Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 2025cb32576ca2b653e30d66744c3861cab4bc19
https://github.com/WebKit/WebKit/commit/2025cb32576ca2b653e30d66744c3861cab4bc19
Author: Ahmad Saleem <[email protected]>
Date: 2026-08-04 (Tue, 04 Aug 2026)
Changed paths:
M
LayoutTests/imported/w3c/web-platform-tests/svg/geometry/svg-image-intrinsic-size-with-cssstyle-auto-expected.txt
M Source/WebCore/Sources.txt
M Source/WebCore/WebCore.xcodeproj/project.pbxproj
M Source/WebCore/rendering/svg/RenderSVGImage.cpp
A Source/WebCore/rendering/svg/SVGImageIntrinsicSizing.cpp
A Source/WebCore/rendering/svg/SVGImageIntrinsicSizing.h
M Source/WebCore/rendering/svg/legacy/LegacyRenderSVGImage.cpp
Log Message:
-----------
<svg:image> 'auto' sizing should follow the CSS default sizing algorithm
https://bugs.webkit.org/show_bug.cgi?id=194815
rdar://122586485
Reviewed by Nikolas Zimmermann.
This patch aligns WebKit with Gecko / Firefox and Blink / Chromium.
Per SVG 2 §12.2 "Placement of the embedded content"
(https://w3c.github.io/svgwg/svg2-draft/embedded.html#Placement):
"The 'auto' value for width or height is used to size the
corresponding element automatically based on the intrinsic
dimensions or intrinsic aspect ratio of the referenced
resource. Computation of automatically-sized values follows
the Default Sizing Algorithm defined for replaced elements in
CSS layout [css-images-3]. In particular, when the referenced
resource does not have an intrinsic size (such as image types
with no defined dimensions), it is assumed to have a width of
300px and a height of 150px."
The default sizing algorithm itself is defined in CSS Images Level 3 §4.3.1
(https://www.w3.org/TR/css-images-3/#default-sizing-algorithm).
calculateObjectBoundingBox() previously used the value returned by
CachedImage::imageSizeForRenderer() as both the intrinsic size and
the intrinsic ratio. For SVG sources this conflated three distinct
cases:
* An SVG with only a viewBox (no intrinsic width/height) reported
the viewBox size as if it were intrinsic, so 'width:auto;
height:auto' returned the viewBox dimensions instead of fitting
the intrinsic ratio into the 300x150 default object size.
* An SVG with one intrinsic dimension plus a viewBox returned the
viewBox size, ignoring the intrinsic dimension that should have
been preserved while the missing dimension is derived from the
ratio.
* An empty SVG (no intrinsic dimensions and no viewBox) fell back
to 300x150 inside imageSizeForRenderer, but the surrounding
logic then treated that fallback as a real 2:1 intrinsic ratio
when one CSS axis was 'auto'.
Add SVGImageIntrinsicSizing.h, a helper shared by the LBSE and legacy
SVG image renderers, which both previously carried identical copies of
this computation. resolveSVGImageIntrinsicSizing() queries
CachedImage::computeIntrinsicDimensions() for SVG sources and applies
the CSS Images Level 3 §4.3.1 default sizing algorithm with a 300x150
default object size, returning an SVGImageIntrinsicSizing struct: a
concrete intrinsic size, the intrinsic ratio, and a HasRatio enum.
HasRatio distinguishes a real aspect ratio from the 300x150 fallback,
which callers need because resolving 'auto' against a fallback ratio
yields the wrong size. When both intrinsic dimensions exist, the
intrinsic ratio is taken from those dimensions (per spec), so the
viewBox-derived ratio cannot override the intrinsic w/h ratio for SVGs
that declare width, height, and viewBox.
calculateSVGImageObjectBoundingBox() resolves the concrete width and
height from the CSS 'width' / 'height' computed values against that
sizing, keying its ratio branches off HasRatio rather than an emptiness
check, so the 300x150 default-object-size fallback no longer poses as an
aspect ratio. Both RenderSVGImage::calculateObjectBoundingBox() and
LegacyRenderSVGImage::calculateObjectBoundingBox() now just delegate to
it.
Non-SVG (raster) sources are unaffected: the helper returns
imageSizeForRenderer() for them, matching the previous behavior.
*
LayoutTests/imported/w3c/web-platform-tests/svg/geometry/svg-image-intrinsic-size-with-cssstyle-auto-expected.txt:
Progressions
* Source/WebCore/Sources.txt:
* Source/WebCore/WebCore.xcodeproj/project.pbxproj:
* Source/WebCore/rendering/svg/RenderSVGImage.cpp:
(WebCore::RenderSVGImage::calculateObjectBoundingBox const):
* Source/WebCore/rendering/svg/SVGImageIntrinsicSizing.cpp: Added.
(WebCore::resolveSVGImageIntrinsicSizing):
(WebCore::calculateSVGImageObjectBoundingBox):
* Source/WebCore/rendering/svg/SVGImageIntrinsicSizing.h: Added.
* Source/WebCore/rendering/svg/legacy/LegacyRenderSVGImage.cpp:
(WebCore::LegacyRenderSVGImage::calculateObjectBoundingBox const):
Canonical link: https://commits.webkit.org/318548@main
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