build STAT table (version 4) manually for variable fonts, re #577

2 files changed, 295 insertions, 21 deletions

diff --git a/Makefile b/Makefile
index 33e4fc141..26021b640 100644
--- a/Makefile
+++ b/Makefile
@@ -190,6 +190,13 @@ $(FONTDIR)/var/.%.var.otf: $(UFODIR)/%.var.designspace build/features_data | $(F
 	. $(VENV) ; misc/tools/woff2 compress -o "$@" "$<"
 
 
+$(FONTDIR)/var/Inter-Variable.ttf: $(FONTDIR)/var/.Inter-Roman.var.ttf
+	. $(VENV) ; python misc/tools/bake-vf.py $^ -o $@
+
+$(FONTDIR)/var/Inter-Variable-Italic.ttf: $(FONTDIR)/var/.Inter-Italic.var.ttf
+	. $(VENV) ; python misc/tools/bake-vf.py $^ -o $@
+
+
 $(FONTDIR)/static:
 	mkdir -p $@
 $(FONTDIR)/static-hinted:
@@ -199,27 +206,6 @@ $(FONTDIR)/var:
 $(UFODIR):
 	mkdir -p $@
 
-# Inter Variable
-$(FONTDIR)/var/.Inter-Variable.stamp: \
-	  $(FONTDIR)/var/.Inter-Roman.var.ttf \
-	  $(FONTDIR)/var/.Inter-Italic.var.ttf \
-	  | venv
-	rm -rf $(FONTDIR)/var/gen-stat
-	mkdir $(FONTDIR)/var/gen-stat
-	. $(VENV) ; gftools gen-stat --out $(FONTDIR)/var/gen-stat $^
-	. $(VENV) ; python misc/tools/rename.py --scrub-display --family "Inter Variable" \
-	              -o $(FONTDIR)/var/Inter-Variable.ttf \
-	              $(FONTDIR)/var/gen-stat/.Inter-Roman.var.ttf
-	. $(VENV) ; python misc/tools/rename.py --scrub-display --family "Inter Variable" \
-	              -o $(FONTDIR)/var/Inter-Variable-Italic.ttf \
-	              $(FONTDIR)/var/gen-stat/.Inter-Italic.var.ttf
-	rm -rf $(FONTDIR)/var/gen-stat
-	touch $@
-
-$(FONTDIR)/var/Inter-Variable.ttf: $(FONTDIR)/var/.Inter-Variable.stamp
-	touch $@
-$(FONTDIR)/var/Inter-Variable-Italic.ttf: $(FONTDIR)/var/.Inter-Variable.stamp
-	touch $@
 
 var: \
 	$(FONTDIR)/var/Inter-Variable.ttf \
diff --git a/misc/tools/bake-vf.py b/misc/tools/bake-vf.py
new file mode 100644
index 000000000..dab74a5d8
--- /dev/null
+++ b/misc/tools/bake-vf.py
@@ -0,0 +1,288 @@
+"""
+This script "bakes" the final Inter variable fonts.
+
+This script performs the following:
+  1. Renames the family to "Inter Variable"
+  2. Updates style names to scrub away "Display"
+  3. Builds a STAT table
+
+How to debug/develop this script:
+
+1. create a working dir and build the initial fonts:
+
+  mkdir -p build/bake
+  make -j var
+
+2. after making changes, run script and inspect with ttx:
+
+  ( for a in build/fonts/var/.Inter-*.var.ttf; do
+      python misc/tools/bake-vf.py "$a" -o build/bake/"$(basename "${a/.Inter/Inter}")"
+    done && ttx -t STAT -i -f -s build/bake/Inter-*.ttf )
+
+"""
+import sys, os, os.path, re, argparse
+from fontTools.ttLib import TTFont
+from fontTools.otlLib.builder import buildStatTable
+
+
+STAT_AXES = [
+  { "name": "Optical Size", "tag": "opsz" },
+  { "name": "Weight",       "tag": "wght" },
+  { "name": "Italic",       "tag": "ital" }
+]
+
+
+def stat_locations(ital):
+  return [
+    { "name": "Thin",       "location": { "wght": 100, "ital": ital } },
+    { "name": "ExtraLight", "location": { "wght": 200, "ital": ital } },
+    { "name": "Light",      "location": { "wght": 300, "ital": ital } },
+    { "name": "Regular",    "location": { "wght": 400, "ital": ital }, "flags": 0x2 },
+    { "name": "Medium",     "location": { "wght": 500, "ital": ital } },
+    { "name": "SemiBold",   "location": { "wght": 600, "ital": ital } },
+    { "name": "Bold",       "location": { "wght": 700, "ital": ital } },
+    { "name": "Heavy",      "location": { "wght": 800, "ital": ital } },
+    { "name": "Black",      "location": { "wght": 900, "ital": ital } },
+  ]
+  # "flags": 0x2
+  #   Indicates that the axis value represents the “normal” value
+  #   for the axis and may be omitted when composing name strings.
+
+
+WINDOWS_ENGLISH_IDS = 3, 1, 0x409
+MAC_ROMAN_IDS = 1, 0, 0
+
+LEGACY_FAMILY       = 1
+SUBFAMILY_NAME      = 2
+TRUETYPE_UNIQUE_ID  = 3
+FULL_NAME           = 4
+POSTSCRIPT_NAME     = 6
+PREFERRED_FAMILY    = 16
+TYPO_SUBFAMILY_NAME = 17
+WWS_FAMILY          = 21
+VAR_PS_NAME_PREFIX  = 25
+
+
+FAMILY_RELATED_IDS = set([
+  LEGACY_FAMILY,
+  TRUETYPE_UNIQUE_ID,
+  FULL_NAME,
+  POSTSCRIPT_NAME,
+  PREFERRED_FAMILY,
+  WWS_FAMILY,
+  VAR_PS_NAME_PREFIX,
+])
+
+WHITESPACE_RE = re.compile(r'\s+')
+
+
+def remove_whitespace(s):
+  return WHITESPACE_RE.sub('', s)
+
+
+def normalize_whitespace(s):
+  return WHITESPACE_RE.sub(' ', s)
+
+
+def remove_substring(s, substr):
+  # examples of remove_substring(s, "Display"):
+  #   "Inter Display"   => "Inter"
+  #   "Display Lol"     => "Lol"
+  #   "Foo Display Lol" => "Foo Lol"
+  #   " Foo   Bar Lol " => "Foo Bar Lol"
+  return normalize_whitespace(s.strip().replace(substr, '')).strip()
+
+
+def font_is_italic(ttfont):
+  """Check if the font has the word "Italic" in its stylename"""
+  stylename = ttfont["name"].getName(2, 3, 1, 0x409).toUnicode()
+  return True if "Italic" in stylename else False
+
+
+def set_full_name(font, fullName, fullNamePs):
+  nameTable = font["name"]
+  nameTable.setName(fullName, FULL_NAME, 1, 0, 0)     # mac
+  nameTable.setName(fullName, FULL_NAME, 3, 1, 0x409) # windows
+  nameTable.setName(fullNamePs, POSTSCRIPT_NAME, 1, 0, 0)     # mac
+  nameTable.setName(fullNamePs, POSTSCRIPT_NAME, 3, 1, 0x409) # windows
+
+
+def getFamilyName(font):
+  nameTable = font["name"]
+  r = None
+  for plat_id, enc_id, lang_id in (WINDOWS_ENGLISH_IDS, MAC_ROMAN_IDS):
+    for name_id in (PREFERRED_FAMILY, LEGACY_FAMILY):
+      r = nameTable.getName(nameID=name_id, platformID=plat_id, platEncID=enc_id, langID=lang_id)
+      if r is not None:
+        break
+    if r is not None:
+      break
+  if not r:
+    raise ValueError("family name not found")
+  return r.toUnicode()
+
+
+def getFamilyNames(font):
+  nameTable = font["name"]
+  r = None
+  names = dict()  # dict in Py >=3.7 maintains insertion order
+  for plat_id, enc_id, lang_id in (WINDOWS_ENGLISH_IDS, MAC_ROMAN_IDS):
+    for name_id in (PREFERRED_FAMILY, LEGACY_FAMILY):
+      r = nameTable.getName(
+        nameID=name_id, platformID=plat_id, platEncID=enc_id, langID=lang_id)
+      if r:
+        names[r.toUnicode()] = True
+  if len(names) == 0:
+    raise ValueError("family name not found")
+  names = list(names.keys())
+  names.sort()
+  names.reverse() # longest first
+  return names
+
+
+def getStyleName(font):
+  nameTable = font["name"]
+  for plat_id, enc_id, lang_id in (WINDOWS_ENGLISH_IDS, MAC_ROMAN_IDS):
+    for name_id in (TYPO_SUBFAMILY_NAME, SUBFAMILY_NAME):
+      r = nameTable.getName(
+        nameID=name_id, platformID=plat_id, platEncID=enc_id, langID=lang_id)
+      if r is not None:
+        return r.toUnicode()
+  raise ValueError("style name not found")
+
+
+def setStyleName(font, newStyleName):
+  newFullName = getFamilyName(font).strip()
+  if newStyleName != 'Regular':
+    newFullName += " " + newStyleName
+  newFullNamePs = remove_whitespace(newFullName)
+  set_full_name(font, newFullName, newFullNamePs)
+
+  nameTable = font["name"]
+  for rec in nameTable.names:
+    rid = rec.nameID
+    if rid in (SUBFAMILY_NAME, TYPO_SUBFAMILY_NAME):
+      rec.string = newStyleName
+
+
+def setFamilyName(font, nextFamilyName):
+  prevFamilyNames = getFamilyNames(font)
+  # if prevFamilyNames[0] == nextFamilyName:
+  #   return
+  #   # raise Exception("identical family name")
+
+  def renameRecord(nameRecord, prevFamilyNames, nextFamilyName):
+    # replaces prevFamilyNames with nextFamilyName in nameRecord
+    s = nameRecord.toUnicode()
+    for prevFamilyName in prevFamilyNames:
+      start = s.find(prevFamilyName)
+      if start == -1:
+        continue
+      end = start + len(prevFamilyName)
+      nextFamilyName = s[:start] + nextFamilyName + s[end:]
+      nameRecord.string = nextFamilyName
+      break
+    return s, nextFamilyName
+
+  # postcript name can't contain spaces
+  psPrevFamilyNames = []
+  for s in prevFamilyNames:
+    s = s.strip()
+    if s.find(' ') == -1:
+      psPrevFamilyNames.append(s)
+    else:
+      # Foo Bar Baz -> FooBarBaz
+      psPrevFamilyNames.append(s.replace(" ", ""))
+      # # Foo Bar Baz -> FooBar-Baz
+      p = s.rfind(' ')
+      s = s[:p] + '-' + s[p+1:]
+      psPrevFamilyNames.append(s)
+
+  psNextFamilyName = nextFamilyName.replace(" ", "")
+  found_VAR_PS_NAME_PREFIX = False
+  nameTable = font["name"]
+
+  for rec in nameTable.names:
+    name_id = rec.nameID
+    if name_id not in FAMILY_RELATED_IDS:
+      # leave uninteresting records unmodified
+      continue
+    if name_id == POSTSCRIPT_NAME:
+      old, new = renameRecord(rec, psPrevFamilyNames, psNextFamilyName)
+    elif name_id == TRUETYPE_UNIQUE_ID:
+      # The Truetype Unique ID rec may contain either the PostScript Name
+      # or the Full Name
+      prev_psname = None
+      for s in psPrevFamilyNames:
+        if s in rec.toUnicode():
+          prev_psname = s
+          break
+      if prev_psname is not None:
+        # Note: This is flawed -- a font called "Foo" renamed to "Bar Lol";
+        # if this record is not a PS record, it will incorrectly be rename "BarLol".
+        # However, in practice this is not a big deal since it's just an ID.
+        old, new = renameRecord(rec, [prev_psname], psNextFamilyName)
+      else:
+        old, new = renameRecord(rec, prevFamilyNames, nextFamilyName)
+    elif name_id == VAR_PS_NAME_PREFIX:
+      # Variations PostScript Name Prefix.
+      # If present in a variable font, it may be used as the family prefix in the
+      # PostScript Name Generation for Variation Fonts algorithm.
+      # The character set is restricted to ASCII-range uppercase Latin letters,
+      # lowercase Latin letters, and digits.
+      found_VAR_PS_NAME_PREFIX = True
+      old, new = renameRecord(rec, prevFamilyNames, nextFamilyName)
+    else:
+      old, new = renameRecord(rec, prevFamilyNames, nextFamilyName)
+    # print("  %r: '%s' -> '%s'" % (rec, old, new))
+
+  # HACK! FIXME!
+  # add name ID 25 "Variations PostScript Name Prefix" if not found
+  if not found_VAR_PS_NAME_PREFIX and nextFamilyName.find('Variable') != -1:
+    varPSNamePrefix = remove_whitespace(nextFamilyName)
+    nameTable.setName(varPSNamePrefix, VAR_PS_NAME_PREFIX, 1, 0, 0)     # mac
+    nameTable.setName(varPSNamePrefix, VAR_PS_NAME_PREFIX, 3, 1, 0x409) # windows
+
+
+def gen_stat(ttfont):
+  ital = 1 if font_is_italic(ttfont) else 0
+  locations = stat_locations(ital)
+  buildStatTable(ttfont, STAT_AXES, locations=locations)
+
+
+def main():
+  argparser = argparse.ArgumentParser(
+    description='Generate STAT table for variable font family')
+  a = lambda *args, **kwargs: argparser.add_argument(*args, **kwargs)
+  a('--family', metavar='<name>',
+    help='Rename family to <name> instead of "Inter Display"')
+  a('-o', '--output', metavar='<file>',
+    help='Output font file. Defaults to input file (overwrite)')
+  a('input', metavar='<file>', help='Input font file')
+
+  args = argparser.parse_args()
+
+  # load font
+  font = TTFont(args.input, recalcBBoxes=False, recalcTimestamp=False)
+
+  # set family name
+  if not args.family:
+    args.family = "Inter Display"
+  setFamilyName(font, args.family)
+
+  # set style name
+  stylename = remove_substring(getStyleName(font), "Display")
+  if stylename == '':
+    stylename = 'Regular'
+  setStyleName(font, stylename)
+
+  # build STAT table
+  gen_stat(font)
+
+  # save font
+  outfile = args.output or args.input
+  font.save(outfile)
+
+
+if __name__ == '__main__':
+  main()