- From: Philip Jägenstedt <philipj@opera.com>
- Date: Tue, 1 Apr 2014 10:06:32 +0700
- To: Richard Eyre <rick.eyre@outlook.com>
- Cc: "public-texttracks@w3.org" <public-texttracks@w3.org>
Hi Rick! The simple answer is that I still don't know exactly what syntax and API changes I would propose, I'm still trying to figure out precisely what the 608/708 model is at the lowest level and whether or not making that model blend with WebVTT is something I could get behind. However, to support things as in the final absolute.html example, the changes would be something like this: * Reduce VTTRegion to just scroll and lines * Make scrolling part of the overlap avoidance algorithms * Maybe some change to how backgrounds are handled * A mode of clipping scrolling cues that is more complex that the current spec, which AFAICT is necessary to make cues keep scrolling once the region is full. To avoid later being accused of less-than-fair play, I'll note that I still think it's more sane for this stuff to be done using JavaScript, but I'm hedging my bets in case some browser vendor feel obligated to support these features declaratively. (If so, speak up!) Philip On Tue, Apr 1, 2014 at 4:58 AM, Richard Eyre <rick.eyre@outlook.com> wrote: > This looks good Philip. Regions would still have to exist in markup though, > correct? In order to comply with 608/708, I forget which one. > > Do you have an example of how the specification would change to implement > this new method? > > > On Sun, Mar 30, 2014 at 1:41 AM, Philip Jägenstedt <philipj@opera.com> > wrote: >> >> Hi all, >> >> As promised, I have put together demos to illustrate how the >> alternative approach to scrolling [1,2] would work in practice. The >> way I have gone about this is to assume a baseline of WebVTT without >> regions, and to try to solve each problem in the simplest way I could >> find. The demos make use of basic TextTrack and WebVTT support. I've >> tested them in Opera, Safari and Chrome. >> >> == Scrolling as an overlap avoidance == >> >> Demo: http://people.opera.com/philipj/2014/03/vttscroll/simple.html >> >> When a cue overlaps, it's moved down until it doesn't overlap, then >> all the cues are moved up. Scrolling is implemented by moving cues, >> not their container. >> >> This approach makes things much more similar to the regular overlap >> avoidance. You will end up with cues occupying approximately the same >> space in both modes, the only difference is the order. >> >> == Background box tweaking == >> >> Demo: http://people.opera.com/philipj/2014/03/vttscroll/background.html >> >> WebVTT doesn't do a good job with the cue background right now. The >> only thing you can put a background on is the line box. One small >> improvement to this would be to allow a background on the cue box >> instead. This demo does exactly that, and visually it looks the same >> as a single region background. >> >> == Clipping to a maximum number of lines == >> >> Demo: http://people.opera.com/philipj/2014/03/vttscroll/clip.html >> >> In the demo captions there can be 4 lines visible at the same time, >> but the top line is a bit distracting. This demo implements a possible >> solution for this problem, by clipping the group of cues to a maximum >> number of lines. >> >> == Absolute positioning and scrolling == >> >> Demo: http://people.opera.com/philipj/2014/03/vttscroll/absolute.html >> >> Finally, an idea for how scrolling might work with absolutely >> positioned cues. You simply position all the cues at the point where >> scrolling should begin, and they'll scroll up from there. >> >> [1] >> http://lists.w3.org/Archives/Public/public-texttracks/2013Nov/0012.html >> [2] >> http://lists.w3.org/Archives/Public/public-texttracks/2014Jan/0025.html >> >> Philip >> >
Received on Tuesday, 1 April 2014 03:07:00 UTC