Bug 311469 – SVGPointList should truncate on odd coordinate count instead of clearing the entire list

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

[Ahmad Saleem]

Hi Team,

Found recently progressed and now with missing coverage failing test, so this is to fix it. 

Per SVG 2 spec [1], when a polyline/polygon points attribute contains an odd number of coordinates (e.g. "0,0 100,0 20" where the trailing y value is missing), the successfully parsed coordinate pairs should be retained. Currently WebKit rejects the entire list and returns 0 items, instead of keeping the 2 valid pairs.
 
This is covered by the WPT test svg/types/scripted/SVGList-parse-invalid-clears-items.html, subtest "SVGPointList truncates items when y attribute value is missing".
 
The fix changes SVGPointList::parse() to break out of the parse loop when x succeeds but y is missing at end-of-string, retaining already-parsed pairs. Invalid tokens (e.g. "INVALID") at any  position still correctly clear the entire list.
 
[1] https://svgwg.org/svg2-draft/shapes.html#PolylineElement — "If an odd number of coordinates is provided, then the element is in error, with the same user agent behavior as occurs with an  incorrectly specified 'path' element."

Thanks!

[Radar WebKit Bug Importer]

<rdar://problem/174069252>

[Ahmad Saleem]

Pull request: https://github.com/WebKit/WebKit/pull/62027

[EWS]

Committed 310798@main (31e8f16d17b1): <https://commits.webkit.org/310798@main>

Reviewed commits have been landed. Closing PR #62027 and removing active labels.