Add a complete SD card font subsystem that enables users to install and
use custom fonts beyond the three built-in families. This combines the
back-end firmware support (#1327) with the font configuration, build
pipeline, CI distribution, and user-facing management UI (#1392).
Core font system:
- Custom .cpfont binary format (v4) with multi-style support (regular,
bold, italic, bold-italic) packed into a single file per size
- On-demand glyph loading from SD card with two-pass prewarm rendering
to bulk-read glyphs per page, achieving near-flash performance for
Latin text (~697ms vs ~681ms) and viable CJK rendering (~32% slower)
- Persistent advance cache for layout measurement without SD I/O
- Overflow ring buffer for glyph cache misses during rendering
- Memory-conscious design: only advance tables kept in RAM; glyph
bitmaps, kern tables, and ligatures loaded on demand from SD
Font management:
- On-device WiFi download from GitHub Releases with manifest-based
discovery, install/update detection, and progress UI
- Web interface font upload, listing, and deletion via /fonts page
- Manual SD card copy to /fonts/ or /.fonts/ directories
- Font selection integrated into Settings > Reader > Font Family
Build pipeline:
- Declarative YAML config (sd-fonts.yaml) as single source of truth
for the 17-family font library (serif, sans, mono, accessibility)
- Python converter (fontconvert_sdcard.py) for TTF/OTF to .cpfont with
FreeType rasterization, class-based kerning, and ligature extraction
- Parallel build orchestrator with variable font instance extraction
- CI workflow publishing versioned + stable releases to a dedicated
crosspoint-fonts repository with auto-incrementing revision tags
- Centralized version constants (cpfont_version.py) shared across
build tooling and CI, with firmware headers as manual sync points
Additional fixes:
- CJK characters no longer get hyphens inserted at line breaks
- Advance table eliminates 30+ second stalls during CJK section
indexing for paragraphs with >512 unique codepoints
Closes#930
Co-authored-by: Zach Nelson <zach@zdnelson.com>
Co-authored-by: Justin <itsthisjustin@users.noreply.github.com>
Co-authored-by: jpirnay <jens@pirnay.com>
Co-authored-by: mcrosson <kemonine@kemonine.info>
## Summary
Fixes#258. Bookerly is not licensed for use in CrossPoint. Switched to
Google's open Noto Serif font.
---
### AI Usage
While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.
Did you use AI tools to help write this code? _**NO**_
## Summary
**What is the goal of this PR?**
Reading a book with frequent numbers, I noticed that the spacing between
numeral glyphs was strangely large. This was because Bookerly and Noto
Sans default to tabular figures, where every digit gets an identical
advance width. This is designed for column alignment in spreadsheets,
but in rendering prose it produces visually wide gaps between digits.
This change adds a `--pnum` flag to fontconvert.py that applies the
font's OpenType `pnum` (proportional numerals) feature during
conversion. When active, the converter:
- Parses the GSUB table for pnum SingleSubst lookups
- Resolves substitute glyph indices via fonttools' glyph order
- Loads the proportional alternate glyphs instead of the tabular
defaults
- Includes substitute glyph names in kern pair extraction, so kerning
data that references proportional alternates is captured
Bookerly's proportional alternates also carry digit-digit and
digit-punctuation kerning that the tabular glyphs lack (e.g., at 16pt
7->4 at -1.69px, 7->. at -2.31px, 7->1 at +1.00px).
Noto Sans gains proportional advances but no new kerning (its
proportional glyphs have no kern class data in the font).
OpenDyslexic is unaffected. Its `cmap` already points to proportional
glyphs, so `--pnum` is a no-op. `--pnum` is intentionally omitted from
OpenDyslexic in the build script for deliberately uniform digit spacing
as an accessibility choice.
UI fonts (Ubuntu, notosans_8) also omit `--pnum` to preserve tabular
alignment for page numbers, battery percentages, etc.
| Before | After |
| -- | -- |
| <img
src="https://github.com/user-attachments/files/26042238/screenshot-31673.bmp"
width="300" /> | <img
src="https://github.com/user-attachments/files/26042241/screenshot-124075.bmp"
width="300" /> |
---
### AI Usage
While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.
Did you use AI tools to help write this code? _**YES**_
## Summary
* Include superscripts and subscripts in fonts
## Additional Context
* Original change came from
https://github.com/crosspoint-reader/crosspoint-reader/pull/248
---
### AI Usage
While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.
Did you use AI tools to help write this code? No
---------
Co-authored-by: cor <cor@pruijs.dev>
## Summary
* Swap from Aleo to Bookerly for wider glyph support
* Swap from Space Grotesk to a small Noto Sans
## Additional Context
* 0.11.0 swapped to Aleo which has a few issues (things like Cyrillic
support for eg)
Uri Tauber
