diff --git a/notes/pdftract-cv4.md b/notes/pdftract-cv4.md new file mode 100644 index 0000000..3354cb0 --- /dev/null +++ b/notes/pdftract-cv4.md @@ -0,0 +1,74 @@ +# Verification Note: pdftract-cv4 + +**Task:** Type 0 composite font + descendant CIDFont loader + +**Date:** 2026-05-23 + +## Summary + +Implemented `Type0Font::load()` following /DescendantFonts to the CIDFont dictionary, classifying the descendant as CIDFontType0 or CIDFontType2, reading /DW (default width), parsing /W array (two formats), and producing Type0Font containing both parent and descendant. + +## Acceptance Criteria Results + +### PASS + +1. **Type0 font with CIDFontType2 descendant loads; widths from `[10 [500 600]]` resolve as CID 10 -> 500, CID 11 -> 600** + - Test: `test_acceptance_type0_with_cidfonttype2` passes + - Implementation: `parse_w_array()` handles per-CID form `[c [w1 w2 ...]]` + +2. **Range form `[100 200 800]` resolves: CIDs 100..=200 all -> 800** + - Test: `test_acceptance_range_form` passes + - Implementation: `parse_w_array()` handles range form `[cfirst clast w]` + +3. **Missing CID falls back to DW (default 1000)** + - Test: `test_acceptance_missing_cid_fallback` passes + - Implementation: `get_width()` returns `widths.get(&cid).copied().unwrap_or(default_width)` + +4. **CIDFontType0 (CFF) descendant: ttf-parser CFF entrypoint used** + - Test: `test_load_type0_font_cidfonttype0` passes + - Implementation: `load_font_program()` delegates to `EmbeddedFont::load()` which uses `OpenTypeMetrics::from_data()` - ttf-parser handles both TrueType and CFF + +### WARN + +None + +### FAIL + +None + +## Files Modified + +- `crates/pdftract-core/src/font/mod.rs`: Added `pub mod type0;` and re-exports +- `crates/pdftract-core/src/font/type0.rs`: New file (1035 lines) implementing: + - `Type0Font::load()` - main entry point + - `parse_w_array()` - parses /W array in both formats + - `load_cid_to_gid_map()` - loads CIDToGIDMap for CIDFontType2 + - `load_font_program()` - loads embedded font from FontDescriptor + - `CIDToGIDMap` enum with Identity and Custom variants + - `DescendantCIDFont` struct with metrics and font program + - 23 unit tests (all passing) + +## Test Results + +``` +cargo test -p pdftract-core --lib font::type0 +running 23 tests +test result: ok. 23 passed; 0 failed +``` + +All 75 font module tests pass. + +## Implementation Notes + +1. **/W Array Parsing**: Token-by-token scan that switches between per-CID and range formats based on whether the second element is an array or integer +2. **Sparse Storage**: Uses `BTreeMap` for widths to handle arbitrary CID values (e.g., 50000+) +3. **CIDToGIDMap**: Supports Identity (GID == CID) and Custom (2-byte big-endian stream) variants +4. **Font Program**: Loaded via `EmbeddedFont::load()` which handles both CFF and TrueType via ttf-parser +5. **Graceful Degradation**: Missing FontDescriptor or font program emits diagnostic but doesn't fail the load + +## Git Commit + +``` +commit c12148a +feat(pdftract-cv4): Type 0 composite font + descendant CIDFont loader +```