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Switch from fontforge to fonttools

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The dependencies of fonttools are much lighter than fontforge, and since all
we need are some metrics, fonttools is very much up to that task.

This addresses issue #288.
This commit is contained in:
Martin von Gagern
2015-07-09 17:33:50 +02:00
parent d26a67f220
commit b290d4ad76
3 changed files with 48 additions and 34 deletions
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68
metrics/extract_ttfs.py
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@@ -1,6 +1,6 @@
#!/usr/bin/env python
import fontforge
from fontTools.ttLib import TTFont
import sys
import json
@@ -60,36 +60,50 @@ def main():
start_json = json.load(sys.stdin)
for font, chars in metrics_to_extract.iteritems():
fontInfo = fontforge.open("../static/fonts/KaTeX_" + font + ".ttf")
fontInfo = TTFont("../static/fonts/KaTeX_" + font + ".ttf")
glyf = fontInfo["glyf"]
unitsPerEm = float(fontInfo["head"].unitsPerEm)
for glyph in fontInfo.glyphs():
try:
char = unichr(glyph.unicode)
except ValueError:
# We keep ALL Unicode cmaps, not just fontInfo["cmap"].getcmap(3, 1).
# This is playing it extra safe, since it reports inconsistencies.
# Platform 0 is Unicode, platform 3 is Windows. For platform 3,
# encoding 1 is UCS-2 and encoding 10 is UCS-4.
cmap = [t.cmap for t in fontInfo["cmap"].tables
if (t.platformID == 0)
or (t.platformID == 3 and t.platEncID in (1, 10))]
for char, base_char in chars.iteritems():
code = ord(char)
names = set(t.get(code) for t in cmap)
if not names:
sys.stderr.write(
"Codepoint {} of font {} maps to no name\n"
.format(code, font))
continue
if len(names) != 1:
sys.stderr.write(
"Codepoint {} of font {} maps to multiple names: {}\n"
.format(code, font, ", ".join(sorted(names))))
continue
name = names.pop()
if char in chars:
_, depth, _, height = glyph.boundingBox()
height = depth = italic = skew = 0
glyph = glyf[name]
if glyph.numberOfContours:
height = glyph.yMax
depth = -glyph.yMin
if base_char:
base_char_str = str(ord(base_char))
base_metrics = start_json[font][base_char_str]
italic = base_metrics["italic"]
skew = base_metrics["skew"]
depth = -depth
base_char = chars[char]
if base_char:
base_char_str = str(ord(base_char))
base_metrics = start_json[font][base_char_str]
italic = base_metrics["italic"]
skew = base_metrics["skew"]
else:
italic = 0
skew = 0
start_json[font][str(ord(char))] = {
"height": height / fontInfo.em,
"depth": depth / fontInfo.em,
"italic": italic,
"skew": skew,
}
start_json[font][str(code)] = {
"height": height / unitsPerEm,
"depth": depth / unitsPerEm,
"italic": italic,
"skew": skew,
}
sys.stdout.write(
json.dumps(start_json, separators=(',', ':'), sort_keys=True))