Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: cdfe0c37be223e40aeb95a9766b80fba4e0f5a5e
https://github.com/WebKit/WebKit/commit/cdfe0c37be223e40aeb95a9766b80fba4e0f5a5e
Author: Alan Baradlay <[email protected]>
Date: 2026-10-09 (Fri, 09 Oct 2026)
Changed paths:
M LayoutTests/TestExpectations
A
LayoutTests/imported/w3c/web-platform-tests/css/css-overflow/line-clamp/line-clamp-dynamic-removal-expected.html
A
LayoutTests/imported/w3c/web-platform-tests/css/css-overflow/line-clamp/line-clamp-dynamic-removal.html
A
LayoutTests/imported/w3c/web-platform-tests/css/css-overflow/line-clamp/reference/line-clamp-dynamic-removal-ref.html
M
Source/WebCore/layout/formattingContexts/inline/display/InlineDisplayBoxInlines.h
M Source/WebCore/rendering/LineClampUpdater.cpp
M Source/WebCore/rendering/LineClampUpdater.h
M Source/WebCore/rendering/RenderBlockFlow.cpp
Log Message:
-----------
[line-clamp] Block boxes after the clamp point are still visible
https://bugs.webkit.org/show_bug.cgi?id=326848
<rdar://problem/189543433>
Reviewed by Antti Koivisto.
<div style="line-clamp: 2"><div>Line 1<br>Line 2<br>Line 3</div><div
style="background-color: red">Line 4</div></div>
Line 3 is gone, but the red box after the clamp point (and its "Line 4") still
paints.
"Within a line-clamp container, the following boxes and line boxes become
invisible boxes: Any in-flow or floating boxes
that follow the clamp point in the box tree."
https://drafts.csswg.org/css-overflow-4/#line-clamp-containers
Now block layout marks each in-flow child that comes after the clamp point (the
line-clamp budget is used up), and every
renderer in it, hidden by line-clamp, which makes their used visibility hidden.
This happens before the child's own
layout and only when the child changes between visible and hidden, so the
subtree is walked once per change, and a box
that stops being a line-clamp container shows its content again. An out-of-flow
box in it is only hidden when its
containing block is in it too ("Any absolutely positioned box which has an
invisible box within its containing block
chain, and all of its descendants."). Inline display boxes now take their
visibility from the used style of their renderer, so text and inline boxes
inside such a block are hidden too.
These boxes still take up space; that is a separate change.
Tests:
imported/w3c/web-platform-tests/css/css-overflow/line-clamp/line-clamp-dynamic-removal.html
imported/w3c/web-platform-tests/css/css-overflow/line-clamp/reference/line-clamp-dynamic-removal-ref.html
* LayoutTests/TestExpectations: 18 tests pass now.
*
LayoutTests/imported/w3c/web-platform-tests/css/css-overflow/line-clamp/line-clamp-dynamic-removal-expected.html:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/css/css-overflow/line-clamp/line-clamp-dynamic-removal.html:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/css/css-overflow/line-clamp/reference/line-clamp-dynamic-removal-ref.html:
Added.
*
Source/WebCore/layout/formattingContexts/inline/display/InlineDisplayBoxInlines.h:
(WebCore::InlineDisplay::Box::isVisible const):
* Source/WebCore/rendering/LineClampUpdater.cpp:
(WebCore::LineClampUpdater::isAfterClampPoint):
(WebCore::LineClampUpdater::setIsForcedHidden):
* Source/WebCore/rendering/LineClampUpdater.h:
* Source/WebCore/rendering/RenderBlockFlow.cpp:
(WebCore::RenderBlockFlow::layoutBlockChild):
Canonical link: https://commits.webkit.org/323220@main
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