Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 40f2d454bc8084bbc80e188b6595dcc3d883dad2
https://github.com/WebKit/WebKit/commit/40f2d454bc8084bbc80e188b6595dcc3d883dad2
Author: Alan Baradlay <[email protected]>
Date: 2026-05-14 (Thu, 14 May 2026)
Changed paths:
A
LayoutTests/imported/w3c/web-platform-tests/css/css-flexbox/flex-svg-no-intrinsic-column-001-expected.html
A
LayoutTests/imported/w3c/web-platform-tests/css/css-flexbox/flex-svg-no-intrinsic-column-001-ref.html
A
LayoutTests/imported/w3c/web-platform-tests/css/css-flexbox/flex-svg-no-intrinsic-column-001.html
M Source/WebCore/rendering/RenderFlexibleBox.cpp
Log Message:
-----------
[Flex] SVG image with no intrinsic dimensions collapses to height 0 in column
flex container
https://bugs.webkit.org/show_bug.cgi?id=314774
Reviewed by Antti Koivisto.
<div style="display: flex; flex-direction: column; width: 150px; height: 0">
<img src="data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' />">
</div>
The image should be 150x150 (the spec's "use 150px for the height" fallback for
boxes without a preferred aspect ratio). Instead it was 150x0 - the flex
algorithm took its automatic minimum size from a bogus aspect-ratio computation
that returned 0.
flexItemHasComputableAspectRatio used "intrinsicSize().height() != 0" as a
shortcut for "this item has a real aspect ratio". RenderReplaced caches a
(300, 150) fallback intrinsic for boxes with no real intrinsic dimensions, so
the check returned true even for our empty SVG. The aspect-ratio branch then
asked preferredAspectRatioAsSize() for the actual ratio, got (0, 0), computed
crossSize * (0/0) = NaN, and the LayoutUnit constructor turned NaN into 0.
Two of the three || checks in this function just repeated what
flexItemHasAspectRatio (called right above) already checks, so they were
doing nothing. The intrinsicSize().height() check was the only one that
actually mattered - and it was the broken one.
The fix replaces the unreliable intrinsicSize().height() shortcut with the
same test the math already uses:
preferredAspectRatioAsSize().aspectRatioDouble() > 0.
This is true exactly when there is a real ratio (CSS aspect-ratio, real
intrinsic dimensions, or SVG viewBox). The same trick is already used by the
existing isSVGRootWithIntrinsicAspectRatio helper.
* Source/WebCore/rendering/RenderFlexibleBox.cpp:
(WebCore::RenderFlexibleBox::flexItemHasComputableAspectRatio const):
*
LayoutTests/imported/w3c/web-platform-tests/css/css-flexbox/flex-svg-no-intrinsic-column-001{,-ref,-expected}.html:
Added.
Canonical link: https://commits.webkit.org/313257@main
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