Merge pull request matplotlib#30206 from anntzer/ad

Use collections.deque to store animation cache data.

Author: jkseppan

lib/matplotlib/animation.py

@@ -1,5 +1,6 @@
 import abc
 import base64
+import collections
 import contextlib
 from io import BytesIO, TextIOWrapper
 import itertools
@@ -1708,13 +1709,13 @@ def iter_frames(frames=frames):
         self._cache_frame_data = cache_frame_data
 
         # Needs to be initialized so the draw functions work without checking
-        self._save_seq = []
+        self._save_seq = collections.deque([], self._save_count)
 
         super().__init__(fig, **kwargs)
 
         # Need to reset the saved seq, since right now it will contain data
         # for a single frame from init, which is not what we want.
-        self._save_seq = []
+        self._save_seq.clear()
 
     def new_frame_seq(self):
         # Use the generating function to generate a new frame sequence
@@ -1727,8 +1728,7 @@ def new_saved_frame_seq(self):
         if self._save_seq:
             # While iterating we are going to update _save_seq
             # so make a copy to safely iterate over
-            self._old_saved_seq = list(self._save_seq)
-            return iter(self._old_saved_seq)
+            return iter([*self._save_seq])
         else:
             if self._save_count is None:
                 frame_seq = self.new_frame_seq()
@@ -1773,13 +1773,12 @@ def _init_draw(self):
                                        'return a sequence of Artist objects.')
                 for a in self._drawn_artists:
                     a.set_animated(self._blit)
-        self._save_seq = []
+        self._save_seq.clear()
 
     def _draw_frame(self, framedata):
         if self._cache_frame_data:
             # Save the data for potential saving of movies.
             self._save_seq.append(framedata)
-            self._save_seq = self._save_seq[-self._save_count:]
 
         # Call the func with framedata and args. If blitting is desired,
         # func needs to return a sequence of any artists that were modified.