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

I noticed in the DCMP caption key link you sent earlier there is a suggestion that font sizes can be varied by the user within the range 50% -> 200% of the 'default' font. This would seem a good suggestion for an authoring guideline to minimise the impact of user-adjusted text style causing text that does not fit in the desired rendering area.

Nigel


On 12/05/2014 13:27, "Christian Vogler" <christian.vogler@gallaudet.edu<mailto:christian.vogler@gallaudet.edu>> wrote:

Why do we need a background that is the bounding box of all future cues? I'm not following here.

From an American point of view, in the use case where we do have a fixed background for an extended period of time, it applies to roll-up captions, and in such cases it is usually reasonable to set a fixed width that extends over a certain portion of the screen. If the font becomes so large that you break up in mid-word, you likely can't accommodate the captions on the video screen at all, not without covering the entire video.

If that happens, you typically are someone with a severe visual impairment, and you also will have problems with the screen real estate taken up by captions in general. For this particular situation, I'd rather suggest an assistive technology mechanism (e.g. browser extension) that places the captions in a box that is separate from the screen.

Christian


On Mon, May 12, 2014 at 8:16 AM, Philip Jägenstedt <philipj@opera.com<mailto:philipj@opera.com>> wrote:
On Mon, May 12, 2014 at 10:24 AM, Silvia Pfeiffer
<silviapfeiffer1@gmail.com<mailto:silviapfeiffer1@gmail.com>> wrote:
> On Mon, May 12, 2014 at 6:12 PM, Philip Jägenstedt <philipj@opera.com<mailto:philipj@opera.com>> wrote:
>> Using the cue box as the background box was what I did in
>> http://people.opera.com/philipj/2014/03/vttscroll/background.html

>
> There's a difference: you're putting a background on the individual
> cues while the background on the region is putting a background on the
> group of cues in one go. There is no chance of a gap appearing between
> the cues because of this.

Yes, that is true. (Trying to emulate a grid-based format should have
similar problems.)

>> 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.
>
> That's what the region is for.

Doesn't regions have exactly the problem I describe? Not that I have a
solution, I don't know how this could be made reliably when fonts and
their sizes is under user control...

>> However, if the background needs to be unchanging over time
>
> What do you mean by "unchanging"?

I mean a background which isn't just the bounding box of the cues
current showing, but those that will be shown. The author cannot know
what that box is, and calculating it at runtime would require
rendering all cues once and assuming scripts won't change them...

Philip



--
Christian Vogler, PhD
Director, Technology Access Program
Department of Communication Studies
SLCC 1116
Gallaudet University
http://tap.gallaudet.edu/

VP: 202-250-2795



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