Add support for Python 3.13

easy_thumbnails/optimize/post_processor.py

@@ -1,6 +1,6 @@
 import logging
 import subprocess
-from imghdr import what as determinetype
+from PIL import Image, UnidentifiedImageError
 from django.core.files.base import ContentFile
 from django.core.files.temp import NamedTemporaryFile
 from easy_thumbnails.optimize.conf import settings
@@ -35,9 +35,30 @@ def check_output(*popenargs, **kwargs):
 
 def optimize_thumbnail(thumbnail):
     '''Optimize thumbnail images by removing unnecessary data'''
+    # Ignore remote storage backends.
     try:
-        optimize_command = settings.THUMBNAIL_OPTIMIZE_COMMAND[
-            determinetype(thumbnail.path)]
+        thumbnail_path = thumbnail.path
+    except NotImplementedError:
+        return
+
+    # We can't use thumbnail.image.format directly because it's set to `None` for images
+    # that have been created by running a method on an existing image. i.e. It's `None`
+    # because of the thumnailing operations.
+    # https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.format
+    #
+    # Image.open() is lazy and the full file will not be read when determining the
+    # format.
+    # https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.open
+    try:
+        with Image.open(thumbnail_path) as img:
+            # Use the lower case version of format to match the output of previously used
+            # imghdr.what() (removed in Python 3.13).
+            format = img.format.lower()
+    except UnidentifiedImageError:
+        return
+
+    try:
+        optimize_command = settings.THUMBNAIL_OPTIMIZE_COMMAND[format]
         if not optimize_command:
             return
     except (TypeError, KeyError, NotImplementedError):

setup.py

@@ -58,6 +58,7 @@ def read_files(*filenames):
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
         "Programming Language :: Python :: 3.12",
+        "Programming Language :: Python :: 3.13",
         "Topic :: Software Development :: Libraries :: Application Frameworks",
         "Topic :: Software Development :: Libraries :: Python Modules",
     ],

tox.ini

@@ -3,7 +3,7 @@ distribute = False
 envlist =
     py{38,39,310,311,312}-django42{-svg,}
     py{310,311,312}-django50{-svg,}
-    py{310,311,312}-django51{-svg,}
+    py{310,311,312,313}-django51{-svg,}
 skip_missing_interpreters = True
 
 [gh-actions]
@@ -12,6 +12,7 @@ python =
     3.10: py310
     3.11: py311
     3.12: py312
+    3.13: py313
 
 [testenv]
 setenv =