pdftract/notes/pdftract-34hxw.md

pdftract-34hxw: AcroForm Tx (text field) value extraction

Status: PASS (implementation already present)

Summary

The AcroForm /Tx (text field) value extraction is already fully implemented in crates/pdftract-core/src/forms/value_text.rs. The implementation correctly handles all requirements from the bead description.

Implementation Verification

Module Location

• File: crates/pdftract-core/src/forms/value_text.rs (737 lines)
• Exports: TextValue struct and extract_text_value function
• Re-exports in: crates/pdftract-core/src/forms/mod.rs

TextValue Struct

pub struct TextValue {
    pub value: Option<String>,      // Current value (/V)
    pub default: Option<String>,    // Default value (/DV)
    pub multiline: bool,            // /Ff bit 12 (1<<12 = 0x1000)
    pub max_length: Option<u32>,    // /MaxLen (negative → None)
}

FormFieldValue::Text Variant

The FormFieldValue::Text variant is properly defined in combiner.rs:

pub enum FormFieldValue {
    Text {
        value: Option<String>,
        default: Option<String>,
        multiline: bool,
        max_length: Option<u32>,
    },
    // ... other variants
}

PDFDocEncoding/UTF-16BE Decoding

The decode_pdf_string() function correctly implements:

1. UTF-16BE BOM detection (0xFE 0xFF prefix)
2. UTF-16BE decoding (with and without BOM)
3. PDFDocEncoding fallback (full 29-character override table from PDF spec Annex D.2)
4. Heuristic UTF-16BE detection for malformed inputs

Acceptance Criteria Status

Criterion	Status	Notes
Text field with /V → FormFieldValue::Text { value: Some(...), ... }	✅ PASS	test_extract_text_value_basic
UTF-16BE BOM-prefixed /V → correct Unicode decode	✅ PASS	test_extract_text_value_utf16be_bom
/Ff multiline bit set → multiline: true	✅ PASS	test_extract_text_value_multiline
/MaxLen 50 → max_length: Some(50)	✅ PASS	test_extract_text_value_with_max_length
Empty /V → value: Some("")	✅ PASS	test_extract_text_value_empty_value
Missing /V → value: None	✅ PASS	test_extract_text_value_no_value

Test Results

All 12 text_value tests passed:

PASS [   0.014s] test_extract_text_value_name_as_value
PASS [   0.016s] test_extract_text_value_with_max_length
PASS [   0.016s] test_extract_text_value_utf16be_bom
PASS [   0.017s] test_text_value_empty_constructor
PASS [   0.016s] test_extract_text_value_multiline
PASS [   0.017s] test_text_value_equality
PASS [   0.017s] test_extract_text_value_with_default
PASS [   0.018s] test_extract_text_value_basic
PASS [   0.018s] test_extract_text_value_no_value
PASS [   0.020s] test_extract_text_value_negative_max_length_ignored
PASS [   0.020s] test_extract_text_value_combined_flags
PASS [   0.021s] test_extract_text_value_empty_value
Summary [   0.028s] 12 tests run: 12 passed, 2660 skipped

Additional Test Coverage

The module also includes comprehensive PDFDocEncoding tests:

• test_decode_pdf_string_ascii
• test_decode_pdf_string_utf16be_bom
• test_decode_pdf_string_utf16be_bom_odd_length
• test_decode_pdf_string_pdfdocencoding_latin1
• test_decode_pdf_string_pdfdocencoding_lower_latin1
• test_decode_pdf_string_pdfdocencoding_bullet
• test_decode_pdf_string_pdfdocencoding_em_dash
• test_decode_pdf_string_pdfdocencoding_quotes
• test_decode_pdf_string_empty
• test_looks_like_utf16be
• test_extract_string_from_value_unrecognized_type
• test_decode_pdf_string_never_panics
• test_extract_text_value_combined_flags

Integration

The implementation is properly integrated:

1. Exported from forms/mod.rs as pub use value_text::{extract_text_value, TextValue}
2. Used by acro_field_to_value() function for Tx field conversion
3. Consumed by combine() function in combiner.rs
4. Part of the FormFieldValue enum for JSON serialization

Conclusion

No code changes were required. The implementation is complete, well-tested, and properly integrated into the forms pipeline. All acceptance criteria are met.