from collections import UserDict, deque
from functools import partial
from fontTools.misc import sstruct
from fontTools.misc.textTools import safeEval
from . import DefaultTable
import array
import itertools
import logging
import struct
import sys
import fontTools.ttLib.tables.TupleVariation as tv
log = logging.getLogger(__name__)
TupleVariation = tv.TupleVariation
# https://www.microsoft.com/typography/otspec/gvar.htm
# https://www.microsoft.com/typography/otspec/otvarcommonformats.htm
#
# Apple's documentation of 'gvar':
# https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6gvar.html
#
# FreeType2 source code for parsing 'gvar':
# http://git.savannah.gnu.org/cgit/freetype/freetype2.git/tree/src/truetype/ttgxvar.c
GVAR_HEADER_FORMAT = """
> # big endian
version: H
reserved: H
axisCount: H
sharedTupleCount: H
offsetToSharedTuples: I
glyphCount: H
flags: H
offsetToGlyphVariationData: I
"""
GVAR_HEADER_SIZE = sstruct.calcsize(GVAR_HEADER_FORMAT)
class _LazyDict(UserDict):
def __init__(self, data):
super().__init__()
self.data = data
def __getitem__(self, k):
v = self.data[k]
if callable(v):
v = v()
self.data[k] = v
return v
[docs]
class table__g_v_a_r(DefaultTable.DefaultTable):
dependencies = ["fvar", "glyf"]
def __init__(self, tag=None):
DefaultTable.DefaultTable.__init__(self, tag)
self.version, self.reserved = 1, 0
self.variations = {}
[docs]
def compile(self, ttFont):
axisTags = [axis.axisTag for axis in ttFont["fvar"].axes]
sharedTuples = tv.compileSharedTuples(
axisTags, itertools.chain(*self.variations.values())
)
sharedTupleIndices = {coord: i for i, coord in enumerate(sharedTuples)}
sharedTupleSize = sum([len(c) for c in sharedTuples])
compiledGlyphs = self.compileGlyphs_(ttFont, axisTags, sharedTupleIndices)
offset = 0
offsets = []
for glyph in compiledGlyphs:
offsets.append(offset)
offset += len(glyph)
offsets.append(offset)
compiledOffsets, tableFormat = self.compileOffsets_(offsets)
header = {}
header["version"] = self.version
header["reserved"] = self.reserved
header["axisCount"] = len(axisTags)
header["sharedTupleCount"] = len(sharedTuples)
header["offsetToSharedTuples"] = GVAR_HEADER_SIZE + len(compiledOffsets)
header["glyphCount"] = len(compiledGlyphs)
header["flags"] = tableFormat
header["offsetToGlyphVariationData"] = (
header["offsetToSharedTuples"] + sharedTupleSize
)
compiledHeader = sstruct.pack(GVAR_HEADER_FORMAT, header)
result = [compiledHeader, compiledOffsets]
result.extend(sharedTuples)
result.extend(compiledGlyphs)
return b"".join(result)
[docs]
def compileGlyphs_(self, ttFont, axisTags, sharedCoordIndices):
result = []
glyf = ttFont["glyf"]
for glyphName in ttFont.getGlyphOrder():
variations = self.variations.get(glyphName, [])
if not variations:
result.append(b"")
continue
pointCountUnused = 0 # pointCount is actually unused by compileGlyph
result.append(
compileGlyph_(
variations, pointCountUnused, axisTags, sharedCoordIndices
)
)
return result
[docs]
def decompile(self, data, ttFont):
axisTags = [axis.axisTag for axis in ttFont["fvar"].axes]
glyphs = ttFont.getGlyphOrder()
sstruct.unpack(GVAR_HEADER_FORMAT, data[0:GVAR_HEADER_SIZE], self)
assert len(glyphs) == self.glyphCount
assert len(axisTags) == self.axisCount
offsets = self.decompileOffsets_(
data[GVAR_HEADER_SIZE:],
tableFormat=(self.flags & 1),
glyphCount=self.glyphCount,
)
sharedCoords = tv.decompileSharedTuples(
axisTags, self.sharedTupleCount, data, self.offsetToSharedTuples
)
variations = {}
offsetToData = self.offsetToGlyphVariationData
glyf = ttFont["glyf"]
def decompileVarGlyph(glyphName, gid):
gvarData = data[
offsetToData + offsets[gid] : offsetToData + offsets[gid + 1]
]
if not gvarData:
return []
glyph = glyf[glyphName]
numPointsInGlyph = self.getNumPoints_(glyph)
return decompileGlyph_(numPointsInGlyph, sharedCoords, axisTags, gvarData)
for gid in range(self.glyphCount):
glyphName = glyphs[gid]
variations[glyphName] = partial(decompileVarGlyph, glyphName, gid)
self.variations = _LazyDict(variations)
if ttFont.lazy is False: # Be lazy for None and True
self.ensureDecompiled()
[docs]
def ensureDecompiled(self, recurse=False):
# The recurse argument is unused, but part of the signature of
# ensureDecompiled across the library.
# Use a zero-length deque to consume the lazy dict
deque(self.variations.values(), maxlen=0)
[docs]
@staticmethod
def decompileOffsets_(data, tableFormat, glyphCount):
if tableFormat == 0:
# Short format: array of UInt16
offsets = array.array("H")
offsetsSize = (glyphCount + 1) * 2
else:
# Long format: array of UInt32
offsets = array.array("I")
offsetsSize = (glyphCount + 1) * 4
offsets.frombytes(data[0:offsetsSize])
if sys.byteorder != "big":
offsets.byteswap()
# In the short format, offsets need to be multiplied by 2.
# This is not documented in Apple's TrueType specification,
# but can be inferred from the FreeType implementation, and
# we could verify it with two sample GX fonts.
if tableFormat == 0:
offsets = [off * 2 for off in offsets]
return offsets
[docs]
@staticmethod
def compileOffsets_(offsets):
"""Packs a list of offsets into a 'gvar' offset table.
Returns a pair (bytestring, tableFormat). Bytestring is the
packed offset table. Format indicates whether the table
uses short (tableFormat=0) or long (tableFormat=1) integers.
The returned tableFormat should get packed into the flags field
of the 'gvar' header.
"""
assert len(offsets) >= 2
for i in range(1, len(offsets)):
assert offsets[i - 1] <= offsets[i]
if max(offsets) <= 0xFFFF * 2:
packed = array.array("H", [n >> 1 for n in offsets])
tableFormat = 0
else:
packed = array.array("I", offsets)
tableFormat = 1
if sys.byteorder != "big":
packed.byteswap()
return (packed.tobytes(), tableFormat)
[docs]
def toXML(self, writer, ttFont):
writer.simpletag("version", value=self.version)
writer.newline()
writer.simpletag("reserved", value=self.reserved)
writer.newline()
axisTags = [axis.axisTag for axis in ttFont["fvar"].axes]
for glyphName in ttFont.getGlyphNames():
variations = self.variations.get(glyphName)
if not variations:
continue
writer.begintag("glyphVariations", glyph=glyphName)
writer.newline()
for gvar in variations:
gvar.toXML(writer, axisTags)
writer.endtag("glyphVariations")
writer.newline()
[docs]
def fromXML(self, name, attrs, content, ttFont):
if name == "version":
self.version = safeEval(attrs["value"])
elif name == "reserved":
self.reserved = safeEval(attrs["value"])
elif name == "glyphVariations":
if not hasattr(self, "variations"):
self.variations = {}
glyphName = attrs["glyph"]
glyph = ttFont["glyf"][glyphName]
numPointsInGlyph = self.getNumPoints_(glyph)
glyphVariations = []
for element in content:
if isinstance(element, tuple):
name, attrs, content = element
if name == "tuple":
gvar = TupleVariation({}, [None] * numPointsInGlyph)
glyphVariations.append(gvar)
for tupleElement in content:
if isinstance(tupleElement, tuple):
tupleName, tupleAttrs, tupleContent = tupleElement
gvar.fromXML(tupleName, tupleAttrs, tupleContent)
self.variations[glyphName] = glyphVariations
[docs]
@staticmethod
def getNumPoints_(glyph):
NUM_PHANTOM_POINTS = 4
if glyph.isComposite():
return len(glyph.components) + NUM_PHANTOM_POINTS
elif glyph.isVarComposite():
count = 0
for component in glyph.components:
count += component.getPointCount()
return count + NUM_PHANTOM_POINTS
else:
# Empty glyphs (eg. space, nonmarkingreturn) have no "coordinates" attribute.
return len(getattr(glyph, "coordinates", [])) + NUM_PHANTOM_POINTS
[docs]
def compileGlyph_(variations, pointCount, axisTags, sharedCoordIndices):
tupleVariationCount, tuples, data = tv.compileTupleVariationStore(
variations, pointCount, axisTags, sharedCoordIndices
)
if tupleVariationCount == 0:
return b""
result = [struct.pack(">HH", tupleVariationCount, 4 + len(tuples)), tuples, data]
if (len(tuples) + len(data)) % 2 != 0:
result.append(b"\0") # padding
return b"".join(result)
[docs]
def decompileGlyph_(pointCount, sharedTuples, axisTags, data):
if len(data) < 4:
return []
tupleVariationCount, offsetToData = struct.unpack(">HH", data[:4])
dataPos = offsetToData
return tv.decompileTupleVariationStore(
"gvar",
axisTags,
tupleVariationCount,
pointCount,
sharedTuples,
data,
4,
offsetToData,
)