Re: TTML writingMode vs CSS Writing Modes Level 3 writing-mode

Hi Glenn,

Thanks! So is writingMode="rltb" in TTML equivalent to {writing-mode:
"horizontal-tb", direction: "rtl"} in CSS? In other words,
writingMode="rltb" sets the default to default paragraph embedding
level to "RTL" just as {direction: "rtl"} does?

Best,

-- Pierre

On Fri, Nov 4, 2016 at 11:00 PM, Glenn Adams <glenn@skynav.com> wrote:
>
>
> On Fri, Nov 4, 2016 at 11:13 PM, Pierre-Anthony Lemieux <pal@sandflow.com>
> wrote:
>>
>> Hi all,
>>
>> TTML allows both 'lrtb' and 'rltb' as values for writingMode, and
>> references Section 7.29.7 at XSL.
>>
>> CSS Writing Modes Level 3 [1] states that both 'lr-tb' and 'rl-tb' (as
>> defined in SVG) are both replaced by 'horizontal-tb'.
>>
>> Why would 'lr-tb' and 'rl-tb' be redundant?
>
>
> They aren't (in XSL-FO or TTML), since they have the added effect of
> indicating the default paragraph embedding level (of LTR or RTL) for all
> content targeted to a region. Keep in mind that XSL-FO defined writing mode
> before CSS3 WM took it up for consideration. Apparently, CSS3 WM prefers to
> use the direction property and/or character properties exclusively for this
> purpose.
>
> In TTML, a paragraph's default embedding level can be influenced by the
> computed value of tts:writingMode, the computed value of tts:direction, and
> the character content of the paragraph.
>
>>
>>
>> Thanks,
>>
>> -- Pierre
>>
>

Received on Saturday, 5 November 2016 06:20:19 UTC