Files
pdfcraft/crates/filters/Cargo.toml
T
Grzegorz MartensandClaude Opus 5.5 ea6c329731 M2.6: JBIG2 decoding in pdfcraft-filters; Document::decoded_image reads JBIG2 images
decode_jbig2 sits next to decode_ccitt, through hayro-jbig2 as Export ▸ Images
used it, and shares CCITT's row sink. The JBIG2 page has to be the image's size:
PdfCraft's renderer draws the whole page into the image (black box: a 4-row page
behind /Height 2 fills the image box with all four rows), so the rows of a taller
page aren't the image's. The decoder decodes a page whole, so the page is checked
before it is decoded: that size, within the caller's bound as rows of one bit, and
at most 2^28 pixels (MAX_JBIG2_PIXELS; the decoder keeps a bit a pixel, about 34 MB
there).

Document::decoded_image_within decodes a JBIG2 image as it does a fax image: the
filters before it undone first, then the decoder with the /JBIG2Globals of the
image's own /DecodeParms entry (/Crypt counts in the position; fax_params and the
globals now share last_filter_parms). Globals have a limit of their own,
MAX_JBIG2_GLOBALS (32 MiB, moved from Export), and globals that can't be read are an
error rather than ignored.

Export ▸ Images reads JBIG2 through it, so its own decoder, row sink and DecodeParms
reader go, and hayro-jbig2 leaves pdfcraft-create. JBIG2 behind another filter now
exports, and so copies (Copy Image uses the same function); a page taller than the
image, which Export cut to the image's rows, now skips the image, as one of another
width did. doc_export_all_images' description no longer lists JBIG2 inside other
filters as skipped.

The optimizer's monochrome step read images through decoded_image_within and
relied on JBIG2 failing there: it now leaves JBIG2 images alone explicitly, as
before (a resampled one would come out Flate under Retain), and the README and
parity note list them as not yet handled.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-30 18:03:06 +01:00

24 lines
699 B
TOML

[package]
name = "pdfcraft-filters"
description = "PDF stream filters (ISO 32000-2 §7.4): Flate, LZW, predictors, ASCII85, ASCIIHex, RunLength, CCITT Group 4 encoding and Group 3 and 4 decoding, JBIG2 encoding and decoding"
version.workspace = true
edition.workspace = true
license.workspace = true
rust-version.workspace = true
repository.workspace = true
[lints]
workspace = true
[dependencies]
fax.workspace = true
# CCITT fax and JBIG2 decoding (`decode_ccitt`, `decode_jbig2`); already in the tree through hayro.
hayro-ccitt.workspace = true
hayro-jbig2.workspace = true
flate2.workspace = true
thiserror.workspace = true
[dev-dependencies]
proptest.workspace = true
weezl.workspace = true