* fix(compose): a wide stroke effect keeps a round outer edge (#3646)
A stroke's outside distance came from the 5x5 chamfer, whose level sets are polygons: at a
245 px outside stroke the boundary wanders ~10 px into visible flat facets. Use the exact
Euclidean distance (edt_nearest, already used for glows and chiselled bevels) for the outer
edge; the inside edge and spread/choke keep the chamfer, whose sub-pixel edge seeding is
fitted to Photoshop at small offsets. A point source dilated by 60 px now stays within 0.5 px
of a circle (was 2.5 px).
Tests: a_wide_outside_stroke_is_round_not_a_polygon; stroke_edges_use_the_exact_euclidean_distance
(a 3 px outside stroke's (1,3) corner coverage is 0.838, the exact distance; it was 0.764).
Full photocraft-compose suite: 206 pass; fmt and clippy clean.
* fix(gpu): a wide stroke keeps its exact outer edge on the GPU (#3646)
1080008a fixed the CPU compositor's stroke outer edge to use the exact
Euclidean distance instead of the 5x5 chamfer, whose level sets are
polygons and facet a wide stroke. The GPU compositor builds the outer
stroke field from FieldKind::StrokeOutside, which still maps to the
chamfer, and the canvas is drawn on the GPU, so the fix did not reach the
app.
Add FieldKind::StrokeOutsideExact (dist_outside_by Euclidean) used only by
the stroke. The spread of drop shadows and softer outer glows keeps the
chamfer on purpose (fitted to Photoshop, #224), so StrokeOutside keeps its
meaning. StrokeOutsideVector is exact too, matching the CPU vector outline
path.
Tests: crates/gpu/src/fx.rs a_raster_stroke_uses_the_exact_outer_field
(stroke uses the exact field, shadow spread keeps the chamfer), and the
banded/whole field test covers the new kind.
* fix(stroke): a stroke keeps the chamfer narrow and the exact edge wide (#3646)
The exact Euclidean outer edge (#3646) fixed a wide stroke's faceting but
regressed Photoshop's own composites against the PSD flatten oracle: the
fitted 5 × 5 chamfer matches Photoshop at small offsets, and only at a large
outside width do its octagon facets show. Pick the metric by the stroke's
outside width instead: below `STROKE_CHAMFER_MAX` (20 px) keep the chamfer and
its sub-pixel edge seeding, at or above it use the exact Euclidean transform.
The measured chamfer deviation from a point source is 0.027 · r px — 0.48 px at
r = 18, the widest outside stroke any Photoshop oracle matches with the chamfer,
and 1.6 px at r = 60, where the boundary visibly facets. Half a pixel is reached
at r ≈ 19, so the switch sits at 20. Inside stroke edges keep the chamfer.
The CPU and GPU compositors pick the same field by the same width
(`stroke_outside_exact`); `FieldKind` gains `StrokeOutsideVectorChamfer` for a
narrow shape-layer outline, while the shadow / glow spread keeps its chamfer.
io corpus: 140 → 148 (floor 146) and psd-tools 231 → 237 (floor 236), both back
to main's counts with no file newly differing; a 60 px outside stroke stays
round (`a_wide_outside_stroke_is_round_not_a_polygon`).
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