Create no-flags CBDT font

drop_flags.py

@@ -0,0 +1,54 @@
+"""Removes regional indicators from a font."""
+
+from fontTools import subset
+from fontTools import ttLib
+import functools
+from pathlib import Path
+import sys
+from typing import Set
+
+
+def codepoints(font: ttLib.TTFont) -> Set[int]:
+    unicode_cmaps = (t.cmap.keys() for t in font['cmap'].tables if t.isUnicode())
+    return functools.reduce(lambda acc, u: acc | u, unicode_cmaps, set())
+
+
+def is_regional_indicator(cp: int) -> bool:
+    return 0x1F1E6 <= cp <= 0x1F1FF
+
+
+def main(argv):
+    for font_file in sorted(argv[1:]):
+        font_file = Path(font_file)
+        assert font_file.is_file(), font_file
+        noflags_file = font_file.with_stem(font_file.stem + "-noflags")
+
+        font = ttLib.TTFont(font_file)
+        if noflags_file.is_file():
+            print(font_file, f"({font_type}) already has", noflags_file, "; nop")
+            continue
+
+        cps = codepoints(font)
+        cps_without_flags = {cp for cp in cps if not is_regional_indicator(cp)}
+
+        font_type = []
+        if "CBDT" in font:
+            font_type.append("CBDT")
+        if "COLR" in font:
+            font_type.append("COLR")
+        font_type = "_".join(font_type)
+
+        if cps == cps_without_flags:
+            print(font_file, f"({font_type}) has no regional indicators")
+            continue
+
+        subsetter = subset.Subsetter()
+        subsetter.populate(unicodes=cps_without_flags)
+        subsetter.subset(font)
+
+        font.save(noflags_file)
+        print(font_file, f"({font_type}) =>" , noflags_file)
+
+
+if __name__ == '__main__':
+  main(sys.argv)