fix(usvg): use the viewport as the bbox of a sliced <image> - #1077
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LaurenzV merged 2 commits intoAug 16, 2026
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An `<image>` with `preserveAspectRatio="… slice"` is scaled to *cover* its viewport and the overflow is cut away by a rectangular clip. Its bounding box is therefore the image's `x/y/width/height` rect (the viewport), but usvg derived it from the children, i.e. the oversized scaled-to-cover image. As a result, an `objectBoundingBox` clip-path (or mask/filter) applied to a sliced image was resolved against the wrong, much larger box. With a non-square viewport this scaled the clip shape anisotropically and made it collapse — e.g. a decorative arched window clipped to a tall image rendered as a flat top instead of the intended curve, differing from Chrome/Firefox. Set the slice wrapper group's bounding box to the image rect so downstream bbox-relative units are resolved correctly. Adds a regression test asserting the clip transform is built from the viewport rect and not the scaled image. Closes linebender#1034 Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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An
<image>withpreserveAspectRatio="… slice"is scaled to cover its viewport and the overflow is cut away by a rectangular clip. Its bounding box is therefore the image'sx/y/width/heightrect (the viewport), but usvg derived it from the children, i.e. the oversized scaled-to-cover image.As a result, an
objectBoundingBoxclip-path (or mask/filter) applied to a sliced image was resolved against the wrong, much larger box. With a non-square viewport this scaled the clip shape anisotropically and made it collapse — e.g. a decorative arched window clipped to a tall image rendered as a flat top instead of the intended curve, differing from Chrome/Firefox.Set the slice wrapper group's bounding box to the image rect so downstream bbox-relative units are resolved correctly.
Adds a regression test asserting the clip transform is built from the viewport rect and not the scaled image.
Closes #1034
Generated by Claude
Note: I accidentally closed the original PR (#1059) by deleting my fork, which auto-closed it. This reopens the same change — the branch and commits are unchanged.