marseymoji/colrv1_postproc.py

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"""
Post-nanoemoji processing of the Noto COLRv1 Emoji file.
For now substantially based on copying from a correct bitmap build.
"""
from absl import app
from fontTools import ttLib
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import map_pua_emoji
from nototools import add_vs_cmap
from nototools import unicode_data
def _is_colrv1(font):
return (
"COLR" in font
and font["COLR"].version == 1
)
def _is_cbdt(font):
return "CBDT" in font
def _is_compat_font(font):
return (
"meta" in font
and "Emji" in font["meta"].data
)
def _copy_emojicompat_data(colr_font, cbdt_font):
colr_font["meta"] = cbdt_font["meta"]
def _set_name(name_table, nameID):
name_table.getName(value, nameID, 3, 1, 0x409)
def _set_name(name_table, nameID, value):
name_table.setName(value, nameID, 3, 1, 0x409)
def _copy_names(colr_font, cbdt_font):
colr_font["name"] = cbdt_font["name"]
name_table = colr_font["name"]
assert all((n.platformID, n.platEncID, n.langID) == (3, 1, 0x409)
for n in name_table.names), "Should only have names Android uses"
# Amendments
_set_name(name_table, 10, "Color emoji font using COLRv1.")
_set_name(name_table, 11, "https://github.com/googlefonts/noto-emoji")
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_set_name(name_table, 12, "https://github.com/googlefonts/noto-emoji")
# CBDT build step: @$(VS_ADDER) -vs 2640 2642 2695 --dstdir '.' -o "$@-with-pua-varsel" "$@-with-pua"
def _add_vs_cmap(colr_font):
emoji_variants = unicode_data.get_unicode_emoji_variants() | {0x2640, 0x2642, 0x2695}
add_vs_cmap.modify_font("COLRv1 Emoji", colr_font, "emoji", emoji_variants)
def _is_variation_selector_cmap_table(table):
assert table.format in {4, 12, 14}
return table.format == 14
def _lookup_in_cmap(colr_font, codepoint):
result = set()
for table in colr_font["cmap"].tables:
if _is_variation_selector_cmap_table(table):
continue
assert codepoint in table.cmap
result.add(table.cmap[codepoint])
assert len(result) == 1, f"Ambiguous mapping for {codepoint}: {result}"
return next(iter(result))
def _map_flag_tag_chars_to_space(colr_font):
gn_space = _lookup_in_cmap(colr_font, ord(" "))
# Add all tag characters used in flags
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tag_cps = (
set(range(0xE0030, 0xE0039 + 1))
| set(range(0xE0061, 0xE007A + 1))
)
# Cancel tag maps to space in bitmap font
tag_cps |= {0xE007F}
# CBDT maps these things to space based on hb-shape testing
# Android fontchain_lint is unhappy if no such mapping exists
for table in colr_font["cmap"].tables:
if _is_variation_selector_cmap_table(table):
continue
for cp in tag_cps:
if not _is_bmp(cp) and table.format == 4:
continue
table.cmap[cp] = gn_space
print(f"Map 0x{cp:04x} to space, format {table.format}")
def _is_bmp(cp):
return cp in range(0x0000, 0xFFFF + 1)
def main(argv):
if len(argv) != 3:
raise ValueError("Must have two args, a COLRv1 font and a CBDT emojicompat font")
colr_font = ttLib.TTFont(argv[1])
if not _is_colrv1(colr_font):
raise ValueError("First arg must be a COLRv1 font")
cbdt_font = ttLib.TTFont(argv[2])
if not _is_cbdt(cbdt_font) or not _is_compat_font(cbdt_font):
raise ValueError("Second arg must be a CBDT emojicompat font")
_copy_emojicompat_data(colr_font, cbdt_font)
_copy_names(colr_font, cbdt_font)
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# CBDT build step: @$(PYTHON) $(PUA_ADDER) "$@" "$@-with-pua"
map_pua_emoji.add_pua_cmap_to_font(colr_font)
_add_vs_cmap(colr_font)
_map_flag_tag_chars_to_space(colr_font)
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colr_font.save('fonts/Noto-COLRv1-noflags.ttf')
if __name__ == "__main__":
app.run(main)