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# Authors: see git history
#
# Copyright (c) 2010 Authors
# Licensed under the GNU GPL version 3.0 or later. See the file LICENSE for details.
from inkex import NSS
from lxml import etree
class FontKerning(object):
"""
This class reads kerning information from an SVG file
"""
def __init__(self, path):
with open(path, 'r', encoding="utf-8") as svg:
self.svg = etree.parse(svg)
# horiz_adv_x defines the wdith of specific letters (distance to next letter)
def horiz_adv_x(self):
# In XPath 2.0 we could use ".//svg:glyph/(@unicode|@horiz-adv-x)"
xpath = ".//svg:glyph[@unicode and @horiz-adv-x]/@*[name()='unicode' or name()='horiz-adv-x']"
hax = self.svg.xpath(xpath, namespaces=NSS)
if len(hax) == 0:
return {}
return dict(zip(hax[0::2], [int(x) for x in hax[1::2]]))
# kerning (specific distances of two specified letters)
def hkern(self):
xpath = ".//svg:hkern[(@u1 or @g1) and (@u1 or @g1) and @k]/@*[contains(name(), '1') or contains(name(), '2') or name()='k']"
hkern = self.svg.xpath(xpath, namespaces=NSS)
# the kerning list now contains the kerning values as a list where every first value contains the first letter(s),
# every second value contains the second letter(s) and every third value contains the kerning
u_first = [k for k in hkern[0::3]]
u_second = [k for k in hkern[1::3]]
k = [int(x) for x in hkern[2::3]]
# sometimes a font file contains conflicting kerning value for a letter pair
# in this case the value which is specified as a single pair overrules the one specified in a list of letters
# therefore we want to sort our list by length of the letter values
kern_list = list(zip(u_first, u_second, k))
kern_list.sort(key=lambda x: len(x[0] + x[1]), reverse=True)
for index, kerning in enumerate(kern_list):
first, second, key = kerning
# fontTools.agl will import fontTools.misc.py23 which will output a deprecation warning
# ignore the warning for now - until the library fixed it
if index == 0:
import warnings
with warnings.catch_warnings():
warnings.simplefilter("ignore")
global toUnicode
from fontTools.agl import toUnicode
first = self.split_glyph_list(first)
second = self.split_glyph_list(second)
kern_list[index] = (first, second, key)
hkern = {}
for first, second, key in kern_list:
for f in first:
for s in second:
hkern[f+s] = key
return hkern
def split_glyph_list(self, glyph):
glyphs = []
if len(glyph) > 1:
# glyph names need to be converted to unicode
# we need to take into account, that there can be more than one first/second letter in the very same hkern element
# in this case they will be commas separated and each first letter needs to be combined with each next letter
# e.g. <hkern g1="A,Agrave,Aacute,Acircumflex,Atilde,Adieresis,Amacron,Abreve,Aogonek" g2="T,Tcaron" k="5" />
glyph_names = glyph.split(",")
for glyph_name in glyph_names:
# each glyph can have additional special markers, e.g. o.cmp
# toUnicode will not respect those and convert them to a simple letter
# this behaviour will generate a wrong spacing for this letter.
# Let's make sure to also transfer the separators and extensions to our json file
separators = [".", "_"]
used_separator = False
for separator in separators:
glyph_with_separator = glyph_name.split(separator)
if len(glyph_with_separator) == 2:
glyphs.append("%s%s%s" % (toUnicode(glyph_with_separator[0]), separator, glyph_with_separator[1]))
used_separator = True
continue
# there is no extra separator
if not used_separator:
glyphs.append(toUnicode(glyph_name))
else:
glyphs.append(glyph)
return glyphs
# the space character
def word_spacing(self):
xpath = "string(.//svg:glyph[@glyph-name='space'][1]/@*[name()='horiz-adv-x'])"
word_spacing = self.svg.xpath(xpath, namespaces=NSS)
try:
return int(word_spacing)
except ValueError:
return None
# default letter spacing
def letter_spacing(self):
xpath = "string(.//svg:font[@horiz-adv-x][1]/@*[name()='horiz-adv-x'])"
letter_spacing = self.svg.xpath(xpath, namespaces=NSS)
try:
return int(letter_spacing)
except ValueError:
return None
# this value will be saved into the json file to preserve it for later font edits
# additionally it serves to automatically define the line height (leading)
def units_per_em(self):
xpath = "string(.//svg:font-face[@units-per-em][1]/@*[name()='units-per-em'])"
units_per_em = self.svg.xpath(xpath, namespaces=NSS)
try:
return int(units_per_em)
except ValueError:
return None
"""
def missing_glyph_spacing(self):
xpath = "string(.//svg:missing-glyph/@*[name()='horiz-adv-x'])"
return float(self.svg.xpath(xpath, namespaces=NSS))
"""
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