Illustrator 30.0's gradient Method, from the public documentation
(https://helpx.adobe.com/illustrator/desktop/paint-and-fill/create-and-edit-gradients/control-perceptual-interpolation-in-gradients.html):
Classic or Perceptual; perceptual interpolation matches colour transitions to
how the eye perceives differences between colours, and perceptual gradients
are rasterised when saved as PDF or SVG.
- Gradient gains `method` (Classic | Perceptual; serde default Classic,
written only when Perceptual, so older files open as Classic and Classic
files are written as before). The colour crate's OKLab helpers open up for it.
- Perceptual mixes neighbouring stop colours in OKLab (sample, and
sample_keep_model for the stroke meshes, Expand and blends); opacity stays
linear. Renderers that mix linearly get stops on the perceptual curve,
placed by halving each half segment where a straight line strays more than
0.4 of a colour level (a nearly straight segment needs none). Classic
gradients expand exactly as before.
- draws_as_pixels includes Perceptual gradients, so SVG and PDF write a
Perceptual fill or stroke as an image at the document's raster effects
resolution, clipped to what it paints. A gradient along or across a stroke
stays slices (PDF no longer draws it as a within-stroke image).
- With Dither: a dithered Perceptual fill is the perceptual mix with dither's
noise (the canvas's dithered grids are keyed by method too); SVG and PDF
write it as an image with the noise, and a dithered Perceptual stroke as an
image without it, as the canvas draws it (GradientPaint::pixels, SVG's
raster_paint and PDF's area are told whether they paint a fill).
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>
Taha-Mahmoodi