init-fonts.el

(require 'cl)


(defun font-name-replace-size (font-name new-size)
  (let ((parts (split-string font-name "-")))
    (setcar (nthcdr 7 parts) (format "%d" new-size))
    (mapconcat 'identity parts "-")))

(defun increment-default-font-height (delta)
  "Adjust the default font height by DELTA on every frame.
The pixel size of the frame is kept (approximately) the same.
DELTA should be a multiple of 10, in the units used by the
:height face attribute."
  (let* ((new-height (+ (face-attribute 'default :height) delta))
         (new-point-height (/ new-height 10)))
    (dolist (f (frame-list))
      (with-selected-frame f
        ;; Latest 'set-frame-font supports a "frames" arg, but
        ;; we cater to Emacs 23 by looping instead.
        (set-frame-font (font-name-replace-size (face-font 'default)
                                                new-point-height)
                        t)))
    (set-face-attribute 'default nil :height new-height)
    (message "default font size is now %d" new-point-height)))

(defun increase-default-font-height ()
  (interactive)
  (increment-default-font-height 10))

(defun decrease-default-font-height ()
  (interactive)
  (increment-default-font-height -10))

(global-set-key (kbd "C-M-=") 'increase-default-font-height)
(global-set-key (kbd "C-M--") 'decrease-default-font-height)



(provide 'init-fonts)