Re: Unifying regions and non-regions layout algorithms

On Nov 21, 2013, at 14:54 , Philip Jägenstedt <philipj@opera.com> wrote:

> So, I have been to FOMS, and there was a lot of talk about WebVTT.
> 
> One of the things we discussed was how to integrate WebVTT Regions
> more deeply into the spec, to not make it look like something bolted
> on to the side. The different layout algorithms for the regions and
> non-regions cases is a key component here.

Bother

certainly, I tried to make suggestions that matched the overall idea that layout (as previously defined) happened within a ‘region’ which, by default, was the entire area assigned to the VTT, and that all the regions bolt-on did was define smaller sub-spaces in which the same layout occurred.  Did we fail?

> 
> I would like to see if we can make regions do nothing other than
> constrain the space available to layout algorithm, so that rendering
> in a region is equivalent to rendering in a smaller video element,
> with the only exception that the vh/vw units would still be relative
> to the entire video.
> 
> As a consequence, scrolling would become possible for any cue, in a
> region or not. I haven't actually read the current spec, but I imagine
> the following. First position the cue in its preferred location. If it
> overlaps any other cue, it move it down until it does not overlap.
> Then it would be moved up, pushing along with it as many cues as are
> necessary to not cause (new) overlap. This "push" may be animated or
> not, subject to author stylesheet and user preference.
> 
> The missing bit is how to switch between the two kinds of overlap
> avoidance we end up with. Here I would suggest making this a cue-level
> setting, and as a possible optimization have global and region-level
> default for cues with no such setting.
> 
> Is this something people are interested in exploring?
> 
> (Many other issues were also discussed, but I think most are
> orthogonal to what I've described here, and can be given separate
> threads. If you would like to explore why I suddenly don't hate
> regions, let's do that on another thread, assuming in this one that
> regions will not just go away.)
> 
> Philip
> 

David Singer
Multimedia and Software Standards, Apple Inc.

Received on Friday, 22 November 2013 01:05:33 UTC