[fontTools.varLib.plot] New module to plot a designspace's VariationModel

The visualization is not as useful as I was hoping would be :(.

Lib/fontTools/varLib/plot.py

@@ -0,0 +1,84 @@
+"""Visualize DesignSpaceDocument and resulting VariationModel."""
+
+from __future__ import print_function, division, absolute_import
+from fontTools.misc.py23 import *
+from fontTools.varLib.models import VariationModel, supportScalar
+from fontTools.designspaceLib import DesignSpaceDocument
+from mpl_toolkits.mplot3d import axes3d
+from matplotlib import pyplot
+from itertools import cycle
+import logging
+import sys
+
+log = logging.getLogger(__name__)
+
+
+def stops(support, count=20):
+	a,b,c = support
+
+	return [a + (b - a) * i / count for i in range(count)] + \
+	       [b + (c - b) * i / count for i in range(count)] + \
+	       [c]
+
+def plotDocument(doc, axis3D, **kwargs):
+	assert len(doc.axes) == 2
+
+	doc.normalize()
+
+	model = VariationModel([s.location for s in doc.sources])
+
+	ax1 = doc.axes[0].name
+	ax2 = doc.axes[1].name
+	for support,color in zip(model.supports, cycle(pyplot.cm.Set1.colors)):
+
+		if not support:
+			continue
+
+		Xs = support.get(ax1, (-1.,0.,+1.))
+		Ys = support.get(ax2, (-1.,0.,+1.))
+		for x in stops(Xs):
+			X, Y, Z = [], [], []
+			for y in Ys:
+				z = supportScalar({ax1:x, ax2:y}, support)
+				X.append(x)
+				Y.append(y)
+				Z.append(z)
+			axis3D.plot_wireframe(X, Y, Z, color=color, **kwargs)
+		for y in stops(Ys):
+			X, Y, Z = [], [], []
+			for x in Xs:
+				z = supportScalar({ax1:x, ax2:y}, support)
+				X.append(x)
+				Y.append(y)
+				Z.append(z)
+			axis3D.plot_wireframe(X, Y, Z, color=color, **kwargs)
+
+
+def main(args=None):
+	from fontTools import configLogger
+
+	if args is None:
+		args = sys.argv[1:]
+
+	# configure the library logger (for >= WARNING)
+	configLogger()
+	# comment this out to enable debug messages from logger
+	# log.setLevel(logging.DEBUG)
+
+	if len(args) < 1:
+		print("usage: fonttools varLib.plot soure.designspace", file=sys.stderr)
+		sys.exit(1)
+
+	doc = DesignSpaceDocument()
+	doc.read(args[0])
+
+	fig = pyplot.figure()
+	axis3D = fig.add_subplot(111, projection='3d')
+
+	plotDocument(doc, axis3D)
+
+	pyplot.show()
+
+if __name__ == '__main__':
+	import sys
+	sys.exit(main())