Sergiu Dumitriu wrote:
> Hello Community,
>
> I have committed today the first implementation of a new XWiki feature:
> rendering mathematical equations into images. It is available as a
> standalone component, and as a syntax 2.0 macro.
>
>
>
> About the functionality.
>
> Equations are written in the TeX/LaTeX syntax, which is pretty simple,
> and seems to be the syntax of choice for mathematical equations in other
> wikis, too. The macro can distinguish between inline and block equations
> and render them accordingly. The output can be either PNG (the default
> one), GIF or JPEG. While PNG is definitely the best, I kept the other
> two in case somebody really wants to use ancient browsers that only
> understand GIF.
>
> Q: Should I leave just PNG as the output format?
>
I would like the PNG output as default, but also keep the GIF and JPEG
since there are some problems with PNG images on "ancient" IE6.
Oana
> Another feature is that the font size can be specified, in order to
> render larger or smaller equations. All the font size commands from
> LaTeX (from \tiny to \Huge) have an equivalent. I renamed them to a more
> easy to understand name (also because the configuration is case
> insensitive, so there's no difference between large and LARGE).
>
> By default images are generated so that the font looks relatively OK
> with the default XWiki skin on a 72 or 96 DPI display. They might look
> disproportionate with a different DPI, or with a different default font
> size.
>
> Q: Is the default DPI setting OK?
>
>
>
> Second, a few technical details:
>
> The standalone component is located in
> platform/core/xwiki-equation-rendering. I don't know if the name is the
> best (Vincent complained). On one hand, this describes better what the
> component does: it renders equations. On the other hand, it might cause
> confusion with the xwiki-rendering system.
>
> The component currently has three implementations:
>
> - a native one, which relies on the latex system being present. It gives
> the best results, from a graphical point of view, but requires the
> presence of external programs, and involves a slight overhead for
> starting new processes and for working with the disk. Currently it might
> have some security problems, I'll have to see if opening input and
> output files from TeX is a problem, or how to disable this. Any help
> from someone who know more about TeX?
>
> Q: Does anybody know of any security issues with running latex, dvips or
> convert? Especially with the \openin and \openout commands?
>
> - one which uses MathTran as a remote service through HTTP requests. It
> gives results as good as the native one, enhanced with some metadata,
> and depending on the configuration of the server, it might have better
> performance than the native one. The disadvantage is that it relies
> heavily on a remote server. Note that MathTran is free software, and can
> be installed locally on the same or a neighboring server. Oh, another
> minor problem is that it uses a variant of the TeX syntax, not LaTeX.
>
> - one which uses SnuggleTeX and JEuclid to transform LaTeX into MathML,
> and then render it into images. The results are not as eye-pleasing as
> those obtained from LaTeX, but it is a self-contained solution, with no
> external dependencies.
>
> SnuggleTeX uses the liberal 3-clause BSD license, JEuclid uses the
> Apache v2 license, so both can be deployed. Together, they weight in at
> 730k, so it's not a big impact. The other two implementations are not
> contaminated by the licenses of the underlying system, so there's no
> license conflict.
>
> Q: Should either one be removed?
>
> Q: Do you know of any other (better) alternative?
>
> By default the native renderer is used, since it gives the best results
> and doesn't depend on an external service. SnuggleTeX is configured as a
> backup (safe) renderer which kicks in when the default one isn't working
> (missing tex subsystem, or communication error with the remote server).
>
> Q: Is this setup OK as the default one? (native by default, snuggletex
> as fallback).
>
> The generated images are stored in a cache (using the cache component),
> for improved performance. This new cache might increase the memory
> requirements, but fortunately it is easy to configure.
>
> The rendering macro is located in
> platform/core/xwiki-rendering/xwiki-renderig-macros/xwiki-rendering-macro-equation,
>
> and the macro can be used with
>
> {{equation}}\sum_{i=0}^{\infty}{{/equation}}.
>
> Q: Is the macro name appropriate? Do you know of a better one?
>
>
>
> Future work:
> - make sure that there are no security issues with the Native backend
> - add support for MathML display for the clients that understand it
> - improve the alignment of images (especially for the Native backend),
> as right now they are a bit raised above the text baseline
>
>
> Many thanks to Guillaume Legris who provided the starting point for this
> component.
>
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