@c This is part of the preview-latex manual.
@c Copyright (C) 2002, 2003, 2004, 2005, 2006, 2009
@c               2017, 2021-2023 Free Software Foundation, Inc.
@c See file preview-latex.texi for copying conditions.
@ifset rawfile
@include macros.texi

@node Frequently Asked Questions, Introduction to FAQ, (dir), (dir)
@top Frequently Asked Questions about @previewlatex{}

@contents

@end ifset

@menu
* Introduction to FAQ::         
* Requirements::                
* Installation Trouble::        
* Customization::               
* Troubleshooting::               
* Other formats::               
@end menu

@comment we need at least one chapter, or the numbers disappear in the
@comment plain version of the FAQ.

@ifset rawfile
@node Introduction to FAQ, Requirements, Frequently Asked Questions, Frequently Asked Questions
@chapter Introduction
@raisesections
@end ifset
@ifclear rawfile
@node Introduction to FAQ, Requirements, Frequently Asked Questions, Frequently Asked Questions
@section Introduction
@end ifclear

@subsection How can I contribute to the FAQ?

Send an email with the subject:
@example
Preview FAQ
@end example
to @email{auctex-devel@@gnu.org}.

@node Requirements, Installation Trouble, Introduction to FAQ, Frequently Asked Questions
@section Requirements

@subsection Which version of Emacs is needed?

@previewlatex{} nominally requires @w{GNU Emacs} with a version of at
least 26.1.

@subsection Which versions of Ghostscript and @AUCTeX{} are needed?

We recommend to use GNU or AFPL Ghostscript with a version of at least
7.07.

@previewlatex{} has been distributed as part of @AUCTeX{} since version
11.80.  If your version of @AUCTeX{} is older than that, or if it does
not contain a working copy of @previewlatex{}, complain to wherever you
got it from.

@subsection I have trouble with the display format...
We recommend keeping the variable @code{preview-image-type} set to
@code{dvipng} (if you have it installed) or @code{png}.  This is the
default and can be set via the @samp{Preview/Customize} menu.

All other formats are known to have inconveniences, either in file size
or quality.  There are some Emacs versions around not supporting
@acronym{PNG}; the proper way to deal with that is to complain to your
Emacs provider.  Short of that, checking out @acronym{PNM} or
@acronym{JPEG} formats might be a good way to find out whether the lack
of @acronym{PNG} format support might be the only problem with your
Emacs.

@subsection For which OS does preview work?

It is known to work under the X Window System for Linux and for several
flavors of Unix: we have reports for HP and Solaris.

There are several development versions of Emacs around for native MacOS
Carbon, and @previewlatex{} is working with them, too.

With Windows, both native Emacs and Cygwin Emacs should work.  However, it
is known that @url{https://miktex.org/,MiK@TeX{}} sometimes doesn't work
with @previewlatex{}.  In that case, use
@url{https://tug.org/texlive/,@TeX{} Live} instead.

@node Installation Trouble, Customization, Requirements, Frequently Asked Questions
@section Installation Trouble

@subsection I just get @samp{LaTeX found no preview images}.

The reason for this is that @LaTeX{} found no preview images in the
document in question.

One reason might be that there are no previews to be seen.  If you have
not used @previewlatex{} before, you might not know its manner of
operation.  One sure-fire way to test if you just have a document where
no previews are to be found is to use the provided example document
@file{circ.tex} (you will have to copy it to some directory where you
have write permissions).  If the symptom persists, you have a problem,
and the problem is most likely a @LaTeX{} problem.  Here are possible
reasons:

@table @asis

@item Filename database not updated
Various @TeX{} distributions have their own ways of knowing where the
files are without actually searching directories.  The normal
@previewlatex{} installation should detect common tools for that purpose
and use them.  If this goes wrong, or if the files get installed into a
place where they are not looked for, the @LaTeX{} run will fail.

@item An incomplete manual installation
This should not happen if you followed installation instructions.
Unfortunately, people know better all the time.  If only
@file{preview.sty} gets installed without a set of supplementary files
also in the @file{latex} subdirectory, @previewlatex{} runs will not
generate any errors, but they will not produce any previews, either.

@item An outdated @file{preview} installation
The @file{preview.sty} package is useful for more than just
@previewlatex{}.  For example, it is part of @w{@TeX{} Live}.  So you have
to make sure that @previewlatex{} does not get to work with outdated
style and configuration files: some newer features will not work with
older @TeX{} style files, and really old files will make
@previewlatex{} fail completely.  There usual is a local @file{texmf}
tree, or even a user-specific tree that are searched before the default
tree.  Make sure that the first version of those files that gets found
is the correct one.
@end table

@node Customization, Troubleshooting, Installation Trouble, Frequently Asked Questions
@section Customization

@subsection How to include additional environments like @code{enumerate}

By default, @previewlatex{} is intended mainly for displaying
mathematical formulas, so environments like @code{enumerate} or
@code{tabular} (except where contained in a float) are not included.
You can include them however manually by adding the lines:

@example
\usepackage[displaymath,textmath,sections,graphics,floats]@{preview@}
\PreviewEnvironment@{enumerate@}
@end example
@noindent
in your document header, that is before 

@example
\begin@{document@}
@end example
@noindent
In general, @file{preview} should be loaded as the last thing before
the start of document.

Be aware that

@example
\PreviewEnvironment@{...@}
@end example
@noindent
does not accept a comma separated
list!  Also note that by putting more and more 

@example
\PreviewEnvironment@{...@}
@end example
@noindent
in your document, it will look more and more like a @acronym{DVI} file
preview when running @previewlatex{}.  Since each preview is treated as
one large monolithic block by Emacs, one should really restrict
previews to those elements where the improvement in visual
representation more than makes up for the decreased editability.

@subsection What if I don't want to change the document?
The easiest way is to generate a configuration file in the current
directory.  You can basically either create @file{prdefault.cfg} which
is used for any use of the @samp{preview} package, or you can use
@file{prauctex.cfg} which only applies to the use from with Emacs.  Let
us assume you use the latter.  In that case you should write something like

@example
\InputIfFileExists@{preview/prauctex.cfg@}@{@}@{@}
\PreviewEnvironment@{enumerate@}
@end example
@noindent
in it.  The first line inputs the system-wide default configuration
(the file name should match that, but not your own
@file{prauctex.cfg}), then you add your own stuff.

@subsection Suddenly I get gazillions of ridiculous pages?!?

When @previewlatex{} works on extracting its stuff, it typesets each
single preview on a page of its own.  This only happens when actual
previews get generated.  Now if you want to configure @previewlatex{} in
your document, you need to add your own @code{\usepackage} call to
@samp{preview} so that it will be able to interpret its various
definition commands.  It is an error to add the @code{active} option to
this invocation: you don't want the package to be active unless
@previewlatex{} itself enables the previewing operation (which it will).

@subsection Does @previewlatex{} work with presentation classes?

@previewlatex{} should work with most presentation classes.  However,
since those classes often have macros or pseudo environments
encompassing a complete slide, you will need to use the customization
facilities of @file{preview.sty} to tell it how to resolve this, whether
you want no previews, previews of whole slides or previews of inner
material.

@node Troubleshooting, Other formats, Customization, Frequently Asked Questions
@section Troubleshooting

@subsection Preview causes all sort of strange error messages

When running @previewlatex{} and taking a look at either log file or
terminal output, lots of messages like

@example
! Preview: Snippet 3 started.
<-><->
      
l.52 \item Sie lassen sich als Funktion $
                                         y = f(x)$ darstellen.
! Preview: Snippet 3 ended.(491520+163840x2494310).
<-><->
      
l.52 \item Sie lassen sich als Funktion $y = f(x)$
                                                   darstellen.
@end example
@noindent
appear (previous versions generated messages looking even more like
errors).  Those are not real errors (as will be noted in the log
file).  Or rather, while they @strong{are} really @TeX{} error
messages, they are intentional.  This currently is the only reliable
way to pass the information from the @LaTeX{} run of @previewlatex{} to
its Emacs part about where the previews originated in the source text.
Since they are actual errors, you will also get @AUCTeX{} to state
@example
Preview-LaTeX exited as expected with code 1 at Wed Sep  4 17:03:30
@end example
@noindent
after the @LaTeX{} run in the run buffer.  This merely indicates that
errors were present, and errors will always be present when
@previewlatex{} is operating.  There might be also real errors, so in
case of doubt, look for them explicitly in either run buffer or the
resulting @file{.log} file.

@subsection Why do my @acronym{DVI} and @acronym{PDF} output files vanish?

In order to produce the preview images @previewlatex{} runs @LaTeX{} on
the master or region file.  The resulting @acronym{DVI} or @acronym{PDF}
file can happen to have the same name as the output file of a regular
@LaTeX{} run.  So the regular output file gets overwritten and is
subsequently deleted by @previewlatex{}.

@subsection My output file suddenly only contains preview images?!

As mentioned in the previews @acronym{FAQ} entry, @previewlatex{} might
use the file name of the original output file for the creation of
preview images.  If the original output file is being displayed with a
viewer when this happens, you might see strange effects depending on the
viewer, e.g.@: a message about the file being corrupted or the display of
all the preview images instead of your typeset document.  (Also
@pxref{Customization}.)


@node Other formats, , Troubleshooting, Frequently Asked Questions
@section @previewlatex{} when not using @LaTeX{}

@subsection Does @previewlatex{} work with  PDF@LaTeX{}?

Yes, as long as you use @AUCTeX{}'s own PDF@LaTeX{} mode and have not
messed with @samp{TeX-command-list}.

@subsection Does @previewlatex{} work with @samp{elatex}?

No problem here.  If you configure your @AUCTeX{} to use @samp{elatex},
or simply have @samp{latex} point to @samp{elatex}, this will work fine.
Modern @TeX{} distributions use e@TeX{} for @LaTeX{}, anyway.

@subsection Does @previewlatex{} work with @ConTeXt{}?

In short, no.  The @samp{preview} package is
@LaTeX{}-dependent.  Adding support for other formats requires
volunteers.

@subsection Does @previewlatex{} work with plain @TeX{}?

Again, no.  Restructuring the @samp{preview} package for @samp{plain}
operation would be required.  Volunteers welcome.

In some cases you might get around by making a wrapper pseudo-Master
file looking like the following:

@example
\documentclass@{article@}
\usepackage@{plain@}
\begin@{document@}
\begin@{plain@}
\input myplainfile
\end@{plain@}
\end@{document@}
@end example