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Overhaul exit Picture-in-Picture algorithm #260

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7ed1fed
Overhaul exit Picture-in-Picture algorithm
theIDinside Jun 16, 2026
4fb83af
Fix specfmt-caused formatting errors
theIDinside Jun 16, 2026
89b43f2
Change promise-or-null till nullable {{Promise}}
theIDinside Jun 25, 2026
a63d659
Change use of [=/Resolve]
theIDinside Jun 25, 2026
39a9130
Use if-then wording
theIDinside Jun 25, 2026
846790f
Change [=/Resolve] wording
theIDinside Jun 25, 2026
bf7bba9
Remove note, use bikeshed syntax for asserts
theIDinside Jun 25, 2026
00918f8
Better wording for exitPictureInPicture steps
theIDinside Jun 25, 2026
5330f78
Add non-fully active document checks & enqueue steps for fullscreen f…
theIDinside Jun 29, 2026
81e4c56
Unloading steps
theIDinside Jun 29, 2026
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91 changes: 57 additions & 34 deletions index.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -221,30 +221,44 @@ Picture-in-Picture window.

## Exit Picture-in-Picture ## {#exit-pip}

When the <dfn>exit Picture-in-Picture algorithm</dfn> is invoked,
the user agent MUST run the following steps:

1. If {{pictureInPictureElement}} is `null`, throw a {{InvalidStateError}} and
abort these steps.
2. Run the <a>close window algorithm</a> with the <a>Picture-in-Picture
window</a> associated with {{pictureInPictureElement}}.
3. <a>Queue a task</a> to <a>fire an event</a> named
{{leavepictureinpicture}} using {{PictureInPictureEvent}} at the
|video| with its {{bubbles}} attribute initialized to `true` and its
{{PictureInPictureEvent/pictureInPictureWindow}} attribute initialized to
<a>Picture-in-Picture window</a> associated with {{pictureInPictureElement}}.
4. Unset {{pictureInPictureElement}}.
5. Remove one <a>item</a> matching <a>relevant settings object</a>'s <a>origin</a> from
<a>initiators of active Picture-in-Picture sessions</a>.
When the <dfn>exit Picture-in-Picture algorithm</dfn> is invoked given |doc|, and nullable

@marcoscaceres marcoscaceres Jul 2, 2026

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Suggested change
When the <dfn>exit Picture-in-Picture algorithm</dfn> is invoked given |doc|, and nullable
When the <dfn>exit Picture-in-Picture algorithm</dfn> is invoked given a {{Document}} |doc|, and nullable

{{Promise}} |p|, run these steps:

1. [=Assert=] that these steps are running on the [=picture-in-picture parallel queue=].
2. Let |global| be |doc|'s [=relevant global object=].
3. Run the <a>close window algorithm</a> with the <a>Picture-in-Picture window</a> associated with
|doc|'s [=Picture-in-Picture element=].
4. [=Queue a global task=] on the [=media element event task source=] given |global|, to perform the
following steps:
1. If |doc| is not [=fully active=] or |doc|'s [=Picture-in-Picture element=] is `null`:
1. If |p| is not `null`, [=/resolve=] |p| with undefined.

@beaufortfrancois beaufortfrancois Jul 1, 2026

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I naively thought we should reject instead of resolve promise. Why not in this case?

@marcoscaceres marcoscaceres Jul 2, 2026

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Agree... this should reject with an InvalidStateError.

@marcoscaceres marcoscaceres Jul 2, 2026

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Also, these should happen both before [=Queue a global task=] and recheck after [=Queue a global task=].

See https://www.w3.org/TR/design-principles/#support-non-fully-active

@theIDinside theIDinside Jul 10, 2026 •
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Left a comment in the main thread, but I think there's an argument for that we should not be doing this check at all.

2. Return.
2. Let |element| be |doc|'s [=Picture-in-Picture element=].

@marcoscaceres marcoscaceres Jun 18, 2026

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Can element be null?

3. Set |doc|'s [=Picture-in-Picture element=] to `null`.
4. <a>Fire an event</a> named {{leavepictureinpicture}} using {{PictureInPictureEvent}} at the

@marcoscaceres marcoscaceres Jul 2, 2026

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[=Queue a task=] to perform the follow steps?

|element| with its {{bubbles}} attribute initialized to `true` and its
{{PictureInPictureEvent/pictureInPictureWindow}} attribute initialized to
<a>Picture-in-Picture window</a> associated with |element|.
5. Remove one <a>item</a> matching <a>relevant settings object</a>'s <a>origin</a> from
<a>initiators of active Picture-in-Picture sessions</a>.
6. If |p| is not `null`, [=/resolve=] |p| with undefined.

It is NOT RECOMMENDED that the video playback state changes when the <a>exit
Picture-in-Picture algorithm</a> is invoked. The website SHOULD be in control
of the experience if it is website initiated. However, the user agent MAY expose
Picture-in-Picture window controls that change video playback state (e.g.,
pause).

As one of the <a>unloading document cleanup steps</a>, run the <a>exit
Picture-in-Picture algorithm</a>.
### Unloading steps ### {#unloading-steps}

@marcoscaceres marcoscaceres Jul 16, 2026

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Talking to @chrisn, would be great to just move these over to HTML.

As one of the <a>unloading document cleanup steps</a> given |doc| run the following steps:

@marcoscaceres marcoscaceres Jul 2, 2026

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Suggested change
As one of the <a>unloading document cleanup steps</a> given |doc| run the following steps:
As one of the <a>unloading document cleanup steps</a> given {{Document}} |doc| run the following steps:

@chrisn chrisn Jul 16, 2026 •
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Suggested change
As one of the <a>unloading document cleanup steps</a> given |doc| run the following steps:
The <dfn export>picture in picture unloading steps</dfn>, given {{Document}} |doc| are:

Exported so we can call this from HTML

@chrisn chrisn Jul 16, 2026

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See whatwg/html#12689 for the corresponding HTML change.

1. If |doc|'s [=Picture-in-Picture element=] is `null`, return.
2. Let |window| be the <a>Picture-in-Picture window</a> associated with |doc|'s
[=Picture-in-Picture element=].
3. Set |doc|'s [=Picture-in-Picture element=] to `null`.
4. Remove one <a>item</a> matching <a>relevant settings object</a>'s <a>origin</a> from
<a>initiators of active Picture-in-Picture sessions</a>.
5. [=Enqueue the following steps=] to |doc|'s <a>picture-in-picture parallel queue</a>:
1. Run the <a>close window algorithm</a> with |window|.

## Disable Picture-in-Picture ## {#disable-pip}

Expand All @@ -271,8 +285,12 @@ the user agent MAY run these steps:

## Interaction with Fullscreen ## {#fullscreen}

It is RECOMMENDED to run the <a>exit Picture-in-Picture algorithm</a> when the
{{pictureInPictureElement}} <a>fullscreen flag</a> is set.
It is RECOMMENDED that when a [=Picture-in-Picture element=]'s <a>fullscreen flag</a> is set, the

@marcoscaceres marcoscaceres Jul 2, 2026

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I think we talked about this, so apologies... why is the RECOMMENDED instead of MUST?

Can we add a note here explaining why it's not a MUST requirement?

@chrisn chrisn Jul 16, 2026

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Need to invoke this from step 3 in https://fullscreen.spec.whatwg.org/#fullscreen-an-element

@chrisn chrisn Jul 16, 2026 •
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See also #191. But let's work on that in a follow up PR.

@marcoscaceres marcoscaceres Jul 16, 2026

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Right, yeah... it's basically transitioning in/out of fullscreen otherwise PiP,

user agent runs these steps:

1. Let |doc| be the [=Picture-in-Picture element=]'s [=node document=].
2. [=Enqueue the following steps=] to |doc|'s <a>picture-in-picture parallel queue</a>:
1. Run the <a>exit Picture-in-Picture algorithm</a> given |doc| and `null`.

## Interaction with Page Visibility ## {#page-visibility}

Expand Down Expand Up @@ -340,18 +358,19 @@ The {{requestPictureInPicture()}} method steps <dfn export>request Picture-in-Pi
[=/reject=] |p| with {{InvalidStateError}} {{DOMException}}.
2. Abort these steps.
4. Let |pipWindow| be a new instance of {{PictureInPictureWindow}} that represents [=this=]'s associated [=Picture-in-Picture window=].
5. [=Queue a global task=] on the [=media element event task source=] given |global|, to perform
5. If |doc|'s [=Picture-in-Picture element=] is not `null`, run the [=exit Picture-in-Picture
algorithm=] given |doc| and `null`.
6. [=Queue a global task=] on the [=media element event task source=] given |global|, to perform
the following steps:
1. If {{pictureInPictureElement}} is not `null`, run the [=exit Picture-in-Picture algorithm=].
2. Set |doc|'s [=Picture-in-Picture element=] to [=this=].
3. [=list/Append=] [=relevant settings object=]'s [=origin=] to [=initiators of active
1. Set |doc|'s [=Picture-in-Picture element=] to [=this=].
2. [=list/Append=] [=relevant settings object=]'s [=origin=] to [=initiators of active
Picture-in-Picture sessions=].
4. If [=this=] is [=fullscreenElement=], [=exit fullscreen=].
5. [=Fire an event=] named {{enterpictureinpicture}} using {{PictureInPictureEvent}} at
3. If [=this=] is [=fullscreenElement=], then [=exit fullscreen=].
4. [=Fire an event=] named {{enterpictureinpicture}} using {{PictureInPictureEvent}} at
[=this=] with its {{bubbles}} attribute initialized to `true` and its
{{PictureInPictureEvent/pictureInPictureWindow}} attribute initialized to
[=Picture-in-Picture window=].
6. [=/Resolve=] |p| with |pipWindow|.
5. [=/Resolve=] |p| with |pipWindow|.


## Extensions to <code>Document</code> ## {#document-extensions}
Expand All @@ -372,14 +391,18 @@ The {{pictureInPictureEnabled}} attribute's getter must return `true` if
<dfn>Picture-in-Picture support</dfn> is `false` if there's a user preference
that disables it or a platform limitation. It is `true` otherwise.

The {{exitPictureInPicture()}} method, when invoked, MUST
return <a>a new promise</a> |promise| and run the following steps <a>in
parallel</a>:

1. Run the <a>exit Picture-in-Picture algorithm</a>.
2. If the previous step threw an exception, reject |promise| with that
exception and abort these steps.
3. [=/Resolve=] |promise|.
The {{exitPictureInPicture()}} method, when invoked, runs the following steps:

1. If [=this=]'s [=Picture-in-Picture element=] is `null` or [=this=] is not [=fully active=],
return [=a promise rejected with=] {{InvalidStateError}} {{DOMException}}.
Comment on lines +396 to +397

@beaufortfrancois beaufortfrancois Jul 1, 2026

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Nit:

Suggested change
1. If [=this=]'s [=Picture-in-Picture element=] is `null` or [=this=] is not [=fully active=],
return [=a promise rejected with=] {{InvalidStateError}} {{DOMException}}.
1. If [=this=] is not [=fully active=],
return [=a promise rejected with=] {{InvalidStateError}} {{DOMException}}.
2. If [=this=]'s [=Picture-in-Picture element=] is `null`,
return [=a promise rejected with=] {{InvalidStateError}} {{DOMException}}.

@beaufortfrancois beaufortfrancois Jul 1, 2026

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Can we also have web-platform tests along this PR to help figuring out what needs to be fixed in different implementations?

@theIDinside theIDinside Jul 10, 2026

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I actually wrote a postMessage web platform tests specifically for this "not fully active" scenario, and it involves actually testing that something "did not happen" - and we wouldn't be able to test this here, I think. This promise will never get resolve or rejected, I believe. It should just be doing the null check.

2. Let |p| be [=a new promise=] created in [=this=]'s [=relevant realm=].
3. Return |p|, and [=enqueue the following steps=] to [=this=]'s [=picture-in-picture parallel
queue=]:
1. If [=this=]'s [=Picture-in-Picture element=] is `null`:
1. [=Queue a global task=] on the [=media element event task source=] given [=this=]'s
[=relevant global object=] to [=/resolve=] |p|.
2. Return.
2. Run the <a>exit Picture-in-Picture algorithm</a> given [=this=] and |p|.

## Extension to <code>DocumentOrShadowRoot</code> ## {#documentorshadowroot-extension}

Expand Down
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