## Summary
**What is the goal of this PR?**
Rewrite of font routines to use std binary search algorithms instead of
custom repeated implementations: `lookupKernClass`,
`EpdFont::getLigature`, and `EpdFont::getGlyph`.
---
### AI Usage
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please be transparent about their usage as it
helps set the right context for reviewers.
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## Summary
**What is the goal of this PR?**
Improved typesetting, including
[kerning](https://en.wikipedia.org/wiki/Kerning) and
[ligatures](https://en.wikipedia.org/wiki/Ligature_(writing)#Latin_alphabet).
**What changes are included?**
- The script to convert built-in fonts now adds kerning and ligature
information to the generated font headers.
- Epub page layout calculates proper kerning spaces and makes ligature
substitutions according to the selected font.
## Additional Context
- I am not a typography expert.
- The implementation has been reworked from the earlier version, so it
is no longer necessary to omit Open Dyslexic, and kerning data now
covers all fonts, styles, and codepoints for which we include bitmap
data.
- Claude Opus 4.6 helped with a lot of this.
- There's an included test epub document with lots of kerning and
ligature examples, shown in the photos.
**_After some time to mature, I think this change is in decent shape to
merge and get people testing._**
After opening this PR I came across #660, which overlaps in adding
ligature support.
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Did you use AI tools to help write this code? _**YES, Claude Opus 4.6**_
---------
Co-authored-by: Cursor <cursoragent@cursor.com>
## Summary
**What is the goal of this PR?**
Consolidated repeated logic to fall back to REPLACEMENT_GLYPH.
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## Summary
* This PR fixes decomposed diacritic handling end-to-end:
- Hyphenation: normalize common Latin base+combining sequences to
precomposed codepoints before Liang pattern matching, so decomposed
words hyphenate correctly
- Rendering: correct combining-mark placement logic so non-spacing marks
are attached to the preceding base glyph in normal and rotated text
rendering paths, with corresponding text-bounds consistency updates.
- Hyphenation around non breaking space variants have been fixed (and
extended)
- Hyphenation of terms that already included of hyphens were fixed to
include Liang pattern application (eg "US-Satellitensystem" was
*exclusively* broken at the existing hyphen)
## Additional Context
* Before
<img width="800" height="480" alt="2"
src="https://github.com/user-attachments/assets/b9c515c4-ab75-45cc-8b52-f4d86bce519d"
/>
* After
<img width="480" height="800" alt="fix1"
src="https://github.com/user-attachments/assets/4999f6a8-f51c-4c0a-b144-f153f77ddb57"
/>
<img width="800" height="480" alt="fix2"
src="https://github.com/user-attachments/assets/7355126b-80c7-441f-b390-4e0897ee3fb6"
/>
* Note 1: the hyphenation fix is not a 100% bullet proof implementation.
It adds composition of *common* base+combining sequences (e.g. O +
U+0308 -> Ö) during codepoint collection. A complete solution would
require implementing proper Unicode normalization (at least NFC,
possibly NFKC in specific cases) before hyphenation and rendering,
instead of hand-mapping a few combining marks. That was beyond the scope
of this fix.
* Note 2: the render fix should be universal and not limited to the
constraints outlined above: it properly x-centers the compund glyph over
the previous one, and it uses at least 1pt of visual distance in y.
Before:
<img width="478" height="167" alt="Image"
src="https://github.com/user-attachments/assets/f8db60d5-35b1-4477-96d0-5003b4e4a2a1"
/>
After:
<img width="479" height="180" alt="Image"
src="https://github.com/user-attachments/assets/1b48ef97-3a77-475a-8522-23f4aca8e904"
/>
* This should resolve the issues described in #998
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## Summary
**What is the goal of this PR?**
`hasPrintableChars` does a pass over text before rendering. It looks up
glyphs in the font and measures dimensions, returning early if the text
results in zero size.
This additional pass doesn't offer any benefit over moving straight to
rendering the text, because the rendering loop already gracefully
handles missing glyphs. This change saves an extra pass over all
rendered text.
Note that both `hasPrintableChars` and `renderChar` replace missing
glyphs with `glyph = getGlyph(REPLACEMENT_GLYPH)`, so there's no
difference for characters which are not present in the font.
---
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helps set the right context for reviewers.
Did you use AI tools to help write this code? _**NO**_
The current behavior of rendering `?` for an unknown Unicode character
can be hard to distinguish from a typo. Use the standard Unicode
"replacement character" instead, that's what it's designed for:
https://en.wikipedia.org/wiki/Specials_(Unicode_block)
I'm making this PR as a draft because I'm not sure I did everything that
was needed to change the character set covered by the fonts. Running
that script is in its own commit. If this is proper, I'll rebase/squash
into one commit and un-draft.
Co-authored-by: Maeve Andrews <maeve@git.mail.maeveandrews.com>
Replace linear O(n) search with binary search O(log n) for unicode
interval lookup. Korean fonts have many intervals (~30,000+ glyphs), so
this improves text rendering performance during page navigation.
## Summary
* **What is the goal of this PR?** (e.g., Fixes a bug in the user
authentication module, Implements the new feature for
file uploading.)
Replace linear `O(n)` glyph lookup with binary search `O(log n)` to
improve text rendering performance during page navigation.
* **What changes are included?**
- Modified `EpdFont::getGlyph()` to use binary search instead of linear
search for unicode interval lookup
- Added early return for empty interval count
## Additional Context
* Add any other information that might be helpful for the reviewer
(e.g., performance implications, potential risks, specific areas to
focus on).
- Performance implications: Fonts with many unicode intervals benefit
the most. Korean fonts have ~30,000+ glyphs across multiple intervals,
but any font with significant glyph coverage (CJK, extended Latin,
emoji, etc.) will see improvement.
- Complexity: from `O(n)` to `O(log n)` where n = number of unicode
intervals. For fonts with 10+ intervals, this reduces lookup iterations
significantly.
- Risk: Low - the binary search logic is straightforward and the
intervals are already sorted by unicode codepoint (required for the
original early-exit optimization).
