FredApps
7d3d4830e5
Includes #4325 #1952 #4180 #2529 #4320 #4805, preserving their original histories. Keep paragraph alignment and hard/soft wrap metadata together; retain CCITT/downsampling/RGB ownership guards with bounded JBIG2 export and exact-copy symbol encoding. Combined interaction regressions added. Validation pending.
13 KiB
PDF specification and standards parity
Last reviewed: 2026-10-10 · Last updated: 2026-10-26 · Change: minor (§7.4: redaction decodes CCITT fax images, Group 3 on bytes aside; earlier, §7.4: CCITT decoding in
pdfcraft-filters) · Target: Adobe Acrobat Pro (Acrobat DC, continuous track 26.002.21931, macOS)
Lossless JBIG2 encoding and image export are included alongside CCITT decoding and monochrome downsampling; combined validation is pending.
JBIG2 exact-copy symbol dictionaries and text regions are included; lossy substitution is not supported.
How much of ISO 32000-2 (PDF 2.0) and the PDF subset standards PdfCraft implements, set against
what Acrobat Pro implements. This is PdfCraft's equivalent of a "geometry" or "codec" checklist:
the parts of the format users never see named but always feel. Feature-level detail is in
parity/acrobat-features.toml; the gaps are ranked in gaps.md.
Legend: own (our code), borrowed (the vendored hayro bootstrap or lopdf), partial,
none. "Evidence" names tests or checklist ids.
PDF specification and standards ≈ 60% ready (estimated): syntax, encryption, annotations, AcroForm, redaction and signatures are our own and well tested; graphics, fonts and image codecs are borrowed; PDF 2.0 additions and most subset standards are missing. 150–260 h to parity (within the features total; most of it is the renderer and font engine, and Preflight).
ISO 32000-2 by clause
| Clause | Topic | Acrobat | PdfCraft | Evidence / what's missing |
|---|---|---|---|---|
| §7.2–7.5 | Syntax, objects, file structure, xref tables and streams, object streams, hybrid files, incremental updates | full | own, tolerant, repairs damaged files | crates/cos; corpus 958 files; fuzzed nightly |
| §7.4 | Stream filters: Flate, LZW, ASCII85, ASCIIHex, RunLength, predictors | full | own | crates/filters |
| §7.4 | Image filters: DCT, JPX, JBIG2, CCITTFax | full | borrowed (decode); CCITT Group 4 encoding | core.image-filters partial; own codecs M1.1/M1.2; CCITT decoding in pdfcraft-filters (decode_ccitt, through hayro-ccitt) for export, redaction and the Optimizer, which encodes Group 4 (optimize.mono-compression); no JBIG2 encoding |
Lossless JBIG2 encoding and image export are included alongside CCITT decoding and monochrome downsampling; combined validation is pending.
JBIG2 exact-copy symbol dictionaries and text regions are included; lossy substitution is not supported.
| §7.5.8 | Linearization | R W | R only | core.linearization planned |
| §7.6.4 | Standard security handler R2–R6 (RC4 40/128, AES-128, AES-256), crypt filters, /EncryptMetadata, SASLprep | full | own, read and write | crates/crypt; written files open in Acrobat DC since #836 (#774: Acrobat needs the catalog outside object streams) |
| §7.6.5 | Public-key security handler | full | none | core.open-public-key, protect.certificate-encryption planned |
| §7.6.2 | Unencrypted signature /Contents | yes | yes | signing encrypted documents (#753) |
| §7.9.2 | Text strings incl. PDF 2.0 UTF-8 | full | PDFDocEncoding and UTF-16; UTF-8 none | core.pdf20-utf8-strings planned |
| §7.11 | File specifications, embedded files | full | read and save attachments; no add/delete/describe | organize.attachments-* planned |
| §7.12 | Extensions dictionary | yes | preserved | |
| §8 | Graphics: paths, colour spaces, patterns, shadings, images, XObjects | full | borrowed renderer; own content parser and serializer (crates/content) for editing and redaction | rendering P0s partial |
| §8.6 | ICC-based colour, output intents, colour management | full | ICC preserved; sRGB output intent for PDF/A; no colour management settings or soft proofing | print.color-management planned |
| §9 | Text and fonts: Type 1, TrueType, OpenType/CFF, Type 3, CID-keyed, CMaps, ToUnicode | full | borrowed rendering; own text extraction (word-F1 0.98); standard-14 metrics for generated appearances; embedded fonts reused for editing, else Helvetica | view.render-type3, view.render-cid-fonts partial; no own font engine; no font embedding/subsetting for arbitrary new text beyond craft-fonts Japanese |
| §10 | Rendering: transfer functions, halftones, overprint, smoothness | full | borrowed; no overprint preview | print.overprint-preview planned |
| §11 | Transparency: blend modes, soft masks, groups, knockout | full | borrowed (knockout shipped) | view.render-transparency partial |
| §12.1–12.3 | Viewer preferences, page layout, page labels, outlines, destinations | full | own: initial view, page labels, bookmarks edit and from structure, named destinations rewired on copy | named-destination editing panel planned |
| §12.4 | Page transitions, thumbnails, articles, presentations | full | /Trans and /Dur read and listed by doc_info, not played; thumbnails discarded or kept | organize.page-transitions partial, view.articles-panel planned |
| §12.5 | Annotations | 28 types | see table below | |
| §12.6 | Actions | 19 types | see table below | |
| §12.7 | Interactive forms (AcroForm): fields, appearances, calculation order, JavaScript actions | full | own: all field types, regenerated appearances, Acrobat's AF functions and event order, sandboxed JavaScript (boa) | form.js-host partial (object-model subset); submit planned |
| §12.7.8 | XFA (deprecated in PDF 2.0; Acrobat still fills XFA) | static and dynamic | own, partial: template layout, FormCalc, XFA JavaScript model, datasets | form.xfa-* partial; no flattening |
| §12.8 | Digital signatures | see table below | | |
| §12.9 | Measurement and geospatial | full | 2D measuring with viewports and calibration; no geospatial | comment.geospatial planned |
| §12.10 | Document requirements | yes | none | |
| §13 | Multimedia: sound, movies, screen, rich media, 3D (U3D, PRC) | yes | preserved untouched; not played or shown | misc.rich-media-*, misc.3d-view planned (P3) |
| §14.3 | Metadata: info dictionary, XMP | full, XMP editor | info dictionary edited, with its XMP counterparts (title, author, subject, keywords, creator tool, producer) kept in step; XMP written for PDF/A; custom properties listed, added, changed and deleted (Document Properties ▸ Custom, doc_info, doc_set_info); no XMP editor | organize.custom-properties partial, organize.xmp-editor planned |
| §14.6–14.8 | Marked content, logical structure, tagged PDF | full, with editing tools | read (checker, bookmarks from structure, redaction of tags); no tag editing or autotag | gap 11 |
| §14.9 | Accessibility support: alt text, ActualText, language | full | alt text figure by figure, language, title | a11y.alt-text-workflow |
| §14.10 | Web capture | yes | none | |
| §14.11 | Prepress: page boxes, output intents, trapping, OPI | full | page boxes and crop; sRGB output intent | print.* production planned |
| §14.12 | Document parts (DPart) | yes | none | core.pdf20-dpart planned |
| §14.13 | Associated files (/AF) | yes | none | core.pdf20-associated-files planned |
| — | Structural validation (Arlington PDF model) | yes (Preflight syntax checks) | none | core.arlington-validation planned |
| — | Optional content (layers) | full | own toggle and default state, reset to the default state; set-OCG-state actions; no layer editing | view.layers-panel, view.layers-reset |
| — | Redaction (/Redact annotations, applying) | full | own: removes glyphs, image pixels, vectors, XObject content, annotations, fields and tags; verifies no residue | protect.redact-*, protect.redaction-verification |
Annotations (§12.5.6)
| Type | Acrobat | PdfCraft | Notes |
|---|---|---|---|
| Text (note), Popup | create, edit | create, edit; pop-ups not movable windows | comment.popups planned |
| Link | create, edit | create, edit, from URLs | edit.link-* |
| FreeText (text box, typewriter, callout) | create, rich text | create; rich text written but no per-run formatting | comment.text-box partial |
| Line, Square, Circle, Polygon, PolyLine | create | create, all ten line endings | |
| Highlight, Underline, Squiggly, StrikeOut | create | create | |
| Caret (insert/replace text) | create | create; snapped to the text in the UI (upright horizontal text, unrotated pages) | comment.insert-text partial |
| Stamp | create, custom, dynamic | create, custom, dynamic, Sign Here | stamp management planned |
| Ink | create, erase | create, erase | no pressure |
| FileAttachment | create | create | |
| Sound | create, play | preserved | P3 |
| Redact | create, apply | create, apply | own |
| Widget | create, edit | create, edit | AcroForm |
| Watermark | create | page-content watermarks (as Acrobat writes them); /Watermark annotations preserved |
|
| Screen, Movie, RichMedia, 3D | create, play | preserved | P3 |
| PrinterMark, TrapNet | create (print production) | preserved | |
| Projection | create (PDF 2.0) | preserved |
Actions (§12.6.4)
| Action | Acrobat | PdfCraft |
|---|---|---|
| GoTo | yes | yes (page with Fit; named destinations and zoom partial) |
| GoToR | yes | partial: local PDF paths open in a PdfCraft tab; /F strings and file-spec dictionaries (/UF, then /F), source-relative paths, and explicit numeric-page destinations are supported. Automation uses the same resolver and --root confinement. Named destinations open at the target's default view with a warning; /NewWindow is a tab hint. Network/URL file systems are refused. |
| GoToE | yes | none (preserved; the Optimizer can remove invalid ones) |
| Launch | yes (restricted) | none |
| Thread | yes | none |
| URI | yes | yes |
| Sound, Movie, Rendition, GoTo3DView, RichMediaExecute | yes | none (P3) |
| Hide | yes | yes |
| Named | yes | safe list (print, page navigation) |
| SubmitForm | yes | explained, not sent |
| ResetForm | yes | yes |
| ImportData | yes | via Import form data, not as an action |
| JavaScript | yes | yes in fields and buttons (sandboxed); document actions none |
| SetOCGState | yes | yes |
| Trans | yes | none |
Digital signatures (§12.8, ETSI EN 319 142 PAdES)
| Capability | Acrobat | PdfCraft |
|---|---|---|
Sub-filters adbe.pkcs7.detached, ETSI.CAdES.detached; read adbe.pkcs7.sha1, adbe.x509.rsa_sha1 |
yes | yes |
| PAdES B-B | yes | yes (PKCS #12, macOS Keychain, Windows store with PIN) |
| PAdES B-T (signature timestamp), document timestamps | yes, with configured TSA | partial: works when a TSA is given; no timestamp-server preferences |
| PAdES B-LT, B-LTA (DSS/VRI, OCSP/CRL) | yes, fetched online | partial: evidence supplied by the caller; no online fetching |
| DocMDP certification | yes | yes |
| FieldMDP (lock fields) | yes | none |
| UR3 usage rights | preserved, Reader-extending is Adobe-only | none (P3) |
| Seed values | yes | none |
| Validation: chain, key usage, EKU, critical extensions, changes after signing, signed version | yes | yes; name constraints and issuer critical extensions missing |
| Trust: own store, OS store, AATL, EUTL | yes | own store only; AATL out of scope; OS and EUTL planned |
| Smart cards and tokens (PKCS #11, CryptoTokenKit) | yes | Windows CNG store (with PIN prompt) only |
Subset standards
| Standard | Acrobat | PdfCraft | Hours |
|---|---|---|---|
| PDF/A-1a/b (ISO 19005-1) | verify, convert | none | |
| PDF/A-2a/b/u, PDF/A-3a/b/u | verify, convert | partial: 2b and 3b structural rules and conversion (sRGB intent; not CMYK) | |
| PDF/A-4, 4e, 4f | verify, convert | none | |
| PDF/X-1a, X-3, X-4 (ISO 15930) | verify, convert | none | |
| PDF/UA-1, PDF/UA-2 (ISO 14289) | verify (Preflight), checker | Accessibility Checker (32 rules, Acrobat's own), no PDF/UA verification | |
| PDF/E, PDF/VT | verify, convert | none | |
| Preflight (profiles, fixups, reports) | hundreds of profiles | none | |
| Factur-X / ZUGFeRD (e-invoice in PDF/A-3) | Preflight checks | none | |
| All subset standards | 65–115 (gap 9) |
Revision history
| Date | Change | Summary |
|---|---|---|
| 2026-10-26 | minor | §7.4: redaction clears pixels in CCITT fax images through the CCITT decoder, instead of removing them whole (Group 4 and Group 3 off bytes; Group 3 on bytes is still removed whole, as the bootstrap renderer may draw it as other rows than the decoder reads) |
| 2026-10-26 | minor | §7.4: CCITT decoding (hayro-ccitt) in pdfcraft-filters, for export and the Optimizer |
Lossless JBIG2 encoding and image export are included alongside CCITT decoding and monochrome downsampling; combined validation is pending.
JBIG2 exact-copy symbol dictionaries and text regions are included; lossy substitution is not supported.
| 2026-10-26 | minor | §7.4: CCITT Group 4 encoding (fax) in the Optimizer |
| 2026-10-14 | minor | §12.4.4: /Trans and /Dur read into DocInfo::transitions and reported by doc_info |
| 2026-10-11 | minor | §7.6.4: encrypted files we write open in Acrobat (#774, fixed by #836) |
| 2026-10-10 | major | Created from the code, vendor/README.md and parity/acrobat-features.toml, against ISO 32000-2 and Acrobat Pro 26.002.21931's documented capabilities |