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# STIX and Asana fonts
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### Overview
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For general description of our font support see
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[A MathJax Q&A -- fonts](https://github.com/mathjax/MathJax/wiki/Drafts).
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Currently, we support MathJax fonts (local and Web versions) as well as STIX
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fonts (local versions). This document suggests a way to support STIX Web fonts
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and Asana fonts. The proposed method
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could also be applied in the future to support
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other free mathematical fonts as Web fonts (e.g Neo Euler or LM-Math).
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The basic issues to support new fonts are the following:
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* The font files are large. In order to make them available to MathJax in
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a reasonable amount of time, we need to split them into smaller font files.
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This is automatically done in [MathJax-dev/fonts/OTF](https://github.com/fred-wang/MathJax-dev/tree/master/fonts/OTF).
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This is a potential difficulty for STIX and Asana fonts since the
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local fonts and Web fonts will be different.
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This also means that browsers may not be able to use the modified
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fonts (see below).
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* In order to detect when the font files are downloaded, we need to add
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three glyphs to the fonts.
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This is also automatically done in [MathJax-dev/fonts/OTF](https://github.com/fred-wang/MathJax-dev/tree/master/fonts/OTF).
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The code points we use are U+EFFE, U+EFFD, U+EFFF and these
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are free in the Asana and STIX font files.
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* Glyph info are not exposed to Javascript. Hence this must be extracted
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and integrated into Javascript files so that they can be handled by MathJax.
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This is automatically done in [MathJax-dev/fonts/AFM](https://github.com/fred-wang/MathJax-dev/tree/master/fonts/AFM) and [MathJax-dev/fonts/SVG](https://github.com/fred-wang/MathJax-dev/tree/master/fonts/SVG) for the HTML+CSS and SVG
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output respectively.
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* Contructions of stretchy operators
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are described in the Open Type Math table, which is
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not exposed to Javascript. Currently, we write tables "by hand"
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in the [fontdata.js files](https://github.com/mathjax/MathJax/blob/master/unpacked/jax/output/HTML-CSS/fonts/). We already support STIX fonts and tables for
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Asana are available in Gecko source code. Moreover the fonts have an OpenType
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Math table that FontForge can read. So the new tables could be obtained
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more or less automatically.
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* Only Unicode code points are accessible from Javascript.
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This is the case for STIX 1.1 "General" (the legacy version)
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and Asana fonts, so we can in theory
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support local and Web versions. For other mathematical fonts like
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STIX 1.1 "Word" (the new version with less files and OpenType Math table),
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Cambria Math, Neo Euler, LM-Math, Lucida fonts ; we could only support
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modified versions with some glyphs moved to Unicode code points.
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* In certain cases (old browsers, security restriction...), Web fonts are not
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available so MathJax has to use images fonts instead. For the
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MathJax TeX fonts, the images are created in
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[MathJax-dev/fonts/IMG](https://github.com/fred-wang/MathJax-dev/tree/master/fonts/IMG). Currently, this is mostly a fallback used in very rare cases and
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has several drawbacks (very large files, style not applied, bad quality).
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Hence, it makes sense to ignore image fonts for Asana or STIX and just
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keep the MathJax TeX versions.
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* Because of some of the previous points, the fonts must be available under a
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flexible license. This is the case for STIX and Asana fonts and we got
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an agreement with the STIX consortium to modify the fonts and still keep
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the font name. This is an issue for proprietary fonts mentioned
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above, like Cambria Math or Lucida.
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### Strategy for Splitting Fonts
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The STIX and Asana fonts are available in the following format:
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* Asana Math: one file with all the glyphs. Contains an OpenType Math table.
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* STIX 1.1 "Word": one file for each style (Regular, Italic, Bold, BoldItalic)
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and one file with an OpenType Math Table (and so glyphs used for stretchy
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operators).
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* STIX 1.1 "General": the old sets with STIXGeneral, various files for
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integral symbols, a STIXNonUnicode file for some non unicode glyphs and
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various files for size variants. Some of these files have variants for each
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style (Regular, Italic, Bold, BoldItalic).
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As a comparison, MathJax fonts is essentially split into main files with
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most of the glyphs, other files for different variants of letters
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(fraktur, monotype...) and other files for stretchy operators. Hence it makes
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sense to use the same categories for Asana and STIX fonts. Some points to
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take into account:
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* Do we want to generate our Web fonts from the STIX "General" or the
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STIX "Word" version? The main advantage
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of the former is that it is already supported by MathJax and we could
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think that it would not be too difficult to adapt the code to a Web fonts
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version, as we did for STIX beta and 1.0. However, the
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set of fonts will not be the same and it could be cleaner to
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use a separate directory for the font data.
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Also, it will be more convenient to
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create subcategories from the 5 STIX "Word" files than to work from the
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messy STIX "General" set of files. Finally we could imagine that in the
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future, STIX "General" could become obsolete or deprecated and so it's
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not a bad idea to directly base our Web fonts on STIX "Word".
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* Do we want to allow the Native MathML output to use the new Web fonts?
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This is really just a problem for stretchy operators that use non-unicode
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constructions. Currently, only Gecko supports STIX/Asana
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via private tables
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and this strongly depends on the font name. This is problematic if we
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change the set of fonts, as Gecko will just not be able to recognize them.
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In [the short term](https://github.com/fred-wang/MathJax/tree/issue301),
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browsers could just use
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the MathJax fonts since the local and Web versions are the same.
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We could also put some copies of the (non-modified) STIX and Asana fonts
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in a separate directory that will be used by the Native MathML output only.
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Note that download time is not a problem for the Native MathML support and
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we can probably just focus on the most recent woff format.
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In the long term, they are likely to support the Open Type tables and we
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could maybe copy this table into our Web fonts. That's another reason why
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it is best to work with STIX "Word".
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* STIX and Asana have much more characters than our MathJax TeX fonts. Of
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course that's one of the reason why we want to support them (besides
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providing alternative styles). So we need more categories than those
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given in MathJax. The most obvious option is classification by font style
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(bold, italic, bold-italic) and to follow existing Unicode
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subcategories (for example those given in
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[chapter 7 of the MathML 3 recommendation](http://www.w3.org/Math/TR/chapter7.html#chars.entities)). Finally, we can provide a file with all the remaining
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characters, that are less often used in mathematics.
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In the future, we could consider a "mixed mode" where MathJax TeX fonts
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are used by default with other STIX/Asana Web fonts covering the missing
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characters.
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### Proposal
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The file hierarchy could look like this:
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* fonts/
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* TeX/: the current directory, with eot, otf, svg, img and woff fonts.
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* STIX/, Asana/: Same, with our modified versions and without the png images.
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* woff/: a directory with the original versions of STIX and Asana files
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(converted into woff) to be used by the Native MathML output.
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* unpacked/
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* output/HTML-CSS/fonts/
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* TeX, STIX: current directories for MathJax fonts and local STIX fonts.
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* Asana: font data for local Asana fonts.
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* STIXWeb, AsanaWeb: font data for our (modified) STIX and Asana Web
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fonts.
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* output/SVG/fonts/
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* Idem mutatis mutandis.
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The STIX and Asana fonts will be split into the following
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categories. Other subdivisions will be used for Regular, Bold, Italic
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Bold-italic. We will preserve the Unicode code points, except for
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STIXMath-Regular where the glyphs must be moved to one of the PUA.
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* Main or Math?
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* Size1
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* Size2
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* Size3
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* Size4
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* Caligraphic (regular, bold, italic, bold-italic)
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* double-struck
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* script
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* fraktur
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* sans-serif
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* monospace
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* isoamsa Added Math Symbols: Arrow Relations
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* isoamsb Added Math Symbols: Binary Operators
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* isoamsc Added Math Symbols: Delimiters
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* isoamsn Added Math Symbols: Negated Relations
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* isoamso Added Math Symbols: Ordinary
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* isoamsr Added Math Symbols: Relations
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* ...
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* Other |
