[selectors] Add :picture-in-picture pseudo-class

[svoisen]

See https://wicg.github.io/picture-in-picture/#css-pseudo-class

The Picture-in-Picture WICG spec proposes adding a pseudo for the picture-in-picture element.

Blink has an intent-to-ship for this pseudo: https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/X-qPSmdSR_g/StUMNNiQAwAJ

[css-meeting-bot]

The CSS Working Group just discussed Add :picture-in-picture pseudo-class, and agreed to the following:

• RESOLVED: add :picture-in-picture and :fullscreen to Selectors 4

The full IRC log of that discussion

Topic: Add :picture-in-picture pseudo-class
github: https://github.com//issues/3796
plinss: Anyone want to talk to this?
fantasai: I don't know too much about this, but it's being shipped by Google immenantly. Generally we put all pseudo classes in selectors so looks like MOz filed an issue to haveit in selectors
fantasai: But I don't know much about what they're about to ship
smfr: Read but was confused about when it applies. I'd like to to say this applies when showing picture-in-picture mode or something like that
fantasai: Is picture-in-picture mode defined?
smfr: Spec defines but not readable by humans except the 2 that know about shadow dom
The shadow dom thing is broken in the spec
AmeliaBR: Looking quickly it's confusing about if this is pseudo class or element. WICG spec desc seems to desc a
fantasai: It's a pseudo class
AmeliaBR: An element that's an active element in the doc. There's also an extra window object.
AmeliaBR: I agreewith smfr the spec needs some work from css people to make sure it's def clear on consistent. Logically makes sense it's a think like fullscreen pseudo class.
AmeliaBR: Someone needs to work on spec
fantasai: Not sure we define fullscreen either
https://drafts.csswg.org/selectors-4/#resource-pseudos
fantasai: WE should add both or neither and have a note about additional selectors. I guess in section 11
s/and have/or have/
myles: Reason these psuedo elements need to be inside our specs?
fantasai: Generally...for the most part we have all selectors in selectors so if you're looking for one you can find it. Detailed desc is deferred to the host spec. But we define it exists and roughly wha tit means
fantasai: Haven't done for full screen or this
gregwhitworth: I'd like it in selectors spec
fantasai: Currently specs that define selectors or css prop not in WG should ask CSSWG members to review specs before shipping, but that's a separate issue
AmeliaBR: Where ever defined needs to be reviewed to be logically consistent. Easier to do if there's a mention in selectors that links out
plinss: Agree this should be in css specs
https://wicg.github.io/picture-in-picture/#htmlvideoelement-extensions
plinss: Do we know where rest of picture-in-picture will spec? Merge into HTML? Spec?
gregwhitworth: I found wicg document but I can ping the person on our team and find out
AmeliaBR: If following fullscreen pattern it's stand alone in WHATWG
fantasai: And for us to cross reference we need to know where the spec will perm. live. If it doesn't have a plan where it should be it needs one. ANd get buy in from people besides Google
plinss: That's what I was driving at. Are other impl on board with this and whatnot
plinss: Sounds like we agree if this moves forward pseudo class should be in our specs. Not sure what we should do with this issue right now
plinss: Other thoughts?
smfr: Webkit supports impl but want a better spec. I think there's enough to give feedback to authors
fantasai: Whole spec shouldn't be CSS. We should add a section to selectors for fullscreen and picture-in-picture. Someone should give feedback to the authors. And we should say hey we need to link to your spec, are you putting it through a standards process somewhere?
plinss: Resolution to add :picture-in-picture and :fullscreen to Selectors?
plinss: Or just leave a note that's where they should live and corrdinate
fantasai: Add an put an issue in there to link to spec once it's somewhere
AmeliaBR: 4 or 5? What's the status of when not quite stable things should be...
fantasai: :fullscreen should def be 4. There's no level 5 so they should go in there. It's being impl so I'm not concerned
plinss: Objections?
RESOLVED: add :picture-in-picture and :fullscreen to Selectors 4

[gregwhitworth]

So the currently active specification for PIP is indeed this WICG one: https://wicg.github.io/picture-in-picture/

[fantasai]

@gregwhitworth Are there any plans to put it through a standards process or is it planning to live in WICG forever?

[gregwhitworth]

@fantasai I spoke with the PM that is driving this spec work and they said that they intend to migrate it to the Media WG which is actively being chartered, so once that is completed you should see it migrate there.