Fix for #1985: ensure that the AxisNameID in the STAT table is > 255 (#1986)

Fix for #1985:
* ensure that the AxisNameID in the STAT table is not less than 256. This needed an additional argument to the addMultiLingualName() name table method.
* fvar axis name IDs must also not be less than 256, just like STAT axis names.

Lib/fontTools/otlLib/builder.py

@@ -784,7 +784,7 @@ def _buildAxisRecords(axes, nameTable):
     for axisRecordIndex, axisDict in enumerate(axes):
         axis = ot.AxisRecord()
         axis.AxisTag = axisDict["tag"]
-        axis.AxisNameID = _addName(nameTable, axisDict["name"])
+        axis.AxisNameID = _addName(nameTable, axisDict["name"], 256)
         axis.AxisOrdering = axisDict.get("ordering", axisRecordIndex)
         axisRecords.append(axis)
 
@@ -837,7 +837,7 @@ def _buildAxisValuesFormat4(locations, axes, nameTable):
     return axisValues
 
 
-def _addName(nameTable, value):
+def _addName(nameTable, value, minNameID=0):
     if isinstance(value, int):
         # Already a nameID
         return value
@@ -847,4 +847,4 @@ def _addName(nameTable, value):
         names = value
     else:
         raise TypeError("value must be int, str or dict")
-    return nameTable.addMultilingualName(names)
+    return nameTable.addMultilingualName(names, minNameID=minNameID)

Lib/fontTools/ttLib/tables/_n_a_m_e.py

@@ -184,7 +184,7 @@ class table__n_a_m_e(DefaultTable.DefaultTable):
 			raise ValueError("nameID must be less than 32768")
 		return nameID
 
-	def findMultilingualName(self, names, windows=True, mac=True):
+	def findMultilingualName(self, names, windows=True, mac=True, minNameID=0):
 		"""Return the name ID of an existing multilingual name that
 		matches the 'names' dictionary, or None if not found.
 
@@ -198,6 +198,9 @@ class table__n_a_m_e(DefaultTable.DefaultTable):
 		platEncID=1.
 		If 'mac' is True, the returned name ID is guaranteed to exist
 		for all requested languages for platformID=1 and platEncID=0.
+
+		The returned name ID will not be less than the 'minNameID'
+		argument.
 		"""
 		# Gather the set of requested
 		#   (string, platformID, platEncID, langID)
@@ -227,7 +230,7 @@ class table__n_a_m_e(DefaultTable.DefaultTable):
 				       name.platEncID, name.langID)
 			except UnicodeDecodeError:
 				continue
-			if key in reqNameSet:
+			if key in reqNameSet and name.nameID >= minNameID:
 				nameSet = matchingNames.setdefault(name.nameID, set())
 				nameSet.add(key)
 
@@ -239,7 +242,7 @@ class table__n_a_m_e(DefaultTable.DefaultTable):
 		return None  # not found
 
 	def addMultilingualName(self, names, ttFont=None, nameID=None,
-	                        windows=True, mac=True):
+	                        windows=True, mac=True, minNameID=0):
 		"""Add a multilingual name, returning its name ID
 
 		'names' is a dictionary with the name in multiple languages,
@@ -258,12 +261,16 @@ class table__n_a_m_e(DefaultTable.DefaultTable):
 
 		If 'windows' is True, a platformID=3 name record will be added.
 		If 'mac' is True, a platformID=1 name record will be added.
+
+		If the 'nameID' argument is None, the created nameID will not
+		be less than the 'minNameID' argument.
 		"""
 		if not hasattr(self, 'names'):
 			self.names = []
 		if nameID is None:
 			# Reuse nameID if possible
-			nameID = self.findMultilingualName(names, windows=windows, mac=mac)
+			nameID = self.findMultilingualName(
+				names, windows=windows, mac=mac, minNameID=minNameID)
 			if nameID is not None:
 				return nameID
 			nameID = self._findUnusedNameID()

Lib/fontTools/varLib/__init__.py

@@ -71,7 +71,7 @@ def _add_fvar(font, axes, instances):
 		axis.axisTag = Tag(a.tag)
 		# TODO Skip axes that have no variation.
 		axis.minValue, axis.defaultValue, axis.maxValue = a.minimum, a.default, a.maximum
-		axis.axisNameID = nameTable.addMultilingualName(a.labelNames, font)
+		axis.axisNameID = nameTable.addMultilingualName(a.labelNames, font, minNameID=256)
 		axis.flags = int(a.hidden)
 		fvar.axes.append(axis)
 

Tests/otlLib/builder_test.py

@@ -1371,6 +1371,11 @@ def test_buildStatTable(axes, axisValues, elidedFallbackName, expected_ttx):
     font = ttLib.TTFont()
     font["name"] = ttLib.newTable("name")
     font["name"].names = []
+    # https://github.com/fonttools/fonttools/issues/1985
+    # Add nameID < 256 that matches a test axis name, to test whether
+    # the nameID is not reused: AxisNameIDs must be > 255 according
+    # to the spec.
+    font["name"].addMultilingualName(dict(en="ABCDTest"), nameID=6)
     builder.buildStatTable(font, axes, axisValues, elidedFallbackName)
     f = io.StringIO()
     font.saveXML(f, tables=["STAT"])

Tests/ttLib/tables/_n_a_m_e_test.py

@@ -294,6 +294,17 @@ class NameTableTest(unittest.TestCase):
 			nameTable.addMultilingualName({"en": "A", "la": "ⱾƤℚⱤ"})
 		captor.assertRegex("cannot store language la into 'ltag' table")
 
+	def test_addMultilingualName_minNameID(self):
+		table = table__n_a_m_e()
+		names, namesSubSet, namesSuperSet = self._get_test_names()
+		nameID = table.addMultilingualName(names, nameID=2)
+		self.assertEqual(nameID, 2)
+		nameID = table.addMultilingualName(names)
+		self.assertEqual(nameID, 2)
+		nameID = table.addMultilingualName(names, minNameID=256)
+		self.assertGreaterEqual(nameID, 256)
+		self.assertEqual(nameID, table.findMultilingualName(names, minNameID=256))
+
 	def test_decompile_badOffset(self):
                 # https://github.com/fonttools/fonttools/issues/525
 		table = table__n_a_m_e()