Forma Runtime SVG Profile v1

Profile v1 is the behavior intersection required from every production Forma SVG backend. The machine fixture source is tests/Forma.Svg.Conformance/SvgProfileV1Fixtures.cs; the policy manifest is tests/Forma.Svg.Conformance/runtime-svg-profile-v1.json.

Included

  • finite positive root dimensions and view boxes;
  • preserveAspectRatio meet, slice, and none;
  • paths, rectangles, rounded rectangles, circles, ellipses, lines, polylines, and polygons;
  • fills, fill rules, strokes, opacity, caps, joins, miter limits, and dash arrays;
  • nested groups and affine transforms;
  • linear/radial gradients, stop opacity, supported spread, and gradient transforms;
  • local clipping, masks, defs, use, and fragment references;
  • bounded presentation attributes, inline class styles, inheritance, and currentColor.

Every fixture must produce non-empty, exact-size, tightly packed, top-left, premultiplied sRGB RGBA8 at 1x, 1.25x, 1.5x, 1.75x, 2x, and 2.5x. Every pixel must satisfy R <= A, G <= A, and B <= A.

Excluded

Core validation rejects scripts/events, animation, foreign objects, image/data/external resources, text and arbitrary fonts, external stylesheets, filters/blur, blend modes, ICC profiles, duplicate IDs, cyclic references, and non-finite or over-budget documents before native parsing. Rejection is part of the profile and may not become an empty successful image or trigger fallback to another backend.

Comparison Rules

Backend-local hashes detect changes within a pinned backend. Cross-backend output is not required to be byte-identical. A comparison passes only when all semantic samples pass and:

  • dimensions and buffer length are exact;
  • transparent/opaque interior sample points agree exactly where antialiasing is irrelevant;
  • non-transparent bounds differ by no more than ceil(scale) pixels per edge;
  • alpha coverage differs by no more than 4 percentage points of total image area for production theme icons and 8 percentage points for tiny semantic fixtures;
  • production theme icons have mean premultiplied channel error at most 12/255 and 95th percentile error at most 48/255;
  • tiny semantic profile fixtures have mean error at most 26/255 and 95th percentile error at most 128/255, alongside their exact semantic sample assertions.

These measured limits account for a one-pixel antialiasing phase in 8-10 px fixtures; they are not relative-to-object percentages, which distort one-pixel lines. Tolerance never permits empty output, a missing shape, wrong clipping, straight alpha, shifted geometry beyond the bound, or an out-of-bounds write. For example, dropping a thin stroke fails its semantic sample/bounds even if mean image error stays low; translating an otherwise identical icon two pixels at 1x fails the geometry rule.

Change Control

Adding a feature requires a positive fixture, deterministic excluded-feature behavior where applicable, both isolated backend runs, visual review at all approved scales, and an updated profile version if public behavior changes. First-party theme/Catalog assets may only use profile features.

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