Closed Bug 1922856 Opened 1 year ago Closed 1 year ago

[wpt-sync] Sync PR 48482 - [line-clamp] Always clamp immediately after a line box

Categories

(Core :: Layout: Scrolling and Overflow, task, P4)

Product:
Core
Component:
Layout: Scrolling and Overflow
Type:
task

Tracking

()

Status:
RESOLVED FIXED
Milestone:
133 Branch
Tracking Flags:
Tracking Status
firefox133 --- fixed

People

(Reporter: wpt-sync, Unassigned)

References

(
URL
)

Details

(Whiteboard: [wptsync downstream])

Sync web-platform-tests PR 48482 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/48482
Details from upstream follow.

Andreu Botella <abotella@igalia.com> wrote:

[line-clamp] Always clamp immediately after a line box

In our initial implementation of line-clamp: auto, we allowed
clamping after lineless boxes, in order to better match the behavior
of line-clamp as it follows from the spec's continue: discard
model, even though our implementation uses a different model which is
not yet in the specification (see
https://github.com/w3c/csswg-drafts/issues/7708).

However, in hallway conversations in TPAC 2024, we agreed that it
would be better for this model to instead only allow clamping
immediately after a line. If the first line does not fit, we calmp at
the first line even if that overflows the clamp height. If there are
no lines, we do not clamp. This patch implements this.

Additionally, a previous patch (https://crrev.com/c/5868971) had
increased the memory size of LineClampData from 8 to 20 bytes,
causing a memory regression. This patch shrinks it to 12 bytes, since
LineClampData no longer needs to keep track of how many block boxes
there are between the last line and the clmap point, and now OOFs
after the clamped line behave the same when clamping by a number of
lines or by a height, so there is no need for a flag to distinguish
these behaviors. This patch also adds a size assertion for
LineClampData.

This patch also changes or removes some WPT tests that were written
assuming the previous behavior.

Bug: 40336192, 368114054
Change-Id: I8c8afebb5dc566de92112cee2fcf24a2e60b42c8
Reviewed-on: https://chromium-review.googlesource.com/5904459
WPT-Export-Revision: b26ebce42446d7ded872d62a1f1b2da5f0d9001a

Component: web-platform-tests → Layout: Scrolling and Overflow
Product: Testing → Core

CI Results

Ran 9 Firefox configurations based on mozilla-central, and Firefox, Chrome, and Safari on GitHub CI

Total 4 tests

Status Summary

Firefox

FAIL: 4

Chrome

FAIL: 4

Safari

FAIL: 4

Links

Gecko CI (Treeherder)
GitHub PR Head
GitHub PR Base

Details

New Tests That Don't Pass

Pushed by wptsync@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/5751601c841d [wpt PR 48482] - [line-clamp] Always clamp immediately after a line box, a=testonly

https://hg.mozilla.org/mozilla-central/rev/5751601c841d

Status: NEW → RESOLVED
Closed: 1 year ago
status-firefox133: --- → fixed
Resolution: --- → FIXED
Target Milestone: --- → 133 Branch
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