[ttGlyphPen] Add preserveTopology=True

If False, perform implicit-oncurve elimination.

Lib/fontTools/pens/ttGlyphPen.py

@@ -7,6 +7,7 @@ from fontTools.misc.roundTools import otRound
 from fontTools.pens.basePen import LoggingPen, PenError
 from fontTools.pens.transformPen import TransformPen, TransformPointPen
 from fontTools.ttLib.tables import ttProgram
+from fontTools.ttLib.tables._g_l_y_f import flagOnCurve
 from fontTools.ttLib.tables._g_l_y_f import Glyph
 from fontTools.ttLib.tables._g_l_y_f import GlyphComponent
 from fontTools.ttLib.tables._g_l_y_f import GlyphCoordinates
@@ -124,7 +125,7 @@ class _TTGlyphBasePen:
             components.append(component)
         return components
 
-    def glyph(self, componentFlags: int = 0x4) -> Glyph:
+    def glyph(self, componentFlags: int = 0x4, preserveTopology=True) -> Glyph:
         """
         Returns a :py:class:`~._g_l_y_f.Glyph` object representing the glyph.
         """
@@ -149,6 +150,52 @@ class _TTGlyphBasePen:
             glyph.program = ttProgram.Program()
             glyph.program.fromBytecode(b"")
 
+        if not preserveTopology:
+
+            # Drop implied on-curve points
+
+            drop = set()
+            start = 0
+            flags = glyph.flags
+            coords = glyph.coordinates
+            for last in glyph.endPtsOfContours:
+                for i in range(start, last + 1):
+                    if not (flags[i] & flagOnCurve):
+                        continue
+                    prv = i - 1 if i > start else last
+                    nxt = i + 1 if i < last else start
+                    if (flags[prv] & flagOnCurve) or flags[prv] != flags[nxt]:
+                        continue
+                    p0 = coords[prv]
+                    p1 = coords[i]
+                    p2 = coords[nxt]
+                    if p1[0] - p0[0] != p2[0] - p1[0] or p1[1] - p0[1] != p2[1] - p1[1]:
+                        continue
+
+                    drop.add(i)
+            if drop:
+                # Do the actual dropping
+                glyph.coordinates = GlyphCoordinates(
+                    coords[i] for i in range(len(coords)) if i not in drop
+                )
+                glyph.flags = array(
+                    "B", (flags[i] for i in range(len(flags)) if i not in drop)
+                )
+
+                endPts = glyph.endPtsOfContours
+                newEndPts = []
+                i = 0
+                delta = 0
+                for d in sorted(drop):
+                    while d > endPts[i]:
+                        newEndPts.append(endPts[i] - delta)
+                        i += 1
+                    delta += 1
+                while i < len(endPts):
+                    newEndPts.append(endPts[i] - delta)
+                    i += 1
+                glyph.endPtsOfContours = newEndPts
+
         return glyph
 
 

Lib/fontTools/qu2cu/cli.py

@@ -29,7 +29,7 @@ def _font_to_cubic(input_path, output_path=None, **kwargs):
         ttpen = TTGlyphPen(glyphSet)
         pen = Qu2CuPen(ttpen, **qu2cu_kwargs)
         glyph.draw(pen)
-        glyf[glyphName] = ttpen.glyph()
+        glyf[glyphName] = ttpen.glyph(preserveTopology=False)
 
     logger.info("Saving %s", output_path)
     font.save(output_path)