diff options
Diffstat (limited to 'lib/lettering/font_info.py')
| -rw-r--r-- | lib/lettering/font_info.py | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/lib/lettering/font_info.py b/lib/lettering/font_info.py new file mode 100644 index 00000000..398786a4 --- /dev/null +++ b/lib/lettering/font_info.py @@ -0,0 +1,137 @@ +# 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 +from ..svg.tags import INKSCAPE_LABEL + + +class FontFileInfo(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)) + """ + + def glyph_list(self): + """ + Returns a list of available glyphs in the font file + """ + glyphs = [] + glyph_layers = self.svg.xpath(".//svg:g[starts-with(@inkscape:label, 'GlyphLayer-')]", namespaces=NSS) + for layer in glyph_layers: + glyph_name = layer.attrib[INKSCAPE_LABEL].replace("GlyphLayer-", "", 1) + glyphs.append(glyph_name) + return glyphs |