get glyph width from ttf font (python 3)

font_width.py

# -*- coding: utf-8 -*-

from fontTools.ttLib import TTFont

font = TTFont('/home/esteban/Downloads/unifont-10.0.07.ttf')
cmap = font['cmap']
t = cmap.getBestCmap()
s = font.getGlyphSet()

def width(c):
    if ord(c) in t and t[ord(c)] in s:
        return s[t[ord(c)]].width
    else:
        return s['.notdef'].width

assert width('a') == 512
assert width('弢') == 512
assert width(chr(0x081C)) == 0
assert width(chr(0x11A7)) == 1024

gen_file.py

res = []
last_cat = width(chr(0))
last_cp = 0
for cp in range(0x10FFFF+1):
    if width(chr(cp)) != last_cat:
        res.append((last_cp, cp - 1, last_cat))
        last_cat = width(chr(cp))
        last_cp = cp
res.append((last_cp, cp, last_cat))

with open('./out', 'w') as fh:
    for cp in res:
        fh.write('%d..%d,%d)' % cp)
        fh.write('\n')

Reminder: check char sequences are present or what's up with that.