From ff46e2838f37d54f4517fa1db6de84e6e38a9db3 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 3 Mar 2021 16:25:35 -0700
Subject: [PATCH 01/13] [varLib.plot] Reorder imports to make missing library
 easier to detect

$ pip install matplotlib
---
 Lib/fontTools/varLib/plot.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/fontTools/varLib/plot.py b/Lib/fontTools/varLib/plot.py
index b6561dc6a..0eb654327 100644
--- a/Lib/fontTools/varLib/plot.py
+++ b/Lib/fontTools/varLib/plot.py
@@ -2,8 +2,8 @@
 
 from fontTools.varLib.models import VariationModel, supportScalar
 from fontTools.designspaceLib import DesignSpaceDocument
-from mpl_toolkits.mplot3d import axes3d
 from matplotlib import pyplot
+from mpl_toolkits.mplot3d import axes3d
 from itertools import cycle
 import math
 import logging

From 28fae1d95f29f5fc866c439a391ff2ee138842d6 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 3 Mar 2021 18:27:06 -0700
Subject: [PATCH 02/13] [cff] Simplify rounding logic

No semantic change. Just refactoring and simplification in anticipation
of coming changes.
---
 Lib/fontTools/pens/t2CharStringPen.py | 13 ++++++-------
 Lib/fontTools/varLib/cff.py           | 17 +++--------------
 Lib/fontTools/varLib/plot.py          |  4 ++--
 3 files changed, 11 insertions(+), 23 deletions(-)

diff --git a/Lib/fontTools/pens/t2CharStringPen.py b/Lib/fontTools/pens/t2CharStringPen.py
index a4b1d8f67..2824b5cf5 100644
--- a/Lib/fontTools/pens/t2CharStringPen.py
+++ b/Lib/fontTools/pens/t2CharStringPen.py
@@ -20,15 +20,14 @@ def t2c_round(number, tolerance=0.5):
         # else return the value un-rounded
         return number
 
-def makeRoundFunc(tolerance):
+def roundFunc(tolerance):
     if tolerance < 0:
         raise ValueError("Rounding tolerance must be positive")
 
-    def roundPoint(point):
-        x, y = point
-        return t2c_round(x, tolerance), t2c_round(y, tolerance)
+    def round(v):
+        return t2c_round(v, tolerance)
 
-    return roundPoint
+    return round
 
 
 class T2CharStringPen(BasePen):
@@ -44,7 +43,7 @@ class T2CharStringPen(BasePen):
 
     def __init__(self, width, glyphSet, roundTolerance=0.5, CFF2=False):
         super(T2CharStringPen, self).__init__(glyphSet)
-        self.roundPoint = makeRoundFunc(roundTolerance)
+        self.round = roundFunc(roundTolerance)
         self._CFF2 = CFF2
         self._width = width
         self._commands = []
@@ -52,7 +51,7 @@ class T2CharStringPen(BasePen):
 
     def _p(self, pt):
         p0 = self._p0
-        pt = self._p0 = self.roundPoint(pt)
+        pt = self._p0 = (self.round(pt[0]), self.round(pt[1]))
         return [pt[0]-p0[0], pt[1]-p0[1]]
 
     def _moveTo(self, pt):
diff --git a/Lib/fontTools/varLib/cff.py b/Lib/fontTools/varLib/cff.py
index 0a6ba220b..6f704bbee 100644
--- a/Lib/fontTools/varLib/cff.py
+++ b/Lib/fontTools/varLib/cff.py
@@ -18,7 +18,7 @@ from fontTools.ttLib import newTable
 from fontTools import varLib
 from fontTools.varLib.models import allEqual
 from fontTools.misc.psCharStrings import T2CharString, T2OutlineExtractor
-from fontTools.pens.t2CharStringPen import T2CharStringPen, t2c_round
+from fontTools.pens.t2CharStringPen import T2CharStringPen, roundFunc
 
 from .errors import VarLibCFFDictMergeError, VarLibCFFPointTypeMergeError, VarLibMergeError
 
@@ -422,16 +422,6 @@ def merge_charstrings(glyphOrder, num_masters, top_dicts, masterModel):
 	return cvData
 
 
-def makeRoundNumberFunc(tolerance):
-	if tolerance < 0:
-		raise ValueError("Rounding tolerance must be positive")
-
-	def roundNumber(val):
-		return t2c_round(val, tolerance)
-
-	return roundNumber
-
-
 class CFFToCFF2OutlineExtractor(T2OutlineExtractor):
 	""" This class is used to remove the initial width from the CFF
 	charstring without trying to add the width to self.nominalWidthX,
@@ -518,7 +508,7 @@ class CFF2CharStringMergePen(T2CharStringPen):
 		self.prev_move_idx = 0
 		self.seen_moveto = False
 		self.glyphName = glyphName
-		self.roundNumber = makeRoundNumberFunc(roundTolerance)
+		self.round = roundFunc(roundTolerance)
 
 	def add_point(self, point_type, pt_coords):
 		if self.m_index == 0:
@@ -649,8 +639,7 @@ class CFF2CharStringMergePen(T2CharStringPen):
 					self, private=None, globalSubrs=None,
 					var_model=None, optimize=True):
 		commands = self._commands
-		commands = self.reorder_blend_args(commands, var_model.getDeltas,
-											self.roundNumber)
+		commands = self.reorder_blend_args(commands, var_model.getDeltas, self.round)
 		if optimize:
 			commands = specializeCommands(
 						commands, generalizeFirst=False,
diff --git a/Lib/fontTools/varLib/plot.py b/Lib/fontTools/varLib/plot.py
index 0eb654327..811559fa6 100644
--- a/Lib/fontTools/varLib/plot.py
+++ b/Lib/fontTools/varLib/plot.py
@@ -68,10 +68,10 @@ def plotLocations(locations, fig, names=None, **kwargs):
 
 
 def _plotLocations2D(model, axis, fig, cols, rows, names, **kwargs):
+	subplot = fig.add_subplot(111)
 	for i, (support, color, name) in enumerate(
 		zip(model.supports, cycle(pyplot.cm.Set1.colors), cycle(names))
 	):
-		subplot = fig.add_subplot(rows, cols, i + 1)
 		if name is not None:
 			subplot.set_title(name)
 		subplot.set_xlabel(axis)
@@ -91,10 +91,10 @@ def _plotLocations2D(model, axis, fig, cols, rows, names, **kwargs):
 def _plotLocations3D(model, axes, fig, rows, cols, names, **kwargs):
 	ax1, ax2 = axes
 
+	axis3D = fig.add_subplot(111, projection='3d')
 	for i, (support, color, name) in enumerate(
 		zip(model.supports, cycle(pyplot.cm.Set1.colors), cycle(names))
 	):
-		axis3D = fig.add_subplot(rows, cols, i + 1, projection='3d')
 		if name is not None:
 			axis3D.set_title(name)
 		axis3D.set_xlabel(ax1)

From ed77aeaebff58abb61baf79d9e481959f56b335c Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 3 Mar 2021 18:31:11 -0700
Subject: [PATCH 03/13] [cff] Speed-up rounding

We can choose specific round function based on tolerance once,
instead of choosing every time a number is being rounded.
---
 Lib/fontTools/pens/t2CharStringPen.py | 28 +++++++++++----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/Lib/fontTools/pens/t2CharStringPen.py b/Lib/fontTools/pens/t2CharStringPen.py
index 2824b5cf5..7af9b7aad 100644
--- a/Lib/fontTools/pens/t2CharStringPen.py
+++ b/Lib/fontTools/pens/t2CharStringPen.py
@@ -7,27 +7,21 @@ from fontTools.pens.basePen import BasePen
 from fontTools.cffLib.specializer import specializeCommands, commandsToProgram
 
 
-def t2c_round(number, tolerance=0.5):
-    if tolerance == 0:
-        return number  # no-op
-    rounded = otRound(number)
-    # return rounded integer if the tolerance >= 0.5, or if the absolute
-    # difference between the original float and the rounded integer is
-    # within the tolerance
-    if tolerance >= .5 or abs(rounded - number) <= tolerance:
-        return rounded
-    else:
-        # else return the value un-rounded
-        return number
-
-def roundFunc(tolerance):
+def roundFunc(tolerance, round=otRound):
     if tolerance < 0:
         raise ValueError("Rounding tolerance must be positive")
 
-    def round(v):
-        return t2c_round(v, tolerance)
+    if tolerance == 0:
+        return lambda x: x
 
-    return round
+    if tolerance >= .5:
+        return round
+
+    def maybe_round(v):
+        rounded = round(v)
+        return rounded if abs(rounded - v) <= tolerance else v
+
+    return maybe_round
 
 
 class T2CharStringPen(BasePen):

From abc1ba07a4046f0f7e955802e695be16967830f3 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 3 Mar 2021 18:48:08 -0700
Subject: [PATCH 04/13] [misc.roundTools] New module; move otRound() here

Code relying on old place (fixedTools.otRound) still works.
---
 Lib/fontTools/colorLib/geometry.py      |  2 +-
 Lib/fontTools/colorLib/table_builder.py |  2 +-
 Lib/fontTools/misc/arrayTools.py        |  2 +-
 Lib/fontTools/misc/fixedTools.py        | 26 +-----------------
 Lib/fontTools/misc/roundTools.py        | 36 +++++++++++++++++++++++++
 Lib/fontTools/pens/roundingPen.py       |  2 +-
 Lib/fontTools/pens/t2CharStringPen.py   |  2 +-
 Lib/fontTools/pens/ttGlyphPen.py        |  1 +
 Lib/fontTools/subset/__init__.py        |  2 +-
 Lib/fontTools/subset/cff.py             |  2 +-
 Lib/fontTools/ttLib/tables/_h_m_t_x.py  |  2 +-
 Lib/fontTools/ttLib/tables/otTables.py  |  2 +-
 Lib/fontTools/varLib/merger.py          |  2 +-
 Lib/fontTools/varLib/mutator.py         |  3 ++-
 14 files changed, 50 insertions(+), 36 deletions(-)
 create mode 100644 Lib/fontTools/misc/roundTools.py

diff --git a/Lib/fontTools/colorLib/geometry.py b/Lib/fontTools/colorLib/geometry.py
index ec6475357..e62aead1c 100644
--- a/Lib/fontTools/colorLib/geometry.py
+++ b/Lib/fontTools/colorLib/geometry.py
@@ -1,7 +1,7 @@
 """Helpers for manipulating 2D points and vectors in COLR table."""
 
 from math import copysign, cos, hypot, pi
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import otRound
 
 
 def _vector_between(origin, target):
diff --git a/Lib/fontTools/colorLib/table_builder.py b/Lib/fontTools/colorLib/table_builder.py
index 18e2de181..6fba6b0fc 100644
--- a/Lib/fontTools/colorLib/table_builder.py
+++ b/Lib/fontTools/colorLib/table_builder.py
@@ -22,7 +22,7 @@ from fontTools.ttLib.tables.otConverters import (
     IntValue,
     FloatValue,
 )
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import otRound
 
 
 class BuildCallback(enum.Enum):
diff --git a/Lib/fontTools/misc/arrayTools.py b/Lib/fontTools/misc/arrayTools.py
index 4b5f08298..9a64b2929 100644
--- a/Lib/fontTools/misc/arrayTools.py
+++ b/Lib/fontTools/misc/arrayTools.py
@@ -3,7 +3,7 @@ so on.
 """
 
 from fontTools.misc.py23 import *
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import otRound
 from fontTools.misc.vector import Vector as _Vector
 import math
 import warnings
diff --git a/Lib/fontTools/misc/fixedTools.py b/Lib/fontTools/misc/fixedTools.py
index 931b665e2..eda81c33c 100644
--- a/Lib/fontTools/misc/fixedTools.py
+++ b/Lib/fontTools/misc/fixedTools.py
@@ -18,6 +18,7 @@ functions for converting between fixed-point, float and string representations.
 """
 
 from fontTools.misc.py23 import *
+from .roundTools import otRound
 import math
 import logging
 
@@ -25,7 +26,6 @@ log = logging.getLogger(__name__)
 
 __all__ = [
 	"MAX_F2DOT14",
-	"otRound",
 	"fixedToFloat",
 	"floatToFixed",
 	"floatToFixedToFloat",
@@ -41,30 +41,6 @@ __all__ = [
 MAX_F2DOT14 = 0x7FFF / (1 << 14)
 
 
-def otRound(value):
-	"""Round float value to nearest integer towards ``+Infinity``.
-
-	The OpenType spec (in the section on `"normalization" of OpenType Font Variations <https://docs.microsoft.com/en-us/typography/opentype/spec/otvaroverview#coordinate-scales-and-normalization>`_)
-	defines the required method for converting floating point values to
-	fixed-point. In particular it specifies the following rounding strategy:
-
-		for fractional values of 0.5 and higher, take the next higher integer;
-		for other fractional values, truncate.
-
-	This function rounds the floating-point value according to this strategy
-	in preparation for conversion to fixed-point.
-
-	Args:
-		value (float): The input floating-point value.
-
-	Returns
-		float: The rounded value.
-	"""
-	# See this thread for how we ended up with this implementation:
-	# https://github.com/fonttools/fonttools/issues/1248#issuecomment-383198166
-	return int(math.floor(value + 0.5))
-
-
 def fixedToFloat(value, precisionBits):
 	"""Converts a fixed-point number to a float given the number of
 	precision bits.
diff --git a/Lib/fontTools/misc/roundTools.py b/Lib/fontTools/misc/roundTools.py
new file mode 100644
index 000000000..af3e317d2
--- /dev/null
+++ b/Lib/fontTools/misc/roundTools.py
@@ -0,0 +1,36 @@
+"""
+Various round-to-integer helpers.
+"""
+
+import math
+import logging
+
+log = logging.getLogger(__name__)
+
+__all__ = [
+	"otRound",
+]
+
+def otRound(value):
+	"""Round float value to nearest integer towards ``+Infinity``.
+
+	The OpenType spec (in the section on `"normalization" of OpenType Font Variations <https://docs.microsoft.com/en-us/typography/opentype/spec/otvaroverview#coordinate-scales-and-normalization>`_)
+	defines the required method for converting floating point values to
+	fixed-point. In particular it specifies the following rounding strategy:
+
+		for fractional values of 0.5 and higher, take the next higher integer;
+		for other fractional values, truncate.
+
+	This function rounds the floating-point value according to this strategy
+	in preparation for conversion to fixed-point.
+
+	Args:
+		value (float): The input floating-point value.
+
+	Returns
+		float: The rounded value.
+	"""
+	# See this thread for how we ended up with this implementation:
+	# https://github.com/fonttools/fonttools/issues/1248#issuecomment-383198166
+	return int(math.floor(value + 0.5))
+
diff --git a/Lib/fontTools/pens/roundingPen.py b/Lib/fontTools/pens/roundingPen.py
index c032cad1f..2a7c476c3 100644
--- a/Lib/fontTools/pens/roundingPen.py
+++ b/Lib/fontTools/pens/roundingPen.py
@@ -1,4 +1,4 @@
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import otRound
 from fontTools.misc.transform import Transform
 from fontTools.pens.filterPen import FilterPen, FilterPointPen
 
diff --git a/Lib/fontTools/pens/t2CharStringPen.py b/Lib/fontTools/pens/t2CharStringPen.py
index 7af9b7aad..8b718ccbc 100644
--- a/Lib/fontTools/pens/t2CharStringPen.py
+++ b/Lib/fontTools/pens/t2CharStringPen.py
@@ -1,7 +1,7 @@
 # Copyright (c) 2009 Type Supply LLC
 # Author: Tal Leming
 
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import otRound
 from fontTools.misc.psCharStrings import T2CharString
 from fontTools.pens.basePen import BasePen
 from fontTools.cffLib.specializer import specializeCommands, commandsToProgram
diff --git a/Lib/fontTools/pens/ttGlyphPen.py b/Lib/fontTools/pens/ttGlyphPen.py
index f493f1acc..e7841efcb 100644
--- a/Lib/fontTools/pens/ttGlyphPen.py
+++ b/Lib/fontTools/pens/ttGlyphPen.py
@@ -1,5 +1,6 @@
 from array import array
 from fontTools.misc.fixedTools import MAX_F2DOT14, otRound, floatToFixedToFloat
+from fontTools.misc.roundTools import otRound
 from fontTools.pens.basePen import LoggingPen
 from fontTools.pens.transformPen import TransformPen
 from fontTools.ttLib.tables import ttProgram
diff --git a/Lib/fontTools/subset/__init__.py b/Lib/fontTools/subset/__init__.py
index 8162c09c2..c2d402162 100644
--- a/Lib/fontTools/subset/__init__.py
+++ b/Lib/fontTools/subset/__init__.py
@@ -2,7 +2,7 @@
 #
 # Google Author(s): Behdad Esfahbod
 
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import otRound
 from fontTools import ttLib
 from fontTools.ttLib.tables import otTables
 from fontTools.otlLib.maxContextCalc import maxCtxFont
diff --git a/Lib/fontTools/subset/cff.py b/Lib/fontTools/subset/cff.py
index 7db6d880a..b59c6b96d 100644
--- a/Lib/fontTools/subset/cff.py
+++ b/Lib/fontTools/subset/cff.py
@@ -1,7 +1,7 @@
 from fontTools.misc import psCharStrings
 from fontTools import ttLib
 from fontTools.pens.basePen import NullPen
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import otRound
 from fontTools.varLib.varStore import VarStoreInstancer
 
 def _add_method(*clazzes):
diff --git a/Lib/fontTools/ttLib/tables/_h_m_t_x.py b/Lib/fontTools/ttLib/tables/_h_m_t_x.py
index a690a6e6e..730574733 100644
--- a/Lib/fontTools/ttLib/tables/_h_m_t_x.py
+++ b/Lib/fontTools/ttLib/tables/_h_m_t_x.py
@@ -1,5 +1,5 @@
 from fontTools.misc.py23 import *
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import otRound
 from fontTools import ttLib
 from fontTools.misc.textTools import safeEval
 from . import DefaultTable
diff --git a/Lib/fontTools/ttLib/tables/otTables.py b/Lib/fontTools/ttLib/tables/otTables.py
index 008909bdd..a65ec7b87 100644
--- a/Lib/fontTools/ttLib/tables/otTables.py
+++ b/Lib/fontTools/ttLib/tables/otTables.py
@@ -9,7 +9,7 @@ from enum import IntEnum
 import itertools
 from collections import namedtuple
 from fontTools.misc.py23 import *
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import otRound
 from fontTools.misc.textTools import pad, safeEval
 from .otBase import (
 	BaseTable, FormatSwitchingBaseTable, ValueRecord, CountReference,
diff --git a/Lib/fontTools/varLib/merger.py b/Lib/fontTools/varLib/merger.py
index 071942b86..cb53f04d3 100644
--- a/Lib/fontTools/varLib/merger.py
+++ b/Lib/fontTools/varLib/merger.py
@@ -3,8 +3,8 @@ Merge OpenType Layout tables (GDEF / GPOS / GSUB).
 """
 import copy
 from operator import ior
-from fontTools.misc.fixedTools import otRound
 from fontTools.misc import classifyTools
+from fontTools.misc.roundTools import otRound
 from fontTools.ttLib.tables import otTables as ot
 from fontTools.ttLib.tables import otBase as otBase
 from fontTools.ttLib.tables.DefaultTable import DefaultTable
diff --git a/Lib/fontTools/varLib/mutator.py b/Lib/fontTools/varLib/mutator.py
index ad76420a1..56f36e6ea 100644
--- a/Lib/fontTools/varLib/mutator.py
+++ b/Lib/fontTools/varLib/mutator.py
@@ -3,7 +3,8 @@ Instantiate a variation font.  Run, eg:
 
 $ fonttools varLib.mutator ./NotoSansArabic-VF.ttf wght=140 wdth=85
 """
-from fontTools.misc.fixedTools import floatToFixedToFloat, otRound, floatToFixed
+from fontTools.misc.fixedTools import floatToFixedToFloat, floatToFixed
+from fontTools.misc.roundTools import otRound
 from fontTools.pens.boundsPen import BoundsPen
 from fontTools.ttLib import TTFont, newTable
 from fontTools.ttLib.tables import ttProgram

From 3a9a2bd4b1afbb75ee33ffff545c50a862484b34 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 3 Mar 2021 18:55:54 -0700
Subject: [PATCH 05/13] [misc.roundTools] Add noRound(), maybeRound(), and
 roundFunc()

Moving out of CFF code, to be used in VariationModel().

Part of https://github.com/fonttools/fonttools/issues/2213
---
 Lib/fontTools/misc/roundTools.py      | 22 ++++++++++++++++++++++
 Lib/fontTools/pens/t2CharStringPen.py | 19 +------------------
 Lib/fontTools/varLib/cff.py           |  3 ++-
 3 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/Lib/fontTools/misc/roundTools.py b/Lib/fontTools/misc/roundTools.py
index af3e317d2..c1d546f1f 100644
--- a/Lib/fontTools/misc/roundTools.py
+++ b/Lib/fontTools/misc/roundTools.py
@@ -3,14 +3,21 @@ Various round-to-integer helpers.
 """
 
 import math
+import functools
 import logging
 
 log = logging.getLogger(__name__)
 
 __all__ = [
+	"noRound",
 	"otRound",
+	"maybeRound",
+	"roundFunc",
 ]
 
+def noRound(value):
+	return value
+
 def otRound(value):
 	"""Round float value to nearest integer towards ``+Infinity``.
 
@@ -34,3 +41,18 @@ def otRound(value):
 	# https://github.com/fonttools/fonttools/issues/1248#issuecomment-383198166
 	return int(math.floor(value + 0.5))
 
+def maybeRound(v, tolerance, round=otRound):
+	rounded = round(v)
+	return rounded if abs(rounded - v) <= tolerance else v
+
+def roundFunc(tolerance, round=otRound):
+    if tolerance < 0:
+        raise ValueError("Rounding tolerance must be positive")
+
+    if tolerance == 0:
+        return noRound
+
+    if tolerance >= .5:
+        return round
+
+    return functools.partial(maybeRound, tolerance=tolerance, round=round)
diff --git a/Lib/fontTools/pens/t2CharStringPen.py b/Lib/fontTools/pens/t2CharStringPen.py
index 8b718ccbc..0fddec1ae 100644
--- a/Lib/fontTools/pens/t2CharStringPen.py
+++ b/Lib/fontTools/pens/t2CharStringPen.py
@@ -1,29 +1,12 @@
 # Copyright (c) 2009 Type Supply LLC
 # Author: Tal Leming
 
-from fontTools.misc.roundTools import otRound
+from fontTools.misc.roundTools import otRound, roundFunc
 from fontTools.misc.psCharStrings import T2CharString
 from fontTools.pens.basePen import BasePen
 from fontTools.cffLib.specializer import specializeCommands, commandsToProgram
 
 
-def roundFunc(tolerance, round=otRound):
-    if tolerance < 0:
-        raise ValueError("Rounding tolerance must be positive")
-
-    if tolerance == 0:
-        return lambda x: x
-
-    if tolerance >= .5:
-        return round
-
-    def maybe_round(v):
-        rounded = round(v)
-        return rounded if abs(rounded - v) <= tolerance else v
-
-    return maybe_round
-
-
 class T2CharStringPen(BasePen):
     """Pen to draw Type 2 CharStrings.
 
diff --git a/Lib/fontTools/varLib/cff.py b/Lib/fontTools/varLib/cff.py
index 6f704bbee..ae14986e5 100644
--- a/Lib/fontTools/varLib/cff.py
+++ b/Lib/fontTools/varLib/cff.py
@@ -17,8 +17,9 @@ from fontTools.cffLib.specializer import (
 from fontTools.ttLib import newTable
 from fontTools import varLib
 from fontTools.varLib.models import allEqual
+from fontTools.misc.roundTools import roundFunc
 from fontTools.misc.psCharStrings import T2CharString, T2OutlineExtractor
-from fontTools.pens.t2CharStringPen import T2CharStringPen, roundFunc
+from fontTools.pens.t2CharStringPen import T2CharStringPen
 
 from .errors import VarLibCFFDictMergeError, VarLibCFFPointTypeMergeError, VarLibMergeError
 

From fdd8267065acdc506786cab3d8a591807589281a Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 3 Mar 2021 19:03:12 -0700
Subject: [PATCH 06/13] [varLib.models] Add optional rounding to
 VariationModel() relevant methods

Users to be updated to benefit.

Part of https://github.com/fonttools/fonttools/issues/2213
---
 Lib/fontTools/varLib/models.py | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/Lib/fontTools/varLib/models.py b/Lib/fontTools/varLib/models.py
index 9cc40b1c9..417ecb42b 100644
--- a/Lib/fontTools/varLib/models.py
+++ b/Lib/fontTools/varLib/models.py
@@ -5,6 +5,7 @@ __all__ = ['nonNone', 'allNone', 'allEqual', 'allEqualTo', 'subList',
 	   'supportScalar',
 	   'VariationModel']
 
+from fontTools.misc.roundTools import noRound
 from .errors import VariationModelError
 
 
@@ -358,7 +359,7 @@ class VariationModel(object):
 		self.supports = supports
 		self.deltaWeights = deltaWeights
 
-	def getDeltas(self, masterValues):
+	def getDeltas(self, masterValues, round=noRound):
 		assert len(masterValues) == len(self.deltaWeights)
 		mapping = self.reverseMapping
 		out = []
@@ -366,12 +367,12 @@ class VariationModel(object):
 			delta = masterValues[mapping[i]]
 			for j,weight in weights.items():
 				delta -= out[j] * weight
-			out.append(delta)
+			out.append(round(delta))
 		return out
 
-	def getDeltasAndSupports(self, items):
+	def getDeltasAndSupports(self, items, round=noRound):
 		model, items = self.getSubModel(items)
-		return model.getDeltas(items), model.supports
+		return model.getDeltas(items, round=round), model.supports
 
 	def getScalars(self, loc):
 		return [supportScalar(loc, support) for support in self.supports]
@@ -393,12 +394,12 @@ class VariationModel(object):
 		scalars = self.getScalars(loc)
 		return self.interpolateFromDeltasAndScalars(deltas, scalars)
 
-	def interpolateFromMasters(self, loc, masterValues):
-		deltas = self.getDeltas(masterValues)
+	def interpolateFromMasters(self, loc, masterValues, round=noRound):
+		deltas = self.getDeltas(masterValues, round=round)
 		return self.interpolateFromDeltas(loc, deltas)
 
-	def interpolateFromMastersAndScalars(self, masterValues, scalars):
-		deltas = self.getDeltas(masterValues)
+	def interpolateFromMastersAndScalars(self, masterValues, scalars, round=noRound):
+		deltas = self.getDeltas(masterValues, round=round)
 		return self.interpolateFromDeltasAndScalars(deltas, scalars)
 
 

From 77acdbced3a3ad0109992194fe43e3dfee64755f Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 3 Mar 2021 19:36:10 -0700
Subject: [PATCH 07/13] [glyf] Remove stale comment about Python 2

---
 Lib/fontTools/ttLib/tables/_g_l_y_f.py | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/Lib/fontTools/ttLib/tables/_g_l_y_f.py b/Lib/fontTools/ttLib/tables/_g_l_y_f.py
index e12969e40..9886d7ab3 100644
--- a/Lib/fontTools/ttLib/tables/_g_l_y_f.py
+++ b/Lib/fontTools/ttLib/tables/_g_l_y_f.py
@@ -1627,10 +1627,6 @@ class GlyphCoordinates(object):
 			a[i] = -a[i]
 		return r
 	def __round__(self):
-		"""
-		Note: This is Python 3 only.  Python 2 does not call __round__.
-		As such, we cannot test this method either. :(
-		"""
 		r = self.copy()
 		r.toInt()
 		return r

From 68004b8fec94729b7cfe9755eb956fa39feff5de Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 3 Mar 2021 19:37:50 -0700
Subject: [PATCH 08/13] [varLib] Shift most (all?) delta-rounding to VarModel

Reduces error.

The main varfont-builder now asks the model to do rounding, and asks
VariationStore to do no rounding, so we don't spend extra times rounding
multiple times (specially with the heavy otRound).

I *think* I got it all and right...

Fixes https://github.com/fonttools/fonttools/issues/2213
---
 Lib/fontTools/varLib/__init__.py              | 23 +++++++++----------
 Lib/fontTools/varLib/cff.py                   |  7 +++---
 Lib/fontTools/varLib/varStore.py              | 21 ++++++++---------
 .../data/test_results/TestSparseCFF2VF.ttx    |  2 +-
 4 files changed, 24 insertions(+), 29 deletions(-)

diff --git a/Lib/fontTools/varLib/__init__.py b/Lib/fontTools/varLib/__init__.py
index dd320b040..4172dd13c 100644
--- a/Lib/fontTools/varLib/__init__.py
+++ b/Lib/fontTools/varLib/__init__.py
@@ -19,7 +19,7 @@ Then you can make a variable-font this way:
 API *will* change in near future.
 """
 from fontTools.misc.py23 import *
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import noRound, otRound
 from fontTools.misc.vector import Vector
 from fontTools.ttLib import TTFont, newTable
 from fontTools.ttLib.tables._f_v_a_r import Axis, NamedInstance
@@ -253,7 +253,7 @@ def _add_gvar(font, masterModel, master_ttfs, tolerance=0.5, optimize=True):
 
 		# Update gvar
 		gvar.variations[glyph] = []
-		deltas = model.getDeltas(allCoords)
+		deltas = model.getDeltas(allCoords, round=round) # builtin round calls into GlyphCoordinates.__round__()
 		supports = model.supports
 		assert len(deltas) == len(supports)
 
@@ -262,7 +262,7 @@ def _add_gvar(font, masterModel, master_ttfs, tolerance=0.5, optimize=True):
 		endPts = control.endPts
 
 		for i,(delta,support) in enumerate(zip(deltas[1:], supports[1:])):
-			if all(abs(v) <= tolerance for v in delta.array) and not isComposite:
+			if all(v == 0 for v in delta.array) and not isComposite:
 				continue
 			var = TupleVariation(support, delta)
 			if optimize:
@@ -304,7 +304,7 @@ def _remove_TTHinting(font):
 	font["glyf"].removeHinting()
 	# TODO: Modify gasp table to deactivate gridfitting for all ranges?
 
-def _merge_TTHinting(font, masterModel, master_ttfs, tolerance=0.5):
+def _merge_TTHinting(font, masterModel, master_ttfs):
 
 	log.info("Merging TT hinting")
 	assert "cvar" not in font
@@ -363,10 +363,9 @@ def _merge_TTHinting(font, masterModel, master_ttfs, tolerance=0.5):
 		return
 
 	variations = []
-	deltas, supports = masterModel.getDeltasAndSupports(all_cvs)
+	deltas, supports = masterModel.getDeltasAndSupports(all_cvs, round=round) # builtin round calls into Vector.__round__
 	for i,(delta,support) in enumerate(zip(deltas[1:], supports[1:])):
-		delta = [otRound(d) for d in delta]
-		if all(abs(v) <= tolerance for v in delta):
+		if all(v == 0 for v in delta):
 			continue
 		var = TupleVariation(support, delta)
 		variations.append(var)
@@ -441,7 +440,7 @@ def _get_advance_metrics(font, masterModel, master_ttfs,
 	vOrigDeltasAndSupports = {}
 	for glyph in glyphOrder:
 		vhAdvances = [metrics[glyph][0] if glyph in metrics else None for metrics in advMetricses]
-		vhAdvanceDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(vhAdvances)
+		vhAdvanceDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(vhAdvances, round=otRound)
 
 	singleModel = models.allEqual(id(v[1]) for v in vhAdvanceDeltasAndSupports.values())
 
@@ -453,7 +452,7 @@ def _get_advance_metrics(font, masterModel, master_ttfs,
 			# glyphs which have a non-default vOrig.
 			vOrigs = [metrics[glyph] if glyph in metrics else defaultVOrig
 				for metrics, defaultVOrig in vOrigMetricses]
-			vOrigDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(vOrigs)
+			vOrigDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(vOrigs, round=otRound)
 
 	directStore = None
 	if singleModel:
@@ -463,7 +462,7 @@ def _get_advance_metrics(font, masterModel, master_ttfs,
 		varTupleIndexes = list(range(len(supports)))
 		varData = builder.buildVarData(varTupleIndexes, [], optimize=False)
 		for glyphName in glyphOrder:
-			varData.addItem(vhAdvanceDeltasAndSupports[glyphName][0])
+			varData.addItem(vhAdvanceDeltasAndSupports[glyphName][0], round=noRound)
 		varData.optimize()
 		directStore = builder.buildVarStore(varTupleList, [varData])
 
@@ -473,14 +472,14 @@ def _get_advance_metrics(font, masterModel, master_ttfs,
 	for glyphName in glyphOrder:
 		deltas, supports = vhAdvanceDeltasAndSupports[glyphName]
 		storeBuilder.setSupports(supports)
-		advMapping[glyphName] = storeBuilder.storeDeltas(deltas)
+		advMapping[glyphName] = storeBuilder.storeDeltas(deltas, round=noRound)
 
 	if vOrigMetricses:
 		vOrigMap = {}
 		for glyphName in glyphOrder:
 			deltas, supports = vOrigDeltasAndSupports[glyphName]
 			storeBuilder.setSupports(supports)
-			vOrigMap[glyphName] = storeBuilder.storeDeltas(deltas)
+			vOrigMap[glyphName] = storeBuilder.storeDeltas(deltas, round=noRound)
 
 	indirectStore = storeBuilder.finish()
 	mapping2 = indirectStore.optimize()
diff --git a/Lib/fontTools/varLib/cff.py b/Lib/fontTools/varLib/cff.py
index ae14986e5..1a6bf14c3 100644
--- a/Lib/fontTools/varLib/cff.py
+++ b/Lib/fontTools/varLib/cff.py
@@ -20,6 +20,7 @@ from fontTools.varLib.models import allEqual
 from fontTools.misc.roundTools import roundFunc
 from fontTools.misc.psCharStrings import T2CharString, T2OutlineExtractor
 from fontTools.pens.t2CharStringPen import T2CharStringPen
+from functools import partial
 
 from .errors import VarLibCFFDictMergeError, VarLibCFFPointTypeMergeError, VarLibMergeError
 
@@ -585,7 +586,7 @@ class CFF2CharStringMergePen(T2CharStringPen):
 	def getCommands(self):
 		return self._commands
 
-	def reorder_blend_args(self, commands, get_delta_func, round_func):
+	def reorder_blend_args(self, commands, get_delta_func):
 		"""
 		We first re-order the master coordinate values.
 		For a moveto to lineto, the args are now arranged as:
@@ -628,8 +629,6 @@ class CFF2CharStringMergePen(T2CharStringPen):
 					else:
 						# convert to deltas
 						deltas = get_delta_func(coord)[1:]
-						if round_func:
-							deltas = [round_func(delta) for delta in deltas]
 						coord = [coord[0]] + deltas
 						new_coords.append(coord)
 				cmd[1] = new_coords
@@ -640,7 +639,7 @@ class CFF2CharStringMergePen(T2CharStringPen):
 					self, private=None, globalSubrs=None,
 					var_model=None, optimize=True):
 		commands = self._commands
-		commands = self.reorder_blend_args(commands, var_model.getDeltas, self.round)
+		commands = self.reorder_blend_args(commands, partial (var_model.getDeltas, round=self.round))
 		if optimize:
 			commands = specializeCommands(
 						commands, generalizeFirst=False,
diff --git a/Lib/fontTools/varLib/varStore.py b/Lib/fontTools/varLib/varStore.py
index b28d2a657..6d2fcebc4 100644
--- a/Lib/fontTools/varLib/varStore.py
+++ b/Lib/fontTools/varLib/varStore.py
@@ -1,4 +1,4 @@
-from fontTools.misc.fixedTools import otRound
+from fontTools.misc.roundTools import noRound, otRound
 from fontTools.ttLib.tables import otTables as ot
 from fontTools.varLib.models import supportScalar
 from fontTools.varLib.builder import (buildVarRegionList, buildVarStore,
@@ -83,15 +83,12 @@ class OnlineVarStoreBuilder(object):
 
 
 	def storeMasters(self, master_values):
-		deltas = self._model.getDeltas(master_values)
-		base = otRound(deltas.pop(0))
-		return base, self.storeDeltas(deltas)
+		deltas = self._model.getDeltas(master_values, round=otRound)
+		base = deltas.pop(0)
+		return base, self.storeDeltas(deltas, round=noRound)
 
-	def storeDeltas(self, deltas):
-		# Pity that this exists here, since VarData_addItem
-		# does the same.  But to look into our cache, it's
-		# good to adjust deltas here as well...
-		deltas = [otRound(d) for d in deltas]
+	def storeDeltas(self, deltas, round=otRound):
+		deltas = [round(d) for d in deltas]
 		if len(deltas) == len(self._supports) + 1:
 			deltas = tuple(deltas[1:])
 		else:
@@ -109,14 +106,14 @@ class OnlineVarStoreBuilder(object):
 			# Full array. Start new one.
 			self._add_VarData()
 			return self.storeDeltas(deltas)
-		self._data.addItem(deltas)
+		self._data.addItem(deltas, round=noRound)
 
 		varIdx = (self._outer << 16) + inner
 		self._cache[deltas] = varIdx
 		return varIdx
 
-def VarData_addItem(self, deltas):
-	deltas = [otRound(d) for d in deltas]
+def VarData_addItem(self, deltas, round=otRound):
+	deltas = [round(d) for d in deltas]
 
 	countUs = self.VarRegionCount
 	countThem = len(deltas)
diff --git a/Tests/varLib/data/test_results/TestSparseCFF2VF.ttx b/Tests/varLib/data/test_results/TestSparseCFF2VF.ttx
index f05f62f74..a4fc03cd0 100644
--- a/Tests/varLib/data/test_results/TestSparseCFF2VF.ttx
+++ b/Tests/varLib/data/test_results/TestSparseCFF2VF.ttx
@@ -290,7 +290,7 @@
         </CharString>
         <CharString name="cid06449" fdSelectIndex="1">
           2 vsindex
-          -60 30 203 30 -9 9 67 7 -7 14 -14 30 -20 20 80 30 59 30 121 30 18 93 -30 30 -30 108 -23 0 -26 67 2 76 -98 -2 -111 42 0 47 -13 0 -14 13 0 14 -33 0 -37 11 0 13 -11 0 -13 8 0 9 -7 0 -8 53 0 60 -32 0 -36 32 0 36 -52 0 -59 57 1 65 -33 0 -38 53 0 60 -83 -1 -93 54 0 60 -6 -19 -24 33 19 55 -76 -1 -86 76 1 86 -76 -1 -86 59 1 67 26 blend
+          -60 30 203 30 -9 9 67 7 -7 14 -14 30 -20 20 80 30 59 30 121 30 18 93 -30 30 -30 108 -23 0 -26 67 2 76 -98 -2 -111 42 0 47 -13 0 -14 13 0 14 -33 0 -37 11 0 13 -11 0 -13 8 0 9 -7 -1 -8 53 0 60 -32 0 -36 32 0 36 -52 0 -59 57 1 65 -33 0 -38 53 0 60 -83 -1 -93 54 0 60 -6 -19 -24 33 19 55 -76 -1 -86 76 1 86 -76 -1 -86 59 1 67 26 blend
           hstemhm
           77 30 42 30 139 30 23 30 71 10 74 30 15 30 16 30 158 30 28 30 -4 29 -14 0 -16 88 1 99 -82 -1 -92 87 1 98 -130 -1 -146 102 1 114 -73 -1 -82 74 2 84 -112 -2 -126 27 0 30 13 0 15 90 1 101 -126 -1 -142 75 1 84 -68 -1 -76 102 1 115 -144 -1 -162 94 1 105 -79 -1 -88 95 1 106 -81 -1 -91 74 1 83 22 blend
           vstemhm

From 606b072f409c79075c7ac2fd6160612e2c3da435 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Thu, 4 Mar 2021 09:31:15 -0700
Subject: [PATCH 09/13] [glyf] Add round=otRound parameter to
 GlyphCoordinates.toInt() & __round__()

---
 Lib/fontTools/ttLib/tables/_g_l_y_f.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Lib/fontTools/ttLib/tables/_g_l_y_f.py b/Lib/fontTools/ttLib/tables/_g_l_y_f.py
index 9886d7ab3..b8ed20d5e 100644
--- a/Lib/fontTools/ttLib/tables/_g_l_y_f.py
+++ b/Lib/fontTools/ttLib/tables/_g_l_y_f.py
@@ -1506,12 +1506,12 @@ class GlyphCoordinates(object):
 			p = self._checkFloat(p)
 			self._a.extend(p)
 
-	def toInt(self):
+	def toInt(self, *, round=otRound):
 		if not self.isFloat():
 			return
 		a = array.array("h")
 		for n in self._a:
-			a.append(otRound(n))
+			a.append(round(n))
 		self._a = a
 
 	def relativeToAbsolute(self):
@@ -1626,9 +1626,9 @@ class GlyphCoordinates(object):
 		for i in range(len(a)):
 			a[i] = -a[i]
 		return r
-	def __round__(self):
+	def __round__(self, *, round=otRound):
 		r = self.copy()
-		r.toInt()
+		r.toInt(round=round)
 		return r
 
 	def __add__(self, other): return self.copy().__iadd__(other)

From f5ef0b517bb0d037fe21e7409a9090f54d9672a7 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Thu, 4 Mar 2021 09:37:43 -0700
Subject: [PATCH 10/13] [varLib] Round most deltas using bankers' round, not
 otRound

See https://github.com/fonttools/fonttools/pull/2214#issuecomment-790742479
---
 Lib/fontTools/varLib/__init__.py | 4 ++--
 Lib/fontTools/varLib/varStore.py | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Lib/fontTools/varLib/__init__.py b/Lib/fontTools/varLib/__init__.py
index 4172dd13c..c2c5ed4c9 100644
--- a/Lib/fontTools/varLib/__init__.py
+++ b/Lib/fontTools/varLib/__init__.py
@@ -440,7 +440,7 @@ def _get_advance_metrics(font, masterModel, master_ttfs,
 	vOrigDeltasAndSupports = {}
 	for glyph in glyphOrder:
 		vhAdvances = [metrics[glyph][0] if glyph in metrics else None for metrics in advMetricses]
-		vhAdvanceDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(vhAdvances, round=otRound)
+		vhAdvanceDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(vhAdvances, round=round)
 
 	singleModel = models.allEqual(id(v[1]) for v in vhAdvanceDeltasAndSupports.values())
 
@@ -452,7 +452,7 @@ def _get_advance_metrics(font, masterModel, master_ttfs,
 			# glyphs which have a non-default vOrig.
 			vOrigs = [metrics[glyph] if glyph in metrics else defaultVOrig
 				for metrics, defaultVOrig in vOrigMetricses]
-			vOrigDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(vOrigs, round=otRound)
+			vOrigDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(vOrigs, round=round)
 
 	directStore = None
 	if singleModel:
diff --git a/Lib/fontTools/varLib/varStore.py b/Lib/fontTools/varLib/varStore.py
index 6d2fcebc4..905f47089 100644
--- a/Lib/fontTools/varLib/varStore.py
+++ b/Lib/fontTools/varLib/varStore.py
@@ -83,11 +83,11 @@ class OnlineVarStoreBuilder(object):
 
 
 	def storeMasters(self, master_values):
-		deltas = self._model.getDeltas(master_values, round=otRound)
+		deltas = self._model.getDeltas(master_values, round=round)
 		base = deltas.pop(0)
 		return base, self.storeDeltas(deltas, round=noRound)
 
-	def storeDeltas(self, deltas, round=otRound):
+	def storeDeltas(self, deltas, round=round):
 		deltas = [round(d) for d in deltas]
 		if len(deltas) == len(self._supports) + 1:
 			deltas = tuple(deltas[1:])
@@ -112,7 +112,7 @@ class OnlineVarStoreBuilder(object):
 		self._cache[deltas] = varIdx
 		return varIdx
 
-def VarData_addItem(self, deltas, round=otRound):
+def VarData_addItem(self, deltas, round=round):
 	deltas = [round(d) for d in deltas]
 
 	countUs = self.VarRegionCount

From 07a7dd3eb544c8b6b7b49acb48b3aecea7e5feba Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Thu, 4 Mar 2021 09:44:34 -0700
Subject: [PATCH 11/13] [varLib] Make newly-added round arguments keyword-only

So they are not accidentally set, only intentionally. Keeps positional-args
open for more direct uses.
---
 Lib/fontTools/varLib/models.py   | 8 ++++----
 Lib/fontTools/varLib/varStore.py | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/Lib/fontTools/varLib/models.py b/Lib/fontTools/varLib/models.py
index 417ecb42b..8c71058b6 100644
--- a/Lib/fontTools/varLib/models.py
+++ b/Lib/fontTools/varLib/models.py
@@ -359,7 +359,7 @@ class VariationModel(object):
 		self.supports = supports
 		self.deltaWeights = deltaWeights
 
-	def getDeltas(self, masterValues, round=noRound):
+	def getDeltas(self, masterValues, *, round=noRound):
 		assert len(masterValues) == len(self.deltaWeights)
 		mapping = self.reverseMapping
 		out = []
@@ -370,7 +370,7 @@ class VariationModel(object):
 			out.append(round(delta))
 		return out
 
-	def getDeltasAndSupports(self, items, round=noRound):
+	def getDeltasAndSupports(self, items, *, round=noRound):
 		model, items = self.getSubModel(items)
 		return model.getDeltas(items, round=round), model.supports
 
@@ -394,11 +394,11 @@ class VariationModel(object):
 		scalars = self.getScalars(loc)
 		return self.interpolateFromDeltasAndScalars(deltas, scalars)
 
-	def interpolateFromMasters(self, loc, masterValues, round=noRound):
+	def interpolateFromMasters(self, loc, masterValues, *, round=noRound):
 		deltas = self.getDeltas(masterValues, round=round)
 		return self.interpolateFromDeltas(loc, deltas)
 
-	def interpolateFromMastersAndScalars(self, masterValues, scalars, round=noRound):
+	def interpolateFromMastersAndScalars(self, masterValues, scalars, *, round=noRound):
 		deltas = self.getDeltas(masterValues, round=round)
 		return self.interpolateFromDeltasAndScalars(deltas, scalars)
 
diff --git a/Lib/fontTools/varLib/varStore.py b/Lib/fontTools/varLib/varStore.py
index 905f47089..8a382df01 100644
--- a/Lib/fontTools/varLib/varStore.py
+++ b/Lib/fontTools/varLib/varStore.py
@@ -87,7 +87,7 @@ class OnlineVarStoreBuilder(object):
 		base = deltas.pop(0)
 		return base, self.storeDeltas(deltas, round=noRound)
 
-	def storeDeltas(self, deltas, round=round):
+	def storeDeltas(self, deltas, *, round=round):
 		deltas = [round(d) for d in deltas]
 		if len(deltas) == len(self._supports) + 1:
 			deltas = tuple(deltas[1:])
@@ -112,7 +112,7 @@ class OnlineVarStoreBuilder(object):
 		self._cache[deltas] = varIdx
 		return varIdx
 
-def VarData_addItem(self, deltas, round=round):
+def VarData_addItem(self, deltas, *, round=round):
 	deltas = [round(d) for d in deltas]
 
 	countUs = self.VarRegionCount

From d56b844142c3b08689dde1d28f19cdf379eb2c8f Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Thu, 4 Mar 2021 13:00:04 -0700
Subject: [PATCH 12/13] [varLib] Round outline deltas using banker's round as
 well

See https://github.com/fonttools/fonttools/pull/2214#issuecomment-790742479
---
 Lib/fontTools/misc/vector.py     | 2 +-
 Lib/fontTools/varLib/__init__.py | 5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/Lib/fontTools/misc/vector.py b/Lib/fontTools/misc/vector.py
index 995385c04..244436e0a 100644
--- a/Lib/fontTools/misc/vector.py
+++ b/Lib/fontTools/misc/vector.py
@@ -71,7 +71,7 @@ class Vector(tuple):
     def __neg__(self):
         return self._unaryOp(operator.neg)
 
-    def __round__(self):
+    def __round__(self, *, round=round):
         return self._unaryOp(round)
 
     def __eq__(self, other):
diff --git a/Lib/fontTools/varLib/__init__.py b/Lib/fontTools/varLib/__init__.py
index c2c5ed4c9..995159bcd 100644
--- a/Lib/fontTools/varLib/__init__.py
+++ b/Lib/fontTools/varLib/__init__.py
@@ -34,6 +34,7 @@ from fontTools.varLib.mvar import MVAR_ENTRIES
 from fontTools.varLib.iup import iup_delta_optimize
 from fontTools.varLib.featureVars import addFeatureVariations
 from fontTools.designspaceLib import DesignSpaceDocument
+from functools import partial
 from collections import OrderedDict, namedtuple
 import os.path
 import logging
@@ -253,7 +254,7 @@ def _add_gvar(font, masterModel, master_ttfs, tolerance=0.5, optimize=True):
 
 		# Update gvar
 		gvar.variations[glyph] = []
-		deltas = model.getDeltas(allCoords, round=round) # builtin round calls into GlyphCoordinates.__round__()
+		deltas = model.getDeltas(allCoords, round=partial(GlyphCoordinates.__round__, round=round))
 		supports = model.supports
 		assert len(deltas) == len(supports)
 
@@ -363,7 +364,7 @@ def _merge_TTHinting(font, masterModel, master_ttfs):
 		return
 
 	variations = []
-	deltas, supports = masterModel.getDeltasAndSupports(all_cvs, round=round) # builtin round calls into Vector.__round__
+	deltas, supports = masterModel.getDeltasAndSupports(all_cvs, round=round) # builtin round calls into Vector.__round__, which uses builtin round as we like
 	for i,(delta,support) in enumerate(zip(deltas[1:], supports[1:])):
 		if all(v == 0 for v in delta):
 			continue

From ed6164a44f685a448d04d7822d6d73767eddcf3c Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Thu, 4 Mar 2021 13:01:09 -0700
Subject: [PATCH 13/13] [varLib.cff] Round deltas using bankers round as well

See https://github.com/fonttools/fonttools/pull/2214#issuecomment-790742479

Good news: this reverted the one CFF test that needed its expectation to
change when I started this patchset. Bad news: it introduced a couple other
diffs to the same glyph of the same test, which is consistent with changing
the rounding from otRound to round3.
---
 Lib/fontTools/varLib/cff.py                         | 2 +-
 Tests/varLib/data/test_results/TestSparseCFF2VF.ttx | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Lib/fontTools/varLib/cff.py b/Lib/fontTools/varLib/cff.py
index 1a6bf14c3..db1889888 100644
--- a/Lib/fontTools/varLib/cff.py
+++ b/Lib/fontTools/varLib/cff.py
@@ -510,7 +510,7 @@ class CFF2CharStringMergePen(T2CharStringPen):
 		self.prev_move_idx = 0
 		self.seen_moveto = False
 		self.glyphName = glyphName
-		self.round = roundFunc(roundTolerance)
+		self.round = roundFunc(roundTolerance, round=round)
 
 	def add_point(self, point_type, pt_coords):
 		if self.m_index == 0:
diff --git a/Tests/varLib/data/test_results/TestSparseCFF2VF.ttx b/Tests/varLib/data/test_results/TestSparseCFF2VF.ttx
index a4fc03cd0..5bbd925c7 100644
--- a/Tests/varLib/data/test_results/TestSparseCFF2VF.ttx
+++ b/Tests/varLib/data/test_results/TestSparseCFF2VF.ttx
@@ -290,7 +290,7 @@
         </CharString>
         <CharString name="cid06449" fdSelectIndex="1">
           2 vsindex
-          -60 30 203 30 -9 9 67 7 -7 14 -14 30 -20 20 80 30 59 30 121 30 18 93 -30 30 -30 108 -23 0 -26 67 2 76 -98 -2 -111 42 0 47 -13 0 -14 13 0 14 -33 0 -37 11 0 13 -11 0 -13 8 0 9 -7 -1 -8 53 0 60 -32 0 -36 32 0 36 -52 0 -59 57 1 65 -33 0 -38 53 0 60 -83 -1 -93 54 0 60 -6 -19 -24 33 19 55 -76 -1 -86 76 1 86 -76 -1 -86 59 1 67 26 blend
+          -60 30 203 30 -9 9 67 7 -7 14 -14 30 -20 20 80 30 59 30 121 30 18 93 -30 30 -30 108 -23 0 -26 67 2 76 -98 -2 -111 42 0 47 -13 0 -14 13 0 14 -33 0 -37 11 0 13 -11 0 -13 8 0 8 -8 0 -8 53 0 60 -32 0 -36 32 0 36 -52 0 -59 57 1 65 -33 0 -38 53 0 60 -83 -1 -93 54 0 60 -6 -19 -24 33 19 55 -76 -1 -86 76 1 86 -76 -1 -86 59 1 67 26 blend
           hstemhm
           77 30 42 30 139 30 23 30 71 10 74 30 15 30 16 30 158 30 28 30 -4 29 -14 0 -16 88 1 99 -82 -1 -92 87 1 98 -130 -1 -146 102 1 114 -73 -1 -82 74 2 84 -112 -2 -126 27 0 30 13 0 15 90 1 101 -126 -1 -142 75 1 84 -68 -1 -76 102 1 115 -144 -1 -162 94 1 105 -79 -1 -88 95 1 106 -81 -1 -91 74 1 83 22 blend
           vstemhm