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

From: Glenn Adams <glenn@skynav.com>
Date: Tue, 27 Jan 2015 10:28:37 -0700
Message-ID: <CACQ=j+ep0G8hp3VGM23e89c6rx+H33qALvHcguqqPY7u-gRSmg@mail.gmail.com>
To: Pierre-Anthony Lemieux <pal@sandflow.com>
Cc: David Singer <singer@apple.com>, TTWG <public-tt@w3.org>
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 17:29:25 UTC

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