@@ -66,24 +66,24 @@ 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 )
7070 return 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 (inp_renderer , _cache = weakref . WeakKeyDictionary () ):
75+ if ( _text_metrics := _cache . get ( inp_renderer , None )) is None :
76+ renderer_ref = weakref . ref ( inp_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+ if ( lcl_renderer := renderer_ref ()) is None :
81+ raise RuntimeError (
82+ "Trying to get text metrics for a renderer that no longer exists. "
83+ "This should never happen and is evidence of a bug elsewhere. "
84+ )
85+ return lcl_renderer . get_text_width_height_descent ( text , fontprop , ismath )
86+ _cache [ inp_renderer ] = _text_metrics
8787
8888 return _text_metrics
8989
0 commit comments