Version 3.0.3
"""
A module for parsing and generating fontconfig patterns.
See the `fontconfig pattern specification
<https://www.freedesktop.org/software/fontconfig/fontconfig-user.html>`_ for
more information.
"""
# This class is defined here because it must be available in:
# - The old-style config framework (:file:`rcsetup.py`)
# - The font manager (:file:`font_manager.py`)
# It probably logically belongs in :file:`font_manager.py`, but placing it
# there would have created cyclical dependency problems.
from functools import lru_cache
import re
from pyparsing import (Literal, ZeroOrMore, Optional, Regex, StringEnd,
ParseException, Suppress)
family_punc = r'\\\-:,'
family_unescape = re.compile(r'\\([%s])' % family_punc).sub
family_escape = re.compile(r'([%s])' % family_punc).sub
value_punc = r'\\=_:,'
value_unescape = re.compile(r'\\([%s])' % value_punc).sub
value_escape = re.compile(r'([%s])' % value_punc).sub
[docs]class FontconfigPatternParser(object):
"""A simple pyparsing-based parser for fontconfig-style patterns.
See the `fontconfig pattern specification
<https://www.freedesktop.org/software/fontconfig/fontconfig-user.html>`_
for more information.
"""
_constants = {
'thin' : ('weight', 'light'),
'extralight' : ('weight', 'light'),
'ultralight' : ('weight', 'light'),
'light' : ('weight', 'light'),
'book' : ('weight', 'book'),
'regular' : ('weight', 'regular'),
'normal' : ('weight', 'normal'),
'medium' : ('weight', 'medium'),
'demibold' : ('weight', 'demibold'),
'semibold' : ('weight', 'semibold'),
'bold' : ('weight', 'bold'),
'extrabold' : ('weight', 'extra bold'),
'black' : ('weight', 'black'),
'heavy' : ('weight', 'heavy'),
'roman' : ('slant', 'normal'),
'italic' : ('slant', 'italic'),
'oblique' : ('slant', 'oblique'),
'ultracondensed' : ('width', 'ultra-condensed'),
'extracondensed' : ('width', 'extra-condensed'),
'condensed' : ('width', 'condensed'),
'semicondensed' : ('width', 'semi-condensed'),
'expanded' : ('width', 'expanded'),
'extraexpanded' : ('width', 'extra-expanded'),
'ultraexpanded' : ('width', 'ultra-expanded')
}
def __init__(self):
family = Regex(r'([^%s]|(\\[%s]))*' %
(family_punc, family_punc)) \
.setParseAction(self._family)
size = Regex(r"([0-9]+\.?[0-9]*|\.[0-9]+)") \
.setParseAction(self._size)
name = Regex(r'[a-z]+') \
.setParseAction(self._name)
value = Regex(r'([^%s]|(\\[%s]))*' %
(value_punc, value_punc)) \
.setParseAction(self._value)
families =(family
+ ZeroOrMore(
Literal(',')
+ family)
).setParseAction(self._families)
point_sizes =(size
+ ZeroOrMore(
Literal(',')
+ size)
).setParseAction(self._point_sizes)
property =( (name
+ Suppress(Literal('='))
+ value
+ ZeroOrMore(
Suppress(Literal(','))
+ value)
)
| name
).setParseAction(self._property)
pattern =(Optional(
families)
+ Optional(
Literal('-')
+ point_sizes)
+ ZeroOrMore(
Literal(':')
+ property)
+ StringEnd()
)
self._parser = pattern
self.ParseException = ParseException
[docs] def parse(self, pattern):
"""
Parse the given fontconfig *pattern* and return a dictionary
of key/value pairs useful for initializing a
:class:`font_manager.FontProperties` object.
"""
props = self._properties = {}
try:
self._parser.parseString(pattern)
except self.ParseException as e:
raise ValueError(
"Could not parse font string: '%s'\n%s" % (pattern, e))
self._properties = None
self._parser.resetCache()
return props
def _family(self, s, loc, tokens):
return [family_unescape(r'\1', str(tokens[0]))]
def _size(self, s, loc, tokens):
return [float(tokens[0])]
def _name(self, s, loc, tokens):
return [str(tokens[0])]
def _value(self, s, loc, tokens):
return [value_unescape(r'\1', str(tokens[0]))]
def _families(self, s, loc, tokens):
self._properties['family'] = [str(x) for x in tokens]
return []
def _point_sizes(self, s, loc, tokens):
self._properties['size'] = [str(x) for x in tokens]
return []
def _property(self, s, loc, tokens):
if len(tokens) == 1:
if tokens[0] in self._constants:
key, val = self._constants[tokens[0]]
self._properties.setdefault(key, []).append(val)
else:
key = tokens[0]
val = tokens[1:]
self._properties.setdefault(key, []).extend(val)
return []
# `parse_fontconfig_pattern` is a bottleneck during the tests because it is
# repeatedly called when the rcParams are reset (to validate the default
# fonts). In practice, the cache size doesn't grow beyond a few dozen entries
# during the test suite.
parse_fontconfig_pattern = lru_cache()(FontconfigPatternParser().parse)
[docs]def generate_fontconfig_pattern(d):
"""
Given a dictionary of key/value pairs, generates a fontconfig
pattern string.
"""
props = []
families = ''
size = ''
for key in 'family style variant weight stretch file size'.split():
val = getattr(d, 'get_' + key)()
if val is not None and val != []:
if type(val) == list:
val = [value_escape(r'\\\1', str(x)) for x in val
if x is not None]
if val != []:
val = ','.join(val)
props.append(":%s=%s" % (key, val))
return ''.join(props)