1327061 - Closed captions twitch when I change zoom level in DOM fullscreen

Status: NEW

(Toolkit :: Video/Audio Controls, defect, P5)

Description

[arni2033]

>>>   My Info:   Win7_64, Nightly 53, 32bit, ID 20161119030204 (2016-11-19)
STR_1:
1. Open https://www.iandevlin.com/html5test/webvtt/html5-video-webvtt-sample.html
2. Click fullscreen button in video controls
3. Seek video to 0:20
4. Hold Ctrl key and rotate mouse wheel up or down several times

AR:  Closed captions twitch
ER:  Closed captions shouldn't twitch

This feature was implemented in broken state in bug 887934. Regression range:
> https://hg.mozilla.org/integration/fx-team/pushloghtml?fromchange=0d361d105c86ff3443c06a7387b994d75035178e&tochange=a1746be133dff55de7588c846aaafbc30534b8bd

This was slightly fixed in bug 1283417. Pushlog:
> https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=f38875b13ca370bf23407270ddc9ad7fe21e16fa&tochange=b47abe0917b074d95b7e240a8deda72bf4a71b84

Comment 1

[Ray Lin[:ralin]]

There's three events might trigger caption-box re-style:
1. seeking
2. video size changed
3. control show/hide

I guess by following the STR would call several times of async re-style task in a short time, that might why CC twitches. I don't think bug 887934 was in regression range as bug 887934 just introduced CC features to UI, and there's no reason to affect caption box rendering. This issue could be somehow optimized to resize smoothly, but I don't see its importance to fix right away since users don't zoom in/out in fullscreen times in moment also CC displays fine in the end.