From 20d13e424fb2e7dcc5e6ea1848bca4376d22bab1 Mon Sep 17 00:00:00 2001 From: Robert Pluim Date: Fri, 11 Sep 2020 10:29:24 +0200 Subject: [PATCH] Stop querying for fonts as soon as a match is found Scanning through fonts can be very slow, especially with the 'x' font backend, and the result is almost always not used. Stop looking for a font as soon as one is found rather than scanning all the backends. * src/font.c (font_list_entities): Stop scanning through the font backends as soon as we find a match unless 'query-all-font-backends is set (Bug#43177). (syms_of_font): New variable 'query-all-font-backends', default false. --- src/font.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/src/font.c b/src/font.c index 2786a772dc3..779b8520962 100644 --- a/src/font.c +++ b/src/font.c @@ -2810,7 +2810,13 @@ font_list_entities (struct frame *f, Lisp_Object spec) || ! NILP (Vface_ignored_fonts))) val = font_delete_unmatched (val, need_filtering ? spec : Qnil, size); if (ASIZE (val) > 0) - list = Fcons (val, list); + { + list = Fcons (val, list); + /* Querying further backends can be very slow, so we only do + it if the user has explicitly requested it (Bug#43177). */ + if (query_all_font_backends == false) + break; + } } list = Fnreverse (list); @@ -5527,6 +5533,13 @@ Non-nil means don't query fontconfig for color fonts, since they often cause Xft crashes. Only has an effect in Xft builds. */); xft_ignore_color_fonts = true; + DEFVAR_BOOL ("query-all-font-backends", query_all_font_backends, + doc: /* +If non-nil attempt to query all available font backends. +By default Emacs will stop searching for a matching font at the first +match. */); + query_all_font_backends = false; + #ifdef HAVE_WINDOW_SYSTEM #ifdef HAVE_FREETYPE syms_of_ftfont (); -- 2.39.5