Making symbol fonts available to Mozilla builds using fontconfig

Ian Hutchinson

12 Jan 2005

1 Quick Fix Summary¹

Download the file symfontconfig.tar.gz to somewhere convenient.

Unpack it by tar xzf symfontconfig.tar.gz

Install it by cd symfontconfig; ./install.sh

Restart Mozilla. It's done.

2 What it is

The package contains a Type 1 symbol font which is deliberately encoded in such a way that the symbol fonts will render in an iso-8859-1 encoded HTML file. The glyphs of the font are refered to via 8-bit codes overlapping the Latin-1 codes that are the default encoding of most HTML files. This makes it possible to render such constructs as <font face="symbol">a</font> and obtain the greek letter alpha. Constructs of this type have been widely used in HTML files for almost ten years.

It can be argued (and undoubtedly will be by those who think they know what is best for us) that this usage contravenes proper font schemes as expressed for example in the HTML standard. However, no automatic validator should care or even detect the "violation". Documents appear as perfectly legal HTML.

3 Why it is necessary

An elaborate standard called Unicode or iso-10646 has been invented to encode all the characters on the planet (and possibly beyond!) It is the official character repertoire of HTML but it is unfortunately not complete; nor, because of its size, is it fully implemented in any browser. The font police have decreed that if you want a character other than the ones that correspond to those present in the document encoding being used (which is typically iso-8859-1 also called Latin-1 for western languages), you are supposed to use iso-10646 codes. Because iso-10646 is incomplete, for example lacking the parts of delimiters that can be used to build up stretched parentheses in equations, etc., it is impossible to embed mathematics in HTML following the formal standard. Therefore the approach of using an iso-8859 encoded font has long been used.

In prior versions of browsers on linux, symbol fonts could be enabled by just creating an alias from a symbol font present on the system. The X display system, used on linux and unix, has recently started to use a new font renderer called fontconfig. Because it only uses scalable outline fonts, it does not access the symbol font via the alias. Therefore it is necessary to provide this font that is explicitly encoded via 8859-1 for versions of browsers that use the fontconfig renderer.

4 Avoiding side-effects in MathML

Unfortunately, despite recommendations to the contrary, the Mozilla MathML style sheet unnecessarily lists Symbol ahead of Times and serif in the mathematics fonts section. When the above steps enable the use of the symbol font for standard encoding documents, it may also cause MathML to use it in preference to Times or serif. The symptom of this problem is that all the latin characters are turned into greek. Therefore if you want to view MathML documents as well as HTML with symbols, you need to edit the file mathml.css normally found at somewhere like

.../mozilla/res/mathml.css.

The install.sh script will do this for you automatically if it can find the file. If the install.sh script succeeds. Then its effects can be reversed by running it again. In other words, a second run uninstalls everything.

If install.sh does not work, you may have to locate the relevant file youself and edit it by hand.

Find the line that starts

font-family: CMSY10, Symbol, Times ..., serif

Bring the Times and serif fonts ahead of Symbol, and ahead of them both add Standard Symbol L (which is the name of the fontconfig Symbol font with standard encoding) thus:

font-family: CMSY10, Standard Symbol L, Times, serif, Symbol ...

Footnotes:

¹For builds that use the older standard X pixel generated fonts, see http://hutchinson.belmont.ma.us/tth/Xfonts.html . The symfontconfig distribution also contains the Xfonts.fix script to fix those fonts.

File translated from T_EX by T_THgold, version 3.70.
On 28 Aug 2005, 18:01.