Port over #866

googlefonts · Sep 3, 2024 · f80b117 · f80b117
1 parent 39cec2d
commit f80b117
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Showing 2 changed files with 8 additions and 13 deletions.
diff --git a/Lib/ufo2ft/featureWriters/kernFeatureWriter2.py b/Lib/ufo2ft/featureWriters/kernFeatureWriter2.py
@@ -552,7 +552,13 @@ def get_variable_kerning_pairs(
         if default_location not in value.values:
             value.values[default_location] = 0
         value = collapse_varscalar(value)
-        result.append(KerningPair(side1, side2, value))
+        pair = KerningPair(side1, side2, value)
+        # Ignore zero-valued class kern pairs. They are the most general
+        # kerns, so they don't override anything else like glyph kerns would
+        # and zero is the default.
+        if pair.firstIsClass and pair.secondIsClass and pair.value == 0:
+            continue
+        result.append(pair)
 
     return result
 

diff --git a/tests/featureWriters/variableFeatureWriter_test.py b/tests/featureWriters/variableFeatureWriter_test.py
@@ -103,16 +103,9 @@ def test_variable_features_old_kern_writer(FontClass):
         markClass dotabove-ar <anchor (wght=100:100 wght=1000:125) (wght=100:320 wght=1000:416)> @MC_top;
         markClass gravecmb <anchor 250 400> @MC_top;
 
-        @kern1.ltr.a = [a];
         @kern1.rtl.alef = [alef-ar.fina];
-        @kern2.ltr.a = [a];
         @kern2.rtl.alef = [alef-ar.fina];
 
-        lookup kern_ltr {
-            lookupflag IgnoreMarks;
-            pos @kern1.ltr.a @kern2.ltr.a 0;
-        } kern_ltr;
-
         lookup kern_rtl {
             lookupflag IgnoreMarks;
             pos alef-ar.fina alef-ar.fina <(wght=100:15 wght=1000:35) 0 (wght=100:15 wght=1000:35) 0>;
@@ -122,15 +115,11 @@ def test_variable_features_old_kern_writer(FontClass):
         feature kern {
             script DFLT;
             language dflt;
-            lookup kern_ltr;
+            lookup kern_rtl;
 
             script arab;
             language dflt;
             lookup kern_rtl;
-
-            script latn;
-            language dflt;
-            lookup kern_ltr;
         } kern;
 
         feature mark {