Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: d1773079b63ba93655cb0eb892b549241c9b87be
https://github.com/WebKit/WebKit/commit/d1773079b63ba93655cb0eb892b549241c9b87be
Author: Ahmad Saleem <[email protected]>
Date: 2026-09-13 (Sun, 13 Sep 2026)
Changed paths:
A
LayoutTests/imported/w3c/web-platform-tests/css/geometry/DOMPoint-matrixTransform-translation-w-expected.txt
A
LayoutTests/imported/w3c/web-platform-tests/css/geometry/DOMPoint-matrixTransform-translation-w.html
M Source/WebCore/platform/graphics/transforms/TransformationMatrix.cpp
Log Message:
-----------
TransformationMatrix::map4ComponentPoint() ignores w in the
identity/translation fast path
https://bugs.webkit.org/show_bug.cgi?id=324067
rdar://187297446
Reviewed by Simon Fraser.
This patch aligns WebKit with Gecko / Firefox and Blink / Chromium.
map4ComponentPoint() has a fast path for identity/translation matrices that
adds the translation directly to x, y, and z. This effectively assumes w == 1
and disagrees with the general v4MulPointByMatrix() path, which computes
x + w*tx, y + w*ty, z + w*tz for a translation matrix. As a result,
DOMMatrixReadOnly.transformPoint() and DOMPointReadOnly.matrixTransform()
produced incorrect coordinates whenever a translation (or identity+translation)
matrix was applied to a point whose w component was not 1.
Scale the translation by w in the fast path so it matches the general path.
Test:
imported/w3c/web-platform-tests/css/geometry/DOMPoint-matrixTransform-translation-w.html
*
LayoutTests/imported/w3c/web-platform-tests/css/geometry/DOMPoint-matrixTransform-translation-w-expected.txt:
Added.
*
LayoutTests/imported/w3c/web-platform-tests/css/geometry/DOMPoint-matrixTransform-translation-w.html:
Added.
* Source/WebCore/platform/graphics/transforms/TransformationMatrix.cpp:
(WebCore::TransformationMatrix::map4ComponentPoint const):
Canonical link: https://commits.webkit.org/321030@main
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