From 3dd09516c9a87f663fefde77befb7d569cbed9f0 Mon Sep 17 00:00:00 2001 From: Eli Zaretskii Date: Fri, 17 May 2024 10:18:35 +0300 Subject: ; Improve documentation of 'set-fontset-font' * doc/lispref/display.texi (Fontsets): * src/fontset.c (Fset_fontset_font): Doc fix (bug#70993). --- doc/lispref/display.texi | 8 ++++++++ src/fontset.c | 11 ++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi index c6b29e87b3a..f20064519fc 100644 --- a/doc/lispref/display.texi +++ b/doc/lispref/display.texi @@ -4015,6 +4015,14 @@ the charset @code{japanese-jisx0208}: (set-fontset-font t 'japanese-jisx0208 (font-spec :family "Kochi Gothic")) @end smallexample + +Note that this function should generally be called from the user's +init files, and more generally before any of @var{characters} were +displayed in the current Emacs session. That's because for some +scripts, Emacs caches the way they are displayed, and the cached +information includes the font used for them -- once these characters +are displayed once, the cached font will continue to be used +regardless of changes in the fontsets. @end defun @defun char-displayable-p char diff --git a/src/fontset.c b/src/fontset.c index 7af6782a37c..4aa2fb7b2c7 100644 --- a/src/fontset.c +++ b/src/fontset.c @@ -1499,7 +1499,16 @@ Optional 5th argument ADD, if non-nil, specifies how to add FONT-SPEC to the previously set font specifications for CHARACTERS. If it is `prepend', FONT-SPEC is prepended to the existing font specifications. If it is `append', FONT-SPEC is appended. By default, FONT-SPEC -overwrites the previous settings. */) +overwrites the previous settings. + +For reliable results, this function should be called before any +of CHARACTERS were displayed in the current Emacs session. In +particular, if some of CHARACTERS are displayed using character +compositions, those compositions will be cached after they are first +produced, and the cached values include the font used for displaying +the composed characters -- calling this function will not affect the +font recorded in the cache of compositions, thus they will continue +to be shown using the fonts from before the call. */) (Lisp_Object fontset, Lisp_Object characters, Lisp_Object font_spec, Lisp_Object frame, Lisp_Object add) { -- cgit v1.2.3