pdf_cos 3.2.0

COS object layer for PDF: tokenizer, parser, filters (incl. CCITT, JBIG2, JPEG 2000), xref machinery, encryption, and serializer. Pure Dart, web-ready.

Changelog

3.2.0

• Lockstep minor release to align the dart-pdf package suite at 3.2.0. No public pdf_cos API changes since 3.1.1.

3.1.1

• Lockstep patch release to align the dart-pdf package suite at 3.1.1. No public pdf_cos API changes since 3.1.0.

3.1.0

• Lossless structural compaction: new CosCompactor/CosCompactionResult rewrite a document's reachable object graph, packing non-stream objects into compressed object streams behind a PDF 1.5 xref stream and re-deflating streams stored uncompressed (kept only when smaller). CosDocumentBuilder gains an objectStreams: mode (W [1 4 2]). The user-facing entry point is PdfEditor.compress() in pdf_document (#368).
• JPX (JPEG 2000) resolution-level skip: decode at a reduced cp_reduce level when an image is displayed far below its native size, instead of decoding full resolution and downscaling (#525).
• Cache decoded JBIG2 globals dictionaries across images on the same page - scanned books with shared /JBIG2Globals decode once, not per image (#532).
• Int-key the loaded-object cache so warm resolves allocate nothing (#522), and drop the double copy of every inflated stream (#533).

3.0.0

Lockstep major release: a breaking change in dart_pdf_editor moves the whole suite to 3.0.0. pdf_cos's own public API is unchanged.

• Cache decoded stream bytes on CosDocument so a stream inflated once (xref reconstruction, content parsing, image extraction) is not re-decoded on the next access (#392).
• Perf micro-batch: chunked message-digest hashing, an in-place JPX inverse DWT, and predictor/lexer/regex fast-path fixes (#407).

2.1.0

• Append incremental saves to the existing bytes instead of rebuilding the whole file: CosUpdater.saveTail() returns only the new tail (the appended objects, xref, and trailer), so an incremental revision costs the size of the change rather than the size of the document. Save cost no longer scales with the base file - a guard test pins that a 2.78x larger base does not make a same-sized edit 2.78x more expensive (#413).

• Memoise the per-object decryption key so a page's streams and strings derive it once per object rather than once per access, cutting repeated MD5/AES key derivation on encrypted documents (#400).

• Speed up CCITT G3/G4 decoding by ~4x on dense scanned pages: a monotonic cursor for the 2-D reference-row scan (was O(transitions^2) per row), peek-once prefix tables for run and mode codes, byte-run span fills, and a byte-at-a-time bit reader. The JBIG2 MMR path, which reuses the same decoder, gains a byte-at-a-time bitmap unpack. Output is byte-identical on well-formed, malformed, and truncated input, locked by golden digests captured from the previous implementation (#398).

2.0.0

• Major version bump for the 2.0.0 package suite. A breaking API change in dart_pdf_editor moves every package to 2.0.0 in lockstep; the COS object model, syntax, and (de)serialization API is source-compatible with 1.4.7.
• Add an asynchronous byte-source API (PdfByteSource) for progressive PDF loading: the reader pulls ranged slices on demand instead of requiring the whole file up front, so remote and large local files can paint their first page before the full download or read completes (#328, #359).
• Decode PDF text strings as PDFDocEncoding rather than Latin-1, so document metadata and outline titles that use PDFDocEncoding-specific code points round-trip correctly (#347).
• Add the crypto primitives behind one-tap and keyless signing identities: P-256 EcPrivateKey.generate, deterministic RFC 6979 ecdsaSign, the X.509 v3 builders buildSelfSignedCertificate / buildCaCertificate / issueCertificate, and ecSubjectPublicKeyInfo / pemEncode for Sigstore/Fulcio (#322, #337, #355).
• Internal refactors with no public API change: extract CosXrefReader from CosDocument, move the encryption object-graph walk behind the security handler, share file-tail framing between the builder and updater, and dedupe ObjStm header parsing between recovery and the stream decoder.

1.4.7

• Version bump to keep the dart-pdf package suite aligned at 1.4.7. No COS API changes since 1.4.6.

1.4.6

• Version bump to keep the dart-pdf package suite aligned at 1.4.6. No COS API changes since 1.4.5.

1.4.5

• Version bump to keep the dart-pdf package suite aligned at 1.4.5. No COS API changes since 1.4.4.

1.4.4

• Version bump to keep the dart-pdf package suite aligned at 1.4.4. No COS API changes since 1.4.3.

1.4.3

• Version bump to keep the dart-pdf package suite aligned at 1.4.3. No COS API changes since 1.4.2.

1.4.2

• Version bump to keep the dart-pdf package suite aligned at 1.4.2. No COS API changes since 1.4.1.

1.4.1

• Speed up dense content parsing with byte-level real-number parsing, operator interning, and streaming content-token handling.
• Keep the low-level parser and writer compatible with the rendering and editing improvements in the 1.4.1 package suite.

1.4.0

• Version bump to keep the dart-pdf package suite aligned at 1.4.0. Low-level parser, writer, filter, and crypto maintenance supports the higher-level editor and document features in this release.

1.3.2

• Version bump to keep the dart-pdf package suite aligned at 1.3.2. No COS API changes since 1.3.1.

1.3.1

• Add ContentStreamSerializer for writing parsed content-stream operations back to PDF syntax, including inline-image (BI/ID/EI) operations.

1.2.3

• Version bump to keep the dart-pdf package suite aligned at 1.2.3. No COS API changes since 1.2.2.

1.2.2

• Version bump to keep the dart-pdf package suite aligned at 1.2.2. No COS API changes since 1.2.1.

1.2.1

• Add a package example for pub.dev scoring.

1.2.0

• Version bump to keep the dart-pdf package suite aligned at 1.2.0. No low-level COS API changes since 1.1.0.

1.1.0

• Performance: a faster content-stream tokenizer. This is the heart of the render-speed work that puts dart-pdf ahead of PDFium on the benchmark corpus.
• Fix: JPEG 2000 tile-part desynchronization, and indexed Lab color palettes now decode correctly.

1.0.0

First stable release. Changes since 0.1.0:

• JBIG2: Huffman-coded symbol dictionaries and text regions, generic refinement regions, and pattern dictionaries with halftone regions.
• JPEG 2000: reset-probabilities (RESET) code-block style support.
• Inline images: correct data-length detection for DCT-filtered streams.

0.1.0

Initial release.

• COS object model: dictionaries, arrays, names, strings, streams, references.
• Lenient tokenizer/parser for real-world PDFs (broken /Length, missing endobj, junk before the header, broken xref chains with object-scan recovery).
• Cross-reference tables and streams; lazy object loading; incremental updates.
• Filters: Flate, LZW, RunLength, ASCIIHex, ASCII85, DCT passthrough, CCITT G3/G4, JBIG2 (embedded profile), JPEG 2000.
• Encryption: RC4, AES-128, AES-256 decryption and encrypt-on-write.
• Crypto primitives for signing/validation: ASN.1, RSA, ECDSA, CMS, X.509 chain verification.
• Content-stream tokenizer and a from-scratch document builder.