Fix tasks for enterPictureInPicture and exitPictureInPicture. by markafoltz · Pull Request #233 · w3c/picture-in-picture

markafoltz · 2024-09-26T23:57:25Z

Closes #230: ensures that Promises returned by these methods use the media element task source.

Also fixes several ambiguous cross references.

markafoltz · 2024-09-27T00:02:18Z

Should also close #225

beaufortfrancois · 2024-09-27T12:47:14Z

@markafoltz From what I can see in https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/modules/document_picture_in_picture/picture_in_picture_controller_impl.cc;l=158?q=kMediaElementEvent%20f:picture&ss=chromium%2Fchromium%2Fsrc, Chromium's implementation will no longer comply with the spec. I may be wrong about this but is this what we want ?

Note that this PR is related to #229

markafoltz · 2024-09-27T16:33:19Z

It should be impossible to fire events or resolve promises off of the main thread in Blink, so where do you see Chrome not complying? (Sorry I don't know the PiP code.)

markafoltz · 2024-09-27T17:17:24Z

Thanks for the pointer as well, this should also close #229

beaufortfrancois · 2024-09-28T05:45:12Z

It should be impossible to fire events or resolve promises off of the main thread in Blink, so where do you see Chrome not complying? (Sorry I don't know the PiP code.)

Like I said, I may be wrong, but https://source.chromium.org/search?q=kMediaElementEvent%20f:picture&sq=&ss=chromium%2Fchromium%2Fsrc returns results where we specifically use the media element task source in Picture-in-Picture, and I'm not sure it covers all the cases you've updated in this PR.

An example would be the user agent MUST <a>queue a picture-in-picture task</a> to <a>fire an event</a> named {{resize}} at {{pictureInPictureElement}}. at https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/modules/picture_in_picture/picture_in_picture_window.cc;l=30;drc=f522344e45882da4c7f7cb1b3a0a7bd747d654bb
I believe we should be using something like EnqueueEvent(*Event::Create(event_type_names::kResize), TaskType::kMediaElementEvent); instead of synchronously dispatching the event with DispatchEvent(*Event::Create(event_type_names::kResize)); like we do today.

marcoscaceres · 2025-10-16T11:35:56Z

 The <a>task source</a> for all the tasks queued in this specification is the
 <a>media element event task source</a> of the video element in question.

+When an algorithm <dfn lt="queue a picture-in-picture task">queues a


I wonder if we should just reuse [[queue a media element task]] instead:
https://html.spec.whatwg.org/multipage/media.html#queue-a-media-element-task

That takes a media element instead it seems... that might make more sense?

marcoscaceres · 2025-12-04T10:51:14Z

+4. [=Queue a picture-in-picture task=] to [=/resolve=] |promise| with the
+    <a>Picture-in-Picture window</a> associated with {{pictureInPictureElement}}.


Suggested change

4. [=Queue a picture-in-picture task=] to [=/resolve=] |promise| with the

<a>Picture-in-Picture window</a> associated with {{pictureInPictureElement}}.

4. [=Queue a picture-in-picture task=] to [=/resolve=] |promise| with the

{{pictureInPictureElement}}'s [=picture-in-Picture window=].

marcoscaceres · 2025-12-04T10:52:07Z

-2. If the previous step threw an exception, reject |promise| with that
+2. If the previous step threw an exception,
+    [=queue a picture-in-picture task=] to reject |promise| with that
    exception and abort these steps.


Suggested change

exception and abort these steps.

[=exception=] and abort these steps.

marcoscaceres · 2025-12-04T10:52:14Z


 1. Run the <a>exit Picture-in-Picture algorithm</a>.
-2. If the previous step threw an exception, reject |promise| with that
+2. If the previous step threw an exception,


Suggested change

2. If the previous step threw an exception,

2. If the previous step threw an [=exception=],

marcoscaceres · 2025-12-04T10:53:07Z

+{{pictureInPictureElement}} changes, the user agent MUST
+<a>queue a picture-in-picture task</a> to <a>fire an event</a> named
+{{resize}} at {{pictureInPictureElement}}.


Suggested change

{{pictureInPictureElement}} changes, the user agent MUST

<a>queue a picture-in-picture task</a> to <a>fire an event</a> named

{{resize}} at {{pictureInPictureElement}}.

{{pictureInPictureElement}} changes, the user agent MUST

<a>queue a picture-in-picture task</a> to [=/fire an event=] named

"{{resize}}" at {{pictureInPictureElement}}.

theIDinside · 2026-02-07T13:24:44Z

I want to suggest the PR I've written which covers this, for requestPictureInPicture, but also makes sure to address more issues than just firing events and resolving. There are other problems.

It's re-written the requestPictureInPicture to look and behave similar to similar algorithms like the fullscreen algorithm requestFullscreen. I think it's nice to have some consistency between specs, beyond the technical details like correctness.

#245

marcoscaceres · 2026-03-12T11:45:59Z

Ok, I'm going to say #245 closes #233.

…not possible Restructures the requestPictureInPicture() algorithm to handle parallel window creation more robustly. The algorithm now creates the Picture-in-Picture window in parallel, then queues subsequent DOM mutations and promise resolutions as a separate task. Key changes: - Steps 1-9 run synchronously with validation checks - Step 10 returns the promise and runs remaining steps in parallel - Within the parallel section, a global task is queued to handle DOM mutations, fire events, and resolve/reject the promise - Enforces one Picture-in-Picture element per top-level browsing context - Mandatorily exits fullscreen when entering PiP - Exits previous PiP session when a new one is requested Addresses #244, #233, and #229. Co-authored-by: Marcos Cáceres <marcos@marcosc.com>

Fix tasks

5d9f665

markafoltz requested a review from beaufortfrancois September 27, 2024 00:01

markafoltz self-assigned this Sep 27, 2024

This was linked to issues Sep 27, 2024

Disable Picture-in-Picture steps should queue a task #225

Open

Investigate if the algorithm and the implementations need to be updated #229

Closed

marcoscaceres reviewed Oct 16, 2025

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marcoscaceres added the TPAC2025 Agenda topic for TPAC 2025 label Oct 16, 2025

marcoscaceres reviewed Dec 4, 2025

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chrisn removed the TPAC2025 Agenda topic for TPAC 2025 label Dec 4, 2025

marcoscaceres mentioned this pull request Feb 26, 2026

Address requestPictureInPicture() algorithm #245

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theIDinside mentioned this pull request Mar 10, 2026

Candidate Recommendation tracking issue #219

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marcoscaceres closed this in #245 May 21, 2026

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Fix tasks for enterPictureInPicture and exitPictureInPicture.#233

Fix tasks for enterPictureInPicture and exitPictureInPicture.#233
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		4. [=Queue a picture-in-picture task=] to [=/resolve=] \|promise\| with the
		<a>Picture-in-Picture window</a> associated with {{pictureInPictureElement}}.

	exception and abort these steps.
	[=exception=] and abort these steps.

	2. If the previous step threw an exception,
	2. If the previous step threw an [=exception=],

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