fonts/kobo-font-fix
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Fix issues with font name changes

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Nico Verbruggen
2025-08-21 17:30:43 +02:00
parent c82ede412b
commit c4ee594300
1 changed files with 248 additions and 129 deletions
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377
kobofix.py
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@@ -5,6 +5,7 @@ Font processing utility for Kobo e-readers.
This script processes TrueType fonts to improve compatibility with
Kobo e-readers by:
- Adding a custom prefix to font names
- Updating the font name if necessary, including PS name
- Extracting GPOS kerning data and creating legacy 'kern' tables
- Validating and correcting PANOSE metadata
- Adjusting font metrics for better line spacing
@@ -22,6 +23,7 @@ import argparse
import logging
from pathlib import Path
from collections import defaultdict
from dataclasses import dataclass
from typing import Dict, Tuple, Optional, List
from fontTools.ttLib import TTFont, newTable
@@ -40,6 +42,15 @@ logging.basicConfig(level=logging.INFO, format='%(message)s')
logger = logging.getLogger(__name__)
@dataclass
class FontMetadata:
"""A container for consistent font naming and metadata."""
family_name: str
style_name: str
full_name: str
ps_name: str
class FontProcessor:
"""Main font processing class."""
@@ -56,6 +67,59 @@ class FontProcessor:
self.line_percent = line_percent
self.kobo_kern_fix = kobo_kern_fix
# ============================================================
# Metadata extraction
# ============================================================
def _get_font_metadata(self, font: TTFont, font_path: str, new_family_name: Optional[str]) -> Optional[FontMetadata]:
"""Extract or infer font metadata from the font and arguments, prioritizing filename suffix."""
if "name" not in font:
logger.warning(" No 'name' table found; cannot determine metadata.")
return None
name_table = font["name"]
# Determine family name
family_name = new_family_name if new_family_name else name_table.getBestFamilyName()
if not family_name:
logger.warning(" Could not determine font family name.")
return None
# Determine style name from filename suffix
base_filename = os.path.basename(font_path)
style_map = {
"-BoldItalic": "Bold Italic",
"-Bold": "Bold",
"-Italic": "Italic",
"-Regular": "Regular",
}
style_name = "Regular" # Default to regular if no suffix found
# Iterate through styles and check if filename contains the style string
for style_key, style_val in style_map.items():
if style_key.lower() in base_filename.lower():
style_name = style_val
break
# Construct the full name and PS name based on style name logic
full_name = f"{family_name}"
if style_name != "Regular":
full_name += f" {style_name}"
ps_name = f"{self.prefix}{family_name.replace(' ', '')}"
if style_name != "Regular":
ps_name += f"-{style_name.replace(' ', '')}"
logger.debug(f" Constructed metadata: family='{family_name}', style='{style_name}', full='{full_name}', ps='{ps_name}'")
return FontMetadata(
family_name=family_name,
style_name=style_name,
full_name=full_name,
ps_name=ps_name
)
# ============================================================
# Kerning extraction methods
# ============================================================
@@ -172,31 +236,25 @@ class FontProcessor:
"""
pairs = defaultdict(int)
if "GPOS" not in font:
return {}
gpos = font["GPOS"].table
lookup_list = getattr(gpos, "LookupList", None)
if not lookup_list or not lookup_list.Lookup:
return {}
for lookup in lookup_list.Lookup:
# Only process Pair Adjustment lookups (type 2)
if getattr(lookup, "LookupType", None) != 2:
continue
if "GPOS" in font:
gpos = font["GPOS"].table
lookup_list = getattr(gpos, "LookupList", None)
for subtable in getattr(lookup, "SubTable", []):
fmt = getattr(subtable, "Format", None)
if fmt == 1:
format1_pairs = self._extract_format1_pairs(subtable)
for key, value in format1_pairs.items():
pairs[key] += value
elif fmt == 2:
format2_pairs = self._extract_format2_pairs(subtable)
for key, value in format2_pairs.items():
pairs[key] += value
if lookup_list and lookup_list.Lookup:
for lookup in lookup_list.Lookup:
# Only process Pair Adjustment lookups (type 2)
if getattr(lookup, "LookupType", None) == 2:
for subtable in getattr(lookup, "SubTable", []):
fmt = getattr(subtable, "Format", None)
if fmt == 1:
format1_pairs = self._extract_format1_pairs(subtable)
for key, value in format1_pairs.items():
pairs[key] += value
elif fmt == 2:
format2_pairs = self._extract_format2_pairs(subtable)
for key, value in format2_pairs.items():
pairs[key] += value
return dict(pairs)
@@ -244,126 +302,121 @@ class FontProcessor:
# Name table methods
# ============================================================
def rename_font(self, font: TTFont, new_name: Optional[str] = None) -> None:
def rename_font(self, font: TTFont, metadata: FontMetadata) -> None:
"""
Prefix the font's family and full names.
Update the font's name-related metadata.
This method prefixes family, full, and unique names, and updates
the PostScript font name.
Args:
font: Font object to modify
new_name: Optional override for the font name
metadata: The FontMetadata object containing the new names
"""
if "name" not in font:
logger.warning(" No 'name' table found; skipping all name changes")
return
name_table = font["name"]
# Name IDs: 1=Family, 4=Full Name, 16=Typographic Family
ids_to_update = {1, 4, 16}
# Update Name ID 1 (Family Name) and 16 (Typographic Family)
family_name_str = f"{self.prefix} {metadata.family_name}"
for record in name_table.names:
if record.nameID in ids_to_update:
if record.nameID in {1, 16}:
try:
base_name = new_name if new_name else record.toUnicode()
new_record_name = f"{self.prefix} {base_name}"
record.string = new_record_name.encode(record.getEncoding())
current_name = record.toUnicode()
if current_name != family_name_str:
record.string = family_name_str.encode(record.getEncoding())
logger.info(f" Name ID {record.nameID} updated: '{current_name}'->'{family_name_str}'")
else:
logger.info(f" Name ID {record.nameID} is already correct")
except Exception:
# Fallback to UTF-16 BE encoding
try:
record.string = new_record_name.encode("utf_16_be")
except Exception:
logger.warning(f"Failed to update name ID {record.nameID}")
def update_unique_id(self, font: TTFont, new_name: Optional[str] = None) -> None:
"""
Update the font's Unique ID (nameID 3) with prefix.
Args:
font: Font object to modify
new_name: Optional override for the font name
"""
if "name" not in font:
return
for record in font["name"].names:
record.string = family_name_str.encode("utf_16_be")
logger.info(f" Name ID {record.nameID} updated with UTF-16 BE encoding")
except Exception as e:
logger.warning(f" Failed to update name ID {record.nameID}: {e}")
# Update Name ID 4 (Full Name)
full_name_str = f"{self.prefix} {metadata.full_name}"
for record in name_table.names:
if record.nameID == 4:
try:
current_name = record.toUnicode()
if current_name != full_name_str:
record.string = full_name_str.encode(record.getEncoding())
logger.info(f" Name ID 4 updated: '{current_name}'->'{full_name_str}'")
else:
logger.info(" Name ID 4 is already correct")
except Exception:
try:
record.string = full_name_str.encode("utf_16_be")
logger.info(" Name ID 4 updated with UTF-16 BE encoding")
except Exception as e:
logger.warning(f" Failed to update name ID 4: {e}")
# --- Update Unique ID (nameID 3) ---
for record in name_table.names:
if record.nameID == 3: # Unique ID
try:
current_unique = record.toUnicode()
# Preserve version info if present
parts = current_unique.split("Version")
version_info = f"Version{parts[1]}" if len(parts) == 2 else "Version 1.000"
base_name = new_name if new_name else parts[0].strip()
new_unique_id = f"{self.prefix} {base_name}:{version_info}"
record.string = new_unique_id.encode(record.getEncoding())
except Exception:
try:
record.string = new_unique_id.encode("utf_16_be")
except Exception:
logger.warning("Failed to update Unique ID")
# ============================================================
# PANOSE methods
# ============================================================
@staticmethod
def check_and_fix_panose(font: TTFont, filename: str) -> None:
"""
Check and adjust PANOSE values based on filename suffix.
new_unique_id = f"{self.prefix} {metadata.family_name.strip()}:{version_info}"
if current_unique != new_unique_id:
record.string = new_unique_id.encode(record.getEncoding())
logger.info(f" Unique ID updated: '{current_unique}'->'{new_unique_id}'")
else:
logger.info(" Unique ID is already correct")
except Exception as e:
logger.warning(f" Failed to update Unique ID: {e}")
# --- Update PostScript Name (nameID 6) and other tables ---
new_ps_name = metadata.ps_name
Args:
font: Font object to modify
filename: Font filename to check suffix
"""
# PANOSE expected values for each style
style_specs = {
"-BoldItalic": {"weight": 8, "letterform": 3},
"-Bold": {"weight": 8, "letterform": 2},
"-Italic": {"weight": 5, "letterform": 3},
"-Regular": {"weight": 5, "letterform": 2},
}
name_updated = False
if "OS/2" not in font:
logger.warning(" No OS/2 table found; skipping PANOSE check")
# 1. Try to update the name table (nameID 6)
for record in name_table.names:
if record.nameID == 6: # PostScript Name
try:
current_name = record.toUnicode()
if current_name != new_ps_name:
record.string = new_ps_name.encode(record.getEncoding())
logger.info(f" PostScript name table (nameID 6) updated: '{current_name}'->'{new_ps_name}'")
else:
logger.info(" PostScript name table (nameID 6) is already correct")
name_updated = True
break
except Exception as e:
logger.warning(f" Failed to update PostScript name in name table: {e}")
if name_updated:
return
if not hasattr(font["OS/2"], "panose") or font["OS/2"].panose is None:
logger.warning(" No PANOSE information; skipping PANOSE check")
return
panose = font["OS/2"].panose
base_filename = os.path.basename(filename)
# Find matching style
matched_style = None
for style, specs in style_specs.items():
if style in base_filename:
matched_style = style
expected = specs
break
if not matched_style:
logger.warning(
f" Filename doesn't match expected patterns {list(style_specs.keys())}. "
"PANOSE check skipped"
)
return
# Check and fix values
changes = []
current_weight = getattr(panose, "bWeight", None)
current_letterform = getattr(panose, "bLetterForm", None)
if current_weight != expected["weight"]:
panose.bWeight = expected["weight"]
changes.append(f"bWeight {current_weight}->{expected['weight']}")
if current_letterform != expected["letterform"]:
panose.bLetterForm = expected["letterform"]
changes.append(f"bLetterForm {current_letterform}->{expected['letterform']}")
if changes:
logger.info(f" PANOSE corrected for {matched_style}: {', '.join(changes)}")
# 2. Fallback to CFF or post table if nameID 6 wasn't found or updated
if "CFF " in font:
top_dict = font["CFF "].cff.topDictIndex[0]
current_name = getattr(top_dict, "fontName", "")
if current_name != new_ps_name:
top_dict.fontName = new_ps_name
logger.info(f" PostScript CFF fontName updated: '{current_name}'->'{new_ps_name}'")
else:
logger.info(" PostScript CFF fontName is already correct")
elif "post" in font:
post_table = font["post"]
current_name = getattr(post_table, "postscriptName", "")
if current_name != new_ps_name:
post_table.postscriptName = new_ps_name
logger.info(f" PostScript 'post' fontName updated: '{current_name}'->'{new_ps_name}'")
else:
logger.info(" PostScript 'post' fontName is already correct")
else:
logger.info(f" PANOSE check passed for {matched_style}")
logger.warning(" No PostScript name found in `name`, `CFF` or `post` tables.")
# ============================================================
# Weight metadata methods
# ============================================================
@@ -432,6 +485,71 @@ class FontProcessor:
logger.info(" PostScript 'post' weight is already correct")
else:
logger.warning(" No CFF or post table weight found; skipping")
# ============================================================
# PANOSE methods
# ============================================================
@staticmethod
def check_and_fix_panose(font: TTFont, filename: str) -> None:
"""
Check and adjust PANOSE values based on filename suffix.
Args:
font: Font object to modify
filename: Font filename to check suffix
"""
# PANOSE expected values for each style
style_specs = {
"-BoldItalic": {"weight": 8, "letterform": 3},
"-Bold": {"weight": 8, "letterform": 2},
"-Italic": {"weight": 5, "letterform": 3},
"-Regular": {"weight": 5, "letterform": 2},
}
if "OS/2" not in font:
logger.warning(" No OS/2 table found; skipping PANOSE check")
return
if not hasattr(font["OS/2"], "panose") or font["OS/2"].panose is None:
logger.warning(" No PANOSE information; skipping PANOSE check")
return
panose = font["OS/2"].panose
base_filename = os.path.basename(filename)
# Find matching style
matched_style = None
for style, specs in style_specs.items():
if style in base_filename:
matched_style = style
expected = specs
break
if not matched_style:
logger.warning(
f" Filename doesn't match expected patterns {list(style_specs.keys())}. "
"PANOSE check skipped"
)
return
# Check and fix values
changes = []
current_weight = getattr(panose, "bWeight", None)
current_letterform = getattr(panose, "bLetterForm", None)
if current_weight != expected["weight"]:
panose.bWeight = expected["weight"]
changes.append(f"bWeight {current_weight}->{expected['weight']}")
if current_letterform != expected["letterform"]:
panose.bLetterForm = expected["letterform"]
changes.append(f"bLetterForm {current_letterform}->{expected['letterform']}")
if changes:
logger.info(f" PANOSE corrected for {matched_style}: {', '.join(changes)}")
else:
logger.info(f" PANOSE check passed for {matched_style}")
# ============================================================
# Line adjustment methods
@@ -511,11 +629,15 @@ class FontProcessor:
logger.error(f" Failed to open font: {e}")
return False
# Generate metadata
metadata = self._get_font_metadata(font, font_path, new_name)
if not metadata:
return False
# Process font
try:
# Update names
self.rename_font(font, new_name)
self.update_unique_id(font, new_name)
self.rename_font(font, metadata)
# Fix PANOSE and weight metadata
self.check_and_fix_panose(font, font_path)
@@ -537,7 +659,7 @@ class FontProcessor:
logger.info(" Skipping `kern` step")
# Generate output filename
output_path = self._generate_output_path(font_path, new_name)
output_path = self._generate_output_path(font_path, metadata)
# Save modified font
font.save(output_path)
@@ -554,7 +676,7 @@ class FontProcessor:
logger.error(f" Processing failed: {e}")
return False
def _generate_output_path(self, original_path: str, new_name: Optional[str]) -> str:
def _generate_output_path(self, original_path: str, metadata: FontMetadata) -> str:
"""Generate the output path for the processed font."""
dirname = os.path.dirname(original_path)
original_name, ext = os.path.splitext(os.path.basename(original_path))
@@ -567,10 +689,7 @@ class FontProcessor:
break
# Build new filename
if new_name:
base_name = f"{self.prefix}_{new_name.replace(' ', '_')}{suffix}"
else:
base_name = f"{self.prefix}_{original_name}"
base_name = f"{self.prefix}_{metadata.family_name.replace(' ', '_')}{suffix}"
return os.path.join(dirname, f"{base_name}{ext.lower()}")