W3C home > Mailing lists > Public > public-tt@w3.org > January 2015

Re: [TTML2] tts:{width,height} rename

From: Pierre-Anthony Lemieux <pal@sandflow.com>
Date: Tue, 27 Jan 2015 09:51:35 -0800
Message-ID: <CAF_7JxDJ+pLmOY73DucUuXDm20o1wOFFAqkgTnBAX-69w08e4w@mail.gmail.com>
To: Glenn Adams <glenn@skynav.com>
Cc: David Singer <singer@apple.com>, TTWG <public-tt@w3.org>
> SMPTE needs to present a viable use case for such a feature

The fact that this is a specification in use today should be
sufficient, a priori. In other words, ST 428-7 could be wrong, but I
would not assume that without clear evidence.

> add a new issue specifically requesting negative space along with use case documentation

Hmmmm. the tts:{ipd,bpd} feature was proposed with the SMPTE liaison
as the sole documented requirement, but fails to meet it... so I do
not think closing the issue can be a reasonable course of action.

If TTWG has concerns/questions about this and other ST 428-7 features,
TTWG should simply collect them and ask for SMPTE's input. ITTWG can
incorporate SMPTE's feedback (if any) in its final disposition.

Best,

-- Pierre

On Tue, Jan 27, 2015 at 9:38 AM, Glenn Adams <glenn@skynav.com> wrote:
>
>
> On Tue, Jan 27, 2015 at 10:33 AM, Pierre-Anthony Lemieux <pal@sandflow.com>
> wrote:
>>
>> > correct; that use case (dubious at best) is not supported by this
>> > feature;
>>
>> Well... this feature is presumably in use (ST 428-7 being in use
>> worldwide), so I do not think TTWG can reasonably call it dubious. If
>> TTWG has concerns/questions, TTWG should simply ask SMPTE. In the
>> meantime, I have reopened ticket #237.
>
>
> SMPTE needs to present a viable use case for such a feature before I'll
> consider it; it would be better to leave 237 closed, and add a new issue
> specifically requesting negative space along with use case documentation
>
>>
>>
>>
>>
>> >it specifies a fixed dimension in inline or block progression;
>>
>> What does "inline dimensions" do for a <div>, which is in block
>> progression?
>
>
> every area generated by content elements has both inline and block
> progression dimensions; constraining the ipd of a div would constrain it in
> the horizontal axis in a horizontal writing mode
>
>>
>>
>> Thanks,
>>
>> -- Pierre
>>
>> On Tue, Jan 27, 2015 at 9:28 AM, Glenn Adams <glenn@skynav.com> wrote:
>> >
>> >
>> > On Tue, Jan 27, 2015 at 10:17 AM, Pierre-Anthony Lemieux
>> > <pal@sandflow.com>
>> > wrote:
>> >>
>> >> > that is a special case of the specified feature
>> >>
>> >> The mechanism specified in the SMPTE liaison allows for negative
>> >> dimensions and notes "Negative values shall be allowed but should be
>> >> used with care as characters could overlap."
>> >>
>> >> The proposed tts:inlineLength/ipd does not allow negative dimensions.
>> >
>> >
>> > correct; that use case (dubious at best) is not supported by this
>> > feature;
>> > you could use negative letter spacing between glyphs as an alternative
>> >
>> >>
>> >>
>> >> Also, if tts:inlineLength/ipd is intended to add/substract space in
>> >> the inline progression, how would it work on <div>, which is in block
>> >> progression?
>> >
>> >
>> > it doesn't add/subtract space; it specifies a fixed dimension in inline
>> > or
>> > block progression; it applies to all content elements;
>> >
>> >>
>> >>
>> >> Thanks,
>> >>
>> >> -- Pierre
>> >>
>> >> On Tue, Jan 27, 2015 at 9:06 AM, Glenn Adams <glenn@skynav.com> wrote:
>> >> >
>> >> > On Tue, Jan 27, 2015 at 10:02 AM, Pierre-Anthony Lemieux
>> >> > <pal@sandflow.com>
>> >> > wrote:
>> >> >>
>> >> >> Hi Glenn,
>> >> >>
>> >> >> Thanks for the pointer.
>> >> >>
>> >> >> The SMPTE liaison referenced in the ticker described "a mechanism to
>> >> >> insert a variable amount of space in the middle of a rendered text
>> >> >> string".
>> >> >
>> >> >
>> >> > that is a special case of the specified feature
>> >> >
>> >> >>
>> >> >>
>> >> >> Is the idea to use an empty <span> with tts:inlineLength/ipd equal
>> >> >> to
>> >> >> the desired amount of space?
>> >> >
>> >> >
>> >> > yes
>> >> >
>> >> >>
>> >> >>
>> >> >> Why is the block progression attribute needed?
>> >> >
>> >> >
>> >> > symmetry
>> >> >
>> >> >>
>> >> >>
>> >> >> Thanks,
>> >> >>
>> >> >> -- Pierre
>> >> >>
>> >> >>
>> >> >> On Tue, Jan 27, 2015 at 8:46 AM, Glenn Adams <glenn@skynav.com>
>> >> >> wrote:
>> >> >> >
>> >> >> > On Tue, Jan 27, 2015 at 9:38 AM, Pierre-Anthony Lemieux
>> >> >> > <pal@sandflow.com>
>> >> >> > wrote:
>> >> >> >>
>> >> >> >> > tts:{ipd,bpd} are used to specify constraints on the dimensions
>> >> >> >> > of
>> >> >> >> > areas
>> >> >> >> > generated by content elements
>> >> >> >>
>> >> >> >> This is in addition to region height/width, or instead, or
>> >> >> >> something
>> >> >> >> else?
>> >> >> >>
>> >> >> >> Is there a ticket related to this feature?
>> >> >> >
>> >> >> >
>> >> >> > not a new feature: just a name change from what was introduced as
>> >> >> > the
>> >> >> > solution for ISSUE-237 [1]
>> >> >> >
>> >> >> > [1] http://www.w3.org/AudioVideo/TT/tracker/issues/237
>> >> >> >
>> >> >> >>
>> >> >> >>
>> >> >> >> Best,
>> >> >> >>
>> >> >> >> -- Pierre
>> >> >> >>
>> >> >> >> On Tue, Jan 27, 2015 at 8:12 AM, Glenn Adams <glenn@skynav.com>
>> >> >> >> wrote:
>> >> >> >> > ipd = inline progression dimension
>> >> >> >> > bpd = block progression dimension
>> >> >> >> >
>> >> >> >> > they are the writing mode relative counterparts to width and
>> >> >> >> > height;
>> >> >> >> > the
>> >> >> >> > problem with the latter is that they are strongly associated
>> >> >> >> > with
>> >> >> >> > absolute
>> >> >> >> > axes (horizontal and vertical), while the former {ipd,bpd}
>> >> >> >> > don't
>> >> >> >> > suffer
>> >> >> >> > from
>> >> >> >> > that association
>> >> >> >> >
>> >> >> >> > it also requires less spec text and results in less confusion
>> >> >> >> > in
>> >> >> >> > the
>> >> >> >> > spec,
>> >> >> >> > since in all places at present (except for line height), width
>> >> >> >> > and
>> >> >> >> > height
>> >> >> >> > are interpreted in an absolute sense independent of writing
>> >> >> >> > mode
>> >> >> >> >
>> >> >> >> > tts:{ipd,bpd} are used to specify constraints on the dimensions
>> >> >> >> > of
>> >> >> >> > areas
>> >> >> >> > generated by content elements
>> >> >> >> >
>> >> >> >> > On Tue, Jan 27, 2015 at 7:37 AM, David Singer
>> >> >> >> > <singer@apple.com>
>> >> >> >> > wrote:
>> >> >> >> >>
>> >> >> >> >> yikes
>> >> >> >> >>
>> >> >> >> >> it’s nice if the terms are readable.  Linewidth and Lineheight
>> >> >> >> >> have
>> >> >> >> >> some …
>> >> >> >> >> recognition, albeit mostly in writing systems that use
>> >> >> >> >> horizontal
>> >> >> >> >> lines
>> >> >> >> >> assembled into vertical blocks.
>> >> >> >> >>
>> >> >> >> >> ipd and bpd are directions, not measurements, aren’t they? and
>> >> >> >> >> they
>> >> >> >> >> don’t
>> >> >> >> >> exactly roll off the tongue or leap to mind in terms of
>> >> >> >> >> recognizability
>> >> >> >> >>
>> >> >> >> >> > On Jan 26, 2015, at 1:01 , Glenn Adams <glenn@skynav.com>
>> >> >> >> >> > wrote:
>> >> >> >> >> >
>> >> >> >> >> > The use of width and height as writing mode relative
>> >> >> >> >> > properties
>> >> >> >> >> > is
>> >> >> >> >> > confusing. Change their names to ipd and bpd, abbreviations
>> >> >> >> >> > for
>> >> >> >> >> > inline
>> >> >> >> >> > progression dimension and block progression dimension,
>> >> >> >> >> > respectively,
>> >> >> >> >> > and
>> >> >> >> >> > document convention that width and height (as well as
>> >> >> >> >> > horizontal
>> >> >> >> >> > and
>> >> >> >> >> > vertical) are always absolute and not writing mode relative.
>> >> >> >> >> > The
>> >> >> >> >> > only
>> >> >> >> >> > exception being that 'height' in lineHeight remains writing
>> >> >> >> >> > mode
>> >> >> >> >> > relative,
>> >> >> >> >> > i.e., specifies the nominal bpd of a line area.
>> >> >> >> >> >
>> >> >> >> >> > Change image to use tts:extent instead of the former
>> >> >> >> >> > tts:{width,height}
>> >> >> >> >> > in order to use absolute axes in expressing explicit image
>> >> >> >> >> > dimensions.
>> >> >> >> >> >
>> >> >> >> >> > Addressed above comments in [1].
>> >> >> >> >> >
>> >> >> >> >> > [1] https://dvcs.w3.org/hg/ttml/rev/69877acd9380
>> >> >> >> >>
>> >> >> >> >> David Singer
>> >> >> >> >> Manager, Software Standards, Apple Inc.
>> >> >> >> >>
>> >> >> >> >>
>> >> >> >> >
>> >> >> >
>> >> >> >
>> >> >
>> >> >
>> >
>> >
>
>
Received on Tuesday, 27 January 2015 17:52:26 UTC

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