%PDF-
%PDF-
Mini Shell
Mini Shell
#!/usr/bin/env python3
__license__ = 'GPL v3'
__copyright__ = '2012, Kovid Goyal <kovid at kovidgoyal.net>'
__docformat__ = 'restructuredtext en'
from struct import unpack_from, calcsize, pack, error as struct_error
from calibre.utils.fonts.sfnt import (UnknownTable, FixedProperty,
max_power_of_two)
from calibre.utils.fonts.sfnt.errors import UnsupportedFont
class KernTable(UnknownTable):
version = FixedProperty('_version')
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self._version, self.num_tables = unpack_from(b'>HH', self.raw)
if self._version == 1 and len(self.raw) >= 8:
self._version, self.num_tables = unpack_from(b'>LL', self.raw)
self.headerfmt = b'>HH' if self._version == 0 else b'>LL'
def restrict_to_glyphs(self, glyph_ids):
if self._version not in {0, 0x10000}:
raise UnsupportedFont('kern table has version: %x'%self._version)
offset = 4 if (self._version == 0) else 8
tables = []
for i in range(self.num_tables):
if self._version == 0:
version, length, coverage = unpack_from(b'>3H', self.raw, offset)
table_format = version
else:
length, coverage = unpack_from(b'>LH', self.raw, offset)
table_format = coverage & 0xff
raw = self.raw[offset:offset+length]
if table_format == 0:
raw = self.restrict_format_0(raw, glyph_ids)
if not raw:
continue
tables.append(raw)
offset += length
self.raw = pack(self.headerfmt, self._version, len(tables)) + b''.join(tables)
def restrict_format_0(self, raw, glyph_ids):
if self._version == 0:
version, length, coverage, npairs = unpack_from(b'>4H', raw)
headerfmt = b'>3H'
else:
length, coverage, tuple_index, npairs = unpack_from(b'>L3H', raw)
headerfmt = b'>L2H'
offset = calcsize(headerfmt + b'4H')
entries = []
entrysz = calcsize(b'>2Hh')
for i in range(npairs):
try:
left, right, value = unpack_from(b'>2Hh', raw, offset)
except struct_error:
offset = len(raw)
break # Buggy kern table
if left in glyph_ids and right in glyph_ids:
entries.append(pack(b'>2Hh', left, right, value))
offset += entrysz
if offset != len(raw):
raise UnsupportedFont('This font has extra data at the end of'
' a Format 0 kern subtable')
npairs = len(entries)
if npairs == 0:
return b''
entry_selector = max_power_of_two(npairs)
search_range = (2 ** entry_selector) * 6
range_shift = (npairs - (2 ** entry_selector)) * 6
entries = b''.join(entries)
length = calcsize(headerfmt + b'4H') + len(entries)
if self._version == 0:
header = pack(headerfmt, version, length, coverage)
else:
header = pack(headerfmt, length, coverage, tuple_index)
return header + pack(b'>4H', npairs, search_range, entry_selector,
range_shift) + entries
Zerion Mini Shell 1.0