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jedarden 5e413d06c3 docs(bf-4ozvw): analyze no-mapping.pdf fixture structure 
Examine the no-mapping.pdf test fixture using PDF analysis tools:
- pdfinfo: extracted metadata (1 page, 660 bytes, PDF 1.4, letter)
- pdffonts: identified CustomNoMap Type 1 font with custom encoding
- Documented structural findings for later reference

Key finding: fixture uses custom encoding with no embedding, designed to
test pdftract's handling of glyphs without standard Unicode mappings.

Closes bf-4ozvw.
2026-07-03 18:46:27 -04:00

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no-mapping.pdf Fixture Structure Analysis

Date: 2026-07-03 Bead: bf-4ozvw Fixture Path: tests/fixtures/encoding/no-mapping.pdf

PDF Metadata (pdfinfo)

Custom Metadata: no
Metadata Stream: no
Tagged:          no
UserProperties:  no
Suspects:        no
Form:            none
JavaScript:      no
Pages:           1
Encrypted:       no
Page size:       612 x 792 pts (letter)
Page rot:        0
File size:       660 bytes
Optimized:       no
PDF version:     1.4

Font and Encoding Information (pdffonts)

name                                 type              encoding         emb sub uni object ID
------------------------------------ ----------------- ---------------- --- --- --- ---------
CustomNoMap                          Type 1            Custom           no  no  no       5  0

Structural Findings

File Characteristics

  • Size: Extremely small (660 bytes) — minimal fixture
  • Pages: Single page document
  • Format: PDF 1.4 (standard version)
  • Page Size: US Letter (612 x 792 pts)
  • Complexity: No JavaScript, forms, or metadata streams

Font Analysis

  • Font Name: CustomNoMap — descriptive name indicating purpose
  • Font Type: Type 1 (PostScript font)
  • Encoding: Custom — this is the key characteristic
  • Embedding: Not embedded (emb: no)
  • Subsetting: Not subset (sub: no)
  • Unicode: No Unicode mapping (uni: no)

Key Observations

  1. Custom Encoding Purpose: The fixture is specifically designed to test handling of custom font encodings that lack standard mappings to Unicode or other character sets.

  2. Minimal Complexity: At 660 bytes, this is likely a handcrafted or programmatically generated PDF with minimal content, focused specifically on the encoding edge case.

  3. No Font Embedding: The font is not embedded, meaning PDF readers would need to have access to the actual font file or rely on the encoding information provided.

  4. Testing Utility: This fixture appears to be designed to test pdftract's handling of:

    • Custom encodings that don't map to standard character sets
    • Glyph-to-text extraction fallback strategies
    • Error recovery when encoding mappings are unavailable

Technical Significance

This fixture is particularly valuable for testing:

  • Font encoding edge cases
  • Glyph recognition without standard mappings
  • Error handling in the text extraction pipeline
  • Fallback strategies when standard encoding tables (AGL, CJK, etc.) don't apply

Notes for Documentation

The fixture name "no-mapping" combined with the custom encoding suggests this is intentionally testing the case where pdftract must handle glyphs that have no direct mapping to readable text. This is a critical edge case for robust PDF text extraction.