varLib: add set_default_weight_width_slant
When building a variable font, varLib.build must make sure that
the OS/2.usWeightClass is equal to the wght axis default location,
that the OS/2.usWidthClass is set to the equivalent value (1-9) of
the wdth axis default location, and finally that post.italicAngle
is set to the same default value as slnt axis.
Sometimes the base master doesn't have these values correctly
set leading to discrepancies between OS/2 and post, on the one
hand, and the fvar axes' default values.
diff --git a/Lib/fontTools/varLib/__init__.py b/Lib/fontTools/varLib/__init__.py
index 891e92c..66b193b 100644
--- a/Lib/fontTools/varLib/__init__.py
+++ b/Lib/fontTools/varLib/__init__.py
@@ -857,6 +857,45 @@
)
+# https://docs.microsoft.com/en-us/typography/opentype/spec/os2#uswidthclass
+WDTH_VALUE_TO_OS2_WIDTH_CLASS = {
+ 50: 1,
+ 62.5: 2,
+ 75: 3,
+ 87.5: 4,
+ 100: 5,
+ 112.5: 6,
+ 125: 7,
+ 150: 8,
+ 200: 9,
+}
+
+
+def set_default_weight_width_slant(font, location):
+ if "OS/2" in font:
+ if "wght" in location:
+ weight_class = otRound(max(1, min(location["wght"], 1000)))
+ if font["OS/2"].usWeightClass != weight_class:
+ log.info("Setting OS/2.usWidthClass = %s", weight_class)
+ font["OS/2"].usWeightClass = weight_class
+
+ if "wdth" in location:
+ # map 'wdth' axis (50..200) to OS/2.usWidthClass (1..9), rounding to closest
+ widthValue = min(max(location["wdth"], 50), 200)
+ widthClass = otRound(
+ models.piecewiseLinearMap(widthValue, WDTH_VALUE_TO_OS2_WIDTH_CLASS)
+ )
+ if font["OS/2"].usWidthClass != widthClass:
+ log.info("Setting OS/2.usWidthClass = %s", widthClass)
+ font["OS/2"].usWidthClass = widthClass
+
+ if "slnt" in location and "post" in font:
+ italicAngle = max(-90, min(location["slnt"], 90))
+ if font["post"].italicAngle != italicAngle:
+ log.info("Setting post.italicAngle = %s", italicAngle)
+ font["post"].italicAngle = italicAngle
+
+
def build(designspace, master_finder=lambda s:s, exclude=[], optimize=True):
"""
Build variation font from a designspace file.
@@ -930,6 +969,10 @@
post.extraNames = []
post.mapping = {}
+ set_default_weight_width_slant(
+ vf, location={axis.axisTag: axis.defaultValue for axis in vf["fvar"].axes}
+ )
+
for tag in exclude:
if tag in vf:
del vf[tag]
diff --git a/Tests/varLib/data/test_results/BuildMain.ttx b/Tests/varLib/data/test_results/BuildMain.ttx
index 7150a57..7e5d956 100644
--- a/Tests/varLib/data/test_results/BuildMain.ttx
+++ b/Tests/varLib/data/test_results/BuildMain.ttx
@@ -55,7 +55,7 @@
will be recalculated by the compiler -->
<version value="4"/>
<xAvgCharWidth value="506"/>
- <usWeightClass value="400"/>
+ <usWeightClass value="368"/>
<usWidthClass value="5"/>
<fsType value="00000000 00000100"/>
<ySubscriptXSize value="650"/>
diff --git a/Tests/varLib/data/test_results/SparseMasters.ttx b/Tests/varLib/data/test_results/SparseMasters.ttx
index 06e58c9..c2aa335 100644
--- a/Tests/varLib/data/test_results/SparseMasters.ttx
+++ b/Tests/varLib/data/test_results/SparseMasters.ttx
@@ -55,7 +55,7 @@
will be recalculated by the compiler -->
<version value="4"/>
<xAvgCharWidth value="580"/>
- <usWeightClass value="400"/>
+ <usWeightClass value="350"/>
<usWidthClass value="5"/>
<fsType value="00000000 00000100"/>
<ySubscriptXSize value="650"/>
diff --git a/Tests/varLib/varLib_test.py b/Tests/varLib/varLib_test.py
index e29befb..ec05d56 100644
--- a/Tests/varLib/varLib_test.py
+++ b/Tests/varLib/varLib_test.py
@@ -4,6 +4,7 @@
from fontTools.varLib import build
from fontTools.varLib.mutator import instantiateVariableFont
from fontTools.varLib import main as varLib_main, load_masters
+from fontTools.varLib import set_default_weight_width_slant
from fontTools.designspaceLib import (
DesignSpaceDocumentError, DesignSpaceDocument, SourceDescriptor,
)
@@ -661,5 +662,81 @@
return extracted_kerning
+@pytest.fixture
+def ttFont():
+ f = TTFont()
+ f["OS/2"] = newTable("OS/2")
+ f["OS/2"].usWeightClass = 400
+ f["OS/2"].usWidthClass = 100
+ f["post"] = newTable("post")
+ f["post"].italicAngle = 0
+ return f
+
+
+class SetDefaultWeightWidthSlantTest(object):
+ @pytest.mark.parametrize(
+ "location, expected",
+ [
+ ({"wght": 0}, 1),
+ ({"wght": 1}, 1),
+ ({"wght": 100}, 100),
+ ({"wght": 1000}, 1000),
+ ({"wght": 1001}, 1000),
+ ],
+ )
+ def test_wght(self, ttFont, location, expected):
+ set_default_weight_width_slant(ttFont, location)
+
+ assert ttFont["OS/2"].usWeightClass == expected
+
+ @pytest.mark.parametrize(
+ "location, expected",
+ [
+ ({"wdth": 0}, 1),
+ ({"wdth": 56}, 1),
+ ({"wdth": 57}, 2),
+ ({"wdth": 62.5}, 2),
+ ({"wdth": 75}, 3),
+ ({"wdth": 87.5}, 4),
+ ({"wdth": 100}, 5),
+ ({"wdth": 112.5}, 6),
+ ({"wdth": 125}, 7),
+ ({"wdth": 150}, 8),
+ ({"wdth": 200}, 9),
+ ({"wdth": 201}, 9),
+ ({"wdth": 1000}, 9),
+ ],
+ )
+ def test_wdth(self, ttFont, location, expected):
+ set_default_weight_width_slant(ttFont, location)
+
+ assert ttFont["OS/2"].usWidthClass == expected
+
+ @pytest.mark.parametrize(
+ "location, expected",
+ [
+ ({"slnt": -91}, -90),
+ ({"slnt": -90}, -90),
+ ({"slnt": 0}, 0),
+ ({"slnt": 11.5}, 11.5),
+ ({"slnt": 90}, 90),
+ ({"slnt": 91}, 90),
+ ],
+ )
+ def test_slnt(self, ttFont, location, expected):
+ set_default_weight_width_slant(ttFont, location)
+
+ assert ttFont["post"].italicAngle == expected
+
+ def test_all(self, ttFont):
+ set_default_weight_width_slant(
+ ttFont, {"wght": 500, "wdth": 150, "slnt": -12.0}
+ )
+
+ assert ttFont["OS/2"].usWeightClass == 500
+ assert ttFont["OS/2"].usWidthClass == 8
+ assert ttFont["post"].italicAngle == -12.0
+
+
if __name__ == "__main__":
sys.exit(unittest.main())
