"""

A class representing a Type 1 font.

This version reads pfa and pfb files and splits them for embedding in

pdf files. It also supports SlantFont and ExtendFont transformations,

similarly to pdfTeX and friends.

Usage::

font = Type1Font(filename)

clear_part, encrypted_part, finale = font.parts

slanted_font = font.transform({'slant': 0.167})

extended_font = font.transform({'extend': 1.2})

subset_font = font.subset([ord(c) for c in 'Hello World'])

Sources:

* Adobe Technical Note #5040, Supporting Downloadable PostScript

Language Fonts.

* Adobe Type 1 Font Format, Adobe Systems Incorporated, third printing,

v1.1, 1993. ISBN 0-201-57044-0.

"""

from __future__ import annotations

import binascii

import functools

import itertools

import logging

import re

import string

import struct

import typing as T

import numpy as np

from matplotlib.cbook import _format_approx

from . import _api

_log = logging.getLogger(__name__)

class _Token:

"""

A token in a PostScript stream.

Attributes

----------

pos : int

Position, i.e. offset from the beginning of the data.

raw : str

Raw text of the token.

kind : str

Description of the token (for debugging or testing).

"""

__slots__ = ('pos', 'raw')

kind = '?'

def __init__(self, pos, raw):

_log.debug('type1font._Token %s at %d: %r', self.kind, pos, raw)

self.pos = pos

self.raw = raw

def __str__(self):

return f"<{self.kind} {self.raw} @{self.pos}>"

def endpos(self):

"""Position one past the end of the token"""

return self.pos + len(self.raw)

def is_keyword(self, *names):

"""Is this a name token with one of the names?"""

return False

def is_slash_name(self):

"""Is this a name token that starts with a slash?"""

return False

def is_delim(self):

"""Is this a delimiter token?"""

return False

def is_number(self):

"""Is this a number token?"""

return False

def value(self):

return self.raw

class _NameToken(_Token):

kind = 'name'

def is_slash_name(self):

return self.raw.startswith('/')

def value(self):

return self.raw[1:]

class _BooleanToken(_Token):

kind = 'boolean'

def value(self):

return self.raw == 'true'

class _KeywordToken(_Token):

kind = 'keyword'

def is_keyword(self, *names):

return self.raw in names

class _DelimiterToken(_Token):

kind = 'delimiter'

def is_delim(self):

return True

def opposite(self):

return {'[': ']', ']': '[',

'{': '}', '}': '{',

'<<': '>>', '>>': '<<'

}[self.raw]

class _WhitespaceToken(_Token):

kind = 'whitespace'

class _StringToken(_Token):

kind = 'string'

_escapes_re = re.compile(r'\\([\\()nrtbf]|[0-7]{1,3})')

_replacements = {'\\': '\\', '(': '(', ')': ')', 'n': '\n',

'r': '\r', 't': '\t', 'b': '\b', 'f': '\f'}

_ws_re = re.compile('[\0\t\r\f\n ]')

@classmethod

def _escape(cls, match):

group = match.group(1)

try:

return cls._replacements[group]

except KeyError:

return chr(int(group, 8))

@functools.lru_cache

def value(self):

if self.raw[0] == '(':

return self._escapes_re.sub(self._escape, self.raw[1:-1])

else:

data = self._ws_re.sub('', self.raw[1:-1])

if len(data) % 2 == 1:

data += '0'

return binascii.unhexlify(data)

class _BinaryToken(_Token):

kind = 'binary'

def value(self):

return self.raw[1:]

class _NumberToken(_Token):

kind = 'number'

def is_number(self):

return True

def value(self):

if '.' not in self.raw:

return int(self.raw)

else:

return float(self.raw)

def _tokenize(data: bytes, skip_ws: bool) -> T.Generator[_Token, int, None]:

"""

A generator that produces _Token instances from Type-1 font code.

The consumer of the generator may send an integer to the tokenizer to

indicate that the next token should be _BinaryToken of the given length.

Parameters

----------

data : bytes

The data of the font to tokenize.

skip_ws : bool

If true, the generator will drop any _WhitespaceTokens from the output.

"""

text = data.decode('ascii', 'replace')

whitespace_or_comment_re = re.compile(r'[\0\t\r\f\n ]+|%[^\r\n]*')

token_re = re.compile(r'/{0,2}[^]\0\t\r\f\n ()<>{}/%[]+')

instring_re = re.compile(r'[()\\]')

hex_re = re.compile(r'^<[0-9a-fA-F\0\t\r\f\n ]*>$')

oct_re = re.compile(r'[0-7]{1,3}')

pos = 0

next_binary: int | None = None

while pos < len(text):

if next_binary is not None:

n = next_binary

next_binary = (yield _BinaryToken(pos, data[pos:pos+n]))

pos += n

continue

match = whitespace_or_comment_re.match(text, pos)

if match:

if not skip_ws:

next_binary = (yield _WhitespaceToken(pos, match.group()))

pos = match.end()

elif text[pos] == '(':

# PostScript string rules:

# - parentheses must be balanced

# - backslashes escape backslashes and parens

# - also codes \n\r\t\b\f and octal escapes are recognized

# - other backslashes do not escape anything

start = pos

pos += 1

depth = 1

while depth:

match = instring_re.search(text, pos)

if match is None:

raise ValueError(

f'Unterminated string starting at {start}')

pos = match.end()

if match.group() == '(':

depth += 1

elif match.group() == ')':

depth -= 1

else: # a backslash

char = text[pos]

if char in r'\()nrtbf':

pos += 1

else:

octal = oct_re.match(text, pos)

if octal:

pos = octal.end()

else:

pass # non-escaping backslash

next_binary = (yield _StringToken(start, text[start:pos]))

elif text[pos:pos + 2] in ('<<', '>>'):

next_binary = (yield _DelimiterToken(pos, text[pos:pos + 2]))

pos += 2

elif text[pos] == '<':

start = pos

try:

pos = text.index('>', pos) + 1

except ValueError as e:

raise ValueError(f'Unterminated hex string starting at {start}'

) from e

if not hex_re.match(text[start:pos]):

raise ValueError(f'Malformed hex string starting at {start}')

next_binary = (yield _StringToken(pos, text[start:pos]))

else:

match = token_re.match(text, pos)

if match:

raw = match.group()

if raw.startswith('/'):

next_binary = (yield _NameToken(pos, raw))

elif match.group() in ('true', 'false'):

next_binary = (yield _BooleanToken(pos, raw))

else:

try:

float(raw)

next_binary = (yield _NumberToken(pos, raw))

except ValueError:

next_binary = (yield _KeywordToken(pos, raw))

pos = match.end()

else:

next_binary = (yield _DelimiterToken(pos, text[pos]))

pos += 1

class _BalancedExpression(_Token):

pass

def _expression(initial, tokens, data):

"""

Consume some number of tokens and return a balanced PostScript expression.

Parameters

----------

initial : _Token

The token that triggered parsing a balanced expression.

tokens : iterator of _Token

Following tokens.

data : bytes

Underlying data that the token positions point to.

Returns

-------

_BalancedExpression

"""

delim_stack = []

token = initial

while True:

if token.is_delim():

if token.raw in ('[', '{'):

delim_stack.append(token)

elif token.raw in (']', '}'):

if not delim_stack:

raise RuntimeError(f"unmatched closing token {token}")

match = delim_stack.pop()

if match.raw != token.opposite():

raise RuntimeError(

f"opening token {match} closed by {token}"

)

if not delim_stack:

break

else:

raise RuntimeError(f'unknown delimiter {token}')

elif not delim_stack:

break

token = next(tokens)

return _BalancedExpression(

initial.pos,

data[initial.pos:token.endpos()].decode('ascii', 'replace')

)

class Type1Font:

"""

A class representing a Type-1 font, for use by backends.

Attributes

----------

parts : tuple

A 3-tuple of the cleartext part, the encrypted part, and the finale of

zeros.

decrypted : bytes

The decrypted form of ``parts[1]``.

prop : dict[str, Any]

A dictionary of font properties. Noteworthy keys include:

- FontName: PostScript name of the font

- Encoding: dict from numeric codes to glyph names

- FontMatrix: bytes object encoding a matrix

- UniqueID: optional font identifier, dropped when modifying the font

- CharStrings: dict from glyph names to byte code

- Subrs: array of byte code subroutines

- OtherSubrs: bytes object encoding some PostScript code

"""

__slots__ = ('parts', 'decrypted', 'prop', '_pos', '_abbr')

# the _pos dict contains (begin, end) indices to parts[0] + decrypted

# so that they can be replaced when transforming the font;

# but since sometimes a definition appears in both parts[0] and decrypted,

# _pos[name] is an array of such pairs

#

# _abbr maps three standard abbreviations to their particular names in

# this font (e.g. 'RD' is named '-|' in some fonts)

def __init__(self, input):

"""

Initialize a Type-1 font.

Parameters

----------

input : str or 3-tuple

Either a pfb file name, or a 3-tuple of already-decoded Type-1

font `~.Type1Font.parts`.

"""

if isinstance(input, tuple) and len(input) == 3:

self.parts = input

else:

with open(input, 'rb') as file:

data = self._read(file)

self.parts = self._split(data)

self.decrypted = self._decrypt(self.parts[1], 'eexec')

self._abbr = {'RD': 'RD', 'ND': 'ND', 'NP': 'NP'}

self._parse()

def _read(self, file):

"""Read the font from a file, decoding into usable parts."""

rawdata = file.read()

if not rawdata.startswith(b'\x80'):

return rawdata

data = b''

while rawdata:

if not rawdata.startswith(b'\x80'):

raise RuntimeError('Broken pfb file (expected byte 128, '

'got %d)' % rawdata[0])

type = rawdata[1]

if type in (1, 2):

length, = struct.unpack('<i', rawdata[2:6])

segment = rawdata[6:6 + length]

rawdata = rawdata[6 + length:]

if type == 1: # ASCII text: include verbatim

data += segment

elif type == 2: # binary data: encode in hexadecimal

data += binascii.hexlify(segment)

elif type == 3: # end of file

break

else:

raise RuntimeError('Unknown segment type %d in pfb file' % type)

return data

def _split(self, data):

"""

Split the Type 1 font into its three main parts.

The three parts are: (1) the cleartext part, which ends in a

eexec operator; (2) the encrypted part; (3) the fixed part,

which contains 512 ASCII zeros possibly divided on various

lines, a cleartomark operator, and possibly something else.

"""

# Cleartext part: just find the eexec and skip whitespace

idx = data.index(b'eexec')

idx += len(b'eexec')

while data[idx] in b' \t\r\n':

idx += 1

len1 = idx

# Encrypted part: find the cleartomark operator and count

# zeros backward

idx = data.rindex(b'cleartomark') - 1

zeros = 512

while zeros and data[idx] in b'0' or data[idx] in b'\r\n':

if data[idx] in b'0':

zeros -= 1

idx -= 1

if zeros:

# this may have been a problem on old implementations that

# used the zeros as necessary padding

_log.info('Insufficiently many zeros in Type 1 font')

# Convert encrypted part to binary (if we read a pfb file, we may end

# up converting binary to hexadecimal to binary again; but if we read

# a pfa file, this part is already in hex, and I am not quite sure if

# even the pfb format guarantees that it will be in binary).

idx1 = len1 + ((idx - len1 + 2) & ~1) # ensure an even number of bytes

binary = binascii.unhexlify(data[len1:idx1])

return data[:len1], binary, data[idx+1:]

@staticmethod

def _decrypt(ciphertext, key, ndiscard=4):

"""

Decrypt ciphertext using the Type-1 font algorithm.

The algorithm is described in Adobe's "Adobe Type 1 Font Format".

The key argument can be an integer, or one of the strings

'eexec' and 'charstring', which map to the key specified for the

corresponding part of Type-1 fonts.

The ndiscard argument should be an integer, usually 4.

That number of bytes is discarded from the beginning of plaintext.

"""

key = _api.getitem_checked({'eexec': 55665, 'charstring': 4330}, key=key)

plaintext = []

for byte in ciphertext:

plaintext.append(byte ^ (key >> 8))

key = ((key+byte) * 52845 + 22719) & 0xffff

return bytes(plaintext[ndiscard:])

@staticmethod

def _encrypt(plaintext, key, ndiscard=4):

"""

Encrypt plaintext using the Type-1 font algorithm.

The algorithm is described in Adobe's "Adobe Type 1 Font Format".

The key argument can be an integer, or one of the strings

'eexec' and 'charstring', which map to the key specified for the

corresponding part of Type-1 fonts.

The ndiscard argument should be an integer, usually 4. That

number of bytes is prepended to the plaintext before encryption.

This function prepends NUL bytes for reproducibility, even though

the original algorithm uses random bytes, presumably to avoid

cryptanalysis.

"""

key = _api.getitem_checked({'eexec': 55665, 'charstring': 4330}, key=key)

ciphertext = []

for byte in b'\0' * ndiscard + plaintext:

c = byte ^ (key >> 8)

ciphertext.append(c)

key = ((key + c) * 52845 + 22719) & 0xffff

return bytes(ciphertext)

def _parse(self):

"""

Find the values of various font properties. This limited kind

of parsing is described in Chapter 10 "Adobe Type Manager

Compatibility" of the Type-1 spec.

"""

# Start with reasonable defaults

prop = {'Weight': 'Regular', 'ItalicAngle': 0.0, 'isFixedPitch': False,

'UnderlinePosition': -100, 'UnderlineThickness': 50}

pos = {}

data = self.parts[0] + self.decrypted

source = _tokenize(data, True)

while True:

# See if there is a key to be assigned a value

# e.g. /FontName in /FontName /Helvetica def

try:

token = next(source)

except StopIteration:

break

if token.is_delim():

# skip over this - we want top-level keys only

_expression(token, source, data)

if token.is_slash_name():

key = token.value()

keypos = token.pos

else:

continue

# Some values need special parsing

if key in ('Subrs', 'CharStrings', 'Encoding', 'OtherSubrs'):

prop[key], endpos = {

'Subrs': self._parse_subrs,

'CharStrings': self._parse_charstrings,

'Encoding': self._parse_encoding,

'OtherSubrs': self._parse_othersubrs

}[key](source, data)

pos.setdefault(key, []).append((keypos, endpos))

continue

try:

token = next(source)

except StopIteration:

break

if isinstance(token, _KeywordToken):

# constructs like

# FontDirectory /Helvetica known {...} {...} ifelse

# mean the key was not really a key

continue

if token.is_delim():

value = _expression(token, source, data).raw

else:

value = token.value()

# look for a 'def' possibly preceded by access modifiers

try:

kw = next(

kw for kw in source

if not kw.is_keyword('readonly', 'noaccess', 'executeonly')

)

except StopIteration:

break

# sometimes noaccess def and readonly def are abbreviated

if kw.is_keyword('def', self._abbr['ND'], self._abbr['NP']):

prop[key] = value

pos.setdefault(key, []).append((keypos, kw.endpos()))

# detect the standard abbreviations

if value == '{noaccess def}':

self._abbr['ND'] = key

elif value == '{noaccess put}':

self._abbr['NP'] = key

elif value == '{string currentfile exch readstring pop}':

self._abbr['RD'] = key

# Fill in the various *Name properties

if 'FontName' not in prop:

prop['FontName'] = (prop.get('FullName') or

prop.get('FamilyName') or

'Unknown')

if 'FullName' not in prop:

prop['FullName'] = prop['FontName']

if 'FamilyName' not in prop:

extras = ('(?i)([ -](regular|plain|italic|oblique|(semi)?bold|'

'(ultra)?light|extra|condensed))+$')

prop['FamilyName'] = re.sub(extras, '', prop['FullName'])

# Parse FontBBox

toks = [*_tokenize(prop['FontBBox'].encode('ascii'), True)]

if ([tok.kind for tok in toks]

!= ['delimiter', 'number', 'number', 'number', 'number', 'delimiter']

or toks[-1].raw != toks[0].opposite()):

raise RuntimeError(

f"FontBBox should be a size-4 array, was {prop['FontBBox']}")

prop['FontBBox'] = [tok.value() for tok in toks[1:-1]]

# Decrypt the encrypted parts

ndiscard = prop.get('lenIV', 4)

cs = prop['CharStrings']

for key, value in cs.items():

cs[key] = self._decrypt(value, 'charstring', ndiscard)

if 'Subrs' in prop:

prop['Subrs'] = [

self._decrypt(value, 'charstring', ndiscard)

for value in prop['Subrs']

]

self.prop = prop

self._pos = pos

def _parse_subrs(self, tokens, _data):

count_token = next(tokens)

if not count_token.is_number():

raise RuntimeError(

f"Token following /Subrs must be a number, was {count_token}"

)

count = count_token.value()

array = [None] * count

next(t for t in tokens if t.is_keyword('array'))

for _ in range(count):

next(t for t in tokens if t.is_keyword('dup'))

index_token = next(tokens)

if not index_token.is_number():

raise RuntimeError(

"Token following dup in Subrs definition must be a "

f"number, was {index_token}"

)

nbytes_token = next(tokens)

if not nbytes_token.is_number():

raise RuntimeError(

"Second token following dup in Subrs definition must "

f"be a number, was {nbytes_token}"

)

token = next(tokens)

if not token.is_keyword(self._abbr['RD']):

raise RuntimeError(

f"Token preceding subr must be {self._abbr['RD']}, "

f"was {token}"

)

binary_token = tokens.send(1+nbytes_token.value())

array[index_token.value()] = binary_token.value()

return array, next(tokens).endpos()

def _parse_charstrings(self, tokens, _data):

count_token = next(tokens)

if not count_token.is_number():

raise RuntimeError(

"Token following /CharStrings must be a number, "

f"was {count_token}"

)

count = count_token.value()

charstrings = {}

next(t for t in tokens if t.is_keyword('begin'))

while True:

token = next(t for t in tokens

if t.is_keyword('end') or t.is_slash_name())

if token.raw == 'end':

return charstrings, token.endpos()

glyphname = token.value()

nbytes_token = next(tokens)

if not nbytes_token.is_number():

raise RuntimeError(

f"Token following /{glyphname} in CharStrings definition "

f"must be a number, was {nbytes_token}"

)

token = next(tokens)

if not token.is_keyword(self._abbr['RD']):

raise RuntimeError(

f"Token preceding charstring must be {self._abbr['RD']}, "

f"was {token}"

)

binary_token = tokens.send(1+nbytes_token.value())

charstrings[glyphname] = binary_token.value()

@staticmethod

def _parse_encoding(tokens, _data):

# this only works for encodings that follow the Adobe manual

# but some old fonts include non-compliant data - we log a warning

# and return a possibly incomplete encoding

encoding = {}

while True:

token = next(t for t in tokens

if t.is_keyword('StandardEncoding', 'dup', 'def'))

if token.is_keyword('StandardEncoding'):

return _StandardEncoding, token.endpos()

if token.is_keyword('def'):

return encoding, token.endpos()

index_token = next(tokens)

if not index_token.is_number():

_log.warning(

f"Parsing encoding: expected number, got {index_token}"

)

continue

name_token = next(tokens)

if not name_token.is_slash_name():

_log.warning(

f"Parsing encoding: expected slash-name, got {name_token}"

)

continue

encoding[index_token.value()] = name_token.value()

def _parse_othersubrs(self, tokens, data):

init_pos = None

while True:

token = next(tokens)

if init_pos is None:

init_pos = token.pos

if token.is_delim():

_expression(token, tokens, data)

elif token.is_keyword('def', self._abbr['ND']):

return data[init_pos:token.endpos()], token.endpos()

def transform(self, effects):

"""

Return a new font that is slanted and/or extended.

Parameters

----------

effects : dict

A dict with optional entries:

- 'slant' : float, default: 0

Tangent of the angle that the font is to be slanted to the

right. Negative values slant to the left.

- 'extend' : float, default: 1

Scaling factor for the font width. Values less than 1 condense

the glyphs.

Returns

-------

`Type1Font`

"""

fontname = self.prop['FontName']

italicangle = self.prop['ItalicAngle']

array = [

float(x) for x in (self.prop['FontMatrix']

.lstrip('[').rstrip(']').split())

]

oldmatrix = np.eye(3, 3)

oldmatrix[0:3, 0] = array[::2]

oldmatrix[0:3, 1] = array[1::2]

modifier = np.eye(3, 3)

if 'slant' in effects:

slant = effects['slant']

fontname += f'_Slant_{int(1000 * slant)}'

italicangle = round(

float(italicangle) - np.arctan(slant) / np.pi * 180,

5

)

modifier[1, 0] = slant

if 'extend' in effects:

extend = effects['extend']

fontname += f'_Extend_{int(1000 * extend)}'

modifier[0, 0] = extend

newmatrix = np.dot(modifier, oldmatrix)

array[::2] = newmatrix[0:3, 0]

array[1::2] = newmatrix[0:3, 1]

fontmatrix = (

f"[{' '.join(_format_approx(x, 6) for x in array)}]"

)

newparts = self._replace(

[(x, f'/FontName/{fontname} def')

for x in self._pos['FontName']]

+ [(x, f'/ItalicAngle {italicangle} def')

for x in self._pos['ItalicAngle']]

+ [(x, f'/FontMatrix {fontmatrix} readonly def')

for x in self._pos['FontMatrix']]

+ [(x, '') for x in self._pos.get('UniqueID', [])]

)

return Type1Font((

newparts[0],

self._encrypt(newparts[1], 'eexec'),

self.parts[2]

))

def with_encoding(self, encoding):

"""

Change the encoding of the font.

Parameters

----------

encoding : dict

A dictionary mapping character codes to glyph names.

Returns

-------

`Type1Font`

"""

newparts = self._replace(

[(x, '') for x in self._pos.get('UniqueID', [])]

+ [(self._pos['Encoding'][0], self._postscript_encoding(encoding))]

)

return Type1Font((

newparts[0],

self._encrypt(newparts[1], 'eexec'),

self.parts[2]

))

def _replace(self, replacements):

"""

Change the font according to `replacements`

Parameters

----------

replacements : list of ((int, int), str)

Each element is ((pos0, pos1), replacement) where pos0 and

pos1 are indices to the original font data (parts[0] and the

decrypted part concatenated). The data in the interval

pos0:pos1 will be replaced by the replacement text. To

accommodate binary data, the replacement is taken to be in

Latin-1 encoding.

The case where pos0 is inside parts[0] and pos1 inside

the decrypted part is not supported.

Returns

-------

(bytes, bytes)

The new parts[0] and decrypted part (which needs to be

encrypted in the transformed font).

"""

data = bytearray(self.parts[0])

data.extend(self.decrypted)

len0 = len(self.parts[0])

for (pos0, pos1), value in sorted(replacements, reverse=True):

data[pos0:pos1] = value.encode('latin-1')

if pos0 < len(self.parts[0]):

if pos1 >= len(self.parts[0]):

raise RuntimeError(

f"text to be replaced with {value} spans "

"the eexec boundary"

)

len0 += len(value) - pos1 + pos0

return bytes(data[:len0]), bytes(data[len0:])

def subset(self, characters, name_prefix):

"""

Return a new font that only defines the given characters.

Parameters

----------

characters : sequence of bytes

The subset of characters to include. These are indices into the

font's encoding array. The encoding array of a Type-1 font can

only include 256 characters, but other glyphs may be accessed

via the seac operator.

name_prefix : str

Prefix to prepend to the font name.

Returns

-------

`Type1Font`

"""

characters = frozenset(characters)

if _log.isEnabledFor(logging.DEBUG):

_log.debug(

"Subsetting font %s to characters %s = %s",

self.prop['FontName'],

sorted(characters),

[self.prop['Encoding'].get(code) for code in sorted(characters)],

)

encoding = {code: glyph

for code, glyph in self.prop['Encoding'].items()

if code in characters}

encoding[0] = '.notdef'

# todo and done include strings (glyph names)

todo = set(encoding.values())

done = set()

seen_subrs = {0, 1, 2, 3}

while todo:

glyph = todo.pop()

called_glyphs, called_subrs = _CharstringSimulator(self).run(glyph)

todo.update(called_glyphs - done)

seen_subrs.update(called_subrs)

done.add(glyph)

charstrings = self._subset_charstrings(done)

subrs = self._subset_subrs(seen_subrs)

newparts = self._replace(

[(x, f'/FontName /{name_prefix}{self.prop["FontName"]} def')

for x in self._pos['FontName']]

+ [(self._pos['CharStrings'][0], charstrings),

(self._pos['Subrs'][0], subrs),

(self._pos['Encoding'][0], self._postscript_encoding(encoding))

] + [(x, '') for x in self._pos.get('UniqueID', [])]

)

return type(self)((

newparts[0],

self._encrypt(newparts[1], 'eexec'),

self.parts[2]

))

@staticmethod

def _charstring_tokens(data):

"""Parse a Type-1 charstring

Yield opcode names and integer parameters.

"""

data = iter(data)

for byte in data:

if 32 <= byte <= 246:

yield byte - 139

elif 247 <= byte <= 250:

byte2 = next(data)

yield (byte-247) * 256 + byte2 + 108

elif 251 <= byte <= 254:

byte2 = next(data)

yield -(byte-251)*256 - byte2 - 108

elif byte == 255:

bs = bytes(itertools.islice(data, 4))

yield struct.unpack('>i', bs)[0]

elif byte == 12:

byte1 = next(data)

yield {

0: 'dotsection',

1: 'vstem3',

2: 'hstem3',

6: 'seac',

7: 'sbw',

12: 'div',

16: 'callothersubr',

17: 'pop',

33: 'setcurrentpoint'

}[byte1]

else:

yield {

1: 'hstem',

3: 'vstem',

4: 'vmoveto',

5: 'rlineto',

6: 'hlineto',

7: 'vlineto',

8: 'rrcurveto',

9: 'closepath',

10: 'callsubr',

11: 'return',

13: 'hsbw',

14: 'endchar',

21: 'rmoveto',

22: 'hmoveto',

30: 'vhcurveto',

31: 'hvcurveto'

}[byte]

def _postscript_encoding(self, encoding):

"""Return a PostScript encoding array for the encoding."""

return '\n'.join([

'/Encoding 256 array\n0 1 255 { 1 index exch /.notdef put} for',

*(

f'dup {i} /{glyph} put'

for i, glyph in sorted(encoding.items())

if glyph != '.notdef'

),

'readonly def\n',

])

def _subset_charstrings(self, glyphs):

"""Return a PostScript CharStrings array for the glyphs."""

charstrings = self.prop['CharStrings']

lenIV = self.prop.get('lenIV', 4)

ordered = sorted(glyphs)

encrypted = [

self._encrypt(charstrings[glyph], 'charstring', lenIV).decode('latin-1')

for glyph in ordered

]

RD, ND = self._abbr['RD'], self._abbr['ND']

return '\n'.join([

f'/CharStrings {len(ordered)} dict dup begin',

*(

f'/{glyph} {len(enc)} {RD} {enc} {ND}'

for glyph, enc in zip(ordered, encrypted)

),

'end\n',

])

def _subset_subrs(self, indices):

"""Return a PostScript Subrs array for the subroutines."""

# we can't remove subroutines, we just replace unused ones with a stub

subrs = self.prop['Subrs']

n_subrs = len(subrs)

lenIV = self.prop.get('lenIV', 4)

stub = self._encrypt(b'\x0b', 'charstring', lenIV).decode('latin-1')

encrypted = [

self._encrypt(subrs[i], 'charstring', lenIV).decode('latin-1')

if i in indices

else stub

for i in range(n_subrs)

]

RD, ND, NP = self._abbr['RD'], self._abbr['ND'], self._abbr['NP']

return '\n'.join([

f'/Subrs {n_subrs} array',

*(

f'dup {i} {len(enc)} {RD} {enc} {NP}'

for i, enc in enumerate(encrypted)

),

])