Phase 8 #4 of REVIEWS/DART_PDF_VS_MAKEPAD_PDF_GAP_ANALYSIS.md
("Advanced colour"). Design and merge criteria in
REVIEWS/adr/0006-pdf-advanced-color.md.
The interpreter tracked only the *name* of the active colour space and
then passed sc/scn operands to the device as if they were already RGBA.
Every non-device space therefore rendered a confident wrong colour with
no error:
/Spot cs 1.0 scn full tint of a spot ink -> pure red
/Idx cs 3 scn palette entry 3 -> near-black
/Lab cs 50 0 0 scn mid gray -> white (clamped)
/DevN cs (5 inks) five colorants -> inks 5+ discarded
/ICCBased profile-defined colour -> profile discarded
DeviceCMYK also used the additive 1-c-k conversion, which crushes any
colour printed over black.
Three new modules in pdf-graphics:
- function.rs PDF functions, all four types. Type 4 runs on a bounded
interpreter: depth 32, 32768 tokens, stack 100, 100000
steps, and an unknown operator is an error rather than a
no-op that would leave a plausible wrong colour.
- icc.rs ICC matrix/TRC and gray kTRC profiles, applied exactly.
LUT-class profiles are reported as such and the caller
falls back to /Alternate; they are never pretended to be
matrix profiles.
- colorspace.rs All eleven families, converting through XYZ with
Bradford adaptation and a real sRGB transfer function.
Wiring:
- PdfDevice gains set_stroke_components/set_fill_components, so SC/SCN
reach the device as components of the active space instead of being
read positionally as RGBA.
- cs/CS now resets to the space's initial colour (table 74), which is
why golden/colors.txt gains a line.
- PdfPage::color_spaces carries /Resources /ColorSpace fully
dereferenced with streams decoded; a half-resolved space would make
every ICC profile, palette and type 0/4 transform silently fall back.
- A space that cannot be resolved keeps the previous colour and records
a typed ColorError. No colour is invented, and no error is swallowed.
Tests: 12 corpus fixtures under tests/corpus/color/, 14 acceptance
tests in pdf-document/tests/color.rs asserting numeric RGB (the broken
code produced a colour for every one of these; only the value was
wrong), plus unit tests per function type and per curve type. Two fuzz
targets added: eval_function and parse_colorspace.
TEST_TARGET=pdf 387 -> 447 passing, TEST_TARGET=pdf-ui 431 -> 491.
rustfmt and clippy -D warnings clean.
Phase 2 of REVIEWS/DART_PDF_VS_MAKEPAD_PDF_GAP_ANALYSIS.md. The exit
criterion is that a real content stream renders through the device path and
is verifiable; previously nothing could fail, so nothing was proven.
Step 2.3, the operations the review calls "the lies", all reached a dead end
in the interpreter. Each now reaches the device:
- Inline images: BI/ID/EI were emitted as two empty marker ops and the
payload was discarded, so an inline image could never be drawn. They are
now parsed into a single InlineImage op carrying the dictionary and bytes.
Abbreviated keys (/W /H /BPC /CS /F) and colour-space and filter
abbreviations are expanded. The EI scan requires delimiters on both sides
so binary data containing the bytes "EI" does not truncate the image, and
an unterminated image yields no image rather than invented pixels.
- Do (XObject) was an empty match arm. The interpreter cannot resolve a
resource name, so it now reports it through PdfDevice::paint_x_object and
the device performs the lookup.
- set_dash and set_miter_limit only mutated interpreter-local state and
emitted no command, so dashes never reached any renderer.
Three further defects surfaced while reviewing the generated goldens, all
of which silently corrupted output rather than failing:
- `cm` was never parsed at all. The single-character `m` arm matched first
and consumed it as a moveto, so every CTM change in every document was
lost and content drew at the wrong position. Two-character operators are
now tested before their one-character prefixes.
- `rg` and `RG` were shadowed by the `r` and `R` arms, so an RGB fill was
read as a single-component grey: `0.1 0.2 0.3 rg` produced 0.1 0.1 0.1.
- ImageInfo defaulted a missing /Filter to FlateDecode. An absent /Filter
means the data is stored raw, so every uncompressed image was undecodable.
Testing: adds format_commands(), a deterministic one-line-per-command text
form of a RenderCommand list, and eight golden files covering vector paths,
text, kerning and spacing, dash and stroke parameters, fill rules, inline
images, XObjects and colour operators. Floats are fixed-precision and
negative zero is normalised so no spurious diffs appear. UPDATE_GOLDEN=1
regenerates them for review.
Also fixes .gitignore: blanket *.txt and *.pdf rules were silently excluding
the golden expectations and the AcroForm fixture added in the previous
commit, which would have left both test suites unable to run on a fresh
clone.
Validation: TEST_TARGET=pdf ./tools/test-rust-clean.sh
132 tests pass; rustfmt and clippy -D warnings clean.
