trouble loading local fonts

[paniterka]

Thanks for developing this package! It really simplifies things.
While installing and managing fonts from the external URL works great, I am having some trouble loading local fonts. I get an error unless the path to the font file is preceded with "file:\\". I am on Windows 11, using Jupyter 7 with Nbclassic, Matplotlib 3.10.0, Python 3.12.9, venv created using anaconda and managed using pip, pyfonts 1.1.3. I guess it is related to how urllib works. If this is intended behavior, it would be great to either include this detail in the documentation (here and on https://python-graph-gallery.com/pyfonts/) or to handle it within load_font.

from pyfonts import load_font
font1 = load_font('C:\\Windows\\Fonts\\arial.ttf') # this doesn't work 
font2 = load_font('file:\\C:\\Windows\\Fonts\\arial.ttf') # this works

---------------------------------------------------------------------------
URLError                                  Traceback (most recent call last)
File C:\APPS\Anaconda3\envs\bib2025\Lib\site-packages\pyfonts\main.py:98, in load_font(font_url, use_cache, danger_not_verify_ssl, font_path)
     97 try:
---> 98     response = urlopen(font_url)
     99 except HTTPError as e:

File C:\APPS\Anaconda3\envs\bib2025\Lib\urllib\request.py:215, in urlopen(url, data, timeout, cafile, capath, cadefault, context)
    214     opener = _opener
--> 215 return opener.open(url, data, timeout)

File C:\APPS\Anaconda3\envs\bib2025\Lib\urllib\request.py:515, in OpenerDirector.open(self, fullurl, data, timeout)
    514 sys.audit('urllib.Request', req.full_url, req.data, req.headers, req.get_method())
--> 515 response = self._open(req, data)
    517 # post-process response

File C:\APPS\Anaconda3\envs\bib2025\Lib\urllib\request.py:537, in OpenerDirector._open(self, req, data)
    535     return result
--> 537 return self._call_chain(self.handle_open, 'unknown',
    538                         'unknown_open', req)

File C:\APPS\Anaconda3\envs\bib2025\Lib\urllib\request.py:492, in OpenerDirector._call_chain(self, chain, kind, meth_name, *args)
    491 func = getattr(handler, meth_name)
--> 492 result = func(*args)
    493 if result is not None:

File C:\APPS\Anaconda3\envs\bib2025\Lib\urllib\request.py:1420, in UnknownHandler.unknown_open(self, req)
   1419 type = req.type
-> 1420 raise URLError('unknown url type: %s' % type)

URLError: <urlopen error unknown url type: c>

During handling of the above exception, another exception occurred:

Exception                                 Traceback (most recent call last)
Cell In[10], line 1
----> 1 font1 = load_font('C:\\Windows\\Fonts\\arial.ttf')

File C:\APPS\Anaconda3\envs\bib2025\Lib\site-packages\pyfonts\main.py:125, in load_font(font_url, use_cache, danger_not_verify_ssl, font_path)
    118             raise Exception(
    119                 "SSL certificate verification failed. "
    120                 "If you are behind a firewall or using a proxy, "
    121                 "try setting `danger_not_verify_ssl=True` to bypass verification."
    122                 "verification."
    123             )
    124     else:
--> 125         raise Exception(
    126             "Failed to load font. This may be due to a lack of internet connection "
    127             "or an environment where local files are not accessible (Pyodide, etc)."
    128         )
    130 content = response.read()
    131 with open(cached_fontfile, "wb") as f:

Exception: Failed to load font. This may be due to a lack of internet connection or an environment where local files are not accessible (Pyodide, etc).

[JosephBARBIERDARNAL]

Hi @paniterka

Thanks, this definitely sounds like a bug and I think I know what happens. Under the hood, pyfonts tries to detect whether the input is an URL or a local font file, and I think it fails in the case you reported.

I'll start working on a fix for this!

[JosephBARBIERDARNAL]

@paniterka Just fixed it! Can you install the latest dev version and tell me how that works for you?

pip install git+https://github.com/y-sunflower/pyfonts.git

If that's okay for you too, I'll just make a new release with this change.

[paniterka]

Wow, thanks for a prompt response! I did some testing:

import os
from pyfonts import load_font

# font1 = load_font('C:\\Windows\\Fonts\\arial.ttf') #works 
# font1 = load_font('file:\\C:\\Windows\\Fonts\\arial.ttf') #doesn't work
# font1 = load_font(os.path.join('C:',os.path.sep,'Windows','Fonts','arial.ttf')) #works 
# font1 = load_font(os.path.join('file:',os.path.sep,'C:',os.path.sep,'Windows','Fonts','arial.ttf')) #works 

[JosephBARBIERDARNAL]

When doing load_font('file:\\C:\\Windows\\Fonts\\arial.ttf'), which error do you have?

Is it "Exception: Failed to load font. This may be due to a lack of internet connection or an environment where local files are not accessible (Pyodide, etc)."?

With the latest dev version, you shouldn't get this error at least (but maybe another one I haven't thought of?) @paniterka

[paniterka]

This is correct, now I get another error for the following cases. But the other cases are working fine :)

import os

from pyfonts import load_font
# font1 = load_font('file:\\C:\\Windows\\Fonts\\arial.ttf') #doesn't work
# font1 = load_font('file:\\\\C:\\Windows\\Fonts\\arial.ttf') #doesn't work

---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
File C:\APPS\Anaconda3\envs\bib2025\Lib\site-packages\pyfonts\main.py:73, in load_font(font_url, use_cache, danger_not_verify_ssl, font_path)
     72 try:
---> 73     font_prop.get_name()
     74 except FileNotFoundError:

File C:\APPS\Anaconda3\envs\bib2025\Lib\site-packages\matplotlib\font_manager.py:731, in FontProperties.get_name(self)
    728 """
    729 Return the name of the font that best matches the font properties.
    730 """
--> 731 return get_font(findfont(self)).family_name

File C:\APPS\Anaconda3\envs\bib2025\Lib\site-packages\matplotlib\font_manager.py:1615, in get_font(font_filepaths, hinting_factor)
   1613     hinting_factor = mpl.rcParams['text.hinting_factor']
-> 1615 return _get_font(
   1616     # must be a tuple to be cached
   1617     paths,
   1618     hinting_factor,
   1619     _kerning_factor=mpl.rcParams['text.kerning_factor'],
   1620     # also key on the thread ID to prevent segfaults with multi-threading
   1621     thread_id=threading.get_ident()
   1622 )

File C:\APPS\Anaconda3\envs\bib2025\Lib\site-packages\matplotlib\font_manager.py:1557, in _get_font(font_filepaths, hinting_factor, _kerning_factor, thread_id)
   1556 first_fontpath, *rest = font_filepaths
-> 1557 return ft2font.FT2Font(
   1558     first_fontpath, hinting_factor,
   1559     _fallback_list=[
   1560         ft2font.FT2Font(
   1561             fpath, hinting_factor,
   1562             _kerning_factor=_kerning_factor
   1563         )
   1564         for fpath in rest
   1565     ],
   1566     _kerning_factor=_kerning_factor
   1567 )

FileNotFoundError: [Errno 2] No such file or directory: 'C:Windows\\Fonts\\arial.ttf'

During handling of the above exception, another exception occurred:

FileNotFoundError                         Traceback (most recent call last)
Cell In[26], line 5
      3 from pyfonts import load_font
      4 # font1 = load_font('file:\\C:\\Windows\\Fonts\\arial.ttf') #doesn't work
----> 5 font1 = load_font('file:\\\\C:\\Windows\\Fonts\\arial.ttf') #doesn't work

File C:\APPS\Anaconda3\envs\bib2025\Lib\site-packages\pyfonts\main.py:75, in load_font(font_url, use_cache, danger_not_verify_ssl, font_path)
     73         font_prop.get_name()
     74     except FileNotFoundError:
---> 75         raise FileNotFoundError(f"Font file not found: '{font_url}'.")
     76     return font_prop
     77 if not _is_valid_raw_url(font_url):

FileNotFoundError: Font file not found: 'file:\\C:\Windows\Fonts\arial.ttf'.

[JosephBARBIERDARNAL]

@paniterka thanks for the detailed answer!

I'm not very knowledgable about how Windows file system works and I don't have a windows machine to try to reproduce this issue.

According to google and chatgpt, it's uncommon to start the file path with file, but it might be wrong. I wonder if this is required sometimes to use that file prefix?

Another thing that might be relevant to say if you're trying to use a font installed on your machine, you might not even need pyfonts! You might be able to to:

import matplotlib.pyplot as plt

plt.text(0.1, 0.1, "hey", font="Arial")

Matplotlib should be able to find it.