Fractions and Tabular Figures in FC 12

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Fractions and Tabular Figures in FC 12

Post by PJMiller »

The automatically generated features of version 12 are great, but it seems they are not complete.

For most of the OpenType features it doesn't matter if they affect each other because they will probably not be applied in combination, however 'tabular numbers' and 'fractions' are one combination that should work well together as these are sometimes applied to the same text.

With the vanilla features as generated by FC 12 if you have 'tabular numbers' and 'fractions' then applying 'tabular numbers' cancels the 'fractions' feature.

To get them to play nicely with each other you need to add 'zero.tnum' to 'nine.tnum' to the class 'latn_figures' and add the 'zero.tnum' to 'nine.tnum' conversions to both the 'latn_frac_figurestonumr' and 'latn_frac_figurestodnom' lookup tables.

It might seem that the program should do this automatically if the 'tabular numbers' feature is present. However, this raises the question of what is the responsibility of the programmer of the font editor program and what is the responsibility of the designer of the font. If the font editor did everything for you then font designers might find it restrictive when they want to do things differently.

Also there is a question of the usefulness of advanced OpenType features to the average user. Font designers are often pedantic about getting everything complete and correct to an extent that the average user will neither use nor appreciate. And all the extra lookup tables and OpenType code can slow down the rendering of a font in applications, which the average user will notice.

Admittedly, there will be some users of high-end desktop publishing applications who will use the features if they are present, but for the average user on a word processor, if they want an arbitrary fraction they will type it out then make the part before the '/' superscript and make the part after the '/' subscript.

On many word processors the OpenType features dialog is hard to find and/or awkward to use.

I think the message here is firstly that the automatically generated OpenType features of version 12 are great and they take away a lot of the grunt work of font making but they are a starting point. You should not assume that they are always correct or complete, check things work just as you used to do when you did it manually.

Secondly you should apply some common sense in which OpenType features are necessary. Just because a particular feature exists does not mean that every font has to have it because most users won't even realise it's there.
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