Fix character spacing in fonts using ligatures #1325
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Please merge this PR. |
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Same issue happened in Gujrati & Hindi Fonts. |
duncanwerner
added a commit
to sdllc/pdf-lib
that referenced
this pull request
Aug 20, 2023
the font embedder was dropping alternate glyphs, which broke (in our case) tnum rendering. fixed via someone else's PR: Hopding#1325
punit-shah
approved these changes
Apr 3, 2024
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What?
Fixes glyph spacing being wrong when fonts use ligatures. This problem was mentioned in issue #440, #871, #1010.
Why?
The suggested workaround was to disable font ligatures, but ligatures are a desirable feature of many fonts, especially on some non-latin scripts, or on fonts that simulate or are inspired by cursive handwriting.
How?
The problem is in PDF-LIB: the code gets the glyph metric this way:
When fonts have ligatures, there might be several glyphs for a single code point, therefore the glyph metric code does not work and misses some glyphs.
This fix just gets the metrics for all glyphs in the font and does not use
glyphForCodePointTesting?
The problem is pretty easy to spot on the rendered PDF when using a font using ligatures, like Lobster. Integration test 1, which tests font rendering, was used to check that the issue was fixed.
New Dependencies?
None
Screenshots
Before
After
Suggested Reading?
Yes
Anything Else?
No
Checklist