From adf3654b33feafaed1741f8e27c3837c6e12715c Mon Sep 17 00:00:00 2001
From: Rasmus Andersson <rasmus@notion.se>
Date: Sat, 15 Oct 2022 16:23:56 -0700
Subject: [PATCH] workaround for bug in glyphslib/fontmake that generates UFO
 glyphs with fractional widths. Closes #508

---
 misc/tools/find-ufo-frac-advance-widths.sh | 15 +++++++++++++++
 misc/tools/postprocess_instance_ufo.py     | 21 ++++++++++++++++++---
 2 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100755 misc/tools/find-ufo-frac-advance-widths.sh

diff --git a/misc/tools/find-ufo-frac-advance-widths.sh b/misc/tools/find-ufo-frac-advance-widths.sh
new file mode 100755
index 000000000..5c5c93a7c
--- /dev/null
+++ b/misc/tools/find-ufo-frac-advance-widths.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+#
+# This script finds UFO glyphs with fractional advance width, which is invalid.
+# See https://github.com/rsms/inter/issues/508
+#
+cd "$(dirname "$0")"/../../build/ufo
+ADVANCES=$(rg 'advance width'|awk 'BEGIN {FS="  "} {print $2}')
+NOTREALLYFLOATS=$((rg '\.0\b'|wc -l) <<< "$ADVANCES")
+FLOATS=$((rg '\.\d+'|wc -l) <<< "$ADVANCES")
+INTS=$((rg -v '\.'|wc -l) <<< "$ADVANCES")
+
+printf "Total: $((INTS+FLOATS)) (sanity: $(wc -l <<< "$ADVANCES"))\nFloats: $((FLOATS-NOTREALLYFLOATS))\nInts: $((INTS+NOTREALLYFLOATS))\n"
+
+echo "Occurance Fraction"
+(rg -o '\.\d{1,12}'|sort|uniq -c) <<< "$ADVANCES"
diff --git a/misc/tools/postprocess_instance_ufo.py b/misc/tools/postprocess_instance_ufo.py
index 26d29aa96..37be67d0f 100644
--- a/misc/tools/postprocess_instance_ufo.py
+++ b/misc/tools/postprocess_instance_ufo.py
@@ -15,12 +15,27 @@ def ufo_set_wws(ufo):
   ufo.info.openTypeNameWWSSubfamilyName = subfamily
 
 
+# See https://github.com/rsms/inter/issues/508
+# TODO: Remove when https://github.com/googlefonts/glyphsLib/issues/821 is fixed
+def fix_fractional_advance_width(ufo):
+  for g in ufo:
+    g.width = round(g.width)
+
+
 def main(argv):
   ufo_file = argv[1]
-  if ufo_file.find("Display") == -1:
-    return  # skip fonts of "default" family
+
+  # TODO: Uncomment when https://github.com/googlefonts/glyphsLib/issues/821 is fixed
+  # if ufo_file.find("Display") == -1:
+  #   return  # skip fonts of "default" family
+
   ufo = defcon.Font(ufo_file)
-  ufo_set_wws(ufo)
+
+  if ufo_file.find("Display") != -1:
+    ufo_set_wws(ufo)
+
+  fix_fractional_advance_width(ufo)
+
   ufo.save(ufo_file)