From 883d7d68b24e750b145502922587f313cb4af6a2 Mon Sep 17 00:00:00 2001 From: jedarden Date: Thu, 28 May 2026 01:36:58 -0400 Subject: [PATCH] docs(pdftract-2k3ms): add verification note for Phase 3.4 Marked Content Tracking coordinator - Verify all 3 children closed (pdftract-1l6wn, pdftract-64atr, pdftract-1q19p) - Verify nested BDC: innermost MCID wins (MarkedContentStack::innermost_mcid) - Verify EMC without BMC: ignored, no panic (pop_emc returns None with diagnostic) - Verify MCID 0: valid (Option allows Some(0)) - Verify OCG default OFF: glyphs emitted with is_hidden flag - Document 68 passing tests (18 stack + 30 operator + 20 OCG) Closes: pdftract-2k3ms --- notes/pdftract-2k3ms.md | 148 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 148 insertions(+) create mode 100644 notes/pdftract-2k3ms.md diff --git a/notes/pdftract-2k3ms.md b/notes/pdftract-2k3ms.md new file mode 100644 index 0000000..ccbf449 --- /dev/null +++ b/notes/pdftract-2k3ms.md @@ -0,0 +1,148 @@ +# Verification Note: pdftract-2k3ms - Phase 3.4 Marked Content Tracking (Coordinator) + +## Bead Description + +Coordinator for sub-phase 3.4: track BMC/BDC/EMC marked-content sequences and populate the `mcid: Option` field on each emitted Glyph with the innermost MCID currently in scope. Also handle Optional Content Group (OCG) /OC tags: glyphs inside an OCG whose default state is OFF are STILL emitted but flagged for downstream filtering. + +## Status: COMPLETE ✅ + +All 3 child beads are closed, and all coordinator acceptance criteria are met. + +## Children Status + +| Child Bead | Title | Status | Verification Note | +|------------|-------|--------|-------------------| +| pdftract-1l6wn | BMC / BDC / EMC operator parsers + marked-content stack | ✅ CLOSED | notes/pdftract-1l6wn.md | +| pdftract-64atr | MCID propagation to Glyph.mcid via emit_glyph wrapper | ✅ CLOSED | notes/pdftract-64atr.md | +| pdftract-1q19p | OCG /OC tag tracking + default-OFF detection via /OCProperties | ✅ CLOSED | Implementation verified in code | + +## Acceptance Criteria Verification + +### 1. All 3 children closed ✅ + +All three child beads are closed: +- `pdftract-1l6wn` (BMC/BDC/EMC operators) - closed +- `pdftract-64atr` (MCID propagation) - closed +- `pdftract-1q19p` (OCG tracking) - closed + +### 2. Nested BDC: innermost MCID wins for enclosed glyphs ✅ + +**Implementation:** `MarkedContentStack::innermost_mcid()` in `marked_content_stack.rs`: +```rust +pub fn innermost_mcid(&self) -> Option { + self.stack.iter().rev().find_map(|frame| frame.mcid) +} +``` + +The method iterates from the innermost frame (`rev()`) and returns the first MCID found, ensuring the innermost MCID wins. + +**Test Coverage:** +- `test_innermost_mcid_with_nested` - verifies innermost MCID wins +- `test_nested_frames` - verifies MCID visibility changes as frames are pushed/popped + +### 3. EMC without matching BMC: ignored, no panic ✅ + +**Implementation:** `MarkedContentStack::pop_emc()` in `marked_content_stack.rs`: +```rust +pub fn pop_emc(&mut self) -> Option { + if self.stack.is_empty() { + self.diagnostics.push(Diagnostic::with_static_no_offset( + DiagCode::EmcWithoutBmc, + "EMC operator without matching BMC/BDC", + )); + None + } else { + self.stack.pop() + } +} +``` + +Returns `None` and emits a diagnostic; no panic occurs. + +**Test Coverage:** +- `test_pop_emc_underflow` - verifies no panic and diagnostic emitted +- `test_parse_emc_underflow` - verifies BDC operator handler handles underflow + +### 4. MCID 0: valid (zero is a legal MCID) ✅ + +**Implementation:** The `mcid` field is `Option`, which allows `Some(0)` as a valid value distinct from `None`. + +**Test Coverage:** +- `test_glyph_with_mcid_zero` (in pdftract-64atr tests) - verifies MCID 0 is treated as valid +- The implementation correctly distinguishes `Some(0)` from `None` + +### 5. OCG default OFF: glyphs inside emitted with `is_hidden` flag ✅ + +**Implementation:** +- `MarkedContentFrame` has `is_hidden: bool` field (line 29) +- `MarkedContentStack::is_hidden()` returns true if ANY frame is hidden (line 160-162) +- `Glyph` struct has `is_hidden: bool` field (glyph/mod.rs line 73) +- BDC parser checks for /OC tag and /OCG property, resolves against OFF set (marked_content_operators.rs lines 69-85) +- `emit_glyph` accepts `is_hidden` parameter and sets it on the glyph + +**Test Coverage:** +- `test_parse_bdc_ocg_not_in_off_set` - OCG not in OFF → not hidden +- `test_parse_bdc_ocg_in_off_set` - OCG in OFF → hidden +- `test_parse_bdc_ocg_with_leading_slash` - /OC with leading slash works +- `test_parse_bdc_non_oc_tag_ignores_ocg` - non-OC tags ignore OCG property +- `test_stack_is_hidden_with_hidden_frame` - hidden flag propagates +- `test_stack_is_hidden_nested_outer_hidden` - outer hidden propagates to inner + +## Test Results + +``` +# Marked-content stack tests (18 tests) +cargo test -p pdftract-core --lib parser::marked_content_stack +Result: 18 passed + +# Marked-content operator tests (30 tests) +cargo test -p pdftract-core --lib parser::marked_content_operators +Result: 30 passed + +# OCG tests (20 tests) +cargo test -p pdftract-core --lib parser::ocg +Result: 20 passed + +# Total: 68 tests passed, 0 failed +``` + +## Integration Points + +### Phase 3.4 → Phase 3.2 (Glyph Emission) +- `emit_glyph()` accepts `mcid: Option` and `is_hidden: bool` parameters +- MCID and hidden flags are set on every emitted glyph +- Downstream Phase 4.6 will filter hidden glyphs based on user preferences + +### Phase 3.4 → Phase 7.1 (StructTree Exploitation) +- MCID links glyphs to structure elements via the StructTree +- Innermost MCID ensures correct structure-based reading order + +### OCG Integration +- `/OCProperties` parsed at document level (parser/ocg.rs) +- OFF set passed to content stream executor +- BDC /OC tags check OCG visibility and set `is_hidden` flag + +## Key Implementation Details + +### INV: Marked Content Stack Independence +The marked-content stack is independent of the graphics state stack (q/Q operators). This is correctly implemented in `content_stream.rs` where the two stacks are managed separately. + +### INV: Hidden Flag OR Semantics +Per bead pdftract-1q19p, the `is_hidden` flag is OR'd through nested frames: if any frame in the stack has `is_hidden=true`, all glyphs within are marked hidden. This is implemented in `MarkedContentStack::is_hidden()`. + +### INV: Innermost MCID Semantics +The `innermost_mcid()` method scans from the innermost frame outward, returning the first MCID found. BMC frames (no MCID) are transparent—the search continues outward. + +## Conclusion + +All coordinator acceptance criteria are met. The marked-content tracking implementation is complete with comprehensive test coverage. The three child beads collectively implement: +- BMC/BDC/EMC operator parsing with depth limiting +- MCID propagation to emitted glyphs (innermost wins) +- OCG /OC tag tracking with default-OFF detection +- Hidden flag propagation through nested marked-content scopes + +**Status: READY TO CLOSE** + +## Git Commit + +No new code changes were required for this coordinator bead. All implementation work was completed by the child beads. This verification note documents the integration and validates the coordinator-level acceptance criteria.