Re: Making necessary OpenType features on by default

[Hans Hagen <pragma@wxs.nl>]

Khaled Hosny wrote:

> Currently, when defining a font feature one has to enable all features
> by hand which is IMHO not very user friendly as it implies prior
> knowledge about OpenType font features and the meaning of each one, not
> every Arabic user, for example, knows what does 'init', 'medi, etc.
> ligatures mean yet to know that he must enable them to get proper font
> rendering. 
> 
> I think some font features should be on by default, so that
> \definefontfeature[script=arabic] should be enough to get an Arabic font
> rendered correctly with the default features as its designer intended
> (designers assume that certain will be on while other are off by
> default, like liga vs. dlig), and if some one wants to disable a certain
> default feature he can turn it off, not the reverse.
> 
> Microsoft's OpenType features list page
> (http://www.microsoft.com/typography/otspec/features_ae.htm) gives a "UI
> suggestion" for each feature noting if it should be on by default, I
> think those are what most OpenType enable by default (at least the ones
> I tested).

i've been thinking of a features=default option (as there is already 
features=yes|no)

even then it can never be fully automatic as some usage of fonts (think 
of verbatim) demands devation from defaults

now, if we implement a default list then we first need to make a 
detailed list of what the supposed defaults are (and i'm not sure if ms 
is the only resource for that; after all, not all machineries support 
all features)

a related issue is that fonts can be used for different languages and 
scripts and therefore a more dynamic feature switching might be needed 
i.e. arabic might need init, but when the same font is used for latin it 
not handy to have it enabled, so there might be a matrix of features / 
scripts needed

if it was trivial i'd already done it -)

(implementing is trivial but i don't want to make the wrong decision 
here as it will influence compatibility)

Hans


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