Wrapper code to use fonttools for subsetting

src/calibre/utils/fonts/subset.py

@@ -0,0 +1,29 @@
+#!/usr/bin/env python
+# License: GPLv3 Copyright: 2023, Kovid Goyal <kovid at kovidgoyal.net>
+
+import sys, os
+from fontTools.subset import Subsetter, load_font, save_font
+
+
+def subset(input_file_object_or_path, output_file_object_or_path, container_type, chars_or_text=''):
+    s = Subsetter()
+    s.options.recommended_glyphs = True
+    container_type = container_type.lower()
+    if 'woff' in container_type:
+        s.options.flavor = 'woff2'
+    font = load_font(input_file_object_or_path, s.options, dontLoadGlyphNames=False)
+    unicodes = {ord(x) for x in chars_or_text}
+    unicodes.add(ord(' '))
+    s.populate(unicodes=unicodes)
+    s.subset(font)
+    save_font(font, output_file_object_or_path, s.options)
+
+
+if __name__ == '__main__':
+    import tempfile
+    src = sys.argv[-1]
+    with open(os.path.join(tempfile.gettempdir(), os.path.basename(src)), 'wb') as output:
+        subset(src, output, os.path.splitext(sys.argv[-1])[1][1:], 'abcdefghijk')
+    a, b = os.path.getsize(src), os.path.getsize(output.name)
+    print(f'Input: {a} Output: {b}')
+    print('Written to:', output.name)