Percentage and writing mode relative edges apply to tts:padding

[skynavga]

Since TTML2 introduces padding on content elements (body, div, p, span), a better definition of percentages and edges is required.

[nigelmegitt]

There's no issue reference for this in the TTML2 WD - is this still current or has it been actioned but not referenced (question for @skynavga)?

[skynavga]

Not referenced but still actionable.

On Fri, Dec 16, 2016 at 11:13 AM, Nigel Megitt notifications@github.com wrote:

There's no issue reference for this in the TTML2 WD - is this still current or has it been actioned but not referenced (question for @skynavga https://github.com/skynavga)?

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[palemieux]

Since TTML2 introduces padding on content elements (body, div, p, span), a better definition of percentages and edges is required.

Why is padding necessary of elements other than <region>? Are the underlying use cases captured somewhere?

[skynavga]

Well, that is how TTML2 supports linePadding, i.e., as padding on span.

On Sat, Dec 17, 2016 at 3:48 PM, Pierre-Anthony Lemieux < notifications@github.com> wrote:

Since TTML2 introduces padding on content elements (body, div, p, span), a better definition of percentages and edges is required.

Why is padding necessary of elements other than ? Are the underlying use cases captured somewhere?

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[palemieux]

Well, that is how TTML2 supports linePadding, i.e., as padding on span.

As noted at https://lists.w3.org/Archives/Public/public-tt/2016Dec/0021.html, linePadding is not padding on <span>, but padding on lines. In other words, applying linePadding to a paragraph containing two spans (whether nested or consecutive), does not yield additional space between the spans.

[skynavga]

I didn't say which span, but I mean an anonymous span that is synthesized to wrap the entire content of the paragraph.

On Sat, Dec 17, 2016 at 4:56 PM, Pierre-Anthony Lemieux < notifications@github.com> wrote:

Well, that is how TTML2 supports linePadding, i.e., as padding on span.

As noted at https://lists.w3.org/Archives/Public/public-tt/2016Dec/0021. html, linePadding is not padding on , but padding on lines. In other words, applying linePadding to a paragraph containing two spans (whether nested or consecutive), does not yield additional space between the spans.

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[palemieux]

I didn't say which span, but I mean an anonymous span that is synthesized to wrap the entire content of the paragraph.

This will not work is there is more than one span in the paragraph, and each one has a different background color.

[skynavga]

On Sat, Dec 17, 2016 at 9:44 PM, Pierre-Anthony Lemieux < notifications@github.com> wrote:

I didn't say which span, but I mean an anonymous span that is synthesized to wrap the entire content of the paragraph.

This will not work is there is more than one span in the paragraph, and each one has a different background color.

Not necessarily. It depends on how we define behavior at line boundaries. We are not obligated to limit ourselves to CSS tools to do this.

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[palemieux]

I see no value in extending tts:padding to all content elements only to satisfy the narrow use case of linePadding, where in any case tts:padding would behave differently than it does on region. Using linePadding as it is used in EBU-TT-D and IMSC would achieve the same result, with fewer implementation requirements (no need to support padding outside of region) and smoother transition from EBU-TT-D and IMSC.

[skynavga]

This has been a long standing ask, along with border on content elements, that goes back at least 3 years, which has effectively been provisionally adopted by the group. If there are insufficient implementations to support going to PR with this feature, then that will be the time to remove it.

On Sat, Dec 17, 2016 at 10:02 PM, Pierre-Anthony Lemieux < notifications@github.com> wrote:

I see no value in extending tts:padding to all content elements only to satisfy the narrow use case of linePadding, where in any case tts:padding would behave differently than it does on region. Using linePadding as it is used in EBU-TT-D and IMSC would achieve the same result, with fewer implementation requirements (no need to support padding outside of region) and smoother transition from EBU-TT-D and IMSC.

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[skynavga]

I should also add that, since this is supported by XSL-FO and CSS, we can't argue against it due to lack of CSS support.

On Sat, Dec 17, 2016 at 10:06 PM, Glenn Adams glenn@skynav.com wrote:

This has been a long standing ask, along with border on content elements, that goes back at least 3 years, which has effectively been provisionally adopted by the group. If there are insufficient implementations to support going to PR with this feature, then that will be the time to remove it.

On Sat, Dec 17, 2016 at 10:02 PM, Pierre-Anthony Lemieux < notifications@github.com> wrote:

I see no value in extending tts:padding to all content elements only to satisfy the narrow use case of linePadding, where in any case tts:padding would behave differently than it does on region. Using linePadding as it is used in EBU-TT-D and IMSC would achieve the same result, with fewer implementation requirements (no need to support padding outside of region) and smoother transition from EBU-TT-D and IMSC.

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[palemieux]

This has been a long standing ask, along with border on content elements, that goes back at least 3 years,

Can you point to the use case?

I should also add that, since this is supported by XSL-FO and CSS, we can't argue against it due to lack of CSS support.

Right.

It is however possible to argue against adding CSS padding to meet the linePadding use case as currently specified in IMSC and EBU-TT-D since CSS padding does not in fact yield the expected result.

[skynavga]

On Sat, Dec 17, 2016 at 10:13 PM, Pierre-Anthony Lemieux < notifications@github.com> wrote:

This has been a long standing ask, along with border on content elements, that goes back at least 3 years,

Can you point to the use case?

adding padding

I should also add that, since this is supported by XSL-FO and CSS, we can't argue against it due to lack of CSS support.

Right.

It is however possible to argue against adding CSS padding to meet the linePadding use case as currently specified in IMSC and EBU-TT-D since CSS padding does not in fact yield the expected result.

supporting line padding is not the sole use case

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[palemieux]

Can you point to the use case? adding padding

What style of subtitles/captions require padding beyond region?

supporting line padding is not the sole use case

It is in fact a different use case since it does not behave like CSS padding.

[skynavga]

On Sat, Dec 17, 2016 at 10:24 PM, Pierre-Anthony Lemieux < notifications@github.com> wrote:

Can you point to the use case? adding padding

What style of subtitles/captions require padding beyond region?

those that wish to use padding on content elements; keep in mind that TTML is not restricted to subtitles and captions

supporting line padding is not the sole use case

It is in fact a different use case since it does not behave like CSS padding.

not so, since we haven't yet defined background behavior at line boundaries

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[nigelmegitt]

Marking as discussed and agreed as per the discussion in w3c/ttml1#205.

[skynavga]

Duplicate of #302.