How to add SHX fonts for use by Matplotlib drawing back-end

[IvanKachaikinCendas]

Hi @mozman! First of all, thanks for an awesome package!🤩

While running the rendering using ezdxf, I often get a warning message saying something like:

findfont: Font family ['isocp'] not found. Falling back to DejaVu Sans.

I succeeded to fix an issue for the fonts available as TFF, however still getting the same warning for the AutoCAD fonts saved as SHX. So my question is: is there a way to somehow import the SHX fonts from AutoCAD into ezdxf?

Thanks in advance for your feedback!🙂

[mozman]

The SHX font format is not documented or supported by many libraries/packages like Matplotlib and qt, therefore only SHX fonts which have corresponding TTF-fonts can be rendered by these backends.

Sometimes the Matplotlib package is stubborn and does not rebuild the font-cache properly if new fonts are installed, deleting the fontlist-v???.json file in ~/.matplotlib may help in this case.

Ezdxf uses it's own font-cache for faster font-measurement if you use the Matplotlib font support which is the default case.
If you use special fonts which are not included in the default cache files of ezdxf, you have to rebuild the font-cache: https://ezdxf.mozman.at/docs/options.html#font-cache-directory

... but "isocp" is included in the default cache files

Edit: usual the "isocp" font should be mapped to "isocp___.ttf", maybe you can upload a simple example DXF which shows your issue.

[IvanKachaikinCendas]

Hi @mozman! Ok got it, thanks for your feedback! Will retry with fontlist-v???.json delete in ~/.matplotlib.

Regarding the "isocp" issue, I created a dummy DXF with some text using "Txt" and "isocp" fonts. By default, it returns me this warning for both of these fonts and draws the text using some default font. You can find this dummy DXF below:
fonts.dxf.zip

Please note: I run the ezdxf==0.17.1 and not the later versions for some backward compatibility reasons. I also run it on MacOS that may be another reason of such an issue.

[mozman]

I tested your fonts.dxf:

• Windows with an Autodesk product (TrueView) installed - no message
• Linux without an Autodesk product: font ... not found message

Next I copied on Linux the replacement fonts into ~/.fonts, same message font ... not found message

Deleted fontlist-v330.json from ~/.cache/matplotlib and everything worked

Conclusion: the TTF replacement fonts are not available system wide, or Matplotlib can't find it, or the Matplotlib font cache is outdated.

[IvanKachaikinCendas]

@mozman Ok sounds clear, thanks for your feedback!🙂

By the way, I also found some solution that is a bit ugly from the software engineering and the code readability point of view, but that does the trick in case when someone has a folder with .ttf files that they don't want to install globally (like it was in my case). More specifically, if custom_fonts_paths is a list with paths to the folders with custom fonts, then the following worked for me:

from os.path import join
import matplotlib.font_manager as font_manager

for font in font_manager.findSystemFonts(custom_fonts_paths):
    font_manager.fontManager.addfont(font)


class FixedFontManager(font_manager.FontManager):
    def __init__(self, size=None, weight='normal'):
        super().__init__(size, weight)
        for font in font_manager.findSystemFonts(custom_fonts_paths):
            self.addfont(font)


font_manager.FontManager = FixedFontManager

Note: the code above must be placed before the code that calls the ezdxf export to PDF/JPG/etc. in the same file.