On 02.07.2016 2:11, Kelvin Ma wrote: > How can I tell if a feature is enabled by default? Is it constant across > scripts?
You can tell by looking at documentation, or source code. No, it's not constant and depends on script/shaper used. > And are feature values always True/False > Already answered. > On Fri, Jul 1, 2016 at 6:34 PM, Ebrahim Byagowi <[email protected] > <mailto:[email protected]>> wrote: > > By passing a list of opentype features to harfbuzz, it just modifies > the default status of them but still has knows which ones should be > enabled or disabled in case user didn't explicitly set them. > > > Because i can turn off LIGA by passing a LIGA feature with value=0 > and nothing will happen to arabic but CALT with value=1 changes it > In case of LIGA and CALT difference, that depends on that > specific font you are using whether it has marked which feature by > which tag. An identical stylic operation can have two different tag > on different fonts. > > On Sat, Jul 2, 2016 at 2:58 AM, Kelvin Ma <[email protected] > <mailto:[email protected]>> wrote: > > Now I’m even more confused, will harfbuzz override the features > in the features array if it’s setting arabic? Because i can turn > off LIGA by passing a LIGA feature with value=0 and nothing will > happen to arabic but CALT with value=1 changes it > > On Fri, Jul 1, 2016 at 6:24 PM, Ebrahim Byagowi > <[email protected] <mailto:[email protected]>> wrote: > > Different and essential operations of a shaper are divided > and marked by features and some features are enabled by > default per the specification, for example on Arabic > > https://www.microsoft.com/typography/OpenTypeDev/arabic/intro.htm#features > > On Sat, Jul 2, 2016 at 2:33 AM, Kelvin Ma > <[email protected] > <mailto:[email protected]>> wrote: > > && why does harfbuzz still use features if I pass it an > empty list? How does it know whether to turn them on or off? > > On Fri, Jul 1, 2016 at 6:02 PM, Kelvin Ma > <[email protected] > <mailto:[email protected]>> wrote: > > So that’s what the value member does. thanks! Will > it always be either 0 or 1? > && what does .tag do? > > On Fri, Jul 1, 2016 at 5:51 PM, Simon Cozens > <[email protected] > <mailto:[email protected]>> wrote: > > On 02/07/2016 07:34, Kelvin Ma wrote: > > So I think I figured out how to turn on font > features, but how do I turn > > ones off that are enabled by default? Like liga or > kern? > > Just set the value to 0 in the features array. > See > > https://github.com/simoncozens/sile/blob/master/src/justenoughharfbuzz.c#L78 > > Simon > > > > > _______________________________________________ > HarfBuzz mailing list > [email protected] > <mailto:[email protected]> > https://lists.freedesktop.org/mailman/listinfo/harfbuzz > > > > > > > > _______________________________________________ > HarfBuzz mailing list > [email protected] > https://lists.freedesktop.org/mailman/listinfo/harfbuzz > _______________________________________________ HarfBuzz mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/harfbuzz
