Compatibility with other formats

1.Compatibility with other formats

TeXmacs documents can be saved without loss of information in three formats: the native TeXmacs format (file extension .tm), Xml (.tmml) and as a Scheme expression (.stm). TeXmacs also provides bi-directional converters for LaTeX, Html and MathML.

In addition to the above textual formats,TeXmacs documents can be exported in a wysiwyg (what-you-see-is-what-you-get) way to either Postscript or Pdf, which are used as the primary formats for printing documents. TeXmacs can also export document fragments to several vector or raster image formats.

TeXmacs documents can be converted to other formats using the different items in the File→Export menu. Similarly, the File→Import menu contains all formats which can be imported into TeXmacs. Besides exporting or importing entire documents, it is also possible to copy and paste document fragments in various formats using Edit→Copy to and Edit→Paste from. The default formats for copy and pasting can be specified in Tools→Miscellaneous→Export selections as and Tools→Miscellaneous→Import selections as.

1.Converters for LaTeX

1.1.Introduction

TeXmacs offers high quality converters to and from LaTeX. For simple documents, it suffices to use File→Export→LaTeX resp. File→Import→LaTeX. However, in order to take fully advantage out of the converts, it is necessary to understand some particularities of LaTeX.

First of all, it should be emphasized that TeX/LaTeX is not a data format. Indeed, TeX is a programming language for which no real standardization process has taken place: valid TeX programs are defined as those which are recognized by the TeX program. In particular, there exists no formal specification of the language and it is not even clear what should be considered to be a valid TeX document. As a consequence of this, a converter from LaTeX to TeXmacs can only be designed to be 100% reliable for a (substantial) subset of the TeX/LaTeX language.

A second important point is that publishers usually impose additional constraints on the kind of LaTeX documents which they accept for submissions. For instance, certain journals provide additional macros for title information, theorems, specific layout features, etc. Other journals forbid for the definition of new macros in the preamble. Since TeXmacs is not a TeX/LaTeX front-end, it is difficult for us to write specific code for each possible journal. Nevertheless, some general principles do hold, and we will describe below how to customize the converter so as to make the conversion process as simple and automatic as possible.

Another point which should be stressed is that TeXmacs aims to provide a strict superset of TeX/LaTeX. This not completely the case yet, but it is already true that many features in TeXmacs admit no direct analogues in TeX/LaTeX or one of its packages. This is for instance the case for computer algebra sessions, folding, actions, graphics and presentations, but also for certain typesetting constructs, like vertical alignment and background filling in tables. When using such additional features, you should be prepared that they will not be converted correctly to LaTeX.

Finally, when preparing journal papers with TeXmacs, please consider submitting them in TeXmacs format. The editors of the journal will probably force you to convert your paper to LaTeX, but repeated submissions in TeXmacs format will put pressure upon them to accept this new format.

1.2.Conversion from TeXmacs to LaTeX

A TeXmacs document can be exported to LaTeX using File→Export→LaTeX. In the case of certain journal styles like svjour or elsart, the user should also make sure that the appropriate style files can be found by LaTeX, when compiling the result of the conversion. Please consult your LaTeX documentation for how to do this; one solution which usually works is to put the style file in the same directory as your file.

Notice that the exportation of a TeXmacs document with images may cause the creation of additional image files. If your destination file is called name.tex, these files are named name-1.eps, name-2.eps, etc. and they are stored in the same directory. In particular, all pictures drawn with the editor and all images which are not already in Postscript format will be converted to encapsulated Postscript files.

In order to ensure that the generated LaTeX document compiles, style files and packages or macros with no LaTeX equivalents are either ignored or replaced by a reasonable substitute. The precise behaviour of the converter may be customized using several user preferences in the Edit→Preferences→Converters→LaTeX→TeXmacs–>LaTeX menu:

Replace unrecognized styles

This option (which is set by default) tells TeXmacs to replace style files with no LaTeX equivalents by the article style. Furthermore, all additional style packages are ignored.

In case you know how to write your own style files, you might wish to create TeXmacs equivalents of those journal styles which you use often. Similarly, you might wish to create a style package with your own macros together with its LaTeX counterpart. In both cases, you might want to disable the style replacement option.

Replace unrecognized macros

By default, all TeXmacs macros are expanded until they admit direct LaTeX counterparts. Primitives with no LaTeX counterparts (like graphics or trees) are ignored. Moreover, in order to convert certain frequently used macros like theorem or strong, TeXmacs may put additional definitions in the preamble.

In some cases, the user may wish to keep unrecognized macros in their unexpanded form. For instance, this may be convenient if you want to import the generated document back into TeXmacs. Another typical situation is when you defined additional macros in a style package. In these cases, you may disable to macro replacement option. Of course, any missing macro definitions may result in LaTeX errors during the compilation.

Expand user-defined macros

When your document or its preamble contains macro definitions, then TeXmacs will convert these macro definitions into LaTeX macro definitions and keep all macro applications in their unexpanded forms. This allows you to preserve as much structure of your document as possible. When enabling the Expand user-defined macros option, all macro definitions in your document will be ignored and all macro applications will be expanded.

Export bibliographies as links

In order to produce stand-alone LaTeX files whenever possible, it is assumed that you generate your bibliographies from within TeXmacs. When exporting to LaTeX, the generated bibliography will be directly included into your LaTeX file. In some cases however, the user might wish to regenerate the bibliography from the LaTeX and the bibliography files, using BibTeX. In this case, you need to enable the Export bibliographies as links option.

Allow for macro definitions in preamble

Certain TeXmacs macros like strong have no direct LaTeX analogues. For a certain number of frequently used macros, TeXmacs automatically generates macro definitions in the preamble of the LaTeX target file. This allows you to preserve as much structure as possible of your document, which is for instance useful if you import the document back into TeXmacs.

However, certain journals instruct authors to refrain from the definition of additional macros in the preamble. When disallowing for macro definitions in preambles, TeXmacs will automatically expand all corresponding macro applications.

Dump TeXmacs document into LaTeX code

When this option is set, a copy of the TeXmacs document is appended to the LaTeX export in a lossless kind. This allows to re-import the document with as few conversion artifacts as possible .

Character encoding

This option defines the behavior of the converter with respect to character encoding. There are three possible choices:

Utf-8 with inputenc

This will generate utf-8 document with the package inputenc loaded. If for any reason you don't want to rely on inputenc, you should consider other options.

Cork with catcodes

Keeps accented characters “as is”. This can be achieved by allowing TeXmacs to put additional catcode definitions into your preamble. This provides a good trade-off between readability (accented characters are kept in an 8 bit charset) and simplicity (you don't need the inputenc package).

Ascii

This will generate pure ascii characters, using plain TeX sequences to compose non-ascii symbols.

Sometimes, the converter does not produce a satisfactory LaTeX file even after some tinkering with the above preferences. The most frequent problem concerns bad line breaks. Occasionally, certain document fragments are also better converted by hand. In order to minimize the need for corrections in the generated LaTeX file (which would be lost when re-exporting the TeXmacs source file after some modifications), TeXmacs provides a mechanism to specify manual conversions to LaTeX in the TeXmacs source file: using Format→Specific→Texmacs and Format→Specific→Latex, you may force certain document fragments to appear only in the source file or the LaTeX target.

For instance, assume that the word “blauwbilgorgel” is hyphenated correctly in the TeXmacs source, but not in the LaTeX conversion. Then you may proceed as follows:

  1. Select “blauwbilgorgel”.

  2. Click on Format→Specific→Texmacs to make the text “blauwbilgorgel” TeXmacs-specific.

  3. Click on Format→Specific→Latex.

  4. Type the latex code blauw\-bil\-gor\-gel with the correct hyphenation.

  5. Press ↩ to activate the LaTeX-specific text.

In a similar fashion, you may insert LaTeX-specific line breaks, page breaks, vertical space, style parameter modifications, etc. You may also force arbitrary content to be exported as an image using Format→Specific→Image.

1.3.Conversion from LaTeX to TeXmacs

In order to import a LaTeX document into TeXmacs, you may use File→Import→Latex. Don't forget to save the file under a new name with the .tm extension, if you want to edit it.

As explained in the introduction, the conversion of LaTeX documents into TeXmacs is more problematic than conversions the other way around. As long as you restrict yourself to using the most common LaTeX commands, the conversion process should not give rise to any major difficulties. However, as soon as your documents contain “weird TeX primitives” (think about \csname…), then the converter may get confused. We also notice that TeXmacs is currently unable to convert LaTeX style files and no plans exist to enhance the converter in this direction.

There are two major reasons for LaTeX documents to get imported in an inappropriate way, and which can easily be corrected by the user. First of all, the parser may get confused because of some exotic syntactic construct. This typically happens in presence of catcodes or uncommon styles of macro definitions. Sometimes, the parser may also be mistaken about the current mode, in which case text gets parsed as a mathematical formula or vice versa. In both cases, the imported document usually becomes “weird” at a certain point. In order to solve the problem, we suggest you to identify the corresponding point in the LaTeX source file and to make an appropriate change which avoids the parser of getting confused.

A second common error is that certain LaTeX macros are not recognized by the converter, in which case they will appear in red. This typically happens if you use one of the hundreds additional LaTeX packages or if you defined some additional macros in another document. In the case when the troublesome macro occurs only a few times, then we suggest you to manually expand the macro in the LaTeX source file before importation. Otherwise, you may try to put the definitions of the missing macros in the preamble of the LaTeX document. Alternatively, you may create a small style package with TeXmacs counterparts for the macros which were not recognized.

The behaviour of the converter may be customized using several user preferences in the Edit→Preferences→Converters→LaTeX→LaTeX–>TeXmacs menu:

Import sophisticated objects as pictures

This option allows TeXmacs to compile the LaTeX document in a temporary directory, with the package preview installed, in order to import some macros or environments as pictures. The source of each picture is also imported in order to be re-exported if needed. Currently, the following macros are imported as pictures when this option is set: \xymatrix, pspicture, tikzpicture.

Keep track of the LaTeX source code

One should be interested in this option in order to use TeXmacs to make small or isolated modifications into a LaTeX file (e.g. for a proofreading). This option allows TeXmacs to import the LaTeX document with added markup in order to track the original sources of the document paragraphs. These tracked sources are, as far as possible, re-used during a LaTeX re-export.

Ensure transparent tracking

This option, subject to the above, verify that the added markup does not change the result of the conversion. It has been added for testing purpose and may strongly increase the time of the import process (at least it double it).

1.4.Limitations of the current LaTeX converters

Limitations of the TeXmacs to LaTeX converter

Some of the TeXmacs primitives have no analogues in LaTeX. When converting such primitives from TeXmacs into LaTeX, they will usually be either ignored or replaced by an approximative translation. A (probably incomplete) list of TeXmacs features with no LaTeX counterparts is as follows:

In addition, several issues are only partially implemented:

Of course, there are also differences between the typesetting algorithms used by TeXmacs and TeX/LaTeX, so the TeXmacs to LaTeX is not intended to be wysiwyg.

Limitations of the LaTeX to TeXmacs converter

As explained in the introduction, the conversion of LaTeX documents into TeXmacs is more problematic than conversions the other way around. Only a subset of LaTeX can be converted to TeXmacs in a fully reliable way. This subset comprises virtually all common constructs, including macro definitions and the additional macros uses by the TeXmacs to LaTeX converter. However, the converter has no knowledge about style parameters. In particular, it cannot be used for the conversion of LaTeX style files.

2.Converters for Html and MathML

Html generation

TeXmacs supports reasonably good converters to Html and MathML. A document can be exported to Html using File→Export→Html. TeXmacs makes moderate use of Css in order to improve the presentation of the generated Html.

By default, TeXmacs does its best in order to render formulas using existing Html/Css primitives. When selecting Edit→Preferences→Converters→TeXmacs->Html→Use MathML, all formulas will be exported as MathML. Notice that this requires you to save the generated documents using the .xhtml extension.

Similarly, the user may force TeXmacs to export all mathematical formulas as images using Edit→Preferences→Converters→TeXmacs->Html→Export formulas as images. If your destination file is called name.html, then the images are stored in the same directory in files name-1.png, name-2.png and so on. Even when formulas are not exported as images, notice that all graphics drawn using TeXmacs are exported in this way. In particular, the exportation of a TeXmacs file with pictures may give rise to the creation of additional image files. You may also force arbitrary content to be exported as an image using Format→Specific→Image.

TeXmacs also provides a facility for the creation of entire websites. For this, you just have to regroup the files for your website into a single directory. Using Tools→Web→Create website you may now convert all TeXmacs files in this directory to Html files in a new directory. The conversion procedure recursively traverses all subdirectories and all non-TeXmacs files are simply copied.

Customized Html generation

The following TeXmacs environment variables can be used to customize the Html generation:

html-title

The title of your exported document.

html-css

A cascaded style sheet for your exported document.

html-head-javascript-src

An external Javascript file to be executed before the body.

html-head-javascript

A Javascript script to be executed before the body.

html-head-favicon

A “favicon” for your webpage.

You may also use the following macros:

<html-class|class|body>

<html-div-class|class|body>

Associate a CSS class to the content body, optionally inside a separate div tag.

<html-style|style|body>

<html-div-style|class|body>

Associate a CSS style to the content body, optionally inside a separate div tag.

<html-javascript-src|src>

Execute a Javascript script from the file src.

<html-javascript|code>

Execute the Javascript script code.

In addition, given a macro my-tag, you may customize the rendering of the tag when exporting to Html by defining a macro tmhtml-my-tag with the same number of arguments. For instance, by putting the declaration

<assign|tmhtml-strong|<macro|body|<with|color|red|font-series|bold|body>>>

inside your style file, all strong text will be exported to Html using a bold red font.

Html importation

TeXmacs also contains an input converter for Html/Mathml. Most of HTML 2.0 and parts of HTML 3.0 are currently supported, and standalone or embedded MathML are reasonably well supported. Entire Html and/or Mathml documents can be imported with File→Import→Html.

When importing HTML documents, files whose names start with http: or ftp: will be downloaded from the web using wget. If you compiled TeXmacs yourself, then you can download wget from 

  ftp://ftp.gnu.org/pub/gnu/wget/

In the binary distributions, we have included wget.

With most web browsers, interesting fragments of a web page can easily be imported into TeXmacs without saving the page to a file: Using the browser's "inspect" contextual menu it is easy to spot the desired fragment in the xml tree, copy it, and then paste it into TeXmacs using Edit→Paste from→Html. When copying Mathml formulas, the entire <math> element should be selected. In some browsers, the "inspect" functionaly needs to be activated in the preferences.

3.Export or Copy selection to graphics

TeXmacs can export the active selection to many graphical formats, either as files (File→Export→Export selection as image) or through the system clipboard (Edit→Copy to…→Image), for pasting into other applications.

Specifying graphics format

In case of file export, the desired graphical format is determined by the file extension you choose (for instance: pdf, eps, jpg…).

For the clipboard mechanism, you need to set in advance the desired format in Edit→Preferences→Converters→TeXmacs -> image→Clipboard image format. This menu offers a choice between png, jpeg, tif, eps, svg and pdf formats, provided a suitable converter is available (see below).

For both the clipboard mechanism and file export, the resolution of bitmap formats is set by the preference Edit→Preferences→Converters→TeXmacs -> image→Bitmap export resolution (dpi).

When Svg format is selected, TeXmacs annotates the image with the source information for the image's content. When inserted in Inkscape or Libreoffice documents, such images can easily be re-edited using the Equation editor plugin.

Required external converters

TeXmacs can natively produce PDF vector images.

In order to produce the various other graphic formats, TeXmacs relies on various libraries or external programs, notably :

Several of these converters are accessed through Scheme converter procedures (defined in $TEXMACS_PATH/progs/convert/images/init-images.scm). Additional converters can be similarly defined, when needed.

When attempting a conversion, TeXmacs looks for suitable external programs in the system PATH, and if none is found, it displays an error message. On Linux if these external programs are not already installed, they are easy to install from your distribution's package manager. On MacOS, pdf2svg and ImageMagick (as well as Inkscape) are available from MacPorts. On Windows, pdftocairo can be obtained from here, or you can get it bundled with TeXmacs.

4.Adding new data formats and converters

Using the Guile/Scheme extension language, it is possible to add new data formats and converters to TeXmacs in a modular way. Usually, the additional formats and converters are declared in your personal ~/.TeXmacs/progs/my-init-texmacs.scm or a dedicated plug-in. Some examples may be found in the directory $TEXMACS_PATH/progs/convert, like init-html.scm.

Declaring new formats

A new format is declared using the command 

(define-format format
  (:name format-name)
  options)

Here format is a symbol which stands for the format and format-name a string which can be used in menus. In fact, a data format usually comes in several variants: a format format-file for files, a format format-document for entire documents, a format format-snippet for snippets, like selections, and format-object for the preferred internal scheme representation for doing conversions (i.e. the parsed variant of the format). Converters from format-file to format-document and vice versa are provided automatically.

The user may specify additional options for the automatic recognition of formats by their file suffix and contents. The possible suffixes for a format, with the default one listed first, may be specified using 

(:suffix default-suffix other-suffix-1 … other-suffix-n)

A (heuristic) routine for recognizing whether a given document matches the format can be specified using either one of the following: 

(:recognize predicate)
(:must-recognize predicate)

In the first case, suffix recognition takes precedence over document recognition and in the second case, the heuristic recognition is entirely determined by the document recognition predicate.

A format can be removed from menus using the following: 

(:hidden)

Declaring new converters

New converters are declared using 

(converter from to
  options)

The actual converter is specified using either one of the following options: 

(:function converter)
(:function-with-options converter-with-options)
(:shell prog prog-pre-args from progs-infix-args to prog-post-args)

In the first case, the converter is a routine which takes an object of the from format and returns a routine of the to format. In the second case, the converter takes an additional association list as its second argument with options for the converter. In the last case, a shell command is specified in order to convert between two file formats. The converter is activated only then, when prog is indeed found in the path. Also, auxiliary files may be created and destroyed automatically.

TeXmacs automatically computes the transitive closure of all converters using a shortest path algorithm. In other words, if you have a converter from to and a converter from to , then you will automatically have a converter from to . A “distance between two formats via a given converter” may be specified using 

(:penalty floating-point-distance)

Further options for converters are: 

(:require cond)
(:option option default-value)

The first option specifies a condition which must be satisfied for this converter to be used. This option should be specified as the first or second option and always after the :penalty option. The :option option specifies an option for the converter with its default value. This option automatically become a user preference and it will be passed to all converters with options.

© 1999–2003 by Joris van der Hoeven