Bug 318103 – SVGMatrix.multiply should accept DOMMatrix2DInit per SVG 2

• Status: RESOLVED
• Resolution: FIXED
• Component: SVG

[Karl Dubost]

The SVG WG resolved in 2019-10 
to revert SVG 2's plan to alias SVG geometry interfaces (SVGPoint / SVGRect / SVGMatrix) to the DOM* geometry interfaces. 
https://github.com/w3c/svgwg/issues/706

The revert merged on 2026-06-29 (commit bc3a4f9cda1a7391cbce66c4e678565a70823119). 
https://github.com/w3c/svgwg/commit/bc3a4f9cda1a7391cbce66c4e678565a70823119

Per the merged spec, 

* SVGMatrix continues to be its own interface in both SVG 1.1 and SVG 2;
* DOM*Init dictionary input types are explicitly KEPT per resolution #3.

The spec-correct IDL for SVGMatrix.multiply is therefore:

    [NewObject] SVGMatrix multiply(optional DOMMatrix2DInit secondMatrix = {});

WebKit currently ships the SVG 1.1 narrow signature (Source/WebCore/svg/SVGMatrix.idl:39):

    [NewObject] SVGMatrix multiply(SVGMatrix secondMatrix);

which rejects DOMMatrix2DInit input with TypeError. 

The existing WPT test
LayoutTests/imported/w3c/web-platform-tests/svg/types/scripted/SVGMatrix-tentative.html
exercises a dict-input case:

    matrix = matrix.multiply({a: 3, d: 2});

and the WebKit-side expected file records this as a known FAIL.

Only Gecko PASS.
This bug fixes the WebKit half.

[Radar WebKit Bug Importer]

<rdar://problem/180896205>

[Karl Dubost]

Pull request: https://github.com/WebKit/WebKit/pull/68084

[EWS]

Committed 318109@main (ce15568a0e8b): <https://commits.webkit.org/318109@main>

Reviewed commits have been landed. Closing PR #68084 and removing active labels.