scarfboy / phplatex

Renders LaTeX into images by calling LaTeX itself from PHP.

See also http://phplatex.scarfboy.com/ and example use on http://latex.knobs-dials.com/

Requirements

• PHP (>=4.3.0, as it uses sha1())
• imagemagick (for convert)
• ghostscript, and TeX Live or teTeX (for latex and dvips)
• TeX packages: color, amsmath, amsfonts, amssymb, and the extarticle document class. Most are standard. You may need non-ancient versions of some.

Installation

• Put phplatex.php somewhere from which you can include it

• Have the requirements installed, and check they are where phplatex.php expects them to be (/usr/bin), or edit it as needed

• Create subdirecties 'tmp' and 'images' in each directory you will be calling the script from, with write permissions for the effective user, for example mkdir tmp images; chown apache:apache tmp images

• If you get "convert: not authorized" this is likely due to an 2018 ImageMagick update that disable PDF/PS conversions by default, apparently for security, and you need to tweak its policy.xml to re-enable it.

Use

• Include the code: include('path/to/phplatex.php');
• To render some TeX: echo texify("TeX");

Due to PHP parsing, you will need to double all your backslahes, and escape your dollar signs, like \$\\sqrt[3]{2}\$. PHP offers no alternatives to this. Yes, you can selectively get away with not doing it (e.g. if dollar signs aren't followed by text so can't name a variable, like in this example), but it's probably less confusing if you are consistent with this.

For advanced/creadive (ab)use, the function definition is actually:

• texify(texstring, dpi, r,g,b, br,bg,bb, extraprelude); So, for example:
• print texify('Times in TeX', 160, 0.2,0.0,0.0, 1.0,1.0,1.0, '\\usepackage{pslatex}');

Maintenance

• Remove leftovers in the tmp directory at will
• You can empty the img directory to remove unused images (still-used one will be regenerated)

Features

• Will cache generated images, based on a hash of the document string. Meaning leaving the texify() calls on your page is cheap as successive runs will not run LaTeX at all.
• CSS lowering to compensate for descenders, so TeX text used inline in HTML should look halfway decent.
• Tweakable size. The default (90) is approximately the same size as HTML text. Capped at 300 for memory reasons.
• Allows inclusion of extra TeX packages, via extraprelude.
• Allows coloring of page background and default text color (default is black on white, 0.,0.,0. on 1.,1.,1.)
• Generates PNGs with transparency (note: consider antialiasing to that background)
• Relies on image trimming (instead of e.g. trusting dvips' bounding box)

Caveats

• Won't work on safe-mode PHP, which is common enough on cheap oldschool shared hosting (though it was removed in PHP5.3)
• I cannot guarantee this is safe from a security standpoint -- in theory it's mostly fine, but TeX is a full-fledged language. There is no input filter on what TeX is allowed, because that wouldn't even work. Know what this means security-wise - USE AT YOUR OWN RISK. In particular, the processes can do everything the effective user (of the apache process) can.
• Fails on TeX that is more than one page. Should not bother you for most things that are inline. Sometimes-workaround: use \small or \footnotesize and a larger DPI setting. TODO: think about better fixes.
• Image conversion can fail for very large images (hence the DPI cap)
• the relative tmp and images directories are a little awkward. But the alternative (having a configurable path, to e.g. share the cache) would involve more thinking of how that is exposed URL-wise

Arguables

• Uses latex's \nonstopmode, meaning TeX will best-guess-fix errors it can, rather than complain and stop. You can get away with some bad TeX and never know it
• On low resolutions, the (default) Computer Modern fonts don't render as nicely as, say, pslatex fonts (Times, Helvatica, Courier), due to thickness and antialiasing. Change fontset to taste.
• Image generation can take a second per image. You may hit your configured PHP max_execution_time limit a few times before a page with a lot of TeX images is all built and cached.
• I'm no particular fan of PHP, but this does make it pretty portable.

When to use something else: Just math with fewer requirements

This project was made to get a real TeX environment, to compile arbitrary TeX.

If you care only about formulae on webpages, and don't care about the precise behaviour of compiled TeX, then you can get 95% of the way there without this heavy depdendency and its security issues, by considering options such as:

• mathJax

  • takes LaTeX, MathML, and AsciiMath
  • produces HTML+CSS (and experimental SVG), or MathML where browser supports
  • code is pure JS

• latex.js

  • takes TeX
  • produces HTML and SVG
  • code is pure JS
  • seems to do a little more than just math

You may also care about live editing, like latex.js's, mathurl's, and others

Less interesting:

• embedded MathML / element

  • has been standardized for a while, but only a few browsers allow direct use in webpages
  • useful as one rendering option among others

• ASCIIMathML.js

  • takes AsciiMath, makes MathML
  • useful as a component, integrated into mathJax

• jsMath

  • takes LaTeX, MathML (XML based), and asciimath
  • produces HTML+CSS
  • code is pure JS
  • succeeded by mathJax

• components such iTeX for TeX to MathML, svgmath for MathML to SVG

  • useful for projects but not end users directly