avif: If save_all is False only save a single frame

Tests/test_file_avif.py

@@ -179,6 +179,13 @@ def test_background_from_gif(self, tmp_path):
         )
         assert difference < 5
 
+    def test_save_single_frame(self, tmp_path):
+        temp_file = str(tmp_path / "temp.avif")
+        with Image.open("Tests/images/chi.gif") as im:
+            im.save(temp_file)
+        with Image.open(temp_file) as im:
+            assert im.n_frames == 1
+
     def test_invalid_file(self):
         invalid_file = "Tests/images/flower.jpg"
 

src/PIL/AvifImagePlugin.py

@@ -85,8 +85,15 @@ def tell(self):
 
 
 def _save_all(im, fp, filename):
+    _save(im, fp, filename, save_all=True)
+
+
+def _save(im, fp, filename, save_all=False):
     info = im.encoderinfo.copy()
-    append_images = list(info.get("append_images", []))
+    if save_all:
+        append_images = list(info.get("append_images", []))
+    else:
+        append_images = []
 
     total = 0
     for ims in [im] + append_images:
@@ -186,6 +193,9 @@ def _save_all(im, fp, filename):
                 # Update frame index
                 frame_idx += 1
 
+                if not save_all:
+                    break
+
     finally:
         im.seek(cur_idx)
 
@@ -199,7 +209,7 @@ def _save_all(im, fp, filename):
 
 Image.register_open(AvifImageFile.format, AvifImageFile, _accept)
 if SUPPORTED:
-    Image.register_save(AvifImageFile.format, _save_all)
+    Image.register_save(AvifImageFile.format, _save)
     Image.register_save_all(AvifImageFile.format, _save_all)
     Image.register_extensions(AvifImageFile.format, [".avif", ".avifs"])
     Image.register_mime(AvifImageFile.format, "image/avif")