sz5000 opened a new pull request, #446:
URL: https://github.com/apache/pdfbox/pull/446
## Summary
Extends `TTFSubsetter` with two new public methods that allow callers to
inject custom cmap
subtables into the subset TTF. This enables correct re-subsetting of
TrueType fonts that use
non-Unicode cmap encodings — in particular fonts produced by Ghostscript
with `TT_BIAS=0xF000`,
where the Mac Roman cmap (platform 1, encoding 0) is the primary rendering
cmap used by viewers.
Fixes PDFBOX-XXXXX.
---
## Changes
**`TTFSubsetter.java`**
- New field `customCmapEntries` — accumulates entries added via the new API
- `buildCmapTable()` extended:
- now produces output even when `uniToGID` is empty (i.e. when only
`addGlyphIds()` was used)
- writes one Format 4 subtable per distinct `(platformId,
platformEncodingId)` pair
- GIDs are translated to renumbered subset GIDs via the existing
`getNewGlyphId()` mechanism
- New private helpers `buildFormat4Subtable()` and
`buildFormat4SubtableNewGids()` extracted
from the previous monolithic `buildCmapTable()` implementation
- New public method `addCustomCmapEntry(platformId, platformEncodingId,
charCode, gid)`
- New public method `addCustomCmap(platformId, platformEncodingId,
Map<Integer,Integer> codeToGid)`
- Javadoc added for `addGlyphIds()` (previously undocumented)
---
## Backwards Compatibility
Fully backwards-compatible. Callers that do not use the new API get
identical behaviour to
the previous implementation.
---
## Testing
Verified against PDFs produced by Ghostscript 10.x containing Thai and other
non-Latin scripts
subsetted with `TT_BIAS=0xF000`. Before this change, re-subsetting such
fonts produced a TTF
with a broken or missing Mac Roman cmap, causing viewers to render blank
glyphs. After this
change, both the Mac Roman and Windows Symbol subtables are correctly
preserved in the subset,
and glyph rendering is identical to the original.
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