EPS: images encoded with CCITTFaxDecode draw

The PostScript interpreter that reads EPS and PostScript files had no
CCITTFaxDecode filter. Reading a file whose image data went through it
stopped at an error naming the filter, and the file opened from a
fallback, such as its preview or the art drawn before the image, or
did not open.

CCITTFaxDecode now decodes CCITT Group 4 (ITU-T T.6) and Group 3
one-dimensional and mixed (ITU-T T.4) data to rows of 1-bit samples.
It reads K, Columns, Rows, EndOfBlock, EndOfLine, EncodedByteAlign and
BlackIs1 (PLRM 3rd ed., §3.13; ISO 32000-2, §7.4.6). With EndOfBlock
the data ends at its EOFB or RTC regardless of Rows, and the RTC of
mixed Group 3 data, six EOLs each with a tag bit, is found by the
filter. Damaged data keeps the rows decoded before it, and damage in
the first row is an ioerror. Columns outside 1 to 65,535 and Rows
below 0 are a rangecheck, and data that would decode to more than
256 MiB is refused. hayro-ccitt 0.3.0, already in Cargo.lock through
hayro-syntax, becomes a dependency of vectorcraft-eps.

The tests encode their images in the test, with the fax crate's
Group 4 encoder and T.4 run codes (a dev-dependency, already in
Cargo.lock through tiff), and fail without the change. The import fuzz
tests read a Group 4 and a Group 3 image coded by hand from the T.4
and T.6 tables, read the same file with random damage, and add the
filter and its parameters to the hostile programs.

Docs: docs/file-format-parity.md, docs/target-app-parity.md.
This commit is contained in:
dotCooCoo
2026-10-17 14:43:14 +07:00
committed by bflatastic
parent 025ce255ae
commit a070d83be3
8 changed files with 395 additions and 4 deletions
+2
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@@ -93,6 +93,8 @@ the app's own editing copy of a file (an EPS after its `%%EOF`, a `.ai`'s `AIPri
| Illustrator `.ai` | open, save | yes (PDF-compatible + editing-data structure, File Info) | PDF-compatible, or legacy version 7 (layers and groups) | see above; no real-file corpus |
| Illustrator template `.ait` | open, save | yes | no (save as `.vctemplate`) | |
| PDF | open, place, save | yes (layers, masks, editable text, security, overprint, File Info from the XMP packet and the document information dictionary; Crop To › Trim takes the bleed box as the document's bleed) | yes (presets, PDF/X-1a/3/4, layers, marks and bleed, ICC, fast web view, 1.3+) | fuzzed import; shared guarded writer and windowed reader ([pdf-backend.md](pdf-backend.md)), metadata, incomplete-content and dependency-source regressions; PDF text placement issues in some files (#722); alpha soft masks drawn as images import with the mask (#1551); a clip only counts as covering the page when its shape does (#1542); a PDF another app copied pastes as editable vector art (#1499); letter-spaced type on a path keeps its length and its glyph-by-glyph stroke comes in as one text object (#1586, #1585); a crafted name tree with shared nodes no longer takes exponential time on open (#1781) |
| EPS | open, place, save | yes (own PostScript L3 interpreter, Illustrator EPS editing data structure) | yes (L2/L3, TIFF previews) | CID-keyed CJK type not read; #505; images encoded with `CCITTFaxDecode` (ITU-T T.4 Group 3 and T.6 Group 4, with `K`, `Columns`, `Rows`, `EndOfBlock`, `EndOfLine`, `EncodedByteAlign` and `BlackIs1`) draw, and damaged data keeps the rows decoded before its first damaged row; Type 42 (TrueType) fonts set type at its size (#1553); a clip only counts as covering the page when its shape does (#1542); an EPS another app copied pastes as editable vector art (`clipboard.importEps`, #1499); a stitched shading keeps its hard colour changes on import (#1654); CMYK images, CMYK JPEGs included, keep their ink amounts on import, as from PDF, and the pixels a `MaskColor` or `ImageType 3` mask hides become a grayscale opacity mask; ruzstd 0.9.1 for compressed editing data (#1807, RUSTSEC-2026-0344) |
| PostScript `.ps` | open | no | via Print to PostScript | |
| EPS | open, place, save | yes (own PostScript L3 interpreter, Illustrator EPS editing data structure) | yes (L2/L3, TIFF previews) | CID-keyed CJK type and CCITTFax images not read; #505; Type 42 (TrueType) fonts set type at its size (#1553); a clip only counts as covering the page when its shape does (#1542); an EPS another app copied pastes as editable vector art (`clipboard.importEps`, #1499); a stitched shading keeps its hard colour changes on import (#1654); CMYK images, CMYK JPEGs included, keep their ink amounts on import, as from PDF, and the pixels a `MaskColor` or `ImageType 3` mask hides become a grayscale opacity mask; ruzstd 0.9.1 for compressed editing data (#1807, RUSTSEC-2026-0344) |
| PostScript `.ps` | open, place | yes (the EPS reader reads its first page; `.epsf` files open and place as EPS) | via Print to PostScript | `tests_epsimport.rs` |
| SVG / SVGZ | open, place, save | yes | yes (SVG Options, Preserve Editing, symbols, filters, rich text) | strongest format; tests in `crates/svg/tests`; text on a path follows basic shapes as their SVG 2 equivalent paths (#1527); CSS transforms and the `font` shorthand (#1565), percentage lengths in symbols (#1596), Inkscape flowed text as area type (#1568) and Inkscape pages as artboards (#1601) import; an unsupported filter is named in its warning (#1598) |