# Phase 3: Content Stream Processing — Verification Note

**Bead ID:** pdftract-57fu
**Date:** 2025-06-03
**Status:** COMPLETE

## Summary

Phase 3: Content Stream Processing is fully implemented and all tests pass. The content stream interpreter successfully executes PDF operators to produce raw glyph lists with positions.

## Sub-phase Status

All 5 sub-phase beads are CLOSED:

| Sub-phase | Bead ID | Status | Key Implementation |
|-----------|---------|--------|-------------------|
| 3.1 Graphics State Machine | pdftract-tuky | ✅ CLOSED | `graphics_state.rs` with full state stack, CTM, text matrices, colors |
| 3.2 Text Operator Processing | pdftract-1byb3 | ✅ CLOSED | `content_stream.rs` with Tj/TJ/'/" operators, `glyph/mod.rs` |
| 3.3 Resource Context and Form XObject Recursion | pdftract-4gxs1 | ✅ CLOSED | ResourceStack, Do operator, cycle detection (depth 20) |
| 3.4 Marked Content Tracking | pdftract-2k3ms | ✅ CLOSED | `marked_content_stack.rs`, BMC/BDC/EMC operators |
| 3.5 Inline Images | pdftract-nf172 | ✅ CLOSED | BI/ID/EI detection and skip |

## Acceptance Criteria Status

### ✅ All 5 sub-phase beads closed
Confirmed: All coordinators closed.

### ✅ pdftract-core::content module compiles and consumes Phase 1 + Phase 2 outputs
- `content_stream.rs` compiles successfully
- Consumes fonts from Phase 2 (Font, UnicodeSource)
- Consumes parser output from Phase 1 (PdfDict, ResourceDict)

### ✅ Per-page Vec<Glyph> produced for all fixture PDFs
The `execute_with_do` function produces `Vec<Glyph>` for any page content stream.

### ✅ All Phase 3 critical tests pass

Test results (cargo nextest run -p pdftract-core --lib content_stream):
- **120/120 content_stream tests passed**

Key tests verified:
- ✅ `q`/`Q` 64-deep nesting: `test_64_nested_q_calls_succeed`, `test_64_q_plus_64_q_restores_initial_state`
- ✅ `Td` chain: `test_execute_with_do_td_chain`
- ✅ TeX-PDF word boundaries: `test_tj_with_kerning_just_above_threshold`
- ✅ TJ kerning: `test_tj_array_with_negative_kerning`, `test_tj_array_with_large_positive_kerning`
- ✅ Invisible text (Tr=3): `test_tr_three_preserves_rendering_mode`
- ✅ Form XObject cycle: `test_execute_with_do_form_xobject_cycle_detected`
- ✅ Marked content nesting: `test_process_with_mode_innermost_mcid_wins`
- ✅ Inline images: `test_inline_image_skip`, `test_inline_image_ei_without_whitespace`

### ✅ Page /Rotate normalization
Function `normalize_glyph_bboxes_by_rotation` implements inverse rotation for 90/180/270°.

## Key Files Implemented

| File | Purpose |
|------|---------|
| `crates/pdftract-core/src/graphics_state.rs` | GraphicsState, Matrix3x3, Color, GraphicsStateStack |
| `crates/pdftract-core/src/content_stream.rs` | process_with_mode, execute_with_do, operator processing |
| `crates/pdftract-core/src/glyph/mod.rs` | Glyph struct, emit_glyph, advance/bbox computation |
| `crates/pdftract-core/src/word_boundary.rs` | WordBoundaryDetector, WordBoundaryManager, TextState |
| `crates/pdftract-core/src/parser/marked_content_stack.rs` | MarkedContentStack for BMC/BDC/EMC |

## Verification Commands

```bash
# Run Phase 3 tests
cargo nextest run -p pdftract-core --lib content_stream graphics_state glyph word_boundary

# Result: 272 tests run: 272 passed
```

## Test Output Summary

```
Summary [   0.501s] 272 tests run: 272 passed, 2605 skipped
```

All Phase 3 content stream, graphics state, glyph, and word boundary tests pass successfully.

## Integration Points

Phase 3 successfully integrates with:
- **Phase 1 (Parser)**: Uses PdfDict, ResourceDict, ObjRef from parser module
- **Phase 2 (Fonts)**: Uses Font, FontKind, UnicodeSource from font module
- **Phase 4 (Layout)**: Provides Vec<Glyph> as input to span merging

## Conclusion

Phase 3: Content Stream Processing is **COMPLETE**. All sub-phases are closed, all tests pass, and the implementation meets all acceptance criteria.