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January 10, 2020 16:42
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JSTF Table builder
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#!/usr/bin/env python | |
# Builds a JSTF table from specially named features | |
# To use: | |
# First, set up the features in your font. | |
# You may add as many or as few features as you like, but they must conform | |
# to the following naming convention: | |
# exs1: First priority extension substitution. | |
# i.e. the first rules we try to substitute glyphs to make the line longer | |
# exp1: First priority extension positioning. | |
# i.e. the first rules we try to reposition glyphs to make the line longer | |
# shs1: First priority shrinkage substitution. | |
# i.e. the first rules we try to substitute glyphs to make the line shorter | |
# exp1: First priority shrinkage positioning. | |
# i.e. the first rules we try to reposition glyphs to make the line shorter | |
# If you want to specify a second level of suggestions to the layout engine, | |
# add one or more features called exs2, exp2, shs2, or shp2. | |
# For example: to tell the layout engine that, if it wants a longer line, it can | |
# try replacing H by H.wide and/or O by O.wide, add a feature: | |
# feature exs1 { | |
# sub H by H.wide; | |
# sub O by O.wide | |
# } exs1; | |
# To tell the layout engine that, if it *still* wants a longer line, it should next | |
# try replacing G by G.wide, add a feature: | |
# feature exs2 { | |
# sub G by G.wide; | |
# } exs2; | |
# Next run this script on your font. Expected output: | |
# % python3 jstf-builder.py JSTFSans-Regular.otf | |
# Looking for suggestion 1... | |
# Found extension substitution feature exs1 (lookups=0) | |
# Found shrinkage substitution feature shs1 (lookups=2) | |
# Looking for suggestion 2... | |
# Found extension substitution feature exs2 (lookups=1) | |
# Found shrinkage substitution feature shs2 (lookups=3) | |
# Looking for suggestion 3... | |
# Not found, ending here | |
# Saving JSTF-JSTFSans-Regular.otf | |
import argparse | |
from fontTools.ttLib import TTFont | |
from fontTools.misc.py23 import * | |
from fontTools import ttLib | |
import sys | |
from fontTools.ttLib.tables import otTables as ot | |
from collections import OrderedDict | |
from argparse import ArgumentParser | |
parser = ArgumentParser() | |
parser.add_argument("input", | |
help="font file to process", metavar="FILE") | |
parser.add_argument("--extender", dest="extenders", action='append', | |
help="Glyph names which act as extenders (tatweels, etc.)") | |
parser.add_argument("-o", dest="output", | |
help="path to output font", metavar="FILE") | |
args = parser.parse_args() | |
extenderGlyphs = args.extenders | |
fontPath = args.input | |
output = args.output | |
if output is None: | |
output = "JSTF-"+args.input | |
font = TTFont(fontPath) | |
tag = Tag("JSTF") | |
jstfTable = ttLib.getTableClass(tag)(tag) | |
tableClass = getattr(ot, tag) | |
jstfTable.table = tableClass() | |
jstfTable.table.populateDefaults() | |
setattr(jstfTable.table, "Version", 0x00010000) | |
# For now, everything lives in DFLT/dflt | |
rec = ot.JstfScriptRecord() | |
setattr(rec, "JstfScriptTag", "DFLT") | |
script = ot.JstfScript() | |
extender = ot.ExtenderGlyph() | |
setattr(extender, "ExtenderGlyph", extenderGlyphs) | |
setattr(script, "ExtenderGlyph", extender) | |
deflang = ot.DefJstfLangSys() | |
setattr(script, "DefJstfLangSys", deflang) | |
# Gather GSUB stuff | |
gsubfeatures = OrderedDict() | |
gposfeatures = OrderedDict() | |
def _prepareFeatureLangSys(langTag, langSys, table, features, scriptTag): | |
# This is a part of prepareFeatures | |
for featureIdx in langSys.FeatureIndex: | |
featureRecord = table.FeatureList.FeatureRecord[featureIdx] | |
featureTag = featureRecord.FeatureTag | |
scripts = features.get(featureTag, None) | |
if scripts is None: | |
scripts = OrderedDict() | |
features[featureTag] = scripts | |
languages = scripts.get(scriptTag, None) | |
if languages is None: | |
languages = OrderedDict() | |
scripts[scriptTag] = languages | |
lookups = languages.get(langTag, None) | |
if lookups is None: | |
lookups = [] | |
languages[langTag] = lookups | |
for lookupIdx in featureRecord.Feature.LookupListIndex: | |
lookups.append(lookupIdx) | |
for scriptRecord in font["GSUB"].table.ScriptList.ScriptRecord: | |
scriptTag = scriptRecord.ScriptTag | |
if scriptRecord.Script.DefaultLangSys is not None: | |
_prepareFeatureLangSys('dflt', scriptRecord.Script.DefaultLangSys, font["GSUB"].table, gsubfeatures, scriptTag) | |
for langSysRecord in scriptRecord.Script.LangSysRecord: | |
_prepareFeatureLangSys(langSysRecord.LangSysTag, langSysRecord.LangSys, font["GSUB"].table, gsubfeatures, scriptTag) | |
for scriptRecord in font["GPOS"].table.ScriptList.ScriptRecord: | |
scriptTag = scriptRecord.ScriptTag | |
if scriptRecord.Script.DefaultLangSys is not None: | |
_prepareFeatureLangSys('dflt', scriptRecord.Script.DefaultLangSys, font["GPOS"].table, gposfeatures, scriptTag) | |
for langSysRecord in scriptRecord.Script.LangSysRecord: | |
_prepareFeatureLangSys(langSysRecord.LangSysTag, langSysRecord.LangSys, font["GPOS"].table, gposfeatures, scriptTag) | |
suggestion = 0 | |
while True: | |
foundAny = False | |
suggestion = suggestion + 1 | |
if suggestion > 10: | |
raise ValueError("More than 10 suggestions not supported") | |
print("\nLooking for suggestion %i..." % suggestion) | |
thisSuggestion = ot.JstfPriority() | |
if ("exs%1i" % suggestion) in gsubfeatures: | |
foundAny = True | |
lookups = gsubfeatures["exs%1i" % suggestion]["DFLT"]["dflt"] | |
print("Found extension substitution feature exs%i (lookups=%s)" % (suggestion, ",".join([str(x) for x in lookups]))) | |
ext = ot.ExtensionEnableGSUB() | |
setattr(ext, "GSUBLookupIndex",lookups) | |
setattr(thisSuggestion, "ExtensionEnableGSUB", ext) | |
if ("exp%1i" % suggestion) in gposfeatures: | |
foundAny = True | |
lookups = gposfeatures["exs%1i" % suggestion]["DFLT"]["dflt"] | |
print("Found extension positioning feature exp%i (lookups=%s)" % (suggestion, ",".join([str(x) for x in lookups]))) | |
ext = ot.ExtensionEnableGPOS() | |
setattr(ext, "GPOSLookupIndex",lookups) | |
setattr(thisSuggestion, "ExtensionEnableGPOS", ext) | |
if ("shs%1i" % suggestion) in gsubfeatures: | |
foundAny = True | |
lookups = gsubfeatures["shs%1i" % suggestion]["DFLT"]["dflt"] | |
print("Found shrinkage substitution feature shs%i (lookups=%s)" % (suggestion, ",".join([str(x) for x in lookups]))) | |
ext = ot.ShrinkageEnableGSUB() | |
setattr(ext, "GSUBLookupIndex",lookups) | |
setattr(thisSuggestion, "ShrinkageEnableGSUB", ext) | |
if ("shp%1i" % suggestion) in gposfeatures: | |
foundAny = True | |
lookups = gposfeatures["shs%1i" % suggestion]["DFLT"]["dflt"] | |
print("Found shrinkage positioning feature shp%i (lookups=%s)" % (suggestion, ",".join([str(x) for x in lookups]))) | |
ext = ot.ShrinkageEnableGPOS() | |
setattr(ext, "GPOSLookupIndex",lookups) | |
setattr(thisSuggestion, "ShrinkageEnableGPOS", ext) | |
if not foundAny: | |
print("Not found, ending here") | |
break | |
if not (hasattr(deflang,"JstfPriority")): | |
setattr(deflang, "JstfPriority", []) | |
newList = getattr(deflang,"JstfPriority") + [thisSuggestion] | |
setattr(deflang, "JstfPriority", getattr(deflang,"JstfPriority") + [thisSuggestion]) | |
setattr(rec, "JstfScript", script) | |
jstfTable.table.JstfScriptRecord.append(rec) | |
font["JSTF"] = jstfTable | |
print("Saving "+output) | |
font.save(output) |
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