#!/usr/bin/env python3

"""

Overrides related to math fonts.

"""

import matplotlib as mpl

from matplotlib.font_manager import findfont, ttfFontProperty

from matplotlib.mathtext import MathTextParser

from . import warnings

try: # newer versions

from matplotlib._mathtext import UnicodeFonts

except ImportError: # older versions

from matplotlib.mathtext import UnicodeFonts

# Global constant

WARN_MATHPARSER = True

class _UnicodeFonts(UnicodeFonts):

"""

A simple `~matplotlib._mathtext.UnicodeFonts` subclass that

interprets ``rc['mathtext.default'] != 'regular'`` in the presence of

``rc['mathtext.fontset'] == 'custom'`` as possibly modifying the active font.

Works by permitting the ``rc['mathtext.rm']``, ``rc['mathtext.it']``,

etc. settings to have the dummy value ``'regular'`` instead of a valid family

name, e.g. ``rc['mathtext.it'] == 'regular:italic'`` (permitted through an

override of the `~matplotlib.rcsetup.validate_font_properties` validator).

When this dummy value is detected then the font properties passed to

`~matplotlib._mathtext.TrueTypeFont` are taken by replacing ``'regular'``

in the "math" fontset with the active font name.

"""

def __init__(self, *args, **kwargs):

# Initialize font

# NOTE: Could also capture the 'default_font_prop' passed as positional

# argument but want to guard against keyword changes. This entire API is

# private and it is easier to do graceful fallback with _fonts dictionary.

ctx = {} # rc context

regular = {} # styles

for texfont in ('cal', 'rm', 'tt', 'it', 'bf', 'sf'):

key = 'mathtext.' + texfont

prop = mpl.rcParams[key]

if prop.startswith('regular'):

ctx[key] = prop.replace('regular', 'sans', 1)

regular[texfont] = prop

with mpl.rc_context(ctx):

super().__init__(*args, **kwargs)

# Apply current font replacements

global WARN_MATHPARSER

if (

hasattr(self, 'fontmap')

and hasattr(self, '_fonts')

and 'regular' in self._fonts

):

font = self._fonts['regular'] # an ft2font.FT2Font instance

font = ttfFontProperty(font)

for texfont, prop in regular.items():

prop = prop.replace('regular', font.name)

self.fontmap[texfont] = findfont(prop, fallback_to_default=False)

elif WARN_MATHPARSER:

# Suppress duplicate warnings in case API changes

warnings._warn_proplot('Failed to update the math text parser.')

WARN_MATHPARSER = False

# Replace the parser

try:

mapping = MathTextParser._font_type_mapping

if mapping['custom'] is UnicodeFonts:

mapping['custom'] = _UnicodeFonts

except (KeyError, AttributeError):

warnings._warn_proplot('Failed to update math text parser.')

WARN_MATHPARSER = False