github web-platform-tests/wpt merge_pr_46685

latest releases: merge_pr_49470, epochs/three_hourly/2024-12-03_06H, epochs/six_hourly/2024-12-03_06H...
6 months ago

[anchor] Update OOF style correctly when nothing fits

We currently have a bug when updating the OOF style for an element
that:

  • Does not contain any anchor*() functions (or similar).
  • Has an overflowing base style.
  • Has at least one item in position-try-options, all of which overflow.

In the above case, neither the base attempt nor the position-try-option
attempts are successfully placed within the CB, and during OOF style
iteration (OOFCandidateStyleIterator) we then go back to the base
styles. The problem is that this we'll then call UpdateStyleForOutOfFlow
with try_set=nullptr and tactic_list=, which (absent any anchor()
queries) causes the current logic to think that no update is needed.
However, the ComputedStyle currently held by the element is the style
from the last (failed) position-try attempt, so an update is needed
if we want to back to base.

To fix this:

  • A call to UpdateStyleForOutOfFlow is now unconditional.
    It will always recalculate the style.
  • When OOFCandidateStyleIterator is initialized, we check if
    we depend on anchor*() queries, and if so update the style.
    This initialization is reached by all OOFs, not just those that
    use anchor positioning features.
  • All other calls to UpdateStyle in OOFCandidateStyleIterator
    will always lead to a style recalc. That's because these calls only
    take place when there's some position-try-option being processed,
    which are exactly the cases where we always need to recalc the style.

Fixed: 339686368
Change-Id: I046e20527e29924d8b6fbbd794232f51b7a2bb59
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5616572
Reviewed-by: Rune Lillesveen futhark@chromium.org
Commit-Queue: Anders Hartvoll Ruud andruud@chromium.org
Cr-Commit-Position: refs/heads/main@{#1313301}

Don't miss a new wpt release

NewReleases is sending notifications on new releases.