stet 0.2.1 — PDF/X CMYK rendering correctness

[0.2.1] — 2026-05-09

Patch release focused on PDF/X CMYK rendering correctness against the
Ghent PDF Output Suite (GWG)
test corpus. Fixes a family of bugs where ICCBased / Lab / DeviceN
fills, images, and transparency groups didn't round-trip through the
document's /OutputIntents profile correctly, producing visible
"X" markers in calibration swatches that should render uniform.

This is an additive, non-breaking release. Downstream code does
not need to change. New public API on stet-graphics::IccCache and
a new rendering_intent: u8 field on stet-graphics::ImageParams
are documented below.

Highlights

• GWG 13.3 — ICCBased RGB paints with /OP true no longer route
  into the custom-spot overprint path; per PDF 1.7 §11.7.4.5 they
  paint as if /OP were false.
• GWG 16.1 — per-intent PDF/X proofing chain (source A2B → PCS → OI B2A → CMYK) is built for every registered ICCBased RGB
  profile, threaded through op_ri / ExtGState /RI.
• GWG 16.4 — transparency groups with no /CS (inherit) now
  resolve correctly to the parent's CMYK compositing space when
  the parent is a /CS DeviceCMYK group.
• GWG 17.2 — ICCBased images now go through the proofing chain
  via convert_image_8bit_with_intent (was bypassing the
  OutputIntent roundtrip and rendering via direct source→sRGB).
• GWG 22.1 — Lab fills populate DeviceColor::native_cmyk via
  a direct Lab → PCS → OI B2A → CMYK chain (matches Adobe ACE),
  and the OutputIntent install path pre-warms the sRGB→CMYK
  reverse transform so the parallel CMYK buffer never falls back
  to the PLRM (1-r, 1-g, 1-b, 0) formula.
• WASM viewer — open_pdf now applies the document's
  OutputIntent before storing the cached state, so PDF/X documents
  render in the browser the same way they do in the CLI.

Added — public API (additive, non-breaking)

stet-graphics:

• IccCache::convert_to_oi_cmyk(hash, components, intent) — run an
  RGB ICC color through the proofing chain at the given intent and
  return the intermediate OutputIntent CMYK.
• IccCache::convert_lab_to_oi_cmyk(l, a, b, intent) — direct
  Lab → OI CMYK via the OI's per-intent B2A LUT.
• IccCache::convert_image_8bit_with_intent(hash, samples, pixel_count, intent) — bulk image conversion with explicit
  rendering intent.
• IccCache::convert_color_with_intent and
  convert_color_readonly_with_intent — per-intent single-color
  conversion.
• IccCache::prepare_lab_to_oi_cmyk() — pre-build per-intent
  Lab→OI samplers; pair with prepare_reverse_cmyk().
• IccCache::intent_from_pdf_byte(b: u8) — map PDF rendering-intent
  bytes (0..3) to IccRenderingIntent.
• pub use moxcms::RenderingIntent as IccRenderingIntent.
• pub struct LabToCmykSampler (in icc::perceptual) with
  pub fn sample_pdf_lab(l, a, b).
• New field ImageParams::rendering_intent: u8. Default is 0
  (Perceptual). Per the documented "be a reader, not a writer"
  policy for param structs (CLAUDE.md), this is additive and not
  treated as a SemVer break.

stet-pdf-reader:

• PdfDocument::apply_output_intent_as_default_cmyk() now also
  pre-warms the sRGB→CMYK reverse and per-intent Lab→OI samplers
  in addition to its previous behaviour. No signature change.
• Image XObjects with /Intent now propagate the per-image
  rendering intent into ImageParams.rendering_intent, overriding
  the gstate /RI per ISO 32000 §11.3.4.

stet-render:

• build_icc_cache_for_list now also pre-warms the per-intent
  Lab→OI samplers when proofing is enabled.

Fixed

• DeviceGray painted in a PDF/X DeviceCMYK page group now routes
  through the K plate (matches DeviceCMYK 0/0/0/(1−g) byte-for-byte).
• DeviceN images with a non-CMYK alternate space go through the
  overprint path so process plates aren't disturbed.
• Paired /OP true /op true ExtGStates are now treated as a
  "strict overprint" signal (matches Adobe Illustrator's emit).
• The custom-spot overprint dispatch and the parallel CMYK buffer's
  is_custom_spot heuristic both now require
  process_cmyk.is_some() so proofing-chain ICCBased RGB stays out.

Verification

• 11 GWG calibration tests pass: 13.0 / 13.3 / 16.1 / 16.4 / 17.2 /
  17.3 / 22.1 / 23.0 / 1.0 / 3.0 / 12.0 / 8.0.1.
• cargo test --workspace --release clean.
• cargo fmt --all -- --check clean. No new clippy errors.
• wasm-pack build --target web --release crates/stet-wasm clean.

Crates published at 0.2.1

stet, stet-cli, stet-fonts, stet-graphics, stet-core,
stet-ops, stet-engine, stet-render, stet-viewer,
stet-pdf-reader, stet-pdf. The vendored stet-tiny-skia /
stet-tiny-skia-path forks remain at 0.11.4. stet-wasm is
excluded from crates.io and bumped to 0.1.1 independently.

Full changelog: v0.2.0...v0.2.1

stet 0.2.0 — ⚠ breaking release

[0.2.0] — 2026-05-01

This release lands a substantial expansion of the stet-pdf-reader
structural API, the PDF imaging-extension operators (transparency,
soft masks, optional content), and the pdfmark PostScript-to-PDF
authoring bridge. Several public match-surface enums are now
#[non_exhaustive] to lock in additive evolution — the breaking
changes are deliberate and documented per-crate below.

⚠ Breaking changes

This is a breaking release. Cargo treats the 0.1 → 0.2 bump as
incompatible (per the SemVer rules for 0.x), so existing users
pinned at stet = "0.1" won't be auto-upgraded.

The breaking surface is concentrated in two places:

1. #[non_exhaustive] markers were added to ~40 public
   match-surface enums across stet-graphics, stet-core, and
   stet-pdf-reader. Any downstream match over DisplayElement,
   PsError, Destination, AnnotationKind, the various pdfmark
   record enums, etc. now requires a _ => { ... } wildcard arm.
   See the "Changed — public API breaking changes" subsection below
   for the complete list.

2. stet-pdf no longer emits PDF/X-3 OutputIntents. PDF output
   is now plain PDF 1.7. PdfDevice::set_output_profile() is
   #[deprecated] as a no-op; existing call sites compile but stop
   producing the (previously broken) PDF/X-3 conformance label.

For a typical downstream renderer that pattern-matches on
DisplayElement, the migration is one wildcard arm per match
site:

 match element {
     DisplayElement::Fill { .. } => { /* … */ }
     DisplayElement::Stroke { .. } => { /* … */ }
     DisplayElement::Image { .. } => { /* … */ }
+    _ => { /* fall through; new variants in 0.2.x are additive */ }
 }

The #[non_exhaustive] ratchet is intentional: it makes future
variant additions non-breaking, so 0.2.x → 0.3.x will be smaller.

Added — stet-pdf-reader structural API

A read-only structural-content API for PDF inspection and tooling.
Every accessor parses lazily on first call and caches its result.

• metadata() — /Info dict (title, author, dates, …) and the
  catalog's /Metadata XMP stream.
• viewer_preferences() — page layout, page mode, print preferences,
  and reading direction hints.
• outline() — bookmark tree as OutlineItems with
  destination/action resolution.
• destinations(), resolve_named_destination(name) — named
  destination table merged from /Catalog /Dests (legacy) and the
  /Names /Dests name tree.
• page_annotations(page) — typed Annotation list with
  destination/action resolution.
• form(), form_fields() — AcroForm field tree (text, choice,
  button, signature) with widget cross-references.
• page_boxes(page) — MediaBox / CropBox / BleedBox / TrimBox /
  ArtBox.
• embedded_files(), embedded_file_bytes(name) — /EmbeddedFiles
  name-tree walker.
• layers(), layer(ocg_id), configurations(),
  default_configuration(), layer_tree(), layer_set_for(intent)
  — Optional Content Group (OCG) metadata, hierarchy, render-intent
  rules, and a runtime LayerSet for visibility overrides.
• parse_warnings() — diagnostic sink for non-fatal parse issues
  (broken outlines, bad name trees, malformed /VE expressions, …).
• New stet inspect <file.pdf> CLI subcommand surfaces the structural
  API at the command line.

See docs/PDF-READER-API.md and docs/PDF-LAYERS.md for full
references.

Added — PDF imaging extensions

Display-list-level support for the PDF transparency and optional-content
imaging models, layered on top of the PostScript interpreter.

• Alpha and blend modes: setblendmode, setfillalpha,
  setstrokealpha, setalphaisshape. All 16 PDF blend modes.
• Transparency groups: begintransparencygroup /
  endtransparencygroup with Knockout, Isolated, and group
  colour space (DeviceGray / DeviceRGB / DeviceCMYK / ICC).
• Soft masks: begintransparencymaskgroup /
  endtransparencymaskgroup with Alpha and Luminosity subtypes,
  transfer functions, and backdrop-colour handling.
• Optional Content (OCG): setocg / endocg operators wrap
  display-list content in OcgGroup elements with
  OcgVisibility::Single / Membership / Expression predicates.
  LayerSet (in stet-graphics) is the consumer's per-render override
  map; render_page_to_rgba_with_layers honours it.
• Filters: JBIG2Decode and JPXDecode for embedded image
  streams.

See docs/PDF-EXTENSIONS.md for the full reference and
docs/PDF-LAYERS.md for the runtime layer-visibility model.

Added — pdfmark PostScript-to-PDF authoring

pdfmark operator dispatch in stet-ops (gated behind
register_pdf_authoring_ops so it's only visible to systemdict on the
PDF output path) plus matching emitters in stet-pdf. Five phases of
authoring support:

• /DOCINFO — document info dictionary (title, author, subject,
  keywords, creator, producer, dates, trapped).
• /OUT — outline (bookmark) tree authoring with destination /
  action targets.
• /ANN — Link, Text, FreeText annotations.
• /DEST, /PAGE, /PAGES — named destinations and per-page-box
  overrides.
• /VIEWERPREFERENCES, /Metadata — viewer preferences and
  document-level XMP metadata.
• /Widget and /FORM — AcroForm widget annotations and field-tree
  emission.
• /EMBED, JavaScript / Named actions, page-level /AA triggers.

See docs/PDFMARK-AUTHORING.md for the full reference.

Added — colour management

• Hand-rolled colorimetric A2B1 CLUT sampler
  (stet-graphics::icc::perceptual). moxcms 0.8's create_transform
  pipeline over-saturates CMYK→sRGB output relative to lcms2 / Acrobat
  / Ghostscript on midtone colours; this module bypasses it for v2
  lut16Type CMYK profiles and matches lcms2 RelCol output to ±1 RGB
  level on a 17⁴ sweep against ISO Coated v2 300% (ECI). Out-of-gamut
  colours clip to the sRGB boundary (matching lcms2 / GS) so pure
  process primaries remain saturated. BPC is calibrated against the
  sampler's own (1, 1, 1, 1) output so K-heavy CMYK lands at the
  correct darkness. Profiles whose tables are mAB / mft1 fall back
  to the moxcms-driven bake.
• Soft-mask CMYK-domain blend gate widened to accept Group-wrapped
  flat CMYK fills (GWG 16.11 "Gradient Feather"). The GWG 16.10
  outer-glow protection still rejects on the inner Fill's blend-mode
  check.

Changed — public API breaking changes

These match-surface enums are now #[non_exhaustive] so adding
variants is non-breaking for any consumer that includes a _ => arm.
Existing consumers must add wildcard arms (or update their match
expressions) to keep building.

• stet-graphics: DisplayElement, ImageColorSpace,
  ShadingColorSpace, SpotColorSpace, LineCap, LineJoin,
  FillRule.
• stet-core: PsError, FilterKind, RleState.
• stet-core::pdfmark: PdfMarkRecord, AnnotationSubtype,
  AnnotationTarget, OutlineDestination, OutlineAction,
  GoToTarget, ViewSpec, FieldType, FieldValue, DocDate,
  TrappedState, TzSign, LinkHighlight, TextAnnotationIcon,
  PageOverrideScope.
• stet-pdf-reader: PdfError, Destination, ViewSpec, Action,
  AnnotationDate, AnnotationKind, AnnotationColor,
  AnnotationKindData, FieldKind, ButtonType, FieldValue,
  TrappedFlag, PageLayout, PageMode, ReadingDirection,
  PrintScaling, Duplex, AfRelationship, ParsePhase,
  LocationHint, Severity, RenderIntent, LayerIntent,
  UsageState, PageElementSubtype, LayerTreeNode, BaseState,
  ListMode, AutoStateEvent.

Param structs (FillParams, StrokeParams, ImageParams, the
pdfmark record structs, Annotation, FormField, Layer, etc.) are
not marked #[non_exhaustive] — adding fields lands additively
and consumers should pattern-match with .. for forward
compatibility.

A scripts/check-non-exhaustive.sh audit runs in the local pre-push
hook; new public enums in the listed files must either carry the
marker or be allow-listed with a one-line justification. See the
"Stable extension points" section of CLAUDE.md and the per-doc
"Stability" sections of docs/DISPLAY-LIST.md,
docs/PDF-READER-API.md, and docs/PDFMARK-AUTHORING.md.

Changed — other

• stet-pdf: removed the PDF/X-3 OutputIntent emission. The writer
  was emitting soft-mask transparency (prohibited by PDF/X-3) while
  labelling output as PDF/X-3:2003 — a conformance conflict any
  preflight tool would flag. PDF output is now plain PDF 1.7 with no
  PDF/X conformance claim. A correct PDF/X-4 implementation is
  planned.
• stet-pdf: PdfDevice::set_output_profile() is #[deprecated]
  as a no-op. Retained for forward API compatibility with the planned
  PDF/X-4 work.
• stet-cli: --width / --height flags for PDF input override
  the page's MediaBox at render time.

Added — documentation

• docs/PDF-READER-API.md — full reference for the structural API.
• docs/PDF-LAYERS.md — full reference for the OCG / layer API.
• docs/PDF-EXTENSIONS.md — full reference for the imaging extension
  operators and the JBIG2 / JPX filters.
• docs/PDFMARK-AUTHORING.md — full reference for the pdfmark
  authoring bridge.
• New Rendering Correctness section in the root README covering
  seam-free rendering on adjacent clipped regions and full overprint
  simulation.

stet 0.1.2

stet-cli bugfix release

Versions 0.1.0 and 0.1.1 of stet-cli have been yanked from crates.io. If you previously installed either one, upgrade with:

cargo install stet-cli --force

What was broken

The stet binary's context setup never registered the embedded resource bundle (init scripts, encodings, CMaps, fonts, ICC profile) into its virtual filesystem. Instead it walked up from the binary location via find_resource_path() looking for a resources/ directory on disk. For anyone who installed via cargo install stet-cli — with no resource tree adjacent to ~/.cargo/bin/stet — findresource for the viewer's OutputDevice failed, the CLI fell back to a PNG-writing rasterizer, and every PostScript page rendered in the interactive viewer would silently write a rogue .png file next to the input.

What's fixed in 0.1.2

stet-cli now calls stet::embedded_resources::register_all() at context creation, matching what the stet facade library has always done. The binary is fully self-contained — no resources/ directory required, no rogue PNGs, viewer mode behaves correctly.

Scope

• Affected: stet-cli 0.1.0 and 0.1.1 (yanked).
• Not affected: the stet library crate (used via Interpreter), stet-pdf-reader, stet-fonts, stet-graphics, and every other library crate in the workspace. All of those were and remain correct.

stet 0.1.0

[0.1.0] — 2026-04-18

Initial public release.

PostScript interpreter

• Level 3 interpreter with ~320 operators covering stack, math, type,
  dict, array, string, control, file, graphics state, path construction,
  painting, clipping, colour, font, show, image, halftone/transfer,
  pattern/device, resource, and param categories.
• Arena + entity-indirection memory model with full save/restore (COW).
• Dual VM (local/global) with unified stores and vm_alloc_mode.
• Name interning via NameTable; dict version cache for O(1) name
  resolution on the hot path.
• Full Type 1, CFF/Type 2, Type 3, TrueType, and Type 42 (CID) font
  support with URW substitutions for the 35 standard PostScript fonts.
• Eexec, ASCIIHex, ASCII85, RLE, Flate, LZW, DCT, SubFile, and their
  encode counterparts as streaming filters.
• CIE-based colour spaces (A/ABC/DEF/DEFG) and ICC-based via moxcms.
• Smooth shading types 1–7 (function, axial, radial, triangle meshes,
  Coons/tensor patches) with native PS function evaluation.

PDF reader (stet-pdf-reader)

• Self-contained PDF parser: xref (including xref streams), decryption
  (RC4/AES), object-stream decompression, page tree, resource
  resolution.
• Content-stream interpreter producing the same DisplayList type the
  PostScript interpreter produces — no dependency on stet-core.
• Transparency groups, soft masks (alpha & luminosity), tiling
  patterns, shadings 1–7.
• All standard stream filters including Flate (with PNG predictors),
  LZW, DCT (two backends), CCITT, JBIG2, JPEG 2000, ASCII85, ASCIIHex.
• Optional Content Groups (OCG) captured in the display list for future
  layer toggling.
• PDF OutputIntent profile honoured by default for PDF/X documents.
• CJK CMap loading (poppler-data / STET_CMAP_DIR).

Rendering (stet-render)

• tiny-skia–based rasterizer (vendored as stet-tiny-skia) producing
  RGBA output.
• Banded rendering sized to L2 cache; rayon-parallel band processing.
• Clip fast path with rect detection, mask caching, and spare mask
  recycling.
• Viewport rendering: render any rectangular region of a display list
  at any zoom without re-interpreting the source.
• ICC-aware CMYK path with black-point compensation and per-pixel
  consistency checks for transparency-group blending.
• Overprint simulation (OPM 0/1), including strict OPM-1 "preserve
  zero components" semantics.
• Hairline and stroke-adjust handling for thin lines.

PDF output (stet-pdf)

• Display list → PDF with embedded fonts (Type 1, TrueType, CFF),
  image compression, shadings, and transparency groups.
• Preserves native CMYK and spot colour spaces (Separation, DeviceN)
  without lossy RGB round-tripping.
• Pre-sampled transfer, halftone, and black-generation/UCR tables
  carried per paint element.
• Print-workflow quality output suitable for pre-press.

Viewer & frontends

• stet-viewer: egui desktop viewer with pan/zoom, minimap,
  multi-page navigation, and drag-and-drop.
• On-demand viewport rendering: zoom/pan without re-interpretation.
• WASM frontend (stet-wasm, excluded from the main workspace):
  browser-side PDF viewer with viewport rendering and SIMD-enabled
  tiny-skia.

Public library API (stet facade)

• Interpreter::new() / Interpreter::builder() for batteries-included
  PostScript rendering.
• render() → RGBA pages, render_to_display_list() → display lists,
  render_to_pdf() → PDF bytes, exec() → side-effects only.
• All 53 resources (fonts, encodings, CMaps, ICC profile) embedded in
  the binary via include_bytes!.
• Example programs: render_ps, render_pdf, display_list.

Workspace

• 13 crates under Apache-2.0 OR MIT, plus two vendored tiny-skia forks
  (stet-tiny-skia, stet-tiny-skia-path) under BSD-3-Clause.
• stet-pdf-reader is intentionally independent of stet-core — it
  can be used as a standalone PDF parser/renderer without pulling in
  the PostScript VM.