diff --git a/changelog.d/9473.bugfix b/changelog.d/9473.bugfix
new file mode 100644
index 0000000000..71fb487cf2
--- /dev/null
+++ b/changelog.d/9473.bugfix
@@ -0,0 +1 @@
+Fix long-standing bug when generating thumbnails for some images with transparency: `TypeError: cannot unpack non-iterable int object`.
diff --git a/synapse/rest/media/v1/thumbnailer.py b/synapse/rest/media/v1/thumbnailer.py
index 07903e4017..988f52c78f 100644
--- a/synapse/rest/media/v1/thumbnailer.py
+++ b/synapse/rest/media/v1/thumbnailer.py
@@ -96,9 +96,14 @@ class Thumbnailer:
def _resize(self, width: int, height: int) -> Image:
# 1-bit or 8-bit color palette images need converting to RGB
# otherwise they will be scaled using nearest neighbour which
- # looks awful
- if self.image.mode in ["1", "P"]:
- self.image = self.image.convert("RGB")
+ # looks awful.
+ #
+ # If the image has transparency, use RGBA instead.
+ if self.image.mode in ["1", "L", "P"]:
+ mode = "RGB"
+ if self.image.info.get("transparency", None) is not None:
+ mode = "RGBA"
+ self.image = self.image.convert(mode)
return self.image.resize((width, height), Image.ANTIALIAS)
def scale(self, width: int, height: int, output_type: str) -> BytesIO:
diff --git a/tests/rest/media/v1/test_media_storage.py b/tests/rest/media/v1/test_media_storage.py
index 36d1e6bc4a..9f77125fd4 100644
--- a/tests/rest/media/v1/test_media_storage.py
+++ b/tests/rest/media/v1/test_media_storage.py
@@ -105,7 +105,7 @@ class MediaStorageTests(unittest.HomeserverTestCase):
self.assertEqual(test_body, body)
-@attr.s
+@attr.s(slots=True, frozen=True)
class _TestImage:
"""An image for testing thumbnailing with the expected results
@@ -117,13 +117,15 @@ class _TestImage:
test should just check for success.
expected_scaled: The expected bytes from scaled thumbnailing, or None if
test should just check for a valid image returned.
+ expected_found: True if the file should exist on the server, or False if
+ a 404 is expected.
"""
data = attr.ib(type=bytes)
content_type = attr.ib(type=bytes)
extension = attr.ib(type=bytes)
- expected_cropped = attr.ib(type=Optional[bytes])
- expected_scaled = attr.ib(type=Optional[bytes])
+ expected_cropped = attr.ib(type=Optional[bytes], default=None)
+ expected_scaled = attr.ib(type=Optional[bytes], default=None)
expected_found = attr.ib(default=True, type=bool)
@@ -153,6 +155,21 @@ class _TestImage:
),
),
),
+ # small png with transparency.
+ (
+ _TestImage(
+ unhexlify(
+ b"89504e470d0a1a0a0000000d49484452000000010000000101000"
+ b"00000376ef9240000000274524e5300010194fdae0000000a4944"
+ b"4154789c636800000082008177cd72b60000000049454e44ae426"
+ b"082"
+ ),
+ b"image/png",
+ b".png",
+ # Note that we don't check the output since it varies across
+ # different versions of Pillow.
+ ),
+ ),
# small lossless webp
(
_TestImage(
@@ -162,8 +179,6 @@ class _TestImage:
),
b"image/webp",
b".webp",
- None,
- None,
),
),
# an empty file
@@ -172,9 +187,7 @@ class _TestImage:
b"",
b"image/gif",
b".gif",
- None,
- None,
- False,
+ expected_found=False,
),
),
],
|
