Reject a single-axis position followed by a length in transform-origin#217
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Reject a single-axis position followed by a length in transform-origin#217jhaygood86 wants to merge 1 commit into
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transform-origin accepted `top 2px` (resolved to center/top with 2px as the z-offset) and `2px left` (a length in the horizontal slot paired with a horizontal keyword in the vertical slot), both invalid per CSS Transforms 1 (https://www.w3.org/TR/css-transforms-1/#transform-origin-property). The two-value form is ordered (horizontal then vertical) and only the keyword-only form may be reordered; the trailing <length> z-offset exists only in the two-value production. Restructure the converter around explicit Horizontal/Vertical axis converters and a TwoValuePosition that requires both axes, and gate the z-offset behind it so it can only follow a genuine two-value position. Fixes the two tests that asserted the non-conformant `2px left` forms.
jhaygood86
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July 24, 2026 19:59
jhaygood86
marked this pull request as draft
July 24, 2026 20:35
jhaygood86
marked this pull request as ready for review
July 24, 2026 20:35
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Summary
transform-originaccepted two forms that are invalid per CSS Transforms 1:transform-origin: top 2px— a single-axis position followed by a length. It was accepted and resolved to center/top with2pxswallowed as the z-offset, but the trailing<length>z-offset only exists in the two-value production.transform-origin: 2px left(and2px left 10px) — a<length>in the horizontal slot paired with a horizontal keywordleftin the vertical slot. The two-value form is ordered (horizontal then vertical), and only the keyword-only form may be reordered, so this pair is invalid.Fix
The converter is restructured around explicit
Horizontal/Verticalaxis converters and aTwoValuePositionthat requires both axes to be present. The<length>z-offset is gated behindTwoValuePosition, so it can only follow a genuine two-value position; a one-or-two-value<position>with no z-offset is the fallback.Grammar
Tests
CssTransformOriginVerticalKeywordThenLengthIllegal/...WithZIllegal(top 2px,top 2px 10px).2px left/2px left 10pxforms to assert rejection.left 2px,2px 30%,right top,2px 30% 10px,left 5px -3px, …) continue to pass. Full suite green.Ported from a fix made in PeachPDF, which vendors ExCSS.