Merge pull request #120 from googlefonts/fix-layer-name-bug

Fix long standing layer name bug

Author: justvanrossum

src/fontra_rcjk/base.py

@@ -128,7 +128,7 @@ def buildVariableGlyphFromLayerGlyphs(layerGlyphs):
     if defaultComponents:
         layers["foreground"].glyph.components += defaultComponents
 
-    fontraLayerNameMapping = defaultGlyph.lib.get("fontra.layerNames", {})
+    fontraLayerNameMapping = dict(defaultGlyph.lib.get("fontra.layerNames", {}))
 
     dcNames = [c.name for c in defaultComponents]
 
@@ -171,6 +171,10 @@ def buildVariableGlyphFromLayerGlyphs(layerGlyphs):
             # We'll delete it to make sure we don't reuse its data
             layers.pop(layerName, None)
 
+        fontraLayerNameMapping[layerName] = varDict.get(
+            "fontraLayerName"
+        ) or fontraLayerNameMapping.get(layerName, layerName)
+
         syntheticLayerNames.add(layerName)
 
         xAdvance = defaultGlyph.width
@@ -314,11 +318,14 @@ def buildLayerGlyphsFromVariableGlyph(
 
         if layerGlyph.hasOutlineOrClassicComponents():
             safeLayerName = makeSafeLayerName(source.layerName)
+            varDict["layerName"] = safeLayerName
             if safeLayerName != source.layerName:
                 fontraLayerNameMapping[safeLayerName] = source.layerName
-            varDict["layerName"] = safeLayerName
+                varDict["fontraLayerName"] = source.layerName
         else:
             varDict["layerName"] = ""  # Mimic RoboCJK
+            if source.layerName != source.name:
+                varDict["fontraLayerName"] = source.layerName
             # This is a "virtual" layer: all info will go to defaultGlyph.lib,
             # and no "true" layer will be written
             del layerGlyphs[source.layerName]
@@ -331,14 +338,14 @@ def buildLayerGlyphsFromVariableGlyph(
         defaultGlyph.lib.pop("robocjk.variationGlyphs", None)
 
     if fontraLayerNameMapping:
-        defaultGlyph.lib["fontra.layerNames"] = fontraLayerNameMapping
         rcjkLayerNameMapping = {v: k for k, v in fontraLayerNameMapping.items()}
         layerGlyphs = {
             rcjkLayerNameMapping.get(layerName, layerName): layerGlyph
             for layerName, layerGlyph in layerGlyphs.items()
         }
-    else:
-        defaultGlyph.lib.pop("fontra.layerNames", None)
+
+    # Get rid of legacy data
+    defaultGlyph.lib.pop("fontra.layerNames", None)
 
     return layerGlyphs
 

tests/test_font.py

@@ -741,13 +741,6 @@ async def test_write_roundtrip(writableTestFont, glyphName):
     "  </outline>",
     "  <lib>",
     "    <dict>",
-    "      <key>fontra.layerNames</key>",
-    "      <dict>",
-    "        <key>boooo_oooold.75e003ed2da2</key>",
-    "        <string>boooo/oooold</string>",
-    "        <key>boooo_ooooldboooo_ooooldboooo_ooooldb.360a3fdd78e6</key>",
-    "        <string>boooo/ooooldboooo/ooooldboooo/ooooldboooo/ooooldboooo/oooold</string>",
-    "      </dict>",
     "      <key>robocjk.status</key>",
     "      <integer>0</integer>",
     "      <key>robocjk.variationGlyphs</key>",
@@ -768,6 +761,8 @@ async def test_write_roundtrip(writableTestFont, glyphName):
     "          <integer>0</integer>",
     "        </dict>",
     "        <dict>",
+    "          <key>fontraLayerName</key>",
+    "          <string>boooo/oooold</string>",
     "          <key>layerName</key>",
     "          <string>boooo_oooold.75e003ed2da2</string>",
     "          <key>location</key>",
@@ -780,6 +775,8 @@ async def test_write_roundtrip(writableTestFont, glyphName):
     "          <integer>0</integer>",
     "        </dict>",
     "        <dict>",
+    "          <key>fontraLayerName</key>",
+    "          <string>boooo/ooooldboooo/ooooldboooo/ooooldboooo/ooooldboooo/oooold</string>",
     "          <key>layerName</key>",
     "          <string>boooo_ooooldboooo_ooooldboooo_ooooldb.360a3fdd78e6</string>",
     "          <key>location</key>",