)
the new definition will not overwrite the old one.
Note : HEVEA now renders the \rule command very similarly to LATEX. Hence the forthcomming section is in some sense obsolete. Nevertheless, the technique described is useful and the section is still worth reading.
Sometimes HEVEA knows about a macro, but the produced html does not look good when seen through a browser. This kind of errors is detected while visually checking the output. However, HEVEA does its best to issue warnings when such situations are likely to occur.
Consider, for instance, this definition of \blob as a small
black square.
\newcommand{\blob}{\rule[.2ex]{1ex}{1ex}}
\blob\ Blob \blob
Which LATEX typesets as follows:
HEVEA always translates \rule as <hr>, ignoring size
arguments.
Hence, it produces the following, wrong, output:
Blob
We may not be particularily commited to a square blob.
In that case, other small symbols would perfectly do the job
of \blob, such as a bullet (\bullet).
Thus, you may choose to give \blob a definition in
trouble.hva:
\newcommand{\blob}{\bullet}
This new definition yields the following, more satisfying output:
• Blob •
In case we do want a square blob, there are two alternatives.
We can have LATEX typeset some subparts of
the document and then to include them as images, section 6
explains how to proceed.
We can also find a square blob somewhere in the variety of Unicode
(or do I mean ISO 10646?) characters,
and define \blob as a numerical
character reference. Here, the character U+02588
seems ok.
\newcommand{\blob}{\@print@u{X2588}}
█ Blob █
However, beware that not all browsers display all of Unicode…
Finally, users that experience poor rendering of the \rule command can also upgrade HEVEA, so as to benefit from the new implementation of this
command:
HEVEA failure may have many causes, including a bug. However, it may also stem from a wrong LATEX input. Thus, this section is to be read before reporting a bug…
In the following source, environments are not properly balanced:
\begin{flushright}
\begin{quote}
This is right-flushed quoted text.
\end{flushright}
\end{quote}
Such a source will make both LATEX and HEVEA choke. HEVEA issues the following error message that shows the LATEX environment that is not closed properly:
./trouble.tex:6: Environment nesting error: html: 'DIV' closes 'BLOCKQUOTE' ./trouble.tex:4: Latex environment 'quote' is pending Adios
Thus, when HEVEA crashes, it is a good idea to check that the input is correct by running LATEX on it.
Unfortunately, HEVEA may crash on input that does not affect LATEX. Such errors usually relate to environment or group nesting.
Consider for instance the following “optimized” version of a
quoteright environment:
\newenvironment{quoteright}{\quote\flushright}{\endquote}
\begin{quoteright}
This a right-flushed quotation
\end{quoteright}
The \quote and \flushright constructs
are intended to replace
\begin{quote} and \begin{flushright},
while \endquote stands for \end{quote}.
Note that the closing \endflushright
is omitted, since it does nothing.
LATEX accepts such an input and produces a right-flushed quotation.
However, HEVEA usually translates LATEX environments to html
block-level elements and it requires
those elements to be nested properly.
Here, \quote translates to <blockquote>,
\flushright translates to <div class="flushright"> and
\endquote translates to </blockquote>.
At that point, HEVEA refuses to generate obviously
non-correct html and it crashes:
Giving up command: \@close Giving up command: \endquote Giving up command: \endquoteright Giving up command: \end ./trouble.tex:7: Environment nesting error: html: 'BLOCKQUOTE' closes 'DIV' ./trouble.tex:5: Latex environment 'quoteright' is pending Adios
Also notice that the error message above includes a backtrace showing the call-chain of commands.
In this case, the solution is easy: environments must be opened and closed consistently. LATEX style being recommended, one should write:
\newenvironment{quoteright}
{\begin{quote}\begin{flushright}}
{\end{flushright}\end{quote}}
And we get:
This is a right-flushed quotation
Unclosed LATEX groups ({…) are another source
of nuisance to HEVEA.
Consider the following horreur.tex file:
\documentclass{article}
\begin{document}
In this sentence, a group is opened now {\em and never closed.
\end{document}
LATEX accepts this file, although it produces a warning:
# latex horreur.tex This is TeX, Version 3.14159 (Web2C 7.2) ... (\end occurred inside a group at level 1) Output written on horreur.dvi (1 page, 280 bytes).
By contrast, running HEVEA on horreur.tex yields a fatal error:
# hevea horreur.tex Giving up command: \@raise@enddocument Giving up command: \enddocument Giving up command: \end ./horreur.tex:4: Environment nesting error: Latex env error: 'document' closes '' ./horreur.tex:3: Latex environment '' is pending Adios
Thus, users should close opening braces where it belongs. Note that HEVEA error message “Latex environment ’env’ is pending” helps a lot in locating the brace that hurts.
If HEVEA crashes on LATEX source (not on TEX source), then you may have discovered a bug, or this manual is not as complete as it should. In any case, please report to Luc.Maranget@inria.fr.
To be useful, your bug report should include LATEX code that triggers the bug (the shorter, the better) and mention HEVEA version number.