- From: Pierre-Anthony Lemieux <pal@sandflow.com>
- Date: Mon, 21 Sep 2015 16:42:53 -0700
- To: Glenn Adams <glenn@skynav.com>
- Cc: "public-tt@w3.org" <public-tt@w3.org>
Hi Glenn, I appreciate the clarifications. I am checking with folks to see if CFF-TT implementations typically implement #lineBreak-uax14. Best, -- Pierre On Mon, Sep 21, 2015 at 4:31 PM, Glenn Adams <glenn@skynav.com> wrote: > > On Mon, Sep 21, 2015 at 3:43 PM, Pierre-Anthony Lemieux <pal@sandflow.com> > wrote: >> >> HI Glenn, >> >> > I presumed that by listing feature designators, you were specifying >> > whether the features so designated may be used in a document. >> >> Yes. This is the intent. >> >> > it appears you may in addition consider the presence of a designator in >> > these sections as indicating whether >> > a feature can be required in a document specific profile over and above >> > the use of an IMSC profile. >> >> No. That is not the intent. >> >> I was merely curious why, as opposed to other TTML parameter that >> impact processor behavior, #lineBreak-uax14 is not controlled using a >> ttp attribute. > > > I don't believe anyone ever suggested defining a parameter, since it would > not be something typically changed on a document by document basis (in a > given profile). Instead, we felt such a requirement was closely aligned to > profile definitions, and that a profile could specify this requirement or > not. > >> >> >> > Given the focus on reproducible behavior, e.g., defining the use of >> > specific glyph metrics, I would expect that UAX14 be mandated by IMSC1. >> >> Ok. To confirm, unless IMSC1 requires that processor implement >> #lineBreak-uax14, a processor may or may not do so. > > > That is correct. In other words, the default is that you have no idea which > line break algorithm is used. If you specify #lineBreak-uax14 as required in > a standard or per-document profile, then at least you know what algorithm is > used (provided the implementation heeds #profile). > >> >> >> Best, >> >> -- Pierre >> >> On Mon, Sep 21, 2015 at 2:15 PM, Glenn Adams <glenn@skynav.com> wrote: >> > I was not sufficiently clear in my description. Of course, the >> > #lineBreak-uax14 designator can be listed in a document defined profile >> > based on IMSC1 text profile as the base profile. >> > >> > What I had apparently not understood was what was meant by "The Document >> > Instance shall conform to the following table:" in Sections 6.10, 7.4, >> > and >> > 8.4. I presumed that by listing feature designators, you were specifying >> > whether the features so designated may be used in a document. In the >> > case of >> > most features, there is a syntactic feature that corresponds to a >> > designator. However, that is not true for #lineBreak-uax14, which may be >> > used by an application to signal whether a particular algorithm is used >> > or >> > not by the implementation, as opposed to whether a syntactic feature is >> > used >> > in the document. >> > >> > From your question, it appears you may in addition consider the presence >> > of >> > a designator in these sections as indicating whether a feature can be >> > required in a document specific profile over and above the use of an >> > IMSC >> > profile. >> > >> > This doesn't seem a legitimate requirement. If an application of IMSC1 >> > also >> > wants to require an implementation to support a superset of IMSC1, then >> > they >> > should be able to additional require features not required by IMSC1. >> > >> > Furthermore, I wonder if the fact that absent a generic requirement for >> > UAX14 line break support, then there is no guarantee of reproducibility >> > of >> > line breaks even given the same font metrics, same resolution, and same >> > region extents? >> > >> > Given the focus on reproducible behavior, e.g., defining the use of >> > specific >> > glyph metrics, I would expect that UAX14 be mandated by IMSC1. >> > >> > >> > >> > >> > >> > >> > >> > On Mon, Sep 21, 2015 at 9:35 AM, Pierre-Anthony Lemieux >> > <pal@sandflow.com> >> > wrote: >> >> >> >> Hi Glenn, >> >> >> >> Couple of questions related to #lineBreak-uax14 and ISSUE-406 [1]. >> >> >> >> - why can #lineBreak-uax14 only be signaled through a profile >> >> declaration and cannot be set through a ttp attribute? >> >> >> >> - what is the default value of #lineBreak-uax14 in absence of a >> >> profile declaration? >> >> >> >> Thanks, >> >> >> >> -- Pierre >> >> >> >> [1] http://www.w3.org/AudioVideo/TT/tracker/issues/406 >> >> >> > > >
Received on Monday, 21 September 2015 23:43:41 UTC