[mpeg-OTspec] RE: [OpenType] Kerning

[Behdad Esfahbod]

On 03/25/2010 08:18 PM, John Hudson wrote:

> Behdad Esfahbod wrote:
> 
>> I think you are missing the point of the discussion. This whole thread is
>> about recommending what layout engines should do when both kern and some
>> GSUB/GPOS is available. Aren't you getting rid of the question instead of
>> answering it?
> 
> I'm wondering whether it is a question that needs to be answered in
> terms of the OpenType specification which is -- notoriously so -- a font
> format specification not a layout implementation specification.

A data format specification without any specification on how the data should
be used is useless.


>> If the recommendation is "no recommendation", sure, that's an
>> option too. But that's not what's currently on the table from my
> understanding.
> 
> I understand what is currently on the table, in terms of the spec
> ammendment proposed by Sairus, as regarding what happens when a font
> contains both a kern table and GPOS *kerning*. I think what you have
> raised in the past few days is a different issue: what to do if a font
> contains a kern table and non-kerning GPOS.

No, I wasn't the one who brought it up.  The current amendment has words to
the effect of "if GPOS has no kern, then kern table is applied followed by
other GPOS features."  I just questioned whether this recommendation is really
the best we can make.


> The presence or absence of GSUB seems to me tangential or, at least, it
> should be tangential, because to make decisions about positioning based
> on anything other than the presence or absence of GPOS seems a bad idea.

I fully agree.

behdad

> J.