[HarfBuzz] Turning off ligatures and kerning

[Kelvin Ma]

How can I tell if a feature is enabled by default? Is it constant across
scripts? And are feature values always True/False

On Fri, Jul 1, 2016 at 6:34 PM, Ebrahim Byagowi <ebraminio at gmail.com> 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 <kelvinsthirteen at gmail.com>
> 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 <ebraminio at gmail.com>
>> 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 <kelvinsthirteen at gmail.com>
>>> 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 <kelvinsthirteen at gmail.com>
>>>> 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 <simon at simon-cozens.org>
>>>>> 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
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>>>> https://lists.freedesktop.org/mailman/listinfo/harfbuzz
>>>>
>>>>
>>>
>>
>
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