From 2761e801dfd81dffe503bd6b1dbeaf5efa20ef5f Mon Sep 17 00:00:00 2001
From: Oliver Falk <oliver@linux-kernel.at>
Date: Mon, 5 Dec 2022 16:15:30 +0100
Subject: [PATCH] Add util function to resize an animated GIF

---
 ivatar/utils.py | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/ivatar/utils.py b/ivatar/utils.py
index aea0920..cf4a524 100644
--- a/ivatar/utils.py
+++ b/ivatar/utils.py
@@ -4,7 +4,8 @@ Simple module providing reusable random_string function
 """
 import random
 import string
-from PIL import Image, ImageDraw
+from io import BytesIO
+from PIL import Image, ImageDraw, ImageSequence
 from urllib.parse import urlparse
 
 
@@ -158,3 +159,25 @@ def is_trusted_url(url, url_filters):
         return True
 
     return False
+
+
+def resize_animated_gif(input_pil: Image, size: list) -> BytesIO:
+    def _thumbnail_frames(image):
+        for frame in ImageSequence.Iterator(image):
+            new_frame = frame.copy()
+            new_frame.thumbnail(size)
+            yield new_frame
+
+    frames = list(_thumbnail_frames(input_pil))
+    output = BytesIO()
+    output_image = frames[0]
+    output_image.save(
+        output,
+        format="gif",
+        save_all=True,
+        optimize=False,
+        append_images=frames[1:],
+        disposal=input_pil.disposal_method,
+        **input_pil.info,
+    )
+    return output