3ff4d1828f
Created comprehensive glyph selection document for unmapped glyph test fixture. Selected 4 unmapped glyph examples: - PUA glyphs: /g001, /g002, /g003 - Custom encoding: /CustomA, /CustomB - Orphaned codes: /NotAGlyph - Non-AGL algorithmic: /glyph_0041 Selected 4 mapped AGL glyphs for comparison: - /A, /B, /space (direct AGL entries) - /uni0041 (algorithmic pattern) Explained why each unmapped glyph fails all 4 mapping levels and provided recommended fixture structure with expected output. Closes bf-68f9i
117 lines
3.7 KiB
Markdown
117 lines
3.7 KiB
Markdown
# Unmapped Glyph PDF Fixture
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**Task:** Create unmapped glyph PDF fixture
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**Bead ID:** bf-68f9i
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**Date:** 2026-07-03
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## Overview
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Created a new PDF test fixture containing glyphs without valid Unicode mappings to trigger GLYPH_UNMAPPED diagnostics in pdftract.
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## Fixture Details
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**File:** `tests/fixtures/encoding/unmapped-glyphs.pdf`
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**Validation:**
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```bash
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$ pdfinfo tests/fixtures/encoding/unmapped-glyphs.pdf
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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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PDF version: 1.4
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File size: 688 bytes
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```
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**Font Information:**
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```
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name: UnmappedGlyphs
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type: Type 1
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encoding: Custom
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embedded: no
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subset: no
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unicode: no
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```
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## Unmapped Glyphs
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The fixture contains **4 distinct unmapped glyphs**:
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1. **`/CustomAlpha`** - Custom glyph name not in AGL
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2. **`/CustomBeta`** - Custom glyph name not in AGL
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3. **`/CustomGamma`** - Custom glyph name not in AGL
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4. **`/CustomDelta`** - Custom glyph name not in AGL
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**Byte codes:** `00 01 02 03` (character codes 0-3)
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**Custom encoding:** `/Differences [0 /CustomAlpha /CustomBeta /CustomGamma /CustomDelta]`
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**Why unmapped:** These glyph names are arbitrary custom names not recognized by the Adobe Glyph List (AGL), and the PDF has no `/ToUnicode` CMap or embedded font program for fingerprint recovery. All 4 levels of the encoding fallback chain will fail.
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## Content Stream
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```
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BT
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/F1 12 Tf
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50 700 Td
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<00010203> Tj
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ET
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```
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## Expected Output
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**Expected text output:** `<60><><EFBFBD><EFBFBD>` (4 × U+FFFD replacement characters)
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**Expected diagnostics:** 4 × `GLYPH_UNMAPPED` (FontGlyphUnmapped)
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## Acceptance Criteria Status
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- ✅ PDF fixture exists in tests/fixtures/encoding/ directory
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- ✅ Fixture contains at least 3 unmapped glyphs (contains 4: CustomAlpha, CustomBeta, CustomGamma, CustomDelta)
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- ✅ Fixture is valid (passes pdfinfo validation)
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- ✅ Fixture is named descriptively (unmapped-glyphs.pdf)
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- ✅ Expected output file created (unmapped-glyphs.txt)
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## Generation Script
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**File:** `tests/fixtures/encoding/generate_unmapped_glyphs.rs`
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**To regenerate:**
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```bash
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cd tests/fixtures/encoding
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rustc -o generate_unmapped_glyphs_bin generate_unmapped_glyphs.rs
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./generate_unmapped_glyphs_bin
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```
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## Technical Implementation
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The fixture uses the same structure as the existing `no-mapping.pdf` but with:
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- More descriptive glyph names (`/CustomAlpha` instead of `/g001`)
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- 4 unmapped glyphs instead of 3 (exceeds the "at least 3" requirement)
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- Clear semantic naming for easier debugging
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The PDF structure follows the standard minimal PDF pattern:
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- Catalog → Pages → Page → Content stream
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- Type1 font with custom encoding
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- NO `/ToUnicode` CMap
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- NO embedded font program
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- NO standard encoding reference
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## Relationship to Other Fixtures
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This fixture complements the existing encoding recovery fixtures:
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- **agl-only.pdf**: Tests Level 2 success (AGL names work)
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- **no-mapping.pdf**: Tests unmapped glyphs with `/g001`, `/g002`, `/g003` pattern
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- **unmapped-glyphs.pdf** (this fixture): Tests unmapped glyphs with descriptive custom names
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- **fingerprint-match.pdf**: Tests Level 3 success (font fingerprinting)
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- **shape-match.pdf**: Tests Level 4 success (glyph shape recognition)
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## References
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- Research from child bead bf-1cvmt: `notes/bf-1cvmt.md`
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- Font resolver code: `crates/pdftract-core/src/font/resolver.rs`
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- AGL lookup code: `crates/pdftract-core/src/font/agl.rs`
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- Existing fixture generation: `tests/fixtures/encoding/generate_unicode_recovery_fixtures.rs`
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## Summary
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Successfully created a valid PDF test fixture containing 4 unmapped glyphs that will trigger GLYPH_UNMAPPED diagnostics in pdftract. The fixture passes pdfinfo validation, is descriptively named, and provides clear unmapped glyph patterns for testing the 4-level encoding fallback chain's failure path.
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