Why is display align not permitted in image profile?

[skynavga]

Display align is allowed in text, but not in image profile. Why? It has as much applicability in the latter as the former.

[nigelmegitt]

My understanding of this is that since the images must be sized identically to the regions display align would have no effect.

[skynavga]

I had been looking for that text (late) last night but didn't find it, but
I see it now. That raises the issue of why multiple divs are allowed in a
region.

On Tue, Dec 8, 2015 at 4:09 AM, nigelmegitt notifications@github.com
wrote:

My understanding of this is that since the images must be sized
identically to the regions display align would have no effect.

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#118 (comment).

[nigelmegitt]

It seems reasonable to permit a region to have multiple child divs that do not temporally overlap.

[skynavga]

True, but there is no constraint (at present) on the presence of multiple
divs in a regiion in a single ISD.

On Tue, Dec 8, 2015 at 9:08 AM, nigelmegitt notifications@github.com
wrote:

It seems reasonable to permit a region to have multiple child divs that do
not temporally overlap.

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#118 (comment).

[nigelmegitt]

That does seem to be a bug.

[palemieux]

See Section 8.2 at https://rawgit.com/w3c/imsc/issue-97/spec/ttml-ww-profiles.html

There is at most at most one presented image per presented region.

[skynavga]

But that doesn't prevent two divs from being assigned to a region in the
same ISD, both having a background image. There should be a constraint of
one div per region in a given ISD.

On Wed, Dec 9, 2015 at 4:09 PM, Pierre-Anthony Lemieux <
notifications@github.com> wrote:

See Section 8.2 at
https://rawgit.com/w3c/imsc/issue-97/spec/ttml-ww-profiles.html

There is at most at most one presented image per presented region.

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#118 (comment).

[palemieux]

How would two div elements, both with a background image and both flowed into the same region in the same ISD, not contradict the restriction that There is at most at most one presented image per presented region?

The intent is for a single div with background image per region in a given ISD. I do not claim that the current text is not broken, but would like to understand why.

[skynavga]

On Wed, Dec 9, 2015 at 6:33 PM, Pierre-Anthony Lemieux <
notifications@github.com> wrote:

How would two div elements, both with a background image and both flowed
into the same region in the same ISD, not contradict the restriction that There
is at most at most one presented image per presented region?

The intent is for a single div with background image per region in a given
ISD. I do not claim that the current text is not broken, but would like to
understand why.

A second div could have no background image, or it could have an image that
overflows the region.

I question the manner in which you expressed the original constraint: in
terms of one presented image.

I would have simply required no more than one div.

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#118 (comment).

[palemieux]

Thanks for clarifying

[palemieux]

What are the dimensions of a div that contains no content?

[skynavga]

As you might expect, [0,0], but as I said, one could have two divs, each
with background image, one of which is presented, and which image geometry
matches region geometry, and a second (third etc) with a background image
which overflows the region (and if overflow is hidden) then is not
presented (and thus satisfies your no more than one presented image
constraint).

On Wed, Dec 9, 2015 at 6:53 PM, Pierre-Anthony Lemieux <
notifications@github.com> wrote:

What are the dimensions of a div that contains no content?

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#118 (comment).

[palemieux]

The pull requests #123 constrains the number of div elements to at most one in presented regions.