[varLib/cff] Allow sparse masters

Fixes #3233
fonttools · Aug 1, 2023 · e375827 · e375827
1 parent 91731f7
commit e375827
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Showing 2 changed files with 25 additions and 9 deletions.
diff --git a/Lib/fontTools/misc/psCharStrings.py b/Lib/fontTools/misc/psCharStrings.py
@@ -1092,7 +1092,6 @@ def op_vstem3(self, index):
 
 
 class T2CharString(object):
-
     operandEncoding = t2OperandEncoding
     operators, opcodes = buildOperatorDict(t2Operators)
     decompilerClass = SimpleT2Decompiler
@@ -1150,6 +1149,8 @@ def draw(self, pen, blender=None):
         self.width = extractor.width
 
     def calcBounds(self, glyphSet):
+        self.decompile()
+        print(self.program)
         boundsPen = BoundsPen(glyphSet)
         self.draw(boundsPen)
         return boundsPen.bounds
@@ -1313,7 +1314,6 @@ def fromXML(self, name, attrs, content):
 
 
 class T1CharString(T2CharString):
-
     operandEncoding = t1OperandEncoding
     operators, opcodes = buildOperatorDict(t1Operators)
 
@@ -1347,7 +1347,6 @@ def draw(self, pen):
 
 
 class DictDecompiler(object):
-
     operandEncoding = cffDictOperandEncoding
 
     def __init__(self, strings, parent=None):

diff --git a/Lib/fontTools/varLib/cff.py b/Lib/fontTools/varLib/cff.py
@@ -350,10 +350,25 @@ def merge_region_fonts(varFont, model, ordered_fonts_list, glyphOrder):
     addCFFVarStore(varFont, model, cvData.varDataList, cvData.masterSupports)
 
 
-def _get_cs(charstrings, glyphName):
+def _get_cs(charstrings, glyphName, filterEmpty=False):
     if glyphName not in charstrings:
         return None
-    return charstrings[glyphName]
+    cs = charstrings[glyphName]
+
+    if filterEmpty:
+        cs.decompile()
+        # print(cs.program)
+        if cs.program == []:  # CFF2 empty charstring
+            return None
+        elif (
+            len(cs.program) <= 2
+            and cs.program[-1] == "endchar"
+            and (len(cs.program) == 1 or type(cs.program[0]) in (int, float))
+        ):  # CFF1 empty charstring
+            cs.program = []
+            return None
+
+    return cs
 
 
 def _add_new_vsindex(
@@ -373,16 +388,15 @@ def _add_new_vsindex(
 
 
 def merge_charstrings(glyphOrder, num_masters, top_dicts, masterModel):
-
     vsindex_dict = {}
     vsindex_by_key = {}
     varDataList = []
     masterSupports = []
     default_charstrings = top_dicts[0].CharStrings
     for gid, gname in enumerate(glyphOrder):
-        all_cs = [_get_cs(td.CharStrings, gname) for td in top_dicts]
-        if len([gs for gs in all_cs if gs is not None]) == 1:
-            continue
+        all_cs = [
+            _get_cs(td.CharStrings, gname, i != 0) for i, td in enumerate(top_dicts)
+        ]
         model, model_cs = masterModel.getSubModel(all_cs)
         # create the first pass CFF2 charstring, from
         # the default charstring.
@@ -402,6 +416,9 @@ def merge_charstrings(glyphOrder, num_masters, top_dicts, masterModel):
             region_charstring.outlineExtractor = MergeOutlineExtractor
             region_charstring.draw(var_pen)
 
+        if not region_cs:
+            continue
+
         # Collapse each coordinate list to a blend operator and its args.
         new_cs = var_pen.getCharString(
             private=default_charstring.private,