@@ -66,24 +66,19 @@ def _get_text_metrics_with_cache(renderer, text, fontprop, ismath, dpi):
6666"""Call ``renderer.get_text_width_height_descent``, caching the results."""
6767# Cached based on a copy of fontprop so that later in-place mutations of
6868# the passed-in argument do not mess up the cache.
69- func = _get_text_metrics_function (weakref . ref ( renderer ) )
69+ func = _get_text_metrics_function (renderer )
7070return func (text ,fontprop .copy (),ismath ,dpi )
7171
7272
73- @functools .lru_cache (25 )
74- def _get_text_metrics_function (renderer_ref ):
75-
76- @functools .lru_cache (4096 )
77- def _text_metrics (text ,fontprop ,ismath ,dpi ):
78- # dpi is unused, but participates in cache invalidation (via the renderer).
79- renderer = renderer_ref ()
80- if renderer is None :
81- raise RuntimeError (
82- "You are trying to get the font metrics for a renderer that no "
83- "longer exists. There is likely a deeper bug someplace else "
84- "as this should never happen."
85- )
86- return renderer .get_text_width_height_descent (text ,fontprop ,ismath )
73+ # use mutable default to carry hidden global state
74+ def _get_text_metrics_function (renderer ,_cache = weakref .WeakKeyDictionary ()):
75+ if (_text_metrics := _cache .get (renderer ,None ))is None :
76+ renderer_ref = weakref .ref (renderer )
77+ @functools .lru_cache (4096 )
78+ def _text_metrics (text ,fontprop ,ismath ,dpi ):
79+ # dpi is unused, but participates in cache invalidation (via the renderer).
80+ return renderer_ref ().get_text_width_height_descent (text ,fontprop ,ismath )
81+ _cache [renderer ]= _text_metrics
8782
8883return _text_metrics
8984