Spaces:
Running
Running
File size: 22,829 Bytes
b72ab63 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 |
"""ttLib/sfnt.py -- low-level module to deal with the sfnt file format.
Defines two public classes:
SFNTReader
SFNTWriter
(Normally you don't have to use these classes explicitly; they are
used automatically by ttLib.TTFont.)
The reading and writing of sfnt files is separated in two distinct
classes, since whenever the number of tables changes or whenever
a table's length changes you need to rewrite the whole file anyway.
"""
from io import BytesIO
from types import SimpleNamespace
from fontTools.misc.textTools import Tag
from fontTools.misc import sstruct
from fontTools.ttLib import TTLibError, TTLibFileIsCollectionError
import struct
from collections import OrderedDict
import logging
log = logging.getLogger(__name__)
class SFNTReader(object):
def __new__(cls, *args, **kwargs):
"""Return an instance of the SFNTReader sub-class which is compatible
with the input file type.
"""
if args and cls is SFNTReader:
infile = args[0]
infile.seek(0)
sfntVersion = Tag(infile.read(4))
infile.seek(0)
if sfntVersion == "wOF2":
# return new WOFF2Reader object
from fontTools.ttLib.woff2 import WOFF2Reader
return object.__new__(WOFF2Reader)
# return default object
return object.__new__(cls)
def __init__(self, file, checkChecksums=0, fontNumber=-1):
self.file = file
self.checkChecksums = checkChecksums
self.flavor = None
self.flavorData = None
self.DirectoryEntry = SFNTDirectoryEntry
self.file.seek(0)
self.sfntVersion = self.file.read(4)
self.file.seek(0)
if self.sfntVersion == b"ttcf":
header = readTTCHeader(self.file)
numFonts = header.numFonts
if not 0 <= fontNumber < numFonts:
raise TTLibFileIsCollectionError(
"specify a font number between 0 and %d (inclusive)"
% (numFonts - 1)
)
self.numFonts = numFonts
self.file.seek(header.offsetTable[fontNumber])
data = self.file.read(sfntDirectorySize)
if len(data) != sfntDirectorySize:
raise TTLibError("Not a Font Collection (not enough data)")
sstruct.unpack(sfntDirectoryFormat, data, self)
elif self.sfntVersion == b"wOFF":
self.flavor = "woff"
self.DirectoryEntry = WOFFDirectoryEntry
data = self.file.read(woffDirectorySize)
if len(data) != woffDirectorySize:
raise TTLibError("Not a WOFF font (not enough data)")
sstruct.unpack(woffDirectoryFormat, data, self)
else:
data = self.file.read(sfntDirectorySize)
if len(data) != sfntDirectorySize:
raise TTLibError("Not a TrueType or OpenType font (not enough data)")
sstruct.unpack(sfntDirectoryFormat, data, self)
self.sfntVersion = Tag(self.sfntVersion)
if self.sfntVersion not in ("\x00\x01\x00\x00", "OTTO", "true"):
raise TTLibError("Not a TrueType or OpenType font (bad sfntVersion)")
tables = {}
for i in range(self.numTables):
entry = self.DirectoryEntry()
entry.fromFile(self.file)
tag = Tag(entry.tag)
tables[tag] = entry
self.tables = OrderedDict(sorted(tables.items(), key=lambda i: i[1].offset))
# Load flavor data if any
if self.flavor == "woff":
self.flavorData = WOFFFlavorData(self)
def has_key(self, tag):
return tag in self.tables
__contains__ = has_key
def keys(self):
return self.tables.keys()
def __getitem__(self, tag):
"""Fetch the raw table data."""
entry = self.tables[Tag(tag)]
data = entry.loadData(self.file)
if self.checkChecksums:
if tag == "head":
# Beh: we have to special-case the 'head' table.
checksum = calcChecksum(data[:8] + b"\0\0\0\0" + data[12:])
else:
checksum = calcChecksum(data)
if self.checkChecksums > 1:
# Be obnoxious, and barf when it's wrong
assert checksum == entry.checkSum, "bad checksum for '%s' table" % tag
elif checksum != entry.checkSum:
# Be friendly, and just log a warning.
log.warning("bad checksum for '%s' table", tag)
return data
def __delitem__(self, tag):
del self.tables[Tag(tag)]
def close(self):
self.file.close()
# We define custom __getstate__ and __setstate__ to make SFNTReader pickle-able
# and deepcopy-able. When a TTFont is loaded as lazy=True, SFNTReader holds a
# reference to an external file object which is not pickleable. So in __getstate__
# we store the file name and current position, and in __setstate__ we reopen the
# same named file after unpickling.
def __getstate__(self):
if isinstance(self.file, BytesIO):
# BytesIO is already pickleable, return the state unmodified
return self.__dict__
# remove unpickleable file attribute, and only store its name and pos
state = self.__dict__.copy()
del state["file"]
state["_filename"] = self.file.name
state["_filepos"] = self.file.tell()
return state
def __setstate__(self, state):
if "file" not in state:
self.file = open(state.pop("_filename"), "rb")
self.file.seek(state.pop("_filepos"))
self.__dict__.update(state)
# default compression level for WOFF 1.0 tables and metadata
ZLIB_COMPRESSION_LEVEL = 6
# if set to True, use zopfli instead of zlib for compressing WOFF 1.0.
# The Python bindings are available at https://pypi.python.org/pypi/zopfli
USE_ZOPFLI = False
# mapping between zlib's compression levels and zopfli's 'numiterations'.
# Use lower values for files over several MB in size or it will be too slow
ZOPFLI_LEVELS = {
# 0: 0, # can't do 0 iterations...
1: 1,
2: 3,
3: 5,
4: 8,
5: 10,
6: 15,
7: 25,
8: 50,
9: 100,
}
def compress(data, level=ZLIB_COMPRESSION_LEVEL):
"""Compress 'data' to Zlib format. If 'USE_ZOPFLI' variable is True,
zopfli is used instead of the zlib module.
The compression 'level' must be between 0 and 9. 1 gives best speed,
9 gives best compression (0 gives no compression at all).
The default value is a compromise between speed and compression (6).
"""
if not (0 <= level <= 9):
raise ValueError("Bad compression level: %s" % level)
if not USE_ZOPFLI or level == 0:
from zlib import compress
return compress(data, level)
else:
from zopfli.zlib import compress
return compress(data, numiterations=ZOPFLI_LEVELS[level])
class SFNTWriter(object):
def __new__(cls, *args, **kwargs):
"""Return an instance of the SFNTWriter sub-class which is compatible
with the specified 'flavor'.
"""
flavor = None
if kwargs and "flavor" in kwargs:
flavor = kwargs["flavor"]
elif args and len(args) > 3:
flavor = args[3]
if cls is SFNTWriter:
if flavor == "woff2":
# return new WOFF2Writer object
from fontTools.ttLib.woff2 import WOFF2Writer
return object.__new__(WOFF2Writer)
# return default object
return object.__new__(cls)
def __init__(
self,
file,
numTables,
sfntVersion="\000\001\000\000",
flavor=None,
flavorData=None,
):
self.file = file
self.numTables = numTables
self.sfntVersion = Tag(sfntVersion)
self.flavor = flavor
self.flavorData = flavorData
if self.flavor == "woff":
self.directoryFormat = woffDirectoryFormat
self.directorySize = woffDirectorySize
self.DirectoryEntry = WOFFDirectoryEntry
self.signature = "wOFF"
# to calculate WOFF checksum adjustment, we also need the original SFNT offsets
self.origNextTableOffset = (
sfntDirectorySize + numTables * sfntDirectoryEntrySize
)
else:
assert not self.flavor, "Unknown flavor '%s'" % self.flavor
self.directoryFormat = sfntDirectoryFormat
self.directorySize = sfntDirectorySize
self.DirectoryEntry = SFNTDirectoryEntry
from fontTools.ttLib import getSearchRange
self.searchRange, self.entrySelector, self.rangeShift = getSearchRange(
numTables, 16
)
self.directoryOffset = self.file.tell()
self.nextTableOffset = (
self.directoryOffset
+ self.directorySize
+ numTables * self.DirectoryEntry.formatSize
)
# clear out directory area
self.file.seek(self.nextTableOffset)
# make sure we're actually where we want to be. (old cStringIO bug)
self.file.write(b"\0" * (self.nextTableOffset - self.file.tell()))
self.tables = OrderedDict()
def setEntry(self, tag, entry):
if tag in self.tables:
raise TTLibError("cannot rewrite '%s' table" % tag)
self.tables[tag] = entry
def __setitem__(self, tag, data):
"""Write raw table data to disk."""
if tag in self.tables:
raise TTLibError("cannot rewrite '%s' table" % tag)
entry = self.DirectoryEntry()
entry.tag = tag
entry.offset = self.nextTableOffset
if tag == "head":
entry.checkSum = calcChecksum(data[:8] + b"\0\0\0\0" + data[12:])
self.headTable = data
entry.uncompressed = True
else:
entry.checkSum = calcChecksum(data)
entry.saveData(self.file, data)
if self.flavor == "woff":
entry.origOffset = self.origNextTableOffset
self.origNextTableOffset += (entry.origLength + 3) & ~3
self.nextTableOffset = self.nextTableOffset + ((entry.length + 3) & ~3)
# Add NUL bytes to pad the table data to a 4-byte boundary.
# Don't depend on f.seek() as we need to add the padding even if no
# subsequent write follows (seek is lazy), ie. after the final table
# in the font.
self.file.write(b"\0" * (self.nextTableOffset - self.file.tell()))
assert self.nextTableOffset == self.file.tell()
self.setEntry(tag, entry)
def __getitem__(self, tag):
return self.tables[tag]
def close(self):
"""All tables must have been written to disk. Now write the
directory.
"""
tables = sorted(self.tables.items())
if len(tables) != self.numTables:
raise TTLibError(
"wrong number of tables; expected %d, found %d"
% (self.numTables, len(tables))
)
if self.flavor == "woff":
self.signature = b"wOFF"
self.reserved = 0
self.totalSfntSize = 12
self.totalSfntSize += 16 * len(tables)
for tag, entry in tables:
self.totalSfntSize += (entry.origLength + 3) & ~3
data = self.flavorData if self.flavorData else WOFFFlavorData()
if data.majorVersion is not None and data.minorVersion is not None:
self.majorVersion = data.majorVersion
self.minorVersion = data.minorVersion
else:
if hasattr(self, "headTable"):
self.majorVersion, self.minorVersion = struct.unpack(
">HH", self.headTable[4:8]
)
else:
self.majorVersion = self.minorVersion = 0
if data.metaData:
self.metaOrigLength = len(data.metaData)
self.file.seek(0, 2)
self.metaOffset = self.file.tell()
compressedMetaData = compress(data.metaData)
self.metaLength = len(compressedMetaData)
self.file.write(compressedMetaData)
else:
self.metaOffset = self.metaLength = self.metaOrigLength = 0
if data.privData:
self.file.seek(0, 2)
off = self.file.tell()
paddedOff = (off + 3) & ~3
self.file.write(b"\0" * (paddedOff - off))
self.privOffset = self.file.tell()
self.privLength = len(data.privData)
self.file.write(data.privData)
else:
self.privOffset = self.privLength = 0
self.file.seek(0, 2)
self.length = self.file.tell()
else:
assert not self.flavor, "Unknown flavor '%s'" % self.flavor
pass
directory = sstruct.pack(self.directoryFormat, self)
self.file.seek(self.directoryOffset + self.directorySize)
seenHead = 0
for tag, entry in tables:
if tag == "head":
seenHead = 1
directory = directory + entry.toString()
if seenHead:
self.writeMasterChecksum(directory)
self.file.seek(self.directoryOffset)
self.file.write(directory)
def _calcMasterChecksum(self, directory):
# calculate checkSumAdjustment
tags = list(self.tables.keys())
checksums = []
for i in range(len(tags)):
checksums.append(self.tables[tags[i]].checkSum)
if self.DirectoryEntry != SFNTDirectoryEntry:
# Create a SFNT directory for checksum calculation purposes
from fontTools.ttLib import getSearchRange
self.searchRange, self.entrySelector, self.rangeShift = getSearchRange(
self.numTables, 16
)
directory = sstruct.pack(sfntDirectoryFormat, self)
tables = sorted(self.tables.items())
for tag, entry in tables:
sfntEntry = SFNTDirectoryEntry()
sfntEntry.tag = entry.tag
sfntEntry.checkSum = entry.checkSum
sfntEntry.offset = entry.origOffset
sfntEntry.length = entry.origLength
directory = directory + sfntEntry.toString()
directory_end = sfntDirectorySize + len(self.tables) * sfntDirectoryEntrySize
assert directory_end == len(directory)
checksums.append(calcChecksum(directory))
checksum = sum(checksums) & 0xFFFFFFFF
# BiboAfba!
checksumadjustment = (0xB1B0AFBA - checksum) & 0xFFFFFFFF
return checksumadjustment
def writeMasterChecksum(self, directory):
checksumadjustment = self._calcMasterChecksum(directory)
# write the checksum to the file
self.file.seek(self.tables["head"].offset + 8)
self.file.write(struct.pack(">L", checksumadjustment))
def reordersTables(self):
return False
# -- sfnt directory helpers and cruft
ttcHeaderFormat = """
> # big endian
TTCTag: 4s # "ttcf"
Version: L # 0x00010000 or 0x00020000
numFonts: L # number of fonts
# OffsetTable[numFonts]: L # array with offsets from beginning of file
# ulDsigTag: L # version 2.0 only
# ulDsigLength: L # version 2.0 only
# ulDsigOffset: L # version 2.0 only
"""
ttcHeaderSize = sstruct.calcsize(ttcHeaderFormat)
sfntDirectoryFormat = """
> # big endian
sfntVersion: 4s
numTables: H # number of tables
searchRange: H # (max2 <= numTables)*16
entrySelector: H # log2(max2 <= numTables)
rangeShift: H # numTables*16-searchRange
"""
sfntDirectorySize = sstruct.calcsize(sfntDirectoryFormat)
sfntDirectoryEntryFormat = """
> # big endian
tag: 4s
checkSum: L
offset: L
length: L
"""
sfntDirectoryEntrySize = sstruct.calcsize(sfntDirectoryEntryFormat)
woffDirectoryFormat = """
> # big endian
signature: 4s # "wOFF"
sfntVersion: 4s
length: L # total woff file size
numTables: H # number of tables
reserved: H # set to 0
totalSfntSize: L # uncompressed size
majorVersion: H # major version of WOFF file
minorVersion: H # minor version of WOFF file
metaOffset: L # offset to metadata block
metaLength: L # length of compressed metadata
metaOrigLength: L # length of uncompressed metadata
privOffset: L # offset to private data block
privLength: L # length of private data block
"""
woffDirectorySize = sstruct.calcsize(woffDirectoryFormat)
woffDirectoryEntryFormat = """
> # big endian
tag: 4s
offset: L
length: L # compressed length
origLength: L # original length
checkSum: L # original checksum
"""
woffDirectoryEntrySize = sstruct.calcsize(woffDirectoryEntryFormat)
class DirectoryEntry(object):
def __init__(self):
self.uncompressed = False # if True, always embed entry raw
def fromFile(self, file):
sstruct.unpack(self.format, file.read(self.formatSize), self)
def fromString(self, str):
sstruct.unpack(self.format, str, self)
def toString(self):
return sstruct.pack(self.format, self)
def __repr__(self):
if hasattr(self, "tag"):
return "<%s '%s' at %x>" % (self.__class__.__name__, self.tag, id(self))
else:
return "<%s at %x>" % (self.__class__.__name__, id(self))
def loadData(self, file):
file.seek(self.offset)
data = file.read(self.length)
assert len(data) == self.length
if hasattr(self.__class__, "decodeData"):
data = self.decodeData(data)
return data
def saveData(self, file, data):
if hasattr(self.__class__, "encodeData"):
data = self.encodeData(data)
self.length = len(data)
file.seek(self.offset)
file.write(data)
def decodeData(self, rawData):
return rawData
def encodeData(self, data):
return data
class SFNTDirectoryEntry(DirectoryEntry):
format = sfntDirectoryEntryFormat
formatSize = sfntDirectoryEntrySize
class WOFFDirectoryEntry(DirectoryEntry):
format = woffDirectoryEntryFormat
formatSize = woffDirectoryEntrySize
def __init__(self):
super(WOFFDirectoryEntry, self).__init__()
# With fonttools<=3.1.2, the only way to set a different zlib
# compression level for WOFF directory entries was to set the class
# attribute 'zlibCompressionLevel'. This is now replaced by a globally
# defined `ZLIB_COMPRESSION_LEVEL`, which is also applied when
# compressing the metadata. For backward compatibility, we still
# use the class attribute if it was already set.
if not hasattr(WOFFDirectoryEntry, "zlibCompressionLevel"):
self.zlibCompressionLevel = ZLIB_COMPRESSION_LEVEL
def decodeData(self, rawData):
import zlib
if self.length == self.origLength:
data = rawData
else:
assert self.length < self.origLength
data = zlib.decompress(rawData)
assert len(data) == self.origLength
return data
def encodeData(self, data):
self.origLength = len(data)
if not self.uncompressed:
compressedData = compress(data, self.zlibCompressionLevel)
if self.uncompressed or len(compressedData) >= self.origLength:
# Encode uncompressed
rawData = data
self.length = self.origLength
else:
rawData = compressedData
self.length = len(rawData)
return rawData
class WOFFFlavorData:
Flavor = "woff"
def __init__(self, reader=None):
self.majorVersion = None
self.minorVersion = None
self.metaData = None
self.privData = None
if reader:
self.majorVersion = reader.majorVersion
self.minorVersion = reader.minorVersion
if reader.metaLength:
reader.file.seek(reader.metaOffset)
rawData = reader.file.read(reader.metaLength)
assert len(rawData) == reader.metaLength
data = self._decompress(rawData)
assert len(data) == reader.metaOrigLength
self.metaData = data
if reader.privLength:
reader.file.seek(reader.privOffset)
data = reader.file.read(reader.privLength)
assert len(data) == reader.privLength
self.privData = data
def _decompress(self, rawData):
import zlib
return zlib.decompress(rawData)
def calcChecksum(data):
"""Calculate the checksum for an arbitrary block of data.
If the data length is not a multiple of four, it assumes
it is to be padded with null byte.
>>> print(calcChecksum(b"abcd"))
1633837924
>>> print(calcChecksum(b"abcdxyz"))
3655064932
"""
remainder = len(data) % 4
if remainder:
data += b"\0" * (4 - remainder)
value = 0
blockSize = 4096
assert blockSize % 4 == 0
for i in range(0, len(data), blockSize):
block = data[i : i + blockSize]
longs = struct.unpack(">%dL" % (len(block) // 4), block)
value = (value + sum(longs)) & 0xFFFFFFFF
return value
def readTTCHeader(file):
file.seek(0)
data = file.read(ttcHeaderSize)
if len(data) != ttcHeaderSize:
raise TTLibError("Not a Font Collection (not enough data)")
self = SimpleNamespace()
sstruct.unpack(ttcHeaderFormat, data, self)
if self.TTCTag != "ttcf":
raise TTLibError("Not a Font Collection")
assert self.Version == 0x00010000 or self.Version == 0x00020000, (
"unrecognized TTC version 0x%08x" % self.Version
)
self.offsetTable = struct.unpack(
">%dL" % self.numFonts, file.read(self.numFonts * 4)
)
if self.Version == 0x00020000:
pass # ignoring version 2.0 signatures
return self
def writeTTCHeader(file, numFonts):
self = SimpleNamespace()
self.TTCTag = "ttcf"
self.Version = 0x00010000
self.numFonts = numFonts
file.seek(0)
file.write(sstruct.pack(ttcHeaderFormat, self))
offset = file.tell()
file.write(struct.pack(">%dL" % self.numFonts, *([0] * self.numFonts)))
return offset
if __name__ == "__main__":
import sys
import doctest
sys.exit(doctest.testmod().failed)
|