Shapes (params `shapes`, a checkbox in the panel; off unless asked for): a filled
outline that is a circle, an ellipse, a rectangle or a regular polygon comes out
as that live shape. A shape is only made when every point of the traced outline
lies within 0.5 px (0.2% of the shape's size, if more) of it; an ellipse whose
radii differ by less than twice that is a circle of its area.
The outline before fitting: a corner's own pixel no longer pulls the two edges
that meet there, and a one-pixel step between two long edges is the corner where
they meet. Sharp corners kept: Default 69% -> 76%, the colour presets 86% -> 91%.
The harness gains plain-shape inputs and "shapes %".
Create: Strokes (the Outline preset, or the option) traced lines along the pixel skeleton: right to a pixel,
with a width counted in pixels, and fitted by a separate, older fitter.
- Each skeleton point is moved to the middle of the line's ink, read from the image across the line: every
pixel counts as much ink as its colour is the line's rather than the paper's, the ink's centroid is the
middle and its sum the width (an anti-aliased or blurred line says both to a fraction of a pixel).
- The stroke width is the median of those widths, no longer a whole number of pixels.
- Each end goes where the ink ends, less the half width a round cap adds.
- Centre lines are fitted as outlines are: a straight line is two anchors, corners stay corners, Snap Curves To
Lines levels them. The old Douglas-Peucker and simplify fitter, and the crate's pathops dependency, go.
Outline on the thin-line inputs, all sizes and variants (docs/image-trace-quality.md), before -> after:
- painted outline 0.310 -> 0.055 px off on average; 81 -> 14 anchors for five lines
- centre line 0.295 -> 0.052 px from the true centre line; stroke width 0.13 -> 0.02 px off; 18.4 -> 2.7
anchors a stroke (blurred, noisy and scanned lines: 2.0 each; aliased: 4.6)
- largest distance 1.84 -> 2.94 px: the square ends of a 10 px line under a round cap
Presets without Create: Strokes are unchanged.
The documented option "replaces slightly curved lines with straight lines and snaps lines near 0 or 90 degrees
to absolute 0 or 90 degrees" (helpx, Image Trace panel options); ours did the first half only.
- With Snap Curves To Lines, a straight piece at least 2 px long and within 2.5 degrees of level or upright is
made exactly so, by moving its ends across it to their mean (the page gives no angle: 2.5 degrees is our
choice). The pieces next to a moved end follow it.
- A junction other regions share stays where it is, so abutting regions still have one curve along their edge;
a line between a junction and a free end is levelled to the junction.
- The harness gains askew inputs (a rectangle, a plus sign and two lines, 1 to 2 degrees off level and upright)
and an "upright %" column: the share of the outline length that is exactly level or upright.
On the clean askew inputs (docs/image-trace-quality.md): Black and White Logo and Technical Drawing, the presets
with the option on, go from 0% to 91% and 95% of their outline exactly level or upright. Their outlines are then
0.49 and 0.59 px from the art as drawn where they were 0.05 (4.2 px at the far end of a 300 px side turned 1.5
degrees): that distance is what the option is for. Presets without the option are unchanged.
Export::class() deduplicated declaration blocks with
classes.iter().position(), an O(n) scan per style, making exports with
many distinct styles (e.g. large palettes) quadratic overall. Track the
1-based class number per declaration in a HashMap alongside the
first-use-ordered Vec, so each lookup is O(1) while output stays
byte-identical.
Also adds a regression test covering 256 distinct declarations with
recurrence of early styles, for both InternalCss and StyleEntities
styling.
usvg takes a `transform` CSS property as a presentation attribute that
overrides the element's own, but reads its value as SVG: CSS units
(`translate(100px, 0)`, `rotate(45deg)`) don't parse, and the object
was left with no transform at all. Before usvg runs, transform
declarations in `style` attributes and `<style>` rules are now written
in SVG syntax (lengths in px, angles in deg/rad/grad/turn, translateX/Y,
scaleX/Y and skew as SVG's functions); values that can't be are left.
The text pass's own cascade now expands the `font` shorthand into its
longhands, as usvg does for the rest of the drawing, so text styled
with `font: italic bold 30px …` keeps its size, weight and style.
Refs #1557
Both readers skipped a clip of at most six straight segments whose
bounding box contained the page. A diamond touching the page edges has
the page as its bounding box, so its clip was dropped and everything it
cuts away showed. geom::hit::polygon_covers_rect answers it properly
(one convex polygon containing the page's corners); any other path is
kept as a clip.
Fixes#1542
fx.rs draws blur, shadow and glow rasters as image paints that map 1:1
onto their rect, but only set the geometry transform: the paint
transform a pattern fill (or a radial or freeform gradient) left on the
context still applied, so in supersampled renders (raster exports) the
effect came out tiny and displaced. Both draws now reset the paint
transform first.
Fixes#1536
Interp::font took a font's FontMatrix times 1000 as the matrix of one
em, the Type 1 convention (glyphs in 1000-unit space). A Type 42 font's
glyph space is one unit an em, its FontMatrix usually the identity, so
type in Type 42 fonts (cairo, Inkscape, LibreOffice) came in 1000 times
too large and off the page. FontType 42 now takes the matrix as it is.
Fixes#1552
An alpha soft mask's vector art is whitened so its luminance is its
alpha, but images kept their colour: cairo (and so Inkscape) draws a
mask as an image whose alpha is in its own SMask, often black pixels,
so the mask came in empty. While reading an alpha mask's art the
importer now reads images white with their own alpha (under their own
cache key, without the JPEG and CMYK shortcuts), and stencil masks
white; a luminosity mask nested inside reads them as they are.
Fixes#1550
Against the documented panel (https://helpx.adobe.com/illustrator/desktop/manage-objects/traces-mockups-symbols/image-trace-panel-options.html):
- Ignore Color: "Ignores a specific color while tracing. Use the color picker to selectively ignore a color."
The panel's Ignore White is now Ignore Color with a colour button beside it (white until another colour is
picked); `imageTrace.make` takes `ignoreColor: "#rrggbb"` beside `ignoreWhite`, and leaves out the palette
colours within about 30 levels of it. Documents saved before have no such setting and ignore white as they
did. Flat Logo mode leaves out white only.
- Auto Color ("Creates a posterized image from a photo or artwork"): Color mode with the Automatic palette.
- Outline ("Simplifies the image to black outlines"): Black and White with Create: Strokes and no fills.
- The Outline preset's name is translated as a preset's name, not as the Outline view's.
Measured (docs/image-trace-quality.md): Auto Color on flat art is 0.140 px off on average with 4.0 paths (16
Colors: 0.141, 4.2). Outline on the line inputs, the first measure of Create: Strokes: 0.310 px off on average,
1.84 at worst, 81 anchors for 5 lines (Line Art's filled outlines: 0.055, 0.96, 46).
Black and White read every pixel as a blend of "black" and "white", and took for those the mean luminance of
the image's black and white pixels. In blurred or scanned line art most black pixels are part paper, so the
mean black was a gray: the middle of every line counted as more than all ink, and by how much changed as the
line crossed the pixel rows, which put a ripple on its edges that the fit then followed with anchors.
- Black is the image's darkest black (the 2nd percentile of its black pixels' luminance).
- White is the lightest pixel within a few pixels of each crack: the paper as it is there. A scan's paper is
darker in one corner than in another, and read against the image's lightest white it counted as part ink.
On each preset's own inputs, all sizes and variants (docs/image-trace-quality.md), before -> after:
- Line Art: 78 -> 46 anchors, outlines 0.093 -> 0.055 px off on average (blurred lines 168 -> 53 anchors,
scanned 199 -> 70); before sub-pixel edges it was 25 anchors and 0.158 px off
- Technical Drawing: 56 -> 46 anchors, 0.092 -> 0.084 px off
- Sketched Art: 0.197 -> 0.186 px off; Default 0.092 -> 0.090; Black and White Logo 0.063 -> 0.059 with
27 -> 29 anchors
Not kept: reading lines up to six pixels deep by their ink's centroid and width, and a looser tolerance for
straight runs, neither of which measured better.
BFlat
Ayanprogrammer11
Gert Pellin
Marco Arnulfo