Class FontManager

lib/matplotlib/font_manager.py:1195–1716

On import, the `FontManager` singleton instance creates a list of ttf and afm fonts and caches their `FontProperties`. The `FontManager.findfont` method does a nearest neighbor search to find the font that most closely matches the specification. If no good enough match is found, t

class FontManager:
    """
    On import, the `FontManager` singleton instance creates a list of ttf and
    afm fonts and caches their `FontProperties`.  The `FontManager.findfont`
    method does a nearest neighbor search to find the font that most closely
    matches the specification.  If no good enough match is found, the default
    font is returned.

    Fonts added with the `FontManager.addfont` method will not persist in the
    cache; therefore, `addfont` will need to be called every time Matplotlib is
    imported. This method should only be used if and when a font cannot be
    installed on your operating system by other means.

    Notes
    -----
    The `FontManager.addfont` method must be called on the global `FontManager`
    instance.

    Example usage::

        import matplotlib.pyplot as plt
        from matplotlib import font_manager

        font_dirs = ["/resources/fonts"]  # The path to the custom font file.
        font_files = font_manager.findSystemFonts(fontpaths=font_dirs)

        for font_file in font_files:
            font_manager.fontManager.addfont(font_file)
    """
    # Increment this version number whenever the font cache data
    # format or behavior has changed and requires an existing font
    # cache files to be rebuilt.
    __version__ = '3.11.0'

    def __init__(self, size=None, weight='normal'):
        self._version = self.__version__

        self.__default_weight = weight
        self.default_size = size

        # Create list of font paths.
        paths = [cbook._get_data_path('fonts', subdir)
                 for subdir in ['ttf', 'afm', 'pdfcorefonts']]
        _log.debug('font search path %s', paths)

        self.defaultFamily = {
            'ttf': 'DejaVu Sans',
            'afm': 'Helvetica'}

        self.afmlist = []
        self.ttflist = []

        # Delay the warning by 5s.
        try:
            timer = threading.Timer(5, lambda: _log.warning(
                'Matplotlib is building the font cache; this may take a moment.'))
            timer.start()
        except RuntimeError: