fonts/kobo-font-fix
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Update README, skip OTF

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Nico Verbruggen
2025-08-21 16:04:00 +02:00
parent 8b1d345b60
commit aeb4fd621b
2 changed files with 55 additions and 25 deletions
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29
README.md
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@@ -1,8 +1,8 @@
# KoboFix Font Processor
# Kobo Font Fix
## Overview
`kobofix.py` is a Python script designed to process TTF and OTF fonts for Kobo e-readers.
`kobofix.py` is a Python script designed to process TTF fonts for Kobo e-readers.
It generates a renamed font, fixes PANOSE information based on the filename, adjusts the baseline with the `font-line` utility, and adds a legacy `kern` table which allows the `kepub` engine for improved rendering of kerned pairs.
@@ -37,14 +37,31 @@ source ~/.zshrc
```
3. The script will:
* Validate filenames.
* Validate the file names (must end with `-Regular`, `-Bold`, `-Italic` or `-BoldItalic` so they're valid for Kobo devices).
* Process each font (e.g. "Lora" becomes "KF Lora").
* Apply kerning, rename, PANOSE adjustments, and baseline shift.
* Save output as `KF_<original_filename>`.
Example:
### Generating KF fonts
This applies the KF prefix, applies 20 percent line spacing and adds a Kobo `kern` table. Ideal if you have an existing TrueType font and you want it on your Kobo device. The `--name` parameter is used to change the name of the font family.
```bash
./kobofix.py --prefix KF --name="Fonty" --line-percent 20 *.ttf
```
### Generating NV fonts
Tight spacing, with a custom font family name, as is required via the OFL license:
```bash
./kobofix.py --prefix NV --name="Fonty" --line-percent 20 --skip-kobo-kern *.ttf
```
Original: Lora-BoldItalic.ttf
Processed: KF_Lora-BoldItalic.ttf
Relaxed spacing, with a custom font family name, as is required via the OFL license:
```bash
./kobofix.py --prefix NV --name="Fonty" --line-percent 50 --skip-kobo-kern *.ttf
```
You can play around with `--line-percent` to see what works for you.

51
kobofix.py
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@@ -2,7 +2,7 @@
"""
Font processing utility for Kobo e-readers.
This script processes TrueType/OpenType fonts to improve compatibility with
This script processes TrueType fonts to improve compatibility with
Kobo e-readers by:
- Adding a custom prefix to font names
- Extracting GPOS kerning data and creating legacy 'kern' tables
@@ -29,8 +29,10 @@ from fontTools.ttLib.tables._k_e_r_n import KernTable_format_0
# Constants
DEFAULT_PREFIX = "KF"
DEFAULT_LINE_PERCENT = 20
DEFAULT_KOBO_KERN = True
VALID_SUFFIXES = ("-Regular", "-Bold", "-Italic", "-BoldItalic")
SUPPORTED_EXTENSIONS = (".ttf", ".otf")
SUPPORTED_EXTENSIONS = (".ttf")
# Configure logging
logging.basicConfig(level=logging.INFO, format='%(message)s')
@@ -40,16 +42,18 @@ logger = logging.getLogger(__name__)
class FontProcessor:
"""Main font processing class."""
def __init__(self, prefix: str = DEFAULT_PREFIX, line_percent: int = DEFAULT_LINE_PERCENT):
def __init__(self, prefix: str = DEFAULT_PREFIX, line_percent: int = DEFAULT_LINE_PERCENT, kobo_kern_fix: bool = DEFAULT_KOBO_KERN):
"""
Initialize the font processor.
Args:
prefix: Prefix to add to font names
line_percent: Percentage for baseline adjustment
kobo_kern_fix: Apply `kern` table fix for Kobo devices
"""
self.prefix = prefix
self.line_percent = line_percent
self.kobo_kern_fix = kobo_kern_fix
# ============================================================
# Kerning extraction methods
@@ -417,7 +421,7 @@ class FontProcessor:
# Main processing method
# ============================================================
def process_font(self, font_path: str, new_name: Optional[str] = None) -> bool:
def process_font(self, kern: bool, font_path: str, new_name: Optional[str] = None) -> bool:
"""
Process a single font file.
@@ -445,17 +449,21 @@ class FontProcessor:
# Fix PANOSE
self.check_and_fix_panose(font, font_path)
# Handle kerning
kern_pairs = self.extract_kern_pairs(font)
if kern_pairs:
written = self.add_legacy_kern(font, kern_pairs)
logger.info(
f" Kerning: extracted {len(kern_pairs)} pairs; "
f"wrote {written} to legacy 'kern' table"
)
if kern:
# Handle kerning
kern_pairs = self.extract_kern_pairs(font)
if kern_pairs:
written = self.add_legacy_kern(font, kern_pairs)
logger.info(
f" Kerning: extracted {len(kern_pairs)} pairs; "
f"wrote {written} to legacy 'kern' table"
)
else:
logger.info(" Kerning: no GPOS kerning found")
else:
logger.info(" Kerning: no GPOS kerning found")
# Skip kerning step
logger.info(" Skipping `kern` step")
# Generate output filename
output_path = self._generate_output_path(font_path, new_name)
@@ -538,16 +546,15 @@ def main():
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog="""
Examples:
%(prog)s font-Regular.ttf font-Bold.ttf
%(prog)s --name "My Font" *.ttf
%(prog)s --prefix KOBO --line-percent 25 font.ttf
%(prog)s --name="Fonty" --line-percent 20 *.ttf
%(prog)s --prefix NV --name="Fonty" --line-percent 20 --skip-kobo-kern *.ttf
"""
)
parser.add_argument(
"fonts",
nargs="+",
help="Font files to process (*.ttf, *.otf)"
help="Font files to process (*.ttf)"
)
parser.add_argument(
"--name",
@@ -566,6 +573,11 @@ Examples:
default=DEFAULT_LINE_PERCENT,
help=f"Line spacing adjustment percentage (default: {DEFAULT_LINE_PERCENT})"
)
parser.add_argument(
"--skip-kobo-kern",
action="store_true",
help="Skip the creation of the legacy 'kern' table from GPOS data."
)
parser.add_argument(
"--verbose",
action="store_true",
@@ -601,12 +613,13 @@ Examples:
# Process fonts
processor = FontProcessor(
prefix=args.prefix,
line_percent=args.line_percent
line_percent=args.line_percent,
)
success_count = 0
for font_path in valid_files:
if processor.process_font(
not args.skip_kobo_kern,
font_path,
args.name,
):