python unicode rendering: how to know if a unicode character is missing from the font

Question

In Python when I render a unicode character, e.g. a Chinese character, with a selected font, sometimes the font is incomplete regarding the common unicode characters, and ca

Answer 1

See https://unix.stackexchange.com/questions/247108/how-to-find-out-which-unicode-codepoints-are-defined-in-a-ttf-file

In short, one can install the fonttools package, supply it with the path to any .ttf font file of interest, and check if the long form of the unicode character of interest is included in the font file's unicode map table.

from fontTools.ttLib import TTFont
font = TTFont(fontpath)   # specify the path to the font in question


def char_in_font(unicode_char, font):
    for cmap in font['cmap'].tables:
        if cmap.isUnicode():
            if ord(unicode_char) in cmap.cmap:
                return True
    return False

Then just call the char_in_font function to check if the unicode character is included in the font.