22.15 Modifying Fontsets

Fontsets do not always have to be created from scratch. If only minor changes are required it may be easier to modify an existing fontset. Modifying ‘fontset-default’ will also affect other fontsets that use it as a fallback, so can be an effective way of fixing problems with the fonts that Emacs chooses for a particular script.

Fontsets can be modified using the function set-fontset-font, specifying a character, a charset, a script, or a range of characters to modify the font for, and a font specification for the font to be used. Some examples are:

;; Use Liberation Mono for latin-3 charset.
(set-fontset-font "fontset-default" 'iso-8859-3
                  "Liberation Mono")

;; Prefer a big5 font for han characters
(set-fontset-font "fontset-default"
                  'han (font-spec :registry "big5")
                  nil 'prepend)

;; Use DejaVu Sans Mono as a fallback in fontset-startup
;; before resorting to fontset-default.
(set-fontset-font "fontset-startup" nil "DejaVu Sans Mono"
                  nil 'append)

;; Use MyPrivateFont for the Unicode private use area.
(set-fontset-font "fontset-default"  '(#xe000 . #xf8ff)
                  "MyPrivateFont")

Some fonts installed on your system might be broken, or produce unpleasant results for characters for which they are used, and you may wish to instruct Emacs to completely ignore them while searching for a suitable font required to display a character. You can do that by adding the offending fonts to the value of face-ignored-fonts variable, which is a list. Here’s an example to put in your ~/.emacs:

(add-to-list 'face-ignored-fonts "Some Bad Font")