Merge pull request #769 from googlefonts/no-convert-cubics

add convertCubics to compileVariable; check no cubics if glyphDataFormat=0

Lib/ufo2ft/__init__.py

@@ -280,6 +280,7 @@ def compileTTF(ufo, **kwargs):
     **dict(
         preProcessorClass=TTFInterpolatablePreProcessor,
         outlineCompilerClass=OutlineTTFCompiler,
+        convertCubics=True,
         cubicConversionError=None,
         reverseDirection=True,
         flattenComponents=False,
@@ -564,6 +565,7 @@ def compileFeatures(
     **dict(
         preProcessorClass=TTFInterpolatablePreProcessor,
         outlineCompilerClass=OutlineTTFCompiler,
+        convertCubics=True,
         cubicConversionError=None,
         reverseDirection=True,
         flattenComponents=False,

Lib/ufo2ft/outlineCompiler.py

@@ -22,7 +22,7 @@
 from fontTools.pens.ttGlyphPen import TTGlyphPointPen
 from fontTools.ttLib import TTFont, newTable
 from fontTools.ttLib.standardGlyphOrder import standardGlyphOrder
-from fontTools.ttLib.tables._g_l_y_f import Glyph
+from fontTools.ttLib.tables._g_l_y_f import Glyph, flagCubic
 from fontTools.ttLib.tables._h_e_a_d import mac_epoch_diff
 from fontTools.ttLib.tables.O_S_2f_2 import Panose
 
@@ -1462,6 +1462,7 @@ def compileGlyphs(self):
         allGlyphs = self.allGlyphs
         ttGlyphs = {}
         round = otRound if self.roundCoordinates else noRound
+        glyphDataFormat = self.glyphDataFormat
         for name in self.glyphOrder:
             glyph = allGlyphs[name]
             pen = TTGlyphPointPen(allGlyphs)
@@ -1475,6 +1476,16 @@ def compileGlyphs(self):
                     dropImpliedOnCurves=self.dropImpliedOnCurves,
                     round=round,
                 )
+                if (
+                    glyphDataFormat == 0
+                    and ttGlyph.numberOfContours > 0
+                    and any(f & flagCubic for f in ttGlyph.flags)
+                ):
+                    raise ValueError(
+                        f"{name!r} has cubic Bezier curves, but glyphDataFormat=0; "
+                        "either convert to quadratic (convertCubics=True) or use "
+                        "allQuadratic=False so that glyphDataFormat=1."
+                    )
             ttGlyphs[name] = ttGlyph
         return ttGlyphs
 

Lib/ufo2ft/preProcessor.py

@@ -262,6 +262,7 @@ def __init__(
         ufos,
         inplace=False,
         flattenComponents=False,
+        convertCubics=True,
         conversionError=None,
         reverseDirection=True,
         rememberCurveType=True,
@@ -289,6 +290,7 @@ def __init__(
             )
             for ufo, layerName in zip(ufos, layerNames)
         ]
+        self.convertCubics = convertCubics
         self._conversionErrors = [
             (conversionError or DEFAULT_MAX_ERR)
             * getAttrWithFallback(ufo.info, "unitsPerEm")
@@ -334,14 +336,15 @@ def process(self):
             for func in funcs:
                 func(ufo, glyphSet)
 
-        fonts_to_quadratic(
-            self.glyphSets,
-            max_err=self._conversionErrors,
-            reverse_direction=self._reverseDirection,
-            dump_stats=True,
-            remember_curve_type=self._rememberCurveType and self.inplace,
-            all_quadratic=self.allQuadratic,
-        )
+        if self.convertCubics:
+            fonts_to_quadratic(
+                self.glyphSets,
+                max_err=self._conversionErrors,
+                reverse_direction=self._reverseDirection,
+                dump_stats=True,
+                remember_curve_type=self._rememberCurveType and self.inplace,
+                all_quadratic=self.allQuadratic,
+            )
 
         # TrueType fonts cannot mix contours and components, so pick out all glyphs
         # that have contours (`bool(len(g)) == True`) and decompose their

tests/outlineCompiler_test.py

@@ -70,22 +70,22 @@ def emptyufo(FontClass):
 
 
 class OutlineTTFCompilerTest:
-    def test_compile_with_gasp(self, testufo):
-        compiler = OutlineTTFCompiler(testufo)
+    def test_compile_with_gasp(self, quadufo):
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         assert "gasp" in compiler.otf
         assert compiler.otf["gasp"].gaspRange == {7: 10, 65535: 15}
 
-    def test_compile_without_gasp(self, testufo):
-        testufo.info.openTypeGaspRangeRecords = None
-        compiler = OutlineTTFCompiler(testufo)
+    def test_compile_without_gasp(self, quadufo):
+        quadufo.info.openTypeGaspRangeRecords = None
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         assert "gasp" not in compiler.otf
 
-    def test_compile_empty_gasp(self, testufo):
+    def test_compile_empty_gasp(self, quadufo):
         # ignore empty gasp
-        testufo.info.openTypeGaspRangeRecords = []
-        compiler = OutlineTTFCompiler(testufo)
+        quadufo.info.openTypeGaspRangeRecords = []
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         assert "gasp" not in compiler.otf
 
@@ -150,10 +150,10 @@ def test_no_contour_glyphs(self, testufo):
         assert compiler.otf["hhea"].minRightSideBearing == 0
         assert compiler.otf["hhea"].xMaxExtent == 0
 
-    def test_os2_no_widths(self, testufo):
-        for glyph in testufo:
+    def test_os2_no_widths(self, quadufo):
+        for glyph in quadufo:
             glyph.width = 0
-        compiler = OutlineTTFCompiler(testufo)
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         assert compiler.otf["OS/2"].xAvgCharWidth == 0
 
@@ -220,8 +220,8 @@ def test_contour_starts_with_offcurve_point(self, emptyufo):
         assert endPts == [4]
         assert list(flags) == [0, 0, 0, 0, 1]
 
-    def test_setupTable_meta(self, testufo):
-        testufo.lib["public.openTypeMeta"] = {
+    def test_setupTable_meta(self, quadufo):
+        quadufo.lib["public.openTypeMeta"] = {
             "appl": b"BEEF",
             "bild": b"AAAA",
             "dlng": ["en-Latn", "nl-Latn"],
@@ -231,7 +231,7 @@ def test_setupTable_meta(self, testufo):
             "PRIU": "Some private unicode string…",
         }
 
-        compiler = OutlineTTFCompiler(testufo)
+        compiler = OutlineTTFCompiler(quadufo)
         ttFont = compiler.compile()
         meta = ttFont["meta"]
 
@@ -243,13 +243,13 @@ def test_setupTable_meta(self, testufo):
         assert meta.data["PRIA"] == b"Some private ascii string"
         assert meta.data["PRIU"] == "Some private unicode string…".encode("utf-8")
 
-    def test_setupTable_name(self, testufo):
-        compiler = OutlineTTFCompiler(testufo)
+    def test_setupTable_name(self, quadufo):
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         actual = compiler.otf["name"].getName(1, 3, 1, 1033).string
         assert actual == "Some Font Regular (Style Map Family Name)"
 
-        testufo.info.openTypeNameRecords.append(
+        quadufo.info.openTypeNameRecords.append(
             {
                 "nameID": 1,
                 "platformID": 3,
@@ -258,20 +258,20 @@ def test_setupTable_name(self, testufo):
                 "string": "Custom Name for Windows",
             }
         )
-        compiler = OutlineTTFCompiler(testufo)
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         actual = compiler.otf["name"].getName(1, 3, 1, 1033).string
         assert actual == "Custom Name for Windows"
 
-    def test_post_underline_without_public_key(self, testufo):
-        compiler = OutlineTTFCompiler(testufo)
+    def test_post_underline_without_public_key(self, quadufo):
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         actual = compiler.otf["post"].underlinePosition
         assert actual == -200
 
-    def test_post_underline_with_public_key(self, testufo):
-        testufo.lib[OPENTYPE_POST_UNDERLINE_POSITION_KEY] = -485
-        compiler = OutlineTTFCompiler(testufo)
+    def test_post_underline_with_public_key(self, quadufo):
+        quadufo.lib[OPENTYPE_POST_UNDERLINE_POSITION_KEY] = -485
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         actual = compiler.otf["post"].underlinePosition
         assert actual == -485
@@ -687,7 +687,7 @@ def test_underline_ps_rounding(self, testufo):
 
 
 class GlyphOrderTest:
-    def test_compile_original_glyph_order(self, testufo):
+    def test_compile_original_glyph_order(self, quadufo):
         DEFAULT_ORDER = [
             ".notdef",
             "space",
@@ -704,11 +704,11 @@ def test_compile_original_glyph_order(self, testufo):
             "k",
             "l",
         ]
-        compiler = OutlineTTFCompiler(testufo)
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         assert compiler.otf.getGlyphOrder() == DEFAULT_ORDER
 
-    def test_compile_tweaked_glyph_order(self, testufo):
+    def test_compile_tweaked_glyph_order(self, quadufo):
         NEW_ORDER = [
             ".notdef",
             "space",
@@ -725,12 +725,12 @@ def test_compile_tweaked_glyph_order(self, testufo):
             "k",
             "l",
         ]
-        testufo.lib["public.glyphOrder"] = NEW_ORDER
-        compiler = OutlineTTFCompiler(testufo)
+        quadufo.lib["public.glyphOrder"] = NEW_ORDER
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         assert compiler.otf.getGlyphOrder() == NEW_ORDER
 
-    def test_compile_strange_glyph_order(self, testufo):
+    def test_compile_strange_glyph_order(self, quadufo):
         """Move space and .notdef to end of glyph ids
         ufo2ft always puts .notdef first.
         """
@@ -751,8 +751,8 @@ def test_compile_strange_glyph_order(self, testufo):
             "k",
             "l",
         ]
-        testufo.lib["public.glyphOrder"] = NEW_ORDER
-        compiler = OutlineTTFCompiler(testufo)
+        quadufo.lib["public.glyphOrder"] = NEW_ORDER
+        compiler = OutlineTTFCompiler(quadufo)
         compiler.compile()
         assert compiler.otf.getGlyphOrder() == EXPECTED_ORDER