Files
kobo-font-fix/kobofix.py

317 lines
11 KiB
Python
Executable File

import sys
import os
import subprocess
from collections import defaultdict
from fontTools.ttLib import TTFont, newTable
from fontTools.ttLib.tables._k_e_r_n import KernTable_format_0
# ------------------------------------------------------------
# Kerning extraction
# ------------------------------------------------------------
def _pair_value_to_kern(v1, v2):
"""Compute a legacy kerning value from a GPOS PairValue (Value1/Value2).
Prefer XAdvance adjustments; if none, fall back to XPlacement.
Returns an int (may be negative). """
val = 0
if v1 is not None:
val += getattr(v1, "XAdvance", 0) or 0
if v2 is not None:
val += getattr(v2, "XAdvance", 0) or 0
if val == 0:
# Some fonts encode kerning via placements only
if v1 is not None:
val += getattr(v1, "XPlacement", 0) or 0
if v2 is not None:
val += getattr(v2, "XPlacement", 0) or 0
return int(val or 0)
def extract_kern_pairs(font):
"""Extract kerning pairs from GPOS PairPos lookups (Format 1 & 2).
Returns:
dict[(leftGlyphName, rightGlyphName)] -> int kerning value
Safe against missing GPOS or unexpected structures.
"""
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:
if getattr(lookup, "LookupType", None) != 2: # Pair Adjustment
continue
for subtable in getattr(lookup, "SubTable", []):
fmt = getattr(subtable, "Format", None)
# -------- PairPos Format 1: per-glyph PairSets --------
if fmt == 1:
coverage = getattr(subtable, "Coverage", None)
pair_sets = getattr(subtable, "PairSet", [])
if not coverage or not hasattr(coverage, "glyphs"):
continue
cov_glyphs = coverage.glyphs
for i, left in enumerate(cov_glyphs):
if i >= len(pair_sets):
break
for rec in getattr(pair_sets[i], "PairValueRecord", []):
right = rec.SecondGlyph
k = _pair_value_to_kern(rec.Value1, rec.Value2)
if k:
pairs[(left, right)] += k
# -------- PairPos Format 2: class-based --------
elif fmt == 2:
coverage = getattr(subtable, "Coverage", None)
class_def1 = getattr(subtable, "ClassDef1", None)
class_def2 = getattr(subtable, "ClassDef2", None)
class1_records = getattr(subtable, "Class1Record", [])
if not coverage or not hasattr(coverage, "glyphs"):
continue
cov_glyphs = coverage.glyphs
# Build glyph lists per class for the left side, limited to covered glyphs
class1_map = getattr(class_def1, "classDefs", {}) if class_def1 else {}
left_by_class = defaultdict(list)
for g in cov_glyphs:
c = class1_map.get(g, 0)
left_by_class[c].append(g)
# Build glyph lists per class for the right side from explicit definitions only
class2_map = getattr(class_def2, "classDefs", {}) if class_def2 else {}
right_by_class = defaultdict(list)
for g, c in class2_map.items():
right_by_class[c].append(g)
for c1, c1rec in enumerate(class1_records):
lefts = left_by_class.get(c1, [])
if not lefts:
continue
for c2, c2rec in enumerate(c1rec.Class2Record):
rights = right_by_class.get(c2, [])
if not rights:
continue
k = _pair_value_to_kern(c2rec.Value1, c2rec.Value2)
if not k:
continue
for L in lefts:
for R in rights:
pairs[(L, R)] += k
else:
# Other formats not handled
continue
return dict(pairs)
# ------------------------------------------------------------
# Legacy 'kern' table builder
# ------------------------------------------------------------
def add_legacy_kern(font, kern_pairs):
"""Create/replace a legacy 'kern' table with the supplied pairs.
"""
if not kern_pairs:
# Remove existing legacy 'kern' if present? We'll leave as-is.
return 0
kern_table = newTable("kern")
kern_table.version = 0
kern_table.kernTables = []
subtable = KernTable_format_0()
subtable.version = 0
subtable.length = None # recalculated by fontTools
subtable.coverage = 1 # horizontal kerning, format 0
# Ensure ints and glyph-name tuple keys
subtable.kernTable = {tuple(k): int(v) for k, v in kern_pairs.items() if v}
kern_table.kernTables.append(subtable)
font["kern"] = kern_table
return len(subtable.kernTable)
# ------------------------------------------------------------
# Name table updates
# ------------------------------------------------------------
def rename_font(font):
"""Prefix the font's family/full names with 'KC '.
Updates name IDs 1 (Family), 4 (Full), and 16 (Typographic Family) when present.
"""
if "name" not in font:
return
name_table = font["name"]
ids_to_prefix = {1, 4, 16}
for record in name_table.names:
if record.nameID in ids_to_prefix:
try:
new_name = "KC " + record.toUnicode()
record.string = new_name.encode(record.getEncoding())
except Exception:
# Fallback encoding if getEncoding fails
try:
record.string = ("KC " + record.toUnicode()).encode("utf_16_be")
except Exception:
pass
# ------------------------------------------------------------
# PANOSE check & fix
# ------------------------------------------------------------
def check_and_fix_panose(font, filename):
"""Check and adjust PANOSE based on filename suffix.
Expected suffixes: -Regular, -Bold, -Italic, -BoldItalic
Adjusts bWeight for Bold/Regular and bLetterForm for Italic/Regular.
Prints status and corrections performed.
"""
# Order matters: test BoldItalic before Bold/Italic
expected_styles = (
("-BoldItalic", {"weight": 8, "letterform": 3}),
("-Bold", {"weight": 8, "letterform": 2}),
("-Italic", {"weight": 5, "letterform": 3}),
("-Regular", {"weight": 5, "letterform": 2}),
)
base = os.path.basename(filename)
matched = False
if "OS/2" not in font:
print(" WARNING: No OS/2 table found; skipping PANOSE check.")
return
if not hasattr(font["OS/2"], "panose") or font["OS/2"].panose is None:
print(" WARNING: Font has no PANOSE information; skipping PANOSE check.")
return
panose = font["OS/2"].panose
for suffix, expected in expected_styles:
if base.endswith(suffix + ".ttf") or base.endswith(suffix + ".otf"):
matched = True
exp_w = expected["weight"]
exp_lf = expected["letterform"]
cur_w = getattr(panose, "bWeight", None)
cur_lf = getattr(panose, "bLetterForm", None)
changes = []
if cur_w != exp_w and exp_w is not None:
panose.bWeight = exp_w
changes.append(f"bWeight {cur_w}{exp_w}")
if cur_lf != exp_lf and exp_lf is not None:
panose.bLetterForm = exp_lf
changes.append(f"bLetterForm {cur_lf}{exp_lf}")
if changes:
print(f" PANOSE corrected for {suffix}: " + ", ".join(changes))
else:
print(f" PANOSE check passed for {suffix}.")
break
if not matched:
print(
" WARNING: Filename does not end with expected suffix "
"(-Regular, -Bold, -Italic, -BoldItalic). PANOSE check skipped."
)
# ------------------------------------------------------------
# Orchestration per font
# ------------------------------------------------------------
def process_font(path):
"""Load, process, and save the font.
Steps (each independent):
1) Prefix names with "KC ".
2) Check & fix PANOSE based on filename.
3) Extract kerning from GPOS and write a legacy 'kern' table.
4) Save as KC_<original>.<ext>
"""
print(f"Processing: {path}")
try:
font = TTFont(path)
except Exception as e:
print(f" ERROR: Failed to open font: {e}")
return
# Always run name prefix & PANOSE checks, regardless of kerning outcome
rename_font(font)
check_and_fix_panose(font, os.path.basename(path))
# Extract kerning (robust against missing/odd structures)
try:
kern_pairs = extract_kern_pairs(font)
pair_count = len(kern_pairs)
if pair_count:
written = add_legacy_kern(font, kern_pairs)
print(f" Kerning: extracted {pair_count} pairs; wrote {written} pairs to legacy 'kern'.")
else:
print(" Kerning: no GPOS kerning found; skipping legacy 'kern' table.")
except Exception as e:
print(f" WARNING: Failed to extract/add kerning: {e}")
# Save
dirname, filename = os.path.split(path)
out_path = os.path.join(dirname, f"KC_{filename}")
try:
font.save(out_path)
print(f" Saved: {out_path}")
# Run font-line adjustment in-place
try:
subprocess.run(["font-line", "percent", "20", "--inplace", out_path], check=True)
print(" font-line applied in-place (20% baseline shift).")
except FileNotFoundError:
print(" ERROR: font-line utility not found. Please install it first (see README). Aborting.")
sys.exit(1)
except Exception as e:
print(f" WARNING: font-line failed: {e}")
except Exception as e:
print(f" ERROR: Failed to save font: {e}")
print("")
# ------------------------------------------------------------
# CLI
# ------------------------------------------------------------
def main():
if len(sys.argv) < 2:
print("Usage: python kobofix.py *.ttf *.otf")
sys.exit(1)
invalid_files = []
valid_suffixes = ("-Regular", "-Bold", "-Italic", "-BoldItalic")
for path in sys.argv[1:]:
if os.path.isfile(path) and path.lower().endswith((".ttf", ".otf")):
base = os.path.basename(path)
if not base.endswith(tuple(s + ext for s in valid_suffixes for ext in (".ttf", ".otf"))):
invalid_files.append(base)
if invalid_files:
print("ERROR: The following fonts have invalid filenames (must end with -Regular, -Bold, -Italic, or -BoldItalic):")
for f in invalid_files:
print(" " + f)
sys.exit(1)
for path in sys.argv[1:]:
if os.path.isfile(path) and path.lower().endswith((".ttf", ".otf")):
process_font(path)
else:
print(f"Skipping non-TTF/OTF file: {path}")
if __name__ == "__main__":
main()