port varfont_info.py script into a gftools subcommand

(issue googlefonts#3)

bin/gftools-varfont-info.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python2
+# Copyright 2017 The Google Font Tools Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+"""
+Lists which variable font axes and named-instances are
+  declared in the 'fvar' table of a given TTF file.
+"""
+import contextlib
+import sys
+from fontTools import ttLib
+
+def _ResolveName(ttf, name_id):
+  if name_id == 0xFFFF:
+    return '[anonymous]'
+  names = [n for n in ttf['name'].names if n.nameID == name_id]
+  if not names:
+    return '[?nameID=%d?]' % name_id
+  unicode_names = [n for n in names if n.isUnicode()]
+  if unicode_names:
+    return unicode_names[0].toUnicode()
+  return names[0].toUnicode()
+
+
+def main(argv):
+  if len(argv) < 2:
+    sys.exit(("{}\n"
+              "usage:\n"
+              "       gftools varfont-info fontfile.ttf").format(__doc__))
+
+  for filename in argv[1:]:
+    with contextlib.closing(ttLib.TTFont(filename)) as ttf:
+      print (filename)
+      if 'fvar' not in ttf:
+        print ("This font file lacks an 'fvar' table.")
+      else:
+        fvar = ttf['fvar']
+        print (' axes')
+        axes = [(a.axisTag, a.minValue, a.defaultValue, a.maxValue)
+                for a in fvar.axes]
+        for tag, minv, defv, maxv in axes:
+          print ("  '%s' %d-%d, default %d" % (tag, minv, maxv, defv))
+
+        if fvar.instances:
+          print (' named-instances')
+          for inst in fvar.instances:
+            print ('   %s %s' % (_ResolveName(ttf, inst.postscriptNameID),
+                                 inst.coordinates))
+
+if __name__ == '__main__':
+  main(sys.argv)