Fix multiplication of fontinfo slant and italic angles

Lib/fontMath/mathFunctions.py

@@ -44,6 +44,10 @@ def divPt(pt, f):
 
 def factorAngle(angle, f, func):
     (f1, f2) = f
+    # If both factors are equal, assume a scalar factor and scale the angle as such.
+    if f1 == f2:
+        return func(angle, f1)
+    # Otherwise, scale x and y components separately.
     rangle = math.radians(angle)
     x = math.cos(rangle)
     y = math.sin(rangle)

Lib/fontMath/test/test_mathGlyph.py

@@ -392,7 +392,7 @@ def test_guidelines_mul(self):
         ]
         glyph2 = glyph1 * 3
         expected = [
-            dict(x=1 * 3, y=3 * 3, angle=5, name="test", identifier="1",
+            dict(x=1 * 3, y=3 * 3, angle=15, name="test", identifier="1",
                  color="0,0,0,0")
         ]
         self.assertEqual(glyph2.guidelines, expected)
@@ -428,11 +428,11 @@ def test_guidelines_valid_angle(self):
         glyph4 = glyph1 - glyph2
         self.assertEqual(glyph4.guidelines, expected_sub)
 
-        expected_mul = [dict(name="foo", identifier="1", x=0, y=0, angle=359)]
+        expected_mul = [dict(name="foo", identifier="1", x=0, y=0, angle=355)]
         glyph5 = glyph2 * 5
         self.assertEqual(glyph5.guidelines, expected_mul)
 
-        expected_div = [dict(name="foo", identifier="1", x=0, y=0, angle=359)]
+        expected_div = [dict(name="foo", identifier="1", x=0, y=0, angle=71.8)]
         glyph6 = glyph2 / 5
         self.assertEqual(glyph6.guidelines, expected_div)
 

Lib/fontMath/test/test_mathInfo.py

@@ -95,6 +95,26 @@ def test_mul(self):
             expected[attr] = expectedValue
         self.assertEqual(sorted(expected.items()), sorted(written.items()))
 
+    def test_angle(self):
+        info1 = MathInfo(_TestInfoObject())
+        info1.italicAngle = 10
+
+        info2 = info1 - info1
+        self.assertEqual(info2.italicAngle, 0)
+        info2 = info1 + info1 + info1
+        self.assertEqual(info2.italicAngle, 30)
+        info2 = 10 * info1
+        self.assertEqual(info2.italicAngle, 100)
+        info2 = info1 / 20 
+        self.assertEqual(info2.italicAngle, 0.5)
+
+        info2 = info1 * 2.5
+        self.assertEqual(info2.italicAngle, 25)
+        info2 = info1 * (2.5, 2.5)
+        self.assertEqual(info2.italicAngle, 25)
+        info2 = info1 * (2.5, 5)
+        self.assertEqual(round(info2.italicAngle), 19)
+
     def test_mul_data_subset(self):
         info1 = MathInfo(_TestInfoObject(_testDataSubset))
         info2 = info1 * 2.5
@@ -268,7 +288,7 @@ def test_number_lists_with_different_lengths(self):
     xHeight=400,
     capHeight=650,
     ascender=700,
-    italicAngle=0,
+    italicAngle=5,
     # head
     openTypeHeadLowestRecPPEM=5,
     # hhea
@@ -304,7 +324,7 @@ def test_number_lists_with_different_lengths(self):
     openTypeVheaCaretSlopeRun=1,
     openTypeVheaCaretOffset=1,
     # postscript
-    postscriptSlantAngle=0,
+    postscriptSlantAngle=-5,
     postscriptUnderlineThickness=100,
     postscriptUnderlinePosition=-150,
     postscriptBlueValues=[-10, 0, 400, 410, 650, 660, 700, 710],