Re: What is the use case for two levels of background colors?

Using the cue box as the background box was what I did in
http://people.opera.com/philipj/2014/03/vttscroll/background.html

However, I've realized that this creates a bit of a tension between
two goals: in order to "look nice" the background should not be much
bigger than the cue text, but to give the cue size to grow when the
font size changes, it should be as big as possible.

This would likely cause authors to create boxes that are too small,
causing unnecessary line wrapping when the font size increases. Note
that using a font-relative unit like em doesn't eliminate the problem,
as illustrated here:
http://jsfiddle.net/zLB3N/

If the use case was to provide a common background for a number of
lines (possibly from different cues) simply taking the bounding box of
those lines and adding some padding would be enough.

However, if the background needs to be unchanging over time the
algorithm would have to be much more complicated, and I don't know how
to solve it. Letting the author set a fixed size will result in text
becoming unreadable in some cases, even if font-relative units are
used.

Philip

On Sat, May 10, 2014 at 11:20 PM, Christian Vogler
<christian.vogler@gallaudet.edu> wrote:
> Maybe I am off-track here, but to me it seems that the cue box (especially
> with an auto width and height) is the logical place for having this visually
> stable background. This should work just fine for pop-on captions, but
> breaks down with roll-up, because in roll-up, each new line/addition is a
> separate cue.
>
> I'm not sure why this decision was made, to have a separate cue of its own
> for each new roll-up line, other than the desire to employ WebVTT's overlap
> avoidance algorithms. Hypothetically speaking, couldn't the same use cases
> be solved with overflow properties on cue boxes? If so, I don't see any need
> for regions anymore. What am I missing?
>
> Christian
>
>
> On Sat, May 10, 2014 at 5:10 PM, Philip Jägenstedt <philipj@opera.com>
> wrote:
>>
>> Thanks David!
>>
>> If "visual stability" can be important to the end user, what should be
>> done in the case where regions aren't used by the caption author? In
>> 708, is it possible to have captions outside of windows?
>>
>> (Note that a VTTRegion background grows and shrinks with the cues
>> within it, but it sounds like you had something slightly different in
>> mind.)
>>
>> Philip
>>
>> On Fri, May 9, 2014 at 10:09 PM, David Singer <singer@apple.com> wrote:
>> > I am not sure that they are useful together, but don’t they have
>> > different visual effects?
>> >
>> > The background for a region causes a stable rectangular area to be
>> > painted in that color, no mater what text (if any) is inside it.
>> >
>> > the background for text is only drawn around the actual characters.
>> >
>> > the first has the advantage of visual stability, while the second
>> > minimizes the amount of the scene obscured.
>> >
>> > On May 9, 2014, at 7:07 , Philip Jägenstedt <philipj@opera.com> wrote:
>> >
>> >> Hi all,
>> >>
>> >> Does anyone know the use case for having two levels of background
>> >> colors, specifically one background color on the individual lines of
>> >> text and another on the region/window?
>> >>
>> >> The only thing I can think of is that it could make the text more
>> >> readable for some people. However, if that is the real use case I
>> >> think relying on regions for it is unacceptable, because the author
>> >> may not have used regions at all. A robust solution would require the
>> >> user agent always add that extra layer behind all cues.
>> >>
>> >> Thoughts?
>> >>
>> >> Philip
>> >>
>> >
>> > David Singer
>> > Manager, Software Standards, Apple Inc.
>> >
>>
>
>
>
> --
> Christian Vogler, PhD
> Director, Technology Access Program
> Department of Communication Studies
> SLCC 1116
> Gallaudet University
> http://tap.gallaudet.edu/
> VP: 202-250-2795

Received on Monday, 12 May 2014 08:12:59 UTC