Re: tts:rubyReserve + tts:lineHeight (issue #779)

Perhaps we could accommodate your concern by a slight change to the current
default length computation: we could make it the maximum of the currently
specified computation and the maximum  used bpd of the any inline area
generated by a ruby text container for that paragraph.

On Mon, May 21, 2018 at 3:22 PM, Pierre-Anthony Lemieux <pal@sandflow.com>
wrote:

> > How is this different from assigning a length value for lineHeight
>
> An author does not need to account for the presence of ruby text when
> specifying tts:lineHeight. Instead, as I understand the specifications, the
> processor automatically grows the line area height if the computed value of
> tts:lineHeight is not sufficient to accommodate the ruby text (of the font
> size specified by the author) -- see attached examples.
>
> Why should the author have to set the line height manually when using
> tts:rubyReserve?
>
> Best,
>
> -- Pierre
>
> [image: 0.png]
>
> On Mon, May 21, 2018 at 1:00 PM Glenn Adams <glenn@skynav.com> wrote:
>
>> How is this different from assigning a length value for lineHeight in a
>> non-ruby paragraph and not knowing whether the fonts used will fit the
>> line? I think you could say exactly the same thing there:
>>
>> >It is therefore impossible for the author to accurately specify a
>> <length>, and the default value might not be appropriate.
>>
>> On Mon, May 21, 2018 at 11:59 AM, Pierre-Anthony Lemieux <
>> pal@sandflow.com> wrote:
>>
>>> Hi Cyril, Glenn et al.,
>>>
>>> The following is based on my working on implementing tts:rubyReserve in
>>> imscJS.
>>>
>>> tts:rubyReserve is intended to reserve room to contain inline areas
>>> generated by ruby annotations and emphasis marks, regardless of whether the
>>> latter are present at a given instant in time.
>>>
>>> As currently specified, the amount of room reserved is explicitly
>>> specified by the author as a <length>, or, if left unspecified, set to a
>>> default value equal to 50% of the used value of the tts:lineHeight
>>> applicable to the p element.
>>>
>>> I see a fundamental challenges with this approach:
>>>
>>> (a) neither tts:ruby nor tts:textEmphasis specify the amount of room
>>> needed for ruby annotations and emphasis marks, respectively -- the amount
>>> of room is left to the implementation. It is therefore impossible for the
>>> author to accurately specify a <length>, and the default value might not be
>>> appropriate.
>>>
>>> (b) the default value is not sufficient if the author specifies a font
>>> size for ruby annotations that is different from the ruby base font size
>>> .
>>>
>>> I suggest exploring the following tweak to the semantics of
>>> tts:rubyReserve:
>>>
>>> """
>>> The implementation reserves room for ruby annotations and emphasis
>>> marks assuming:
>>> - the font size of the base text is the same as that of the <p>
>>> - the font size of the annotation/emphasis mark is specified by the
>>> <length> or, if the <length> is not specified, computed according
>>> to 10.2.21.1
>>> """
>>>
>>> I will be on the road and unavailable for the next two TTWG calls. I am
>>> however available today and tomorrow to discuss live​, and will be
>>> available over email.
>>>
>>> Best,
>>>
>>> -- Pierre
>>>
>>
>>