Merge pull request #5 from anthrotype/desubroutinize

add function to desubroutinize

src/cffsubr/__init__.py

@@ -16,7 +16,7 @@
 from fontTools import ttLib
 
 
-__all__ = ["subroutinize", "Error"]
+__all__ = ["subroutinize", "desubroutinize", "has_subroutines", "Error"]
 
 
 try:
@@ -117,15 +117,18 @@ def _tx_subroutinize(data: bytes, output_format: str = CFFTableTag.CFF) -> bytes
     return output_data
 
 
-def _sniff_cff_table_format(otf: ttLib.TTFont) -> Optional[CFFTableTag]:
-    return next(
+def _sniff_cff_table_format(otf: ttLib.TTFont) -> CFFTableTag:
+    cff_tag = next(
         (
             CFFTableTag(tag)
             for tag in otf.keys()
             if tag in CFFTableTag.__members__.values()
         ),
         None,
     )
+    if not cff_tag:
+        raise Error("Invalid OTF: no 'CFF ' or 'CFF2' tables found")
+    return cff_tag
 
 
 def subroutinize(
@@ -158,8 +161,6 @@ def subroutinize(
         or if subroutinization process fails.
     """
     input_format = _sniff_cff_table_format(otf)
-    if not input_format:
-        raise Error("Invalid OTF: no 'CFF ' or 'CFF2' tables found")
 
     if cff_version is None:
         output_format = input_format
@@ -197,3 +198,49 @@ def subroutinize(
             post_table.glyphOrder = glyphOrder
 
     return otf
+
+
+def has_subroutines(otf: ttLib.TTFont) -> bool:
+    """Return True if the font's CFF or CFF2 table contains any subroutines."""
+    table_tag = _sniff_cff_table_format(otf)
+    top_dict = otf[table_tag].cff.topDictIndex[0]
+    all_subrs = [top_dict.GlobalSubrs]
+    if hasattr(top_dict, "FDArray"):
+        all_subrs.extend(
+            fd.Private.Subrs for fd in top_dict.FDArray if hasattr(fd.Private, "Subrs")
+        )
+    elif hasattr(top_dict.Private, "Subrs"):
+        all_subrs.append(top_dict.Private.Subrs)
+    return any(all_subrs)
+
+
+def desubroutinize(otf: ttLib.TTFont, inplace=True) -> ttLib.TTFont:
+    """Remove all subroutines from the font.
+
+    Args:
+        otf (ttLib.TTFont): the input font object.
+        inplace (bool): whether to create a copy or modify the input font. By default
+            the input font is modified.
+
+    Returns:
+        The modified font containing the desubroutinized CFF or CFF2 table.
+        This will be a different TTFont object if inplace=False.
+
+    Raises:
+        cffsubr.Error if the font doesn't contain 'CFF ' or 'CFF2' table,
+        or if desubroutinization process fails.
+    """
+    # the 'desubroutinize' method is dynamically added to the CFF table class
+    # as a side-effect of importing the fontTools.subset.cff module...
+    from fontTools.subset import cff as _
+
+    if not inplace:
+        otf = copy.deepcopy(otf)
+
+    table_tag = _sniff_cff_table_format(otf)
+    try:
+        otf[table_tag].desubroutinize()
+    except Exception as e:
+        raise Error("Desubroutinization failed") from e
+
+    return otf

src/cffsubr/__main__.py

@@ -39,6 +39,12 @@ def main(args=None):
         action="store_false",
         help="whether to drop postscript glyph names when converting from CFF to CFF2.",
     )
+    parser.add_argument(
+        "-d",
+        "--desubroutinize",
+        action="store_true",
+        help="Don't subroutinize, instead remove all subroutines (in any).",
+    )
     options = parser.parse_args(args)
 
     if options.inplace:
@@ -47,7 +53,10 @@ def main(args=None):
         options.output_file = sys.stdout.buffer
 
     with ttLib.TTFont(options.input_file, lazy=True) as font:
-        cffsubr.subroutinize(font, options.cff_version, options.keep_glyph_names)
+        if options.desubroutinize:
+            cffsubr.desubroutinize(font)
+        else:
+            cffsubr.subroutinize(font, options.cff_version, options.keep_glyph_names)
         font.save(options.output_file)
 
 

tests/cffsubr_test.py

@@ -99,3 +99,46 @@ def test_drop_glyph_names(self):
         font2 = ttLib.TTFont(buf)
 
         assert font2.getGlyphOrder() != glyph_order
+
+
+@pytest.mark.parametrize(
+    "testfile, table_tag",
+    [
+        ("SourceSansPro-Regular.subset.ttx", "CFF "),
+        ("SourceSansVariable-Roman.subset.ttx", "CFF2"),
+    ],
+)
+def test_sniff_cff_table_format(testfile, table_tag):
+    font = load_test_font(testfile)
+
+    assert cffsubr._sniff_cff_table_format(font) == table_tag
+
+
+def test_sniff_cff_table_format_invalid():
+    with pytest.raises(cffsubr.Error, match="Invalid OTF"):
+        cffsubr._sniff_cff_table_format(ttLib.TTFont())
+
+
+@pytest.mark.parametrize(
+    "testfile",
+    ["SourceSansPro-Regular.subset.ttx", "SourceSansVariable-Roman.subset.ttx"],
+)
+def test_has_subroutines(testfile):
+    font = load_test_font(testfile)
+
+    assert not cffsubr.has_subroutines(font)
+    assert cffsubr.has_subroutines(cffsubr.subroutinize(font))
+
+
+@pytest.mark.parametrize(
+    "testfile",
+    ["SourceSansPro-Regular.subset.ttx", "SourceSansVariable-Roman.subset.ttx"],
+)
+def test_desubroutinize(testfile):
+    font = load_test_font(testfile)
+    cffsubr.subroutinize(font)
+
+    font2 = cffsubr.desubroutinize(font, inplace=False)
+
+    assert cffsubr.has_subroutines(font)
+    assert not cffsubr.has_subroutines(font2)