- From: Philip Jägenstedt <philipj@opera.com>
- Date: Mon, 5 May 2014 14:14:16 +0200
- To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- Cc: "public-texttracks@w3.org" <public-texttracks@w3.org>
On Mon, May 5, 2014 at 1:33 PM, Silvia Pfeiffer <silviapfeiffer1@gmail.com> wrote: > On Mon, May 5, 2014 at 7:58 PM, Philip Jägenstedt <philipj@opera.com> wrote: >> On Tue, Apr 8, 2014 at 9:06 AM, Silvia Pfeiffer >> <silviapfeiffer1@gmail.com> wrote: >>> On Sun, Mar 30, 2014 at 4:41 PM, Philip Jägenstedt <philipj@opera.com> wrote: >>>> >>>> == 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. >>> >>> There is a difference between the background on the cue and the >>> background on the region. CEA708 distinguishes between the two. >> >> The only thing you can style in WebVTT now is the "WebVTT cue >> background box", which I called the "line box" above because it's an >> inline element that behaves like a <span> wrapping the text. >> >> My tweak was to style the cue box itself, a box for which there is no >> pseudo-element currently but there could be. >> >> In other words, there would still be two things to set a background on. > > Right. We need three concepts for putting backgrounds on: we need the > line box, the cue box, and the group of cues - the latter of which is > for CEA708. There's currently no way to style the cue box. Are there clear use cases for styling the cue box, other than faking a region as in my case? >>> That works well for individual cues. It works badly for groups of cues >>> that are in a region. Try zooming the page in and out with your demo. >>> At some points you will see a line going through the otherwise solid >>> box. That's because we're faking a solid square through its individual >>> line components. That's bound to come back and hurt us, in particular >>> if somebody decides to make the individual lines not the same width. >>> >>> I'm not a fan of faking it in this way. >> >> OK, this is a problem. The same problem will happen when trying to map >> the fixed-grid 608 to WebVTT, because you'll get numerical errors when >> trying to get exactly 15 rows of text and the backgrounds of the >> individual lines won't line up as they should. Any ideas for how to >> fix that? > > I don't follow: how is that the same problem? > > In any case, the 608 spec at > https://dvcs.w3.org/hg/text-tracks/raw-file/default/608toVTT/608toVTT.html > has a line height of 5.33% to make 15 rows on 80% of the screen > height. That gives an error or 0.05% which is likely acceptable. Since > we've moved to floats for percentages, we've done much better than > before when it was all int. In my demo the boxes are exactly aligned and you still get gaps when zooming. In other words, you'll have the same problem even if you manage to get 15 exactly aligned lines. Philip
Received on Monday, 5 May 2014 12:14:44 UTC