Each rib of a dashed stroke with a width profile looked up to 256 points
either way along the path, asking the profile at every step, and reached
as wide as the stroke gets anywhere past that. A sliding maximum over the
points' precomputed cover now gives every rib's reach in time in
proportion to the points, with no bound and no fallback to the widest
width (review on #6093).
With a width profile, every slice of a stroke gradient (along or across)
reached as far as the stroke is wide anywhere. Where the stroke crosses
or runs close by itself, the later, narrower part painted a square of
its colour over the wider part beside it, clipped only to the whole
outline. Each rib now reaches as far as the stroke is wide there and on
its way to the next points (each side of a profile stays between its
widths at a span's points); for a dashed stroke, as wide as it gets
within a cap's reach, since caps and dots reach along the path.
With ribs only at the path's corners (an Along gradient), the ribs that reach
across an arrowhead stopped at the last corner inside its reach, so the slice
narrowed from the head's tip towards the next corner and left the corners of
a Triangle head's base outside every slice. Where each arrowhead's reach ends
now gets a rib of its own.
The width between two width points was a straight line, so a variable-width
stroke turned a corner at every width point.
- Each side of a width profile now follows a monotone cubic (Fritsch-Carlson)
through its points: no kink at a point, flat at a point wider or narrower
than both neighbours, never past either point of a span. Points on one line
stay on it and two-point tapers are unchanged; stacked points still step.
- widest() counts each span's wider left and wider right, since the two sides
needn't peak together.
- The outliner samples straight runs between width points closely enough to
follow the curve to the drawing tolerance (at most 64 samples per span and
4,096 per piece); straight spans get none.
- Tests that expected straight-line widths now expect the curve. The stroke
gradient coverage test uses Teardrop instead of Wave until #5964 is fixed.
The Gradient panel's Stroke buttons now work: with the Stroke proxy on a
linear or radial gradient they lay it within the stroke (placed on the
page, as before), along the path (start to end of each subpath) or across
it (left edge to right edge; inside/outside strokes span their visible
side). `paint.editGradient {stroke: true, strokeMode}` sets it (new art
too with nothing selected); `document.inspect` reports
strokeOptions.gradientMode. Model: StrokeLayer.gradient_mode (default
Within, not written).
Shared geometry in effects::stroke::gradient: ribs on the bisectors of
the flattened path (fans round sharp corners, widened under arrowheads,
following width profiles) cut slices each painted with a linear piece of
the gradient (Gradient::span). The canvas and raster export clip them to
the stroke's outline and arrowheads, grown a pixel and composited with
copy so there are no seams and translucent stops paint once. SVG and PDF
write the same slices clipped to the outline, with a warning (new
vectorcraft_svg::export_with_report). Outline Stroke and Expand make
gradient meshes clipped to the outline. Mesh quads now grow along their
edges so thin quads show no seams. Dashes, profiles and arrowheads keep
working in both modes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Sven Lafebre