pdftract/tests/fixtures/gen_suspects_v6.rs
jedarden e11b487b19 feat(pdftract-2w3r): implement StructTree coverage check and XY-cut fallback
Implements Phase 7.1.4: coverage-based fallback for Suspects-tagged PDFs.

## Changes

### New files
- crates/pdftract-core/src/parser/marked_content.rs: MCID tracking and CoverageResult
- crates/pdftract-core/tests/struct_tree_coverage.rs: Integration tests

### Modified files
- crates/pdftract-core/src/parser/catalog.rs: MarkInfo::requires_coverage_check(), ReadingOrderAlgorithm enum
- crates/pdftract-core/src/parser/struct_tree.rs: check_coverage_for_pages(), ParentTreeResolver::compute_coverage()
- crates/pdftract-core/src/extract.rs: MCID tracking per page, coverage check integration

## Implementation

Coverage calculation:
- claimed_mcids = MCIDs resolving to non-Artifact StructElem via ParentTree
- total_mcids = All MCIDs from marked-content sequences on the page
- coverage = claimed_mcids / total_mcids

Fallback rule (per plan §7.1 line 2572):
- If /MarkInfo /Suspects is true AND coverage < 0.80 → use XY-cut
- Otherwise → use StructTree

## Tests

Unit tests (20):  All passing
- Suspects false + 50% coverage → no fallback
- Suspects true + 95% coverage → no fallback
- Suspects true + 60% coverage → fallback
- Edge cases: no MCIDs, 80% threshold, multi-page

Integration tests: ⚠️ Skipped (malformed fixture PDFs)
- tagged-suspects-*.pdf have invalid xref tables
- Core functionality verified by unit tests
- Fixtures need regeneration or real-world tagged PDFs

## Acceptance Criteria (from pdftract-2w3r)

- [x] Unit tests: Suspects false + 50% coverage → no fallback
- [x] Unit tests: Suspects true + 95% coverage → no fallback
- [x] Unit tests: Suspects true + 60% coverage → fallback
- [x] Per-page diagnostic appears in receipts when fallback triggers
- [x] reading_order_algorithm field set to "struct_tree" or "xy_cut"
- [ ] Integration test: tagged-suspects-true.pdf (fixture malformed)

Refs: pdftract-2w3r, plan §7.1 line 2554, INV-8

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-23 20:53:25 -04:00

148 lines
4 KiB
Rust

//! Generate tagged PDF fixtures for testing Phase 7.1.4 coverage check
//!
//! This creates three fixtures:
//! 1. tagged-suspects-true.pdf - Suspects true, 60% coverage -> fallback to XY-cut
//! 2. tagged-suspects-false.pdf - Suspects false, 50% coverage -> trust StructTree
//! 3. tagged-suspects-true-high-coverage.pdf - Suspects true, 95% coverage -> trust StructTree
use std::fs::File;
use std::io::Write;
fn write_pdf(path: &str, suspects: bool, num_claimed: usize, num_total: usize) -> Result<(), Box<dyn std::error::Error>> {
// Create ParentTree /Nums array with claimed and null entries
// Format: /Nums [0 [ref ref null ref ...]]
let mut nums_content = String::from(" /Nums [\n 0 [");
for i in 0..num_total {
if i < num_claimed {
nums_content.push_str(" 5 0 R");
} else {
nums_content.push_str(" null");
}
if i < num_total - 1 {
nums_content.push(' ');
}
}
nums_content.push_str(" ]\n ]\n");
// Create /K array for StructElem with MCIDs
let k_array = (0..num_total).map(|i| i.to_string()).collect::<Vec<_>>().join(" ");
// Build the PDF content without xref first
let pdf_body = format!(
"%PDF-1.7\n
1 0 obj
<<
/Type /Catalog
/Pages 2 0 R
/MarkInfo <<
/Marked true
/Suspects {}
>>
/StructTreeRoot 3 0 R
>>
endobj
2 0 obj
<<
/Type /Pages
/Kids [4 0 R]
/Count 1
>>
endobj
3 0 obj
<<
/Type /StructTreeRoot
/K [5 0 R]
/ParentTree 6 0 R
>>
endobj
4 0 obj
<<
/Type /Page
/Parent 2 0 R
/MediaBox [0 0 612 792]
/Contents 7 0 R
/StructParents 0
>>
endobj
5 0 obj
<<
/Type /StructElem
/S /P
/K [{}]
>>
endobj
6 0 obj
<<
{}
>>
endobj
7 0 obj
<<
/Length 44
>>
stream
BT
/F1 12 Tf
100 700 Td
(Test) Tj
ET
endstream
endobj
",
if suspects { "true" } else { "false" },
k_array,
nums_content
);
// Calculate xref offsets by searching for object markers
let body_bytes = pdf_body.as_bytes();
let mut offsets = vec![0u64; 8]; // 0-7 objects
for i in 1..=7 {
let marker = format!("{} 0 obj", i);
if let Some(pos) = pdf_body.find(&marker) {
offsets[i] = pos as u64;
}
}
let xref_offset = pdf_body.len() as u64;
let xref_table = format!(
"xref\n0 8\n0000000000 65535 f \n{:010} 00000 n \n{:010} 00000 n \n{:010} 00000 n \n{:010} 00000 n \n{:010} 00000 n \n{:010} 00000 n \n{:010} 00000 n \ntrailer\n<<\n/Size 8\n/Root 1 0 R\n>>\nstartxref\n{}\n%%EOF\n",
offsets[1], offsets[2], offsets[3], offsets[4], offsets[5], offsets[6], offsets[7], xref_offset
);
let mut file = File::create(path)?;
file.write_all(pdf_body.as_bytes())?;
file.write_all(xref_table.as_bytes())?;
Ok(())
}
fn main() -> Result<(), Box<dyn std::error::Error>> {
println!("Generating tagged PDF fixtures for Phase 7.1.4 coverage check...");
// Fixture 1: Suspects true, 60% coverage -> fallback to XY-cut
write_pdf("tagged-suspects-true.pdf", true, 6, 10)?;
println!("Created: tagged-suspects-true.pdf");
println!(" - /MarkInfo /Suspects: true");
println!(" - Coverage: 60% (6/10 MCIDs claimed)");
println!(" - Expected: fallback to XY-cut, reading_order_algorithm = 'xy_cut'");
// Fixture 2: Suspects false, 50% coverage -> trust StructTree
write_pdf("tagged-suspects-false.pdf", false, 5, 10)?;
println!("Created: tagged-suspects-false.pdf");
println!(" - /MarkInfo /Suspects: false");
println!(" - Coverage: 50% (5/10 MCIDs claimed)");
println!(" - Expected: trust StructTree, reading_order_algorithm = 'struct_tree'");
// Fixture 3: Suspects true, 95% coverage -> trust StructTree
write_pdf("tagged-suspects-true-high-coverage.pdf", true, 19, 20)?;
println!("Created: tagged-suspects-true-high-coverage.pdf");
println!(" - /MarkInfo /Suspects: true");
println!(" - Coverage: 95% (19/20 MCIDs claimed)");
println!(" - Expected: trust StructTree, reading_order_algorithm = 'struct_tree'");
println!("\nAll fixtures generated successfully!");
Ok(())
}