Merge pull request #2549 from fonttools/fix-lazy-collection

fix opening TTCollection with lazy=True

Lib/fontTools/ttLib/ttCollection.py

@@ -38,7 +38,12 @@ class TTCollection(object):
 			font = TTFont(file, fontNumber=i, _tableCache=tableCache, **kwargs)
 			fonts.append(font)
 
-		if closeStream:
+		# don't close file if lazy=True, as the TTFont hold a reference to the original
+		# file; the file will be closed once the TTFonts are closed in the
+		# TTCollection.close(). We still want to close the file if lazy is None or
+		# False, because in that case the TTFont no longer need the original file
+		# and we want to avoid 'ResourceWarning: unclosed file'.
+		if not kwargs.get("lazy") and closeStream:
 			file.close()
 
 	def __enter__(self):

Tests/ttLib/ttCollection_test.py

@@ -0,0 +1,27 @@
+import os
+from pathlib import Path
+from fontTools.ttLib import TTCollection
+import pytest
+
+TTX_DATA_DIR = Path(__file__).parent.parent / "ttx" / "data"
+
+
+@pytest.fixture(params=[None, True, False])
+def lazy(request):
+    return request.param
+
+
+def test_lazy_open_path(lazy):
+    ttc_path = TTX_DATA_DIR / "TestTTC.ttc"
+    with TTCollection(ttc_path, lazy=lazy) as collection:
+        assert len(collection) == 2
+        assert collection[0]["maxp"].numGlyphs == 6
+        assert collection[1]["maxp"].numGlyphs == 6
+
+
+def test_lazy_open_file(lazy):
+    with (TTX_DATA_DIR / "TestTTC.ttc").open("rb") as file:
+        collection = TTCollection(file, lazy=lazy)
+        assert len(collection) == 2
+        assert collection[0]["maxp"].numGlyphs == 6
+        assert collection[1]["maxp"].numGlyphs == 6