Cambria Math Font has too much leading

[shoose]

Hi all,

We are working on a math-intensive product that requires a wide range of math symbols.  For this, we are using Lucida Sans Unicode, which is fine.  We select that font and input the codepoint using the Char Palette.

There are some symbols, however, that Lucida Sans Unicode cannot render.  The other obvious font (as far as I can tell) is Cambria Math, made by Microsoft and shipping with all Windows OSs.  When we try that font, however, its behavior is strange in Frame: when you try to select a character formatted with this font, the cursor appears to grab several lines both above and below it, although it really is just selecting what you wish.  This affects the usability in Frame but we can live with that.

The problem is that it then renders in some browsers with a very large amount of leading above and below.  Firefox and IE render it properly; Chrome and Safari create extra leading. 

Has anyone else used this font and seen similar issues?  If we cannot tweak something to get this font to work, we'll have to find another -- any font suggestions for fonts with large sets of math symbols would be appreciated.

Thanks,

Shelley

Shelley Hoose

Sr Documentation Developer

Rogue Wave Software

[Bob_Niland]

A quick search on:

Cambria Math font metrics

gains a generous number of hits, including this one on MSDN:

font metrics are wrong for Cambria Math

There are similar complaints about Arial Unicode MS.

It would seem that Mr. Bill is incompetent at typography.

[MrMathType — Retired]

Shelley, Code2000 is a font that's commonly used for mathematical applications and technical publishing.

[Sairjohn · Accepted solution]

(This answer will probably not serve Shelley anymore, as her team may have already found a solution by now; but maybe it will serve to others with similar problems.)

I have studied typography for several months last year and used some fonts, specially the ones in Cambria family, as “guinea pigs” in my explorations with the Font Creator Professional software. What I found was that Cambria Math is an expansion of Cambria Regular, with many extra glyphs suited to writing equations. (In fact, more than any true type font I know.) Some of these glyphs are “gigantic”, as they are intended to compose complex equations that span vertically on the page through a space equivalent to several lines of text. (For example, brackets that enclose multi-line matrices, radices and integrals that precede formulae with “fractions inside fractions”, and so on.)

TrueType standard was not originally developed to easily acomodate such gigantic glyphs amidst the other, normal-sized ones. So, when the metrics parameters of fonts like Cambria Math are defined (including the ones that specify leading above and below), the designers must choose between:

– define the leading above and below all the glyphs to ensure adequate space betwen lines of common text;

– define the leadings for all the glyphs to acomodate all the symbols, including the gigantic ones, in equations.

In the first case, the leadings will serve the letters and numbers well, but the gigantic glyphs will extrapolate the line boundaries (in Font Creator’s validation reports, they are said to be “not fully in visible area”). In the second case, the leadings will acomodate even the largest glyphs, but will be ridiculously excessive to normal text — that’s exactly the case with Cambia Math font!

Some applications, like Word, are smart enough to cut off the excess of leading space in normal text, and use it full only when necessary in equations. So, you will not have trouble changing the font of a document from Cambria to Cambria Math in Word. (I suppose, but am not sure, that some arcane code is embedded in the font itself to guide the application software.) But other applications are not so smart.

The easiest technical solution I have found to deal with this problem was to use Font Creator (or other font-editing software) to modify the leading spaces above and below glyphs of Cambria Math to be the same of Cambria Regular (i.e., changing the second-case to the first-case scenarios described above). But this is not allowed by the license terms of Cambria family fonts...

So, the only legal solutions are either: acquiring a special license from Microsoft to modify Cambria Math to your needs; or use another font. Latin Modern Math is a viable alternative. It is based on the typefaces designed by Donald E. Knuth for his TeX typesetting system (the de facto standard used in Math and Science academic papers and books). Latin Modern Math also have the same vertical leading problem of Cambria Math, but its open source license allows anyone to modify it at will.

There are, however, two main disadvantages of Latin Modern Math: it has fewer glyphs than Cambria Math, so you may need to create some new ones (not a big issue); it looks awfull on screen, since its modeled on Knuth’s fonts, that were intended to look good in print (a big issue, indeed). Cambria Math is still the best (or the less bad) font for displaying Math equations on screen.