[doc] Add help options to fonttools CLI (#1920)

This adds a `help` verb (and `--help` option) to the `fonttools` command line tool. Submodules will be listed in the help text if they have an importable `main` function with a docstring, and `main`'s docstring will be used as the one-line description for the help text.

Lib/fontTools/__main__.py

@@ -5,8 +5,6 @@ def main(args=None):
 	if args is None:
 		args = sys.argv[1:]
 
-	# TODO Add help output, --help, etc.
-
 	# TODO Handle library-wide options. Eg.:
 	# --unicodedata
 	# --verbose / other logging stuff
@@ -20,6 +18,10 @@ def main(args=None):
 	# can be added.  Should we just try importing the fonttools
 	# module first and try without if it fails?
 
+	if len(sys.argv) < 2:
+		sys.argv.append("help")
+	if sys.argv[1] == "-h" or sys.argv[1] == "--help":
+		sys.argv[1] = "help"
 	mod = 'fontTools.'+sys.argv[1]
 	sys.argv[1] = sys.argv[0] + ' ' + sys.argv[1]
 	del sys.argv[0]

Lib/fontTools/cffLib/width.py

@@ -146,12 +146,8 @@ def optimizeWidths(widths):
 
 	return default, nominal
 
-
-if __name__ == '__main__':
-	import sys
-	if len(sys.argv) == 1:
-		import doctest
-		sys.exit(doctest.testmod().failed)
+def main():
+	"""Calculate optimum defaultWidthX/nominalWidthX values"""
 	for fontfile in sys.argv[1:]:
 		font = TTFont(fontfile)
 		hmtx = font['hmtx']
@@ -160,3 +156,10 @@ def optimizeWidths(widths):
 		print("glyphs=%d default=%d nominal=%d byteCost=%d" % (len(widths), default, nominal, byteCost(widths, default, nominal)))
 		#default, nominal = optimizeWidthsBruteforce(widths)
 		#print("glyphs=%d default=%d nominal=%d byteCost=%d" % (len(widths), default, nominal, byteCost(widths, default, nominal)))
+
+if __name__ == '__main__':
+	import sys
+	if len(sys.argv) == 1:
+		import doctest
+		sys.exit(doctest.testmod().failed)
+	main()

Lib/fontTools/cu2qu/cli.py

@@ -59,6 +59,7 @@ def _copytree(input_path, output_path):
 
 
 def main(args=None):
+    """Convert a UFO font from cubic to quadratic curves"""
     parser = argparse.ArgumentParser(prog="cu2qu")
     parser.add_argument(
         "--version", action="version", version=fontTools.__version__)

Lib/fontTools/feaLib/__main__.py

@@ -13,6 +13,7 @@
 
 
 def main(args=None):
+    """Add features from a feature file (.fea) into a OTF font"""
     parser = argparse.ArgumentParser(
         description="Use fontTools to compile OpenType feature files (*.fea).")
     parser.add_argument(

Lib/fontTools/help.py

@@ -0,0 +1,34 @@
+import pkgutil
+import sys
+import fontTools
+import importlib
+import os
+from pathlib import Path
+
+
+def main():
+    """Show this help"""
+    path = fontTools.__path__
+    descriptions = {}
+    for pkg in sorted(
+        mod.name
+        for mod in pkgutil.walk_packages([fontTools.__path__[0]], prefix="fontTools.")
+    ):
+        try:
+            imports = __import__(pkg, globals(), locals(), ["main"])
+        except ImportError as e:
+            continue
+        try:
+            description = imports.main.__doc__
+            if description:
+                pkg = pkg.replace("fontTools.", "").replace(".__main__", "")
+                descriptions[pkg] = description
+        except AttributeError as e:
+            pass
+    for pkg, description in descriptions.items():
+        print("fonttools %-12s %s" % (pkg, description), file=sys.stderr)
+
+
+if __name__ == "__main__":
+    print("fonttools v%s\n" % fontTools.__version__, file=sys.stderr)
+    main()

Lib/fontTools/merge.py

@@ -2,9 +2,6 @@
 #
 # Google Author(s): Behdad Esfahbod, Roozbeh Pournader
 
-"""Font merger.
-"""
-
 from fontTools.misc.py23 import *
 from fontTools.misc.timeTools import timestampNow
 from fontTools import ttLib, cffLib
@@ -1136,6 +1133,7 @@ def _postMerge(self, font):
 
 @timer("make one with everything (TOTAL TIME)")
 def main(args=None):
+	"""Merge multiple fonts into one"""
 	from fontTools import configLogger
 
 	if args is None:

Lib/fontTools/mtiLib/__init__.py

@@ -1151,6 +1151,7 @@ def build(f, font, tableTag=None):
 
 
 def main(args=None, font=None):
+	"""Convert a FontDame OTL file to TTX XML"""
 	import sys
 	from fontTools import configLogger
 	from fontTools.misc.testTools import MockFont

Lib/fontTools/subset/__init__.py

@@ -2778,6 +2778,7 @@ def usage():
 
 @timer("make one with everything (TOTAL TIME)")
 def main(args=None):
+	"""OpenType font subsetter and optimizer"""
 	from os.path import splitext
 	from fontTools import configLogger
 

Lib/fontTools/subset/__main__.py

@@ -2,5 +2,6 @@
 import sys
 from fontTools.subset import main
 
+
 if __name__ == '__main__':
     sys.exit(main())

Lib/fontTools/ttLib/woff2.py

@@ -1390,6 +1390,7 @@ def decompress(input_file, output_file):
 
 
 def main(args=None):
+	"""Compress and decompress WOFF2 fonts"""
 	import argparse
 	from fontTools import configLogger
 	from fontTools.ttx import makeOutputFileName
@@ -1404,7 +1405,7 @@ def __call__(self, parser, namespace, values, option_string=None):
 
 	parser = argparse.ArgumentParser(
 		prog="fonttools ttLib.woff2",
-		description="Compress and decompress WOFF2 fonts",
+		description=main.__doc__
 	)
 
 	parser_group = parser.add_subparsers(title="sub-commands")

Lib/fontTools/ttx.py

@@ -384,6 +384,7 @@ def waitForKeyPress():
 
 
 def main(args=None):
+	"""Convert OpenType fonts to XML and back"""
 	from fontTools import configLogger
 
 	if args is None:

Lib/fontTools/varLib/__init__.py

@@ -1007,6 +1007,7 @@ def __call__(self, src_path):
 
 
 def main(args=None):
+	"""Build a variable font from a designspace file and masters"""
 	from argparse import ArgumentParser
 	from fontTools import configLogger
 

Lib/fontTools/varLib/__main__.py

@@ -1,5 +1,6 @@
 import sys
 from fontTools.varLib import main
 
+
 if __name__ == '__main__':
 	sys.exit(main())

Lib/fontTools/varLib/instancer.py

@@ -1375,6 +1375,7 @@ def parseArgs(args):
 
 
 def main(args=None):
+    """Partially instantiate a variable font."""
     infile, axisLimits, options = parseArgs(args)
     log.info("Restricting axes: %s", axisLimits)
 

Lib/fontTools/varLib/interpolatable.py

@@ -158,6 +158,7 @@ def test(glyphsets, glyphs=None, names=None):
 	#	print(x)
 
 def main(args):
+	"""Test for interpolatability issues between fonts"""
 	filenames = args
 	glyphs = None
 	#glyphs = ['uni08DB', 'uniFD76']

Lib/fontTools/varLib/interpolate_layout.py

@@ -58,6 +58,7 @@ def interpolate_layout(designspace, loc, master_finder=lambda s:s, mapped=False)
 
 
 def main(args=None):
+	"""Interpolate GDEF/GPOS/GSUB tables for a point on a designspace"""
 	from fontTools import configLogger
 
 	import sys

Lib/fontTools/varLib/models.py

@@ -423,6 +423,7 @@ def piecewiseLinearMap(v, mapping):
 
 
 def main(args):
+	"""Normalize locations on a given designspace"""
 	from fontTools import configLogger
 
 	args = args[1:]

Lib/fontTools/varLib/mutator.py

@@ -399,6 +399,7 @@ def instantiateVariableFont(varfont, location, inplace=False, overlap=True):
 
 
 def main(args=None):
+	"""Instantiate a variation font"""
 	from fontTools import configLogger
 	import argparse
 

Lib/fontTools/varLib/varStore.py

@@ -545,6 +545,7 @@ def VarStore_optimize(self):
 
 
 def main(args=None):
+	"""Optimize a font's GDEF variation store"""
 	from argparse import ArgumentParser
 	from fontTools import configLogger
 	from fontTools.ttLib import TTFont