5e413d06c3
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.
74 lines
2.7 KiB
Markdown
74 lines
2.7 KiB
Markdown
# no-mapping.pdf Fixture Structure Analysis
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**Date:** 2026-07-03
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**Bead:** bf-4ozvw
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**Fixture Path:** `tests/fixtures/encoding/no-mapping.pdf`
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## PDF Metadata (pdfinfo)
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```
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Custom Metadata: no
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Metadata Stream: no
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Tagged: no
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UserProperties: no
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Suspects: no
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Form: none
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JavaScript: no
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Pages: 1
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Encrypted: no
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Page size: 612 x 792 pts (letter)
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Page rot: 0
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File size: 660 bytes
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Optimized: no
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PDF version: 1.4
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```
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## Font and Encoding Information (pdffonts)
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```
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name type encoding emb sub uni object ID
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------------------------------------ ----------------- ---------------- --- --- --- ---------
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CustomNoMap Type 1 Custom no no no 5 0
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```
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## Structural Findings
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### File Characteristics
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- **Size:** Extremely small (660 bytes) — minimal fixture
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- **Pages:** Single page document
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- **Format:** PDF 1.4 (standard version)
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- **Page Size:** US Letter (612 x 792 pts)
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- **Complexity:** No JavaScript, forms, or metadata streams
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### Font Analysis
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- **Font Name:** `CustomNoMap` — descriptive name indicating purpose
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- **Font Type:** Type 1 (PostScript font)
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- **Encoding:** Custom — this is the key characteristic
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- **Embedding:** Not embedded (`emb: no`)
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- **Subsetting:** Not subset (`sub: no`)
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- **Unicode:** No Unicode mapping (`uni: no`)
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### Key Observations
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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.
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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.
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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.
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4. **Testing Utility:** This fixture appears to be designed to test pdftract's handling of:
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- Custom encodings that don't map to standard character sets
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- Glyph-to-text extraction fallback strategies
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- Error recovery when encoding mappings are unavailable
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### Technical Significance
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This fixture is particularly valuable for testing:
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- Font encoding edge cases
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- Glyph recognition without standard mappings
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- Error handling in the text extraction pipeline
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- Fallback strategies when standard encoding tables (AGL, CJK, etc.) don't apply
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## Notes for Documentation
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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.
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