From dacda5bcfd4241a191811e66e0f4f181113b95d2 Mon Sep 17 00:00:00 2001 From: jedarden Date: Sat, 23 May 2026 15:25:05 -0400 Subject: [PATCH] docs(pdftract-3qz): add verification note for Phase 2.1 Font Type Detection coordinator All 5 child beads completed: - pdftract-3uq: Font subtype classifier and BaseFont prefix stripper - pdftract-juc: Standard 14 font registry with hardcoded metrics - pdftract-6ah: Embedded font program loader (ttf-parser/owned_ttf_parser) - pdftract-cv4: Type 0 composite font + descendant CIDFont loader - pdftract-5sh: CIDToGIDMap resolver (Identity and stream forms) 77 font module tests pass. Acceptance criteria: - PASS: All children closed - PASS: Classifier returns all 8 FontKind variants - PASS: Subset prefix stripping works correctly - PASS: CIDToGIDMap Identity and stream forms verified - PASS: No unwrap/expect on resource dict access Co-Authored-By: Claude Opus 4.7 --- notes/pdftract-3qz.md | 138 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 138 insertions(+) create mode 100644 notes/pdftract-3qz.md diff --git a/notes/pdftract-3qz.md b/notes/pdftract-3qz.md new file mode 100644 index 0000000..a335b71 --- /dev/null +++ b/notes/pdftract-3qz.md @@ -0,0 +1,138 @@ +# pdftract-3qz: Phase 2.1 Font Type Detection (coordinator) + +## Summary + +Coordinator for sub-phase 2.1: Font Type Detection. All 5 child beads completed successfully, delivering a comprehensive font module that can classify, load, and provide metrics for all PDF font types. + +## Children Completed + +| Bead ID | Title | Commit | Verification Note | +|---------|-------|--------|-------------------| +| pdftract-3uq | Font subtype classifier and BaseFont prefix stripper | 46c515e | notes/pdftract-3uq.md | +| pdftract-juc | Standard 14 font registry with hardcoded metrics | 7429a67 | (included below) | +| pdftract-6ah | Embedded font program loader (ttf-parser/owned_ttf_parser) | ffaaf69 | notes/pdftract-6ah.md | +| pdftract-cv4 | Type 0 composite font + descendant CIDFont loader | 5e2390f | notes/pdftract-cv4.md | +| pdftract-5sh | CIDToGIDMap resolver (Identity and stream forms) | 03aa4da | notes/pdftract-5sh.md | + +## Acceptance Criteria Status + +| Criterion | Status | +|-----------|--------| +| All children closed | PASS - All 5 child beads closed | +| Classifier returns one of {Type1, Type1Std14, TrueType, Type0, CIDFontType0, CIDFontType2, Type3, OpenTypeCFF} | PASS | +| Subset prefix `ABCDEF+Times-Roman` strips to `Times-Roman` for Std-14 lookup | PASS | +| CIDFontType2 with `/CIDToGIDMap /Identity`: GID == CID | PASS | +| CIDFontType2 with stream CIDToGIDMap: 2-byte big-endian decode verified | PASS | +| Module unit tests in `crates/pdftract-core/src/font/` pass | PASS - 77 tests | +| No unwrap/expect on resource dict access | PASS - uses `.and_then()` and defaults | + +## Module Structure + +``` +crates/pdftract-core/src/font/ +├── mod.rs # FontKind enum, classify_font(), strip_subset_prefix() +├── std14.rs # Standard 14 font metrics registry (build.rs generated) +├── embedded.rs # EmbeddedFont, FontMetrics, OpenTypeMetrics, EmptyFontMetrics +└── type0.rs # Type0Font, DescendantCIDFont, CIDToGIDMap, /W array parsing +``` + +## Test Results + +``` +test result: ok. 77 passed; 0 failed; 0 ignored +``` + +All font module tests pass, covering: +- Font classification (Type1, Type1Std14, TrueType, Type0, CIDFontType0, CIDFontType2, Type3, OpenTypeCFF) +- Subset prefix stripping (valid, invalid, edge cases) +- Standard 14 font detection +- Type0 composite font loading +- CIDToGIDMap resolution (Identity and stream forms) +- /W array parsing (per-CID and range forms) +- Embedded font program loading (TrueType, OpenType CFF) + +## Child Bead Summaries + +### pdftract-3uq: Font subtype classifier and BaseFont prefix stripper +- Implemented `FontKind` enum with all 8 PDF font types +- `strip_subset_prefix()` - validates exactly 6 ASCII uppercase + `+` +- `classify_font()` - reads `/Subtype`, `/BaseFont`, descendant CIDFont, FontDescriptor +- 21 unit tests covering all branches + +### pdftract-juc: Standard 14 font registry with hardcoded metrics +- `build.rs` generates compile-time metrics from AFM-derived JSON +- `Std14Metrics` struct with widths, ascent, descent, italic_angle, font_bbox +- `get_std14_metrics()` lookup by canonical name (post-prefix-strip) +- Symbol/ZapfDingbats use distinct encodings (SymbolEncoding, ZapfDingbatsEncoding) +- Binary footprint: ~20 KB generated source, ~8 KB data (well under 60 KB limit) + +### pdftract-6ah: Embedded font program loader +- `EmbeddedFont` wrapping `owned_ttf_parser::OwnedFace` +- `FontMetrics` trait with `glyph_id_for()`, `advance()`, `bbox()` +- `EmptyFontMetrics` fallback for corrupt/missing font programs +- Graceful handling of subset fonts (unmapped chars return None) +- Diagnostic `FONT_PARSE_FAILED` for corrupt programs + +### pdftract-cv4: Type 0 composite font + descendant CIDFont loader +- `Type0Font` with descendant `DescendantCIDFont` +- `/DW` default width parsing (default 1000) +- `/W` array parsing (per-CID `[c [w1 w2 ...]]` and range `[cfirst clast w]`) +- Sparse `BTreeMap` storage for CID widths +- CIDFontType0 (CFF) vs CIDFontType2 (TrueType) detection + +### pdftract-5sh: CIDToGIDMap resolver +- `CidToGidMap::{Identity, Array(Box<[u16]>)}` enum +- Identity short-circuit (zero allocation, GID == CID) +- Stream form: 2-byte big-endian u16 array indexed by CID +- Diagnostic `CIDTOGIDMAP_TRUNCATED` for odd-byte-count input +- Out-of-range CID returns GID 0 (notdef glyph) + +## Integration Points + +This module delivers the `Font` value needed by: +- **Phase 2.2**: Encoding resolution (ToUnicode, differences, AGL fallback) +- **Phase 2.3**: CJK CMap parsing and CID-to-Unicode mapping +- **Phase 2.4**: Type3 font content stream execution +- **Phase 3**: Content stream execution (Tj, TJ, BT/ET operators) + +## Files Modified/Created + +**Created:** +- `crates/pdftract-core/src/font/mod.rs` +- `crates/pdftract-core/src/font/std14.rs` +- `crates/pdftract-core/src/font/embedded.rs` +- `crates/pdftract-core/src/font/type0.rs` +- `crates/pdftract-core/build.rs` +- `crates/pdftract-core/build/std14-metrics.json` +- `crates/pdftract-core/build/generate_std14_metrics.py` +- `crates/pdftract-core/build/fix_std14_weights.py` + +**Modified:** +- `crates/pdftract-core/src/lib.rs` - added `pub mod font;` +- `crates/pdftract-core/src/diagnostics.rs` - added `FONT_PARSE_FAILED`, `CIDTOGIDMAP_TRUNCATED` +- `.gitignore` - added `!/crates/pdftract-core/build/` exceptions + +## Commits Referenced + +- `46c515e` feat(pdftract-3uq): add font type classifier and subset prefix stripper +- `7429a67` feat(pdftract-juc): implement Standard 14 font metrics registry +- `ffaaf69` feat(pdftract-6ah): implement embedded font program loader +- `5e2390f` feat(pdftract-cv4): Type 0 composite font + descendant CIDFont loader +- `03aa4da` feat(pdftract-5sh): CIDToGIDMap resolver for CIDFontType2 +- `075de55` docs(pdftract-cv4): add verification note +- `b7392f1` docs(pdftract-6ah): add verification note + +## Notes + +- All child beads have verification notes in `notes/` directory +- Type3 font `/CharProcs` execution deferred to Phase 2.4 (as planned) +- OpenType CFF uses same `owned_ttf_parser` entrypoint as TrueType (CFF support via `opentype-layout` feature) +- The classifier handles indirect references gracefully (returns default, does not crash) +- Standard 14 fonts may have embedded font programs; registry serves as fallback + +## Ready for Next Phase + +Phase 2.1 is complete. The font module is ready for: +- **Phase 2.2**: Encoding resolution (ToUnicode, differences, AGL) +- **Phase 2.3**: CJK CMap parsing +- **Phase 2.4**: Type3 content stream execution