How to set a nested strategy #3

Activity

1. jdapena commented on Feb 13, 2025

   

   jdapena

   on Feb 13, 2025

   Contributor

   More actions

   The proposal with PerformanceObserverInit has two problems:

   • It requires to change PerformanceObserverInit to add the new fields. This is shared with other timing events and would get a new field that is only usable for ContainerTiming.
   • We cannot know the nesting policy when the events are happening. So, when painting happens, and the information is stored, we need to store all the information for the 3 nesting modes.

   As a solution I am proposing (and implementing) a new approach that consist of defining a new attribute, containertiming-nesting for specifying the policy. This attribute gets the same values discussed before (ignore, transparent, shadowed). This way, when a paint needs to be processed, we already know the propagation rules, so we can immediately register the paint in all the roots that expect the value.
2. aarongable

   added a commit that references this issue on Aug 22, 2025

   ContainerTiming: add containerTimingNesting attribute support

   ...

   a09b5bd
3. chromium-wpt-export-bot

   added 2 commits that reference this issue on Aug 22, 2025

   ContainerTiming: add containerTimingNesting attribute support

   ...

   248d432

   ContainerTiming: add containerTimingNesting attribute support

   ...

   e78317d
4. lando-worker

   added a commit that references this issue on Aug 28, 2025

   Bug 1984620 [wpt PR 54456] - ContainerTiming: add containerTimingNest…

   ...

   0c7b295
5. jasonwilliams commented on Nov 5, 2025

   

   jasonwilliams

   on Nov 5, 2025

   CollaboratorAuthor

   More actions

   https://github.com/bloomberg/container-timing/blob/main/docs/container-definitions.md addresses this issue.
6. chromium-wpt-export-bot

   added a commit that references this issue on Nov 18, 2025

   ContainerTiming: drop containertiming-nesting and behave always as tr…

   ...

   d51b01a
7. aarongable

   added a commit that references this issue on Nov 18, 2025

   ContainerTiming: drop containertiming-nesting and behave always as tr…

   ...

   6a36f65
8. chromium-wpt-export-bot

   added 2 commits that reference this issue on Nov 18, 2025

   ContainerTiming: drop containertiming-nesting and behave always as tr…

   ...

   615b6e5

   ContainerTiming: drop containertiming-nesting and behave always as tr…

   ...

   8d6f5b9
9. lando-worker

   added a commit that references this issue on Nov 19, 2025

   Bug 2000897 [wpt PR 56094] - ContainerTiming: drop containertiming-ne…

   ...

   9c9a814
10. gecko-dev-updater

    added 3 commits that reference this issue on Nov 20, 2025

    Bug 2000897 [wpt PR 56094] - ContainerTiming: drop containertiming-ne…

    ...

    6f36972

    Bug 2000897 [wpt PR 56094] - ContainerTiming: drop containertiming-ne…

    ...

    6037bab

    Bug 2000897 [wpt PR 56094] - ContainerTiming: drop containertiming-ne…

    ...

    2eef272
11. jdapena commented on Aug 14, 2026

    

    jdapena

    on Aug 14, 2026

    Contributor

    More actions

    Final nested strategy has been landed already:

    • containertiming always propagates to parents (so paints are propagated to all containertiming root ancestors.
    • containertimingignore blocks propagation to parents.

    The old containertiming-nesting attribute is gone.

    I don't have permission to close this. @jasonwilliams < Could you close?