"""\
MS VOLT ``.vtp`` to AFDKO ``.fea`` OpenType Layout converter.
Usage
-----
To convert a VTP project file:
$ fonttools voltLib.voltToFea input.vtp output.fea
It is also possible convert font files with `TSIV` table (as saved from Volt),
in this case the glyph names used in the Volt project will be mapped to the
actual glyph names in the font files when written to the feature file:
$ fonttools voltLib.voltToFea input.ttf output.fea
The ``--quiet`` option can be used to suppress warnings.
The ``--traceback`` can be used to get Python traceback in case of exceptions,
instead of suppressing the traceback.
Limitations
-----------
* Not all VOLT features are supported, the script will error if it it
encounters something it does not understand. Please report an issue if this
happens.
* AFDKO feature file syntax for mark positioning is awkward and does not allow
setting the mark coverage. It also defines mark anchors globally, as a result
some mark positioning lookups might cover many marks than what was in the VOLT
file. This should not be an issue in practice, but if it is then the only way
is to modify the VOLT file or the generated feature file manually to use unique
mark anchors for each lookup.
* VOLT allows subtable breaks in any lookup type, but AFDKO feature file
implementations vary in their support; currently AFDKO’s makeOTF supports
subtable breaks in pair positioning lookups only, while FontTools’ feaLib
support it for most substitution lookups and only some positioning lookups.
"""
import logging
import re
from io import StringIO
from fontTools.feaLib import ast
from fontTools.ttLib import TTFont, TTLibError
from fontTools.voltLib import ast as VAst
from fontTools.voltLib.parser import Parser as VoltParser
log = logging.getLogger("fontTools.voltLib.voltToFea")
TABLES = ["GDEF", "GSUB", "GPOS"]
[docs]
class MarkClassDefinition(ast.MarkClassDefinition):
[docs]
def asFea(self, indent=""):
res = ""
if not getattr(self, "used", False):
res += "#"
res += ast.MarkClassDefinition.asFea(self, indent)
return res
# For sorting voltLib.ast.GlyphDefinition, see its use below.
[docs]
class Group:
def __init__(self, group):
self.name = group.name.lower()
self.groups = [
x.group.lower() for x in group.enum.enum if isinstance(x, VAst.GroupName)
]
def __lt__(self, other):
if self.name in other.groups:
return True
if other.name in self.groups:
return False
if self.groups and not other.groups:
return False
if not self.groups and other.groups:
return True
[docs]
class VoltToFea:
_NOT_LOOKUP_NAME_RE = re.compile(r"[^A-Za-z_0-9.]")
_NOT_CLASS_NAME_RE = re.compile(r"[^A-Za-z_0-9.\-]")
def __init__(self, file_or_path, font=None):
self._file_or_path = file_or_path
self._font = font
self._glyph_map = {}
self._glyph_order = None
self._gdef = {}
self._glyphclasses = {}
self._features = {}
self._lookups = {}
self._marks = set()
self._ligatures = {}
self._markclasses = {}
self._anchors = {}
self._settings = {}
self._lookup_names = {}
self._class_names = {}
def _lookupName(self, name):
if name not in self._lookup_names:
res = self._NOT_LOOKUP_NAME_RE.sub("_", name)
while res in self._lookup_names.values():
res += "_"
self._lookup_names[name] = res
return self._lookup_names[name]
def _className(self, name):
if name not in self._class_names:
res = self._NOT_CLASS_NAME_RE.sub("_", name)
while res in self._class_names.values():
res += "_"
self._class_names[name] = res
return self._class_names[name]
def _collectStatements(self, doc, tables):
# Collect and sort group definitions first, to make sure a group
# definition that references other groups comes after them since VOLT
# does not enforce such ordering, and feature file require it.
groups = [s for s in doc.statements if isinstance(s, VAst.GroupDefinition)]
for statement in sorted(groups, key=lambda x: Group(x)):
self._groupDefinition(statement)
for statement in doc.statements:
if isinstance(statement, VAst.GlyphDefinition):
self._glyphDefinition(statement)
elif isinstance(statement, VAst.AnchorDefinition):
if "GPOS" in tables:
self._anchorDefinition(statement)
elif isinstance(statement, VAst.SettingDefinition):
self._settingDefinition(statement)
elif isinstance(statement, VAst.GroupDefinition):
pass # Handled above
elif isinstance(statement, VAst.ScriptDefinition):
self._scriptDefinition(statement)
elif not isinstance(statement, VAst.LookupDefinition):
raise NotImplementedError(statement)
# Lookup definitions need to be handled last as they reference glyph
# and mark classes that might be defined after them.
for statement in doc.statements:
if isinstance(statement, VAst.LookupDefinition):
if statement.pos and "GPOS" not in tables:
continue
if statement.sub and "GSUB" not in tables:
continue
self._lookupDefinition(statement)
def _buildFeatureFile(self, tables):
doc = ast.FeatureFile()
statements = doc.statements
if self._glyphclasses:
statements.append(ast.Comment("# Glyph classes"))
statements.extend(self._glyphclasses.values())
if self._markclasses:
statements.append(ast.Comment("\n# Mark classes"))
statements.extend(c[1] for c in sorted(self._markclasses.items()))
if self._lookups:
statements.append(ast.Comment("\n# Lookups"))
for lookup in self._lookups.values():
statements.extend(getattr(lookup, "targets", []))
statements.append(lookup)
# Prune features
features = self._features.copy()
for ftag in features:
scripts = features[ftag]
for stag in scripts:
langs = scripts[stag]
for ltag in langs:
langs[ltag] = [l for l in langs[ltag] if l.lower() in self._lookups]
scripts[stag] = {t: l for t, l in langs.items() if l}
features[ftag] = {t: s for t, s in scripts.items() if s}
features = {t: f for t, f in features.items() if f}
if features:
statements.append(ast.Comment("# Features"))
for ftag, scripts in features.items():
feature = ast.FeatureBlock(ftag)
stags = sorted(scripts, key=lambda k: 0 if k == "DFLT" else 1)
for stag in stags:
feature.statements.append(ast.ScriptStatement(stag))
ltags = sorted(scripts[stag], key=lambda k: 0 if k == "dflt" else 1)
for ltag in ltags:
include_default = True if ltag == "dflt" else False
feature.statements.append(
ast.LanguageStatement(ltag, include_default=include_default)
)
for name in scripts[stag][ltag]:
lookup = self._lookups[name.lower()]
lookupref = ast.LookupReferenceStatement(lookup)
feature.statements.append(lookupref)
statements.append(feature)
if self._gdef and "GDEF" in tables:
classes = []
for name in ("BASE", "MARK", "LIGATURE", "COMPONENT"):
if name in self._gdef:
classname = "GDEF_" + name.lower()
glyphclass = ast.GlyphClassDefinition(classname, self._gdef[name])
statements.append(glyphclass)
classes.append(ast.GlyphClassName(glyphclass))
else:
classes.append(None)
gdef = ast.TableBlock("GDEF")
gdef.statements.append(ast.GlyphClassDefStatement(*classes))
statements.append(gdef)
return doc
[docs]
def convert(self, tables=None):
doc = VoltParser(self._file_or_path).parse()
if tables is None:
tables = TABLES
if self._font is not None:
self._glyph_order = self._font.getGlyphOrder()
self._collectStatements(doc, tables)
fea = self._buildFeatureFile(tables)
return fea.asFea()
def _glyphName(self, glyph):
try:
name = glyph.glyph
except AttributeError:
name = glyph
return ast.GlyphName(self._glyph_map.get(name, name))
def _groupName(self, group):
try:
name = group.group
except AttributeError:
name = group
return ast.GlyphClassName(self._glyphclasses[name.lower()])
def _coverage(self, coverage):
items = []
for item in coverage:
if isinstance(item, VAst.GlyphName):
items.append(self._glyphName(item))
elif isinstance(item, VAst.GroupName):
items.append(self._groupName(item))
elif isinstance(item, VAst.Enum):
items.append(self._enum(item))
elif isinstance(item, VAst.Range):
items.append((item.start, item.end))
else:
raise NotImplementedError(item)
return items
def _enum(self, enum):
return ast.GlyphClass(self._coverage(enum.enum))
def _context(self, context):
out = []
for item in context:
coverage = self._coverage(item)
if not isinstance(coverage, (tuple, list)):
coverage = [coverage]
out.extend(coverage)
return out
def _groupDefinition(self, group):
name = self._className(group.name)
glyphs = self._enum(group.enum)
glyphclass = ast.GlyphClassDefinition(name, glyphs)
self._glyphclasses[group.name.lower()] = glyphclass
def _glyphDefinition(self, glyph):
try:
self._glyph_map[glyph.name] = self._glyph_order[glyph.id]
except TypeError:
pass
if glyph.type in ("BASE", "MARK", "LIGATURE", "COMPONENT"):
if glyph.type not in self._gdef:
self._gdef[glyph.type] = ast.GlyphClass()
self._gdef[glyph.type].glyphs.append(self._glyphName(glyph.name))
if glyph.type == "MARK":
self._marks.add(glyph.name)
elif glyph.type == "LIGATURE":
self._ligatures[glyph.name] = glyph.components
def _scriptDefinition(self, script):
stag = script.tag
for lang in script.langs:
ltag = lang.tag
for feature in lang.features:
lookups = {l.split("\\")[0]: True for l in feature.lookups}
ftag = feature.tag
if ftag not in self._features:
self._features[ftag] = {}
if stag not in self._features[ftag]:
self._features[ftag][stag] = {}
assert ltag not in self._features[ftag][stag]
self._features[ftag][stag][ltag] = lookups.keys()
def _settingDefinition(self, setting):
if setting.name.startswith("COMPILER_"):
self._settings[setting.name] = setting.value
else:
log.warning(f"Unsupported setting ignored: {setting.name}")
def _adjustment(self, adjustment):
adv, dx, dy, adv_adjust_by, dx_adjust_by, dy_adjust_by = adjustment
adv_device = adv_adjust_by and adv_adjust_by.items() or None
dx_device = dx_adjust_by and dx_adjust_by.items() or None
dy_device = dy_adjust_by and dy_adjust_by.items() or None
return ast.ValueRecord(
xPlacement=dx,
yPlacement=dy,
xAdvance=adv,
xPlaDevice=dx_device,
yPlaDevice=dy_device,
xAdvDevice=adv_device,
)
def _anchor(self, adjustment):
adv, dx, dy, adv_adjust_by, dx_adjust_by, dy_adjust_by = adjustment
assert not adv_adjust_by
dx_device = dx_adjust_by and dx_adjust_by.items() or None
dy_device = dy_adjust_by and dy_adjust_by.items() or None
return ast.Anchor(
dx or 0,
dy or 0,
xDeviceTable=dx_device or None,
yDeviceTable=dy_device or None,
)
def _anchorDefinition(self, anchordef):
anchorname = anchordef.name
glyphname = anchordef.glyph_name
anchor = self._anchor(anchordef.pos)
if anchorname.startswith("MARK_"):
name = "_".join(anchorname.split("_")[1:])
markclass = ast.MarkClass(self._className(name))
glyph = self._glyphName(glyphname)
markdef = MarkClassDefinition(markclass, anchor, glyph)
self._markclasses[(glyphname, anchorname)] = markdef
else:
if glyphname not in self._anchors:
self._anchors[glyphname] = {}
if anchorname not in self._anchors[glyphname]:
self._anchors[glyphname][anchorname] = {}
self._anchors[glyphname][anchorname][anchordef.component] = anchor
def _gposLookup(self, lookup, fealookup):
statements = fealookup.statements
pos = lookup.pos
if isinstance(pos, VAst.PositionAdjustPairDefinition):
for (idx1, idx2), (pos1, pos2) in pos.adjust_pair.items():
coverage_1 = pos.coverages_1[idx1 - 1]
coverage_2 = pos.coverages_2[idx2 - 1]
# If not both are groups, use “enum pos” otherwise makeotf will
# fail.
enumerated = False
for item in coverage_1 + coverage_2:
if not isinstance(item, VAst.GroupName):
enumerated = True
glyphs1 = self._coverage(coverage_1)
glyphs2 = self._coverage(coverage_2)
record1 = self._adjustment(pos1)
record2 = self._adjustment(pos2)
assert len(glyphs1) == 1
assert len(glyphs2) == 1
statements.append(
ast.PairPosStatement(
glyphs1[0], record1, glyphs2[0], record2, enumerated=enumerated
)
)
elif isinstance(pos, VAst.PositionAdjustSingleDefinition):
for a, b in pos.adjust_single:
glyphs = self._coverage(a)
record = self._adjustment(b)
assert len(glyphs) == 1
statements.append(
ast.SinglePosStatement([(glyphs[0], record)], [], [], False)
)
elif isinstance(pos, VAst.PositionAttachDefinition):
anchors = {}
for marks, classname in pos.coverage_to:
for mark in marks:
# Set actually used mark classes. Basically a hack to get
# around the feature file syntax limitation of making mark
# classes global and not allowing mark positioning to
# specify mark coverage.
for name in mark.glyphSet():
key = (name, "MARK_" + classname)
self._markclasses[key].used = True
markclass = ast.MarkClass(self._className(classname))
for base in pos.coverage:
for name in base.glyphSet():
if name not in anchors:
anchors[name] = []
if classname not in anchors[name]:
anchors[name].append(classname)
for name in anchors:
components = 1
if name in self._ligatures:
components = self._ligatures[name]
marks = []
for mark in anchors[name]:
markclass = ast.MarkClass(self._className(mark))
for component in range(1, components + 1):
if len(marks) < component:
marks.append([])
anchor = None
if component in self._anchors[name][mark]:
anchor = self._anchors[name][mark][component]
marks[component - 1].append((anchor, markclass))
base = self._glyphName(name)
if name in self._marks:
mark = ast.MarkMarkPosStatement(base, marks[0])
elif name in self._ligatures:
mark = ast.MarkLigPosStatement(base, marks)
else:
mark = ast.MarkBasePosStatement(base, marks[0])
statements.append(mark)
elif isinstance(pos, VAst.PositionAttachCursiveDefinition):
# Collect enter and exit glyphs
enter_coverage = []
for coverage in pos.coverages_enter:
for base in coverage:
for name in base.glyphSet():
enter_coverage.append(name)
exit_coverage = []
for coverage in pos.coverages_exit:
for base in coverage:
for name in base.glyphSet():
exit_coverage.append(name)
# Write enter anchors, also check if the glyph has exit anchor and
# write it, too.
for name in enter_coverage:
glyph = self._glyphName(name)
entry = self._anchors[name]["entry"][1]
exit = None
if name in exit_coverage:
exit = self._anchors[name]["exit"][1]
exit_coverage.pop(exit_coverage.index(name))
statements.append(ast.CursivePosStatement(glyph, entry, exit))
# Write any remaining exit anchors.
for name in exit_coverage:
glyph = self._glyphName(name)
exit = self._anchors[name]["exit"][1]
statements.append(ast.CursivePosStatement(glyph, None, exit))
else:
raise NotImplementedError(pos)
def _gposContextLookup(
self, lookup, prefix, suffix, ignore, fealookup, targetlookup
):
statements = fealookup.statements
assert not lookup.reversal
pos = lookup.pos
if isinstance(pos, VAst.PositionAdjustPairDefinition):
for (idx1, idx2), (pos1, pos2) in pos.adjust_pair.items():
glyphs1 = self._coverage(pos.coverages_1[idx1 - 1])
glyphs2 = self._coverage(pos.coverages_2[idx2 - 1])
assert len(glyphs1) == 1
assert len(glyphs2) == 1
glyphs = (glyphs1[0], glyphs2[0])
if ignore:
statement = ast.IgnorePosStatement([(prefix, glyphs, suffix)])
else:
lookups = (targetlookup, targetlookup)
statement = ast.ChainContextPosStatement(
prefix, glyphs, suffix, lookups
)
statements.append(statement)
elif isinstance(pos, VAst.PositionAdjustSingleDefinition):
glyphs = [ast.GlyphClass()]
for a, b in pos.adjust_single:
glyph = self._coverage(a)
glyphs[0].extend(glyph)
if ignore:
statement = ast.IgnorePosStatement([(prefix, glyphs, suffix)])
else:
statement = ast.ChainContextPosStatement(
prefix, glyphs, suffix, [targetlookup]
)
statements.append(statement)
elif isinstance(pos, VAst.PositionAttachDefinition):
glyphs = [ast.GlyphClass()]
for coverage, _ in pos.coverage_to:
glyphs[0].extend(self._coverage(coverage))
if ignore:
statement = ast.IgnorePosStatement([(prefix, glyphs, suffix)])
else:
statement = ast.ChainContextPosStatement(
prefix, glyphs, suffix, [targetlookup]
)
statements.append(statement)
else:
raise NotImplementedError(pos)
def _gsubLookup(self, lookup, prefix, suffix, ignore, chain, fealookup):
statements = fealookup.statements
sub = lookup.sub
for key, val in sub.mapping.items():
if not key or not val:
path, line, column = sub.location
log.warning(f"{path}:{line}:{column}: Ignoring empty substitution")
continue
statement = None
glyphs = self._coverage(key)
replacements = self._coverage(val)
if ignore:
chain_context = (prefix, glyphs, suffix)
statement = ast.IgnoreSubstStatement([chain_context])
elif isinstance(sub, VAst.SubstitutionSingleDefinition):
assert len(glyphs) == 1
assert len(replacements) == 1
statement = ast.SingleSubstStatement(
glyphs, replacements, prefix, suffix, chain
)
elif isinstance(sub, VAst.SubstitutionReverseChainingSingleDefinition):
assert len(glyphs) == 1
assert len(replacements) == 1
statement = ast.ReverseChainSingleSubstStatement(
prefix, suffix, glyphs, replacements
)
elif isinstance(sub, VAst.SubstitutionMultipleDefinition):
assert len(glyphs) == 1
statement = ast.MultipleSubstStatement(
prefix, glyphs[0], suffix, replacements, chain
)
elif isinstance(sub, VAst.SubstitutionLigatureDefinition):
assert len(replacements) == 1
statement = ast.LigatureSubstStatement(
prefix, glyphs, suffix, replacements[0], chain
)
else:
raise NotImplementedError(sub)
statements.append(statement)
def _lookupDefinition(self, lookup):
mark_attachement = None
mark_filtering = None
flags = 0
if lookup.direction == "RTL":
flags |= 1
if not lookup.process_base:
flags |= 2
# FIXME: Does VOLT support this?
# if not lookup.process_ligatures:
# flags |= 4
if not lookup.process_marks:
flags |= 8
elif isinstance(lookup.process_marks, str):
mark_attachement = self._groupName(lookup.process_marks)
elif lookup.mark_glyph_set is not None:
mark_filtering = self._groupName(lookup.mark_glyph_set)
lookupflags = None
if flags or mark_attachement is not None or mark_filtering is not None:
lookupflags = ast.LookupFlagStatement(
flags, mark_attachement, mark_filtering
)
if "\\" in lookup.name:
# Merge sub lookups as subtables (lookups named “base\sub”),
# makeotf/feaLib will issue a warning and ignore the subtable
# statement if it is not a pairpos lookup, though.
name = lookup.name.split("\\")[0]
if name.lower() not in self._lookups:
fealookup = ast.LookupBlock(self._lookupName(name))
if lookupflags is not None:
fealookup.statements.append(lookupflags)
fealookup.statements.append(ast.Comment("# " + lookup.name))
else:
fealookup = self._lookups[name.lower()]
fealookup.statements.append(ast.SubtableStatement())
fealookup.statements.append(ast.Comment("# " + lookup.name))
self._lookups[name.lower()] = fealookup
else:
fealookup = ast.LookupBlock(self._lookupName(lookup.name))
if lookupflags is not None:
fealookup.statements.append(lookupflags)
self._lookups[lookup.name.lower()] = fealookup
if lookup.comments is not None:
fealookup.statements.append(ast.Comment("# " + lookup.comments))
contexts = []
if lookup.context:
for context in lookup.context:
prefix = self._context(context.left)
suffix = self._context(context.right)
ignore = context.ex_or_in == "EXCEPT_CONTEXT"
contexts.append([prefix, suffix, ignore, False])
# It seems that VOLT will create contextual substitution using
# only the input if there is no other contexts in this lookup.
if ignore and len(lookup.context) == 1:
contexts.append([[], [], False, True])
else:
contexts.append([[], [], False, False])
targetlookup = None
for prefix, suffix, ignore, chain in contexts:
if lookup.sub is not None:
self._gsubLookup(lookup, prefix, suffix, ignore, chain, fealookup)
if lookup.pos is not None:
if self._settings.get("COMPILER_USEEXTENSIONLOOKUPS"):
fealookup.use_extension = True
if prefix or suffix or chain or ignore:
if not ignore and targetlookup is None:
targetname = self._lookupName(lookup.name + " target")
targetlookup = ast.LookupBlock(targetname)
fealookup.targets = getattr(fealookup, "targets", [])
fealookup.targets.append(targetlookup)
self._gposLookup(lookup, targetlookup)
self._gposContextLookup(
lookup, prefix, suffix, ignore, fealookup, targetlookup
)
else:
self._gposLookup(lookup, fealookup)
[docs]
def main(args=None):
"""Convert MS VOLT to AFDKO feature files."""
import argparse
from pathlib import Path
from fontTools import configLogger
parser = argparse.ArgumentParser(
"fonttools voltLib.voltToFea", description=main.__doc__
)
parser.add_argument(
"input", metavar="INPUT", type=Path, help="input font/VTP file to process"
)
parser.add_argument(
"featurefile", metavar="OUTPUT", type=Path, help="output feature file"
)
parser.add_argument(
"-t",
"--table",
action="append",
choices=TABLES,
dest="tables",
help="List of tables to write, by default all tables are written",
)
parser.add_argument(
"-q", "--quiet", action="store_true", help="Suppress non-error messages"
)
parser.add_argument(
"--traceback", action="store_true", help="Don’t catch exceptions"
)
options = parser.parse_args(args)
configLogger(level=("ERROR" if options.quiet else "INFO"))
file_or_path = options.input
font = None
try:
font = TTFont(file_or_path)
if "TSIV" in font:
file_or_path = StringIO(font["TSIV"].data.decode("utf-8"))
else:
log.error('"TSIV" table is missing, font was not saved from VOLT?')
return 1
except TTLibError:
pass
converter = VoltToFea(file_or_path, font)
try:
fea = converter.convert(options.tables)
except NotImplementedError as e:
if options.traceback:
raise
location = getattr(e.args[0], "location", None)
message = f'"{e}" is not supported'
if location:
path, line, column = location
log.error(f"{path}:{line}:{column}: {message}")
else:
log.error(message)
return 1
with open(options.featurefile, "w") as feafile:
feafile.write(fea)
if __name__ == "__main__":
import sys
sys.exit(main())