Re: Agenda for telcon Oct. 7

On 9/10/15 19:31, Levantovsky, Vladimir wrote:
> As a follow up on the last telcon discussion about allowing null
> transform for any and all tables (including glyf/loca) and
> considering the changes that have just been implemented w.r.t.
> transformLength field (clarifying that it is never optional) - one
> solution that may not be pretty but functional - treat the presence
> of the transformLength field in table directory as a global transform
> flag, and the flag bits purely as a transform number.

Unless I'm misunderstanding something, we can't do that: there's no 
separate indication of whether transformLength is present. The presence 
of this field is implied by the fact that a non-null transform is used 
for the table. So a decoder has to first read the table tag and flag 
bits, to determine whether a non-null transform is involved, and only 
then does it know whether to read a transformLength field. It can't 
"detect" the presence of the transformLength field independently, can it?

> By doing so we
> can introduce the null transform option for glyf/loca tables without
> breaking anything that has already been deployed.
>
> Comments?

AFAICS, this doesn't work! See above.

JK

Received on Friday, 9 October 2015 20:26:57 UTC