fix(usvg): inherit gradientTransform and patternTransform via href - #1135
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killerdevildog wants to merge 1 commit into
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A gradient or pattern that references another one through `href`/`xlink:href` did not inherit its `gradientTransform` or `patternTransform`. Stops, coordinates, units and `spreadMethod` were inherited, but the transform was silently dropped. For example, `<linearGradient id="lg2" xlink:href="#lg1"/>`, where `lg1` has `gradientTransform="rotate(90 0.5 0.5)"`, rendered left-to-right instead of top-to-bottom, and a referencing pattern lost its rotation. This is a regression from 9101f30 ("Add support for the `transform-origin` attribute"), which replaced `resolve_attr(node, AId::GradientTransform).attribute(..)` with `node.resolve_transform(..)`. `resolve_transform` only reads the attribute from the element itself, so the `GradientTransform` entries in `resolve_lg_attr` and `resolve_rg_attr` became unused. SVG 2 lists `gradientTransform` among the attributes copied from a template `linearGradient` or `radialGradient`, and `patternTransform` among those copied from a template `pattern` (https://www.w3.org/TR/SVG2/pservers.html). SVG 1.1 likewise states that attributes defined on the referenced element but not on this element are inherited. Resolve the element that defines the transform with `resolve_attr` before calling `resolve_transform`, in `convert_linear`, `convert_radial` and `convert_pattern`. A transform set on the element itself still takes precedence over the referenced one. Signed-off-by: killerdevildog <quaylynrimer11@gmail.com> Signed-off-by: killerdevildog <software.quaylynrimer@gmail.com>
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Fix looks good to me but we should have a test added to avoid this issue regressing in the future. |
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Fixes #1134.
A gradient or pattern that references another one through
hrefdid not inherit itsgradientTransformorpatternTransform. For example,<linearGradient id="lg2" xlink:href="#lg1"/>, wherelg1hasgradientTransform="rotate(90 0.5 0.5)", rendered left to right instead of top to bottom.This regressed in 9101f30 (first released in v0.37.0), which replaced
resolve_attr(node, AId::GradientTransform).attribute(..)withnode.resolve_transform(..)to supporttransform-origin.resolve_transformonly reads the element itself, so thehreflookup was lost and theGradientTransformentries inresolve_lg_attrandresolve_rg_attrbecame unused. Resolving the defining element withresolve_attrfirst restores inheritance and keepstransform-originsupport. A transform set on the element itself still takes precedence. When the transform is inherited,transform-originis read from the same element that defines the transform.This PR changes only
crates/usvg/src/parser/paint_server.rs.Validation: the reproducer from #1134 fails before the change and passes afterward; resvg's output now matches rsvg-convert 2.58 to within 1/255 per color channel (before the change it differed by up to 255). Local paired cases covering linear, radial and pattern templates, a radial gradient using a linear template, a two-level
hrefchain, and an element that overrides the inherited transform each render pixel-identically to the same transform set directly on the element.cargo test --release -p resvg -p usvgpasses (1731 integration tests, no reference image changes) andcargo fmt --checkis clean. The local regression tests are not included in this PR. Tested on Linux only.