210 lines
6.5 KiB
Python
210 lines
6.5 KiB
Python
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"""
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A module for parsing and generating `fontconfig patterns`_.
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.. _fontconfig patterns:
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https://www.freedesktop.org/software/fontconfig/fontconfig-user.html
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"""
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# This class logically belongs in `matplotlib.font_manager`, but placing it
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# there would have created cyclical dependency problems, because it also needs
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# to be available from `matplotlib.rcsetup` (for parsing matplotlibrc files).
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from functools import lru_cache
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import re
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import numpy as np
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from pyparsing import (Literal, ZeroOrMore, Optional, Regex, StringEnd,
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ParseException, Suppress)
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family_punc = r'\\\-:,'
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family_unescape = re.compile(r'\\([%s])' % family_punc).sub
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family_escape = re.compile(r'([%s])' % family_punc).sub
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value_punc = r'\\=_:,'
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value_unescape = re.compile(r'\\([%s])' % value_punc).sub
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value_escape = re.compile(r'([%s])' % value_punc).sub
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class FontconfigPatternParser:
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"""
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A simple pyparsing-based parser for `fontconfig patterns`_.
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.. _fontconfig patterns:
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https://www.freedesktop.org/software/fontconfig/fontconfig-user.html
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"""
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_constants = {
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'thin': ('weight', 'light'),
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'extralight': ('weight', 'light'),
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'ultralight': ('weight', 'light'),
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'light': ('weight', 'light'),
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'book': ('weight', 'book'),
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'regular': ('weight', 'regular'),
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'normal': ('weight', 'normal'),
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'medium': ('weight', 'medium'),
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'demibold': ('weight', 'demibold'),
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'semibold': ('weight', 'semibold'),
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'bold': ('weight', 'bold'),
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'extrabold': ('weight', 'extra bold'),
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'black': ('weight', 'black'),
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'heavy': ('weight', 'heavy'),
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'roman': ('slant', 'normal'),
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'italic': ('slant', 'italic'),
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'oblique': ('slant', 'oblique'),
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'ultracondensed': ('width', 'ultra-condensed'),
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'extracondensed': ('width', 'extra-condensed'),
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'condensed': ('width', 'condensed'),
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'semicondensed': ('width', 'semi-condensed'),
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'expanded': ('width', 'expanded'),
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'extraexpanded': ('width', 'extra-expanded'),
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'ultraexpanded': ('width', 'ultra-expanded')
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}
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def __init__(self):
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family = Regex(
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r'([^%s]|(\\[%s]))*' % (family_punc, family_punc)
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).setParseAction(self._family)
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size = Regex(
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r"([0-9]+\.?[0-9]*|\.[0-9]+)"
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).setParseAction(self._size)
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name = Regex(
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r'[a-z]+'
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).setParseAction(self._name)
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value = Regex(
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r'([^%s]|(\\[%s]))*' % (value_punc, value_punc)
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).setParseAction(self._value)
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families = (
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family
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+ ZeroOrMore(
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Literal(',')
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+ family)
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).setParseAction(self._families)
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point_sizes = (
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size
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+ ZeroOrMore(
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Literal(',')
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+ size)
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).setParseAction(self._point_sizes)
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property = (
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(name
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+ Suppress(Literal('='))
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+ value
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+ ZeroOrMore(
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Suppress(Literal(','))
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+ value))
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).setParseAction(self._property)
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pattern = (
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Optional(
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families)
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+ Optional(
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Literal('-')
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+ point_sizes)
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+ ZeroOrMore(
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Literal(':')
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+ property)
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+ StringEnd()
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)
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self._parser = pattern
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self.ParseException = ParseException
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def parse(self, pattern):
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"""
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Parse the given fontconfig *pattern* and return a dictionary
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of key/value pairs useful for initializing a
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`.font_manager.FontProperties` object.
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"""
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props = self._properties = {}
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try:
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self._parser.parseString(pattern)
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except self.ParseException as e:
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raise ValueError(
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"Could not parse font string: '%s'\n%s" % (pattern, e)) from e
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self._properties = None
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self._parser.resetCache()
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return props
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def _family(self, s, loc, tokens):
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return [family_unescape(r'\1', str(tokens[0]))]
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def _size(self, s, loc, tokens):
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return [float(tokens[0])]
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def _name(self, s, loc, tokens):
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return [str(tokens[0])]
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def _value(self, s, loc, tokens):
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return [value_unescape(r'\1', str(tokens[0]))]
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def _families(self, s, loc, tokens):
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self._properties['family'] = [str(x) for x in tokens]
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return []
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def _point_sizes(self, s, loc, tokens):
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self._properties['size'] = [str(x) for x in tokens]
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return []
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def _property(self, s, loc, tokens):
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if len(tokens) == 1:
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if tokens[0] in self._constants:
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key, val = self._constants[tokens[0]]
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self._properties.setdefault(key, []).append(val)
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else:
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key = tokens[0]
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val = tokens[1:]
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self._properties.setdefault(key, []).extend(val)
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return []
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# `parse_fontconfig_pattern` is a bottleneck during the tests because it is
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# repeatedly called when the rcParams are reset (to validate the default
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# fonts). In practice, the cache size doesn't grow beyond a few dozen entries
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# during the test suite.
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parse_fontconfig_pattern = lru_cache()(FontconfigPatternParser().parse)
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def _escape_val(val, escape_func):
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"""
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Given a string value or a list of string values, run each value through
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the input escape function to make the values into legal font config
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strings. The result is returned as a string.
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"""
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if not np.iterable(val) or isinstance(val, str):
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val = [val]
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return ','.join(escape_func(r'\\\1', str(x)) for x in val
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if x is not None)
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def generate_fontconfig_pattern(d):
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"""
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Given a dictionary of key/value pairs, generates a fontconfig
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pattern string.
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"""
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props = []
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# Family is added first w/o a keyword
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family = d.get_family()
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if family is not None and family != []:
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props.append(_escape_val(family, family_escape))
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# The other keys are added as key=value
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for key in ['style', 'variant', 'weight', 'stretch', 'file', 'size']:
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val = getattr(d, 'get_' + key)()
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# Don't use 'if not val' because 0 is a valid input.
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if val is not None and val != []:
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props.append(":%s=%s" % (key, _escape_val(val, value_escape)))
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return ''.join(props)
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