Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: b86834d40591aed86d62b57dd4b7dd27aa6d6b7c
https://github.com/WebKit/WebKit/commit/b86834d40591aed86d62b57dd4b7dd27aa6d6b7c
Author: Karl Dubost <[email protected]>
Date: 2026-06-26 (Fri, 26 Jun 2026)
Changed paths:
A
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-font-change-expected.txt
A
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-font-change.html
A
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-non-px-source-expected.txt
A
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-non-px-source.html
A
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-percentage-directionality-expected.txt
A
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-percentage-directionality.html
A
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-readonly-expected.txt
A
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-readonly.html
A
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-reserialization-expected.txt
A
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-reserialization.html
M
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-px-expected.txt
M
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-px.html
R LayoutTests/svg/dom/SVGLength-px-expected.txt
R LayoutTests/svg/dom/SVGLength-px.html
M Source/WebCore/svg/SVGLength.cpp
M Source/WebCore/svg/SVGLengthContext.cpp
Log Message:
-----------
convertToSpecifiedUnits - conversion from px to percentage, em and ex is
failing
https://bugs.webkit.org/show_bug.cgi?id=308949
rdar://172056830
Reviewed by Nikolas Zimmermann.
Per the SVG2 spec algorithm for convertToSpecifiedUnits,
See
https://w3c.github.io/svgwg/svg2-draft/single-page.html#types-__svg__SVGLength__convertToSpecifiedUnits
when an SVGLength has no associated element:
1. the viewport size basis is 100 for percentages
2. the font-size basis is the initial value of the font-size property for
em/ex units.
CSS defines this initial value as 'medium' but does not specify its
absolute size. 16px is a universal UA convention, matching DefaultFontSize
in UnifiedWebPreferences.yaml.
Since detached SVGLengths have no document to query Settings from, the
value is hardcoded as a file-scope constant (initialFontSizePx).
Previously WebKit threw NotSupportedError for these conversions on detached
elements. This patch implements the spec-defined fallbacks in SVGLengthContext.
Additionally, SVGLength::convertToSpecifiedUnits was missing a call to
updateStyleIfNeeded() before performing the conversion, unlike
valueForBindings().
This caused em/ex conversions on attached elements with custom font-sizes to
use stale style data (initial 16px instead of the element's computed font-size).
Also fixes the upstream WPT test SVGLength-px.html which called
getComputedStyle()
on a detached element (returns empty string per CSSOM spec), producing NaN as
the reference font-size. The fix uses a temporary attached probe element
instead.
This was also an opportunity to add more test cases in WPT for handling
different variations of the convertToSpecifiedUnits method.
Tests:
imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-font-change.html
imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-non-px-source.html
imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-percentage-directionality.html
imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-readonly.html
imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-reserialization.html
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-font-change-expected.txt:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-font-change.html:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-non-px-source-expected.txt:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-non-px-source.html:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-percentage-directionality-expected.txt:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-percentage-directionality.html:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-readonly-expected.txt:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-readonly.html:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-reserialization-expected.txt:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-convertToSpecifiedUnits-reserialization.html:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-px-expected.txt:
*
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGLength-px.html:
Fix getComputedStyle on detached element producing NaN; use attached probe
element.
Fix exact valueAsString comparison for em (trailing zero serialization
varies).
* LayoutTests/svg/dom/SVGLength-px-expected.txt: Removed.
* LayoutTests/svg/dom/SVGLength-px.html: Removed.
* Source/WebCore/svg/SVGLength.cpp:
(WebCore::SVGLength::convertToSpecifiedUnits):
Add updateStyleIfNeeded() before conversion, matching valueForBindings().
(WebCore::SVGLength::convertToSpecifiedUnits):
* Source/WebCore/svg/SVGLengthContext.cpp:
(WebCore::SVGLengthContext::computeNonCalcLength):
Fall back to initial font-size (16px) for font-relative units when no
associated element.
(WebCore::SVGLengthContext::convertValueFromUserUnitsToPercentage):
Fall back to viewport basis of 100 when no associated element.
(WebCore::SVGLengthContext::convertValueFromPercentageToUserUnits):
Same fallback for the reverse direction.
(WebCore::SVGLengthContext::convertValueFromUserUnitsToEXS):
Fall back to 0.5em (8px) x-height when no associated element.
(WebCore::SVGLengthContext::convertValueFromEXSToUserUnits):
Same fallback for the reverse direction.
(WebCore::SVGLengthContext::computeNonCalcLength const):
(WebCore::SVGLengthContext::convertValueFromUserUnitsToPercentage const):
(WebCore::SVGLengthContext::convertValueFromPercentageToUserUnits const):
(WebCore::SVGLengthContext::convertValueFromUserUnitsToEXS const):
(WebCore::SVGLengthContext::convertValueFromEXSToUserUnits const):
Canonical link: https://commits.webkit.org/315953@main
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