Fix: Preserve loop attribute for animated images in processors

easy_thumbnails/processors.py

@@ -52,8 +52,9 @@ def apply_to_frames(self, method, *args, **kwargs):
             self.im.seek(i)
             new_frames.append(method(*args, **kwargs))
         write_to = BytesIO()
+        loop = self.im.info.get('loop', 0)
         new_frames[0].save(
-            write_to, format=self.im.format, save_all=True, append_images=new_frames[1:]
+            write_to, format=self.im.format, save_all=True, append_images=new_frames[1:], loop=loop
         )
         return Image.open(write_to)
 
@@ -104,6 +105,7 @@ def colorspace(im, bw=False, replace_alpha=False, **kwargs):
                 im = base
             else:
                 frames = []
+                loop = im.info.get('loop', 0)
                 for i in range(im.n_frames):
                     im.seek(i)
                     if im.mode != 'RGBA':
@@ -113,7 +115,7 @@ def colorspace(im, bw=False, replace_alpha=False, **kwargs):
                     frames.append(base)
                 write_to = BytesIO()
                 frames[0].save(
-                    write_to, format=im.format, save_all=True, append_images=frames[1:]
+                    write_to, format=im.format, save_all=True, append_images=frames[1:], loop=loop
                 )
                 return Image.open(write_to)
         else:
@@ -376,13 +378,14 @@ def background(im, size, background=None, **kwargs):
         return new_im
     else:
         frames = []
+        loop = im.info.get('loop', 0)
         for i in range(im.n_frames):
             im.seek(i)
             copied_new_im = new_im.copy()
             copied_new_im.paste(im, offset)
             frames.append(copied_new_im)
         write_to = BytesIO()
         frames[0].save(
-            write_to, format=im.format, save_all=True, append_images=frames[1:]
+            write_to, format=im.format, save_all=True, append_images=frames[1:], loop=loop
         )
         return Image.open(write_to)

easy_thumbnails/tests/test_animated_formats.py

@@ -4,7 +4,7 @@
 from unittest import TestCase
 
 
-def create_animated_image(mode='RGB', format="gif", size=(1000, 1000), no_frames=6):
+def create_animated_image(mode='RGB', format="gif", size=(1000, 1000), no_frames=6, loop=None):
     frames = []
     for i in range(no_frames):
         image = Image.new(mode, size, (255, 255, 255))
@@ -14,9 +14,10 @@ def create_animated_image(mode='RGB', format="gif", size=(1000, 1000), no_frames
         draw.rectangle((x_bit * 2, y_bit, x_bit * 3, y_bit * 8), 'yellow')
         frames.append(image)
     write_to = BytesIO()
-    frames[0].save(
-        write_to, format=format, save_all=True, append_images=frames[1:]
-    )
+    save_kwargs = {'format': format, 'save_all': True, 'append_images': frames[1:]}
+    if loop is not None:
+        save_kwargs['loop'] = loop
+    frames[0].save(write_to, **save_kwargs)
     im = Image.open(write_to)
     # for debugging
     # with open(f"animated{no_frames}.{format}", "wb") as f:
@@ -81,3 +82,17 @@ def test_background(self):
         # indeed processed?
         self.assertEqual(frames_count, processed_frames_count)
         self.assertEqual(processed.size, (1000, 1800))
+
+    def test_background_loop_preserved(self):
+        no_frames = 5
+        loop_value = 3
+        im = create_animated_image(format="gif", no_frames=no_frames, loop=loop_value)
+
+        original_loop = im.info.get('loop', 0)
+        self.assertEqual(original_loop, loop_value)
+
+        processed = processors.background(im, background="#00ff00", size=(1200, 1200))
+
+        processed_loop = processed.info.get('loop', 0)
+        self.assertEqual(processed_loop, original_loop)
+        self.assertEqual(processed_loop, loop_value)