Merge pull request #441 from anthrotype/custom-ufo2ft-feature-writers

set custom 'append' mode for ufo2ft KernFeatureWriter

Lib/glyphsLib/builder/constants.py

@@ -81,3 +81,21 @@
 }
 
 REVERSE_CODEPAGE_RANGES = {value: key for key, value in CODEPAGE_RANGES.items()}
+
+UFO2FT_FEATURE_WRITERS_KEY = "com.github.googlei18n.ufo2ft.featureWriters"
+
+# ufo2ft KernFeatureWriter default to "skip" mode (i.e. do not write features
+# if they are already present), while Glyphs.app always adds its automatic
+# kerning to any user written kern lookups. So we need to pass custom "append"
+# mode for the ufo2ft KernFeatureWriter whenever the GSFont contain a non-automatic
+# 'kern' feature.
+# See https://glyphsapp.com/tutorials/contextual-kerning
+# NOTE: Even though we use the default "skip" mode for the MarkFeatureWriter,
+# we still must include it this custom featureWriters list, as this is used
+# instead of the default ufo2ft list of feature writers.
+# This also means that if ufo2ft adds new writers to that default list, we
+# would need to update this accordingly... :-/
+DEFAULT_FEATURE_WRITERS = [
+    {"class": "KernFeatureWriter", "options": {"mode": "append"}},
+    {"class": "MarkFeatureWriter", "options": {"mode": "skip"}},
+]

Lib/glyphsLib/builder/user_data.py

@@ -17,7 +17,13 @@
 import os
 import posixpath
 
-from .constants import GLYPHS_PREFIX, GLYPHLIB_PREFIX, PUBLIC_PREFIX
+from .constants import (
+    GLYPHS_PREFIX,
+    GLYPHLIB_PREFIX,
+    PUBLIC_PREFIX,
+    UFO2FT_FEATURE_WRITERS_KEY,
+    DEFAULT_FEATURE_WRITERS,
+)
 
 UFO_DATA_KEY = GLYPHLIB_PREFIX + "ufoData"
 FONT_USER_DATA_KEY = GLYPHLIB_PREFIX + "fontUserData"
@@ -26,12 +32,27 @@
 NODE_USER_DATA_KEY = GLYPHLIB_PREFIX + "nodeUserData"
 
 
+def _has_manual_kern_feature(font):
+    """Return true if the GSFont contains a manually written 'kern' feature."""
+    return any(f for f in font.features if f.name == "kern" and not f.automatic)
+
+
 def to_designspace_family_user_data(self):
     if self.use_designspace:
         for key, value in dict(self.font.userData).items():
             if _user_data_has_no_special_meaning(key):
                 self.designspace.lib[key] = value
 
+        # only write our custom ufo2ft featureWriters settings if the font
+        # does have a manually written 'kern' feature; and if the lib key wasn't
+        # already set in font.userData (in which case we assume the user knows
+        # what she's doing).
+        if (
+            _has_manual_kern_feature(self.font)
+            and UFO2FT_FEATURE_WRITERS_KEY not in self.designspace.lib
+        ):
+            self.designspace.lib[UFO2FT_FEATURE_WRITERS_KEY] = DEFAULT_FEATURE_WRITERS
+
 
 def to_ufo_family_user_data(self, ufo):
     """Set family-wide user data as Glyphs does."""
@@ -83,6 +104,10 @@ def to_glyphs_family_user_data_from_designspace(self):
     """Set the GSFont userData from the designspace family-wide lib data."""
     target_user_data = self.font.userData
     for key, value in self.designspace.lib.items():
+        if key == UFO2FT_FEATURE_WRITERS_KEY and value == DEFAULT_FEATURE_WRITERS:
+            # if the designspace contains featureWriters settings that are the
+            # same as glyphsLib default settings, there's no need to store them
+            continue
         if _user_data_has_no_special_meaning(key):
             target_user_data[key] = value
 

setup.cfg

@@ -21,3 +21,7 @@ python_classes =
 addopts =
 	-v
 	-r a
+filterwarnings =
+	default::DeprecationWarning
+	default::PendingDeprecationWarning
+	ignore:The 'path':DeprecationWarning:.*defcon.*

tests/builder/lib_and_user_data_test.py

@@ -21,8 +21,11 @@
 from fontTools.designspaceLib import DesignSpaceDocument
 from glyphsLib import classes
 from glyphsLib.types import BinaryData
-from glyphsLib.builder.constants import GLYPHLIB_PREFIX
-
+from glyphsLib.builder.constants import (
+    GLYPHLIB_PREFIX,
+    UFO2FT_FEATURE_WRITERS_KEY,
+    DEFAULT_FEATURE_WRITERS,
+)
 from glyphsLib import to_glyphs, to_ufos, to_designspace
 
 
@@ -49,6 +52,64 @@ def test_designspace_lib_equivalent_to_font_user_data(tmpdir):
     assert designspace.lib["designspaceLibKey1"] == "designspaceLibValue1"
 
 
+def test_default_featureWriters_in_designspace_lib(tmpdir):
+    """Test that the glyphsLib custom featureWriters settings (with mode="append")
+    are exported to the designspace lib whenever a GSFont contains a manual 'kern'
+    feature. And that they are not imported back to GSFont.userData if they are
+    the same as the default value.
+    """
+    font = classes.GSFont()
+    font.masters.append(classes.GSFontMaster())
+    kern = classes.GSFeature(name="kern", code="pos a b 100;")
+    font.features.append(kern)
+
+    designspace = to_designspace(font)
+    path = str(tmpdir / "test.designspace")
+    designspace.write(path)
+    for source in designspace.sources:
+        source.font.save(str(tmpdir / source.filename))
+
+    designspace2 = DesignSpaceDocument.fromfile(path)
+
+    assert UFO2FT_FEATURE_WRITERS_KEY in designspace2.lib
+    assert designspace2.lib[UFO2FT_FEATURE_WRITERS_KEY] == DEFAULT_FEATURE_WRITERS
+
+    font2 = to_glyphs(designspace2)
+
+    assert not len(font2.userData)
+    assert len([f for f in font2.features if f.name == "kern"]) == 1
+
+
+def test_custom_featureWriters_in_designpace_lib(tmpdir):
+    """Test that we can roundtrip custom user-defined ufo2ft featureWriters
+    settings that are stored in the designspace lib or GSFont.userData.
+    """
+    font = classes.GSFont()
+    font.masters.append(classes.GSFontMaster())
+    kern = classes.GSFeature(name="kern", code="pos a b 100;")
+    font.features.append(kern)
+    customFeatureWriters = list(DEFAULT_FEATURE_WRITERS) + [
+        {"class": "MyCustomWriter", "module": "myCustomWriter"}
+    ]
+    font.userData[UFO2FT_FEATURE_WRITERS_KEY] = customFeatureWriters
+
+    designspace = to_designspace(font)
+    path = str(tmpdir / "test.designspace")
+    designspace.write(path)
+    for source in designspace.sources:
+        source.font.save(str(tmpdir / source.filename))
+
+    designspace2 = DesignSpaceDocument.fromfile(path)
+
+    assert UFO2FT_FEATURE_WRITERS_KEY in designspace2.lib
+    assert designspace2.lib[UFO2FT_FEATURE_WRITERS_KEY] == customFeatureWriters
+
+    font2 = to_glyphs(designspace2)
+
+    assert len(font2.userData) == 1
+    assert font2.userData[UFO2FT_FEATURE_WRITERS_KEY] == customFeatureWriters
+
+
 def test_font_user_data_to_ufo_lib():
     # This happens only when not building a designspace
     # Since there is no designspace.lib to store the font userData,

tox.ini

@@ -19,7 +19,6 @@ commands =
     python -c 'print(r"hint: run {envdir}/bin/pre-commit or {envdir}/Scripts/pre-commit install to add checks as pre-commit hook")'
 
 [testenv:htmlcov]
-basepython = python3.6
 deps =
     coverage
 skip_install = true