Simple script to remap a font's cmap table (#738)

Lib/gftools/scripts/remap_font.py

@@ -0,0 +1,71 @@
+#!/usr/bin/env python3
+"""
+Remap a font's encoded glyphs.
+
+Changes font cmap table. User can also specify their
+own output path.
+
+Usage:
+
+gftools remap-font -o font-remap.ttf font.ttf A=A.alt B=B.alt U+0175=wcircumflex.alt
+gftools remap-font --map-file=remapping.txt -o font-remap.ttf font.ttf
+"""
+import argparse
+import sys
+
+from fontTools.ttLib import TTFont
+
+
+def main(args=None):
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--map-file", metavar="TXT", help="Newline-separated mappings")
+    parser.add_argument("--output", "-o", metavar="TTF", help="Output font binary")
+    parser.add_argument("font", metavar="TTF", help="Input font binary")
+    parser.add_argument("mapping", nargs="*", help="Codepoint-to-glyph mapping")
+
+    args = parser.parse_args(args)
+
+    if not args.mapping and not args.map_file:
+        print("You must either specify a mapping or a map file")
+        sys.exit(1)
+    if args.mapping and args.map_file:
+        print("You must specify either a mapping or a map file, not both")
+        sys.exit(1)
+
+    mapping = {}
+    font = TTFont(args.font)
+
+    if args.map_file:
+        incoming_map = open(args.map_file).readlines()
+    else:
+        incoming_map = args.mapping
+
+    for entry in incoming_map:
+        entry = entry.strip()
+        if not entry or entry.startswith("#"):
+            continue
+        codepoint, glyph = entry.split("=")
+        if codepoint.startswith("U+") or codepoint.startswith("0x"):
+            codepoint = int(codepoint[2:], 16)
+        else:
+            codepoint = ord(codepoint)
+        mapping[codepoint] = glyph
+        if glyph not in font.getGlyphOrder():
+            print(f"Glyph {glyph} (to be mapped to {codepoint}) not found in font")
+            sys.exit(1)
+
+    cmap = font["cmap"]
+    for table in cmap.tables:
+        for codepoint, glyph in mapping.items():
+            table.cmap[codepoint] = glyph
+
+    if args.output:
+        out = args.output
+    else:
+        out = args.font
+    print(f"Saving font: {out}")
+    font.save(out)
+
+
+if __name__ == "__main__":
+    main()

pyproject.toml

@@ -131,6 +131,7 @@ gftools-push-status = "gftools.scripts.push_status:main"
 gftools-qa = "gftools.scripts.qa:main"
 gftools-rangify = "gftools.scripts.rangify:main"
 gftools-rename-font = "gftools.scripts.rename_font:main"
+gftools-remap-font = "gftools.scripts.remap_font:main"
 gftools-sanity-check = "gftools.scripts.sanity_check:main"
 gftools-set-primary-script = "gftools.scripts.set_primary_script:main"
 gftools-space-check = "gftools.scripts.space_check:main"