Snippet to programmatically cycle through frame size

[Pankaj Jangid]

Inspired by two threads on the mailing-list:

1) Cycle Auto-fill
2) Programmatically maximize Emacs during startup?

I have written this code snippet to cycle through default, small and big
frame sizes. The definitions are arbitrarily hard-coded. Need to fix
those. My monitor is at 2560x1440 pixel resolution. You should change
the values as per your context if you use this snippet.

Key binding is set to M-<f9>.

M-<f10> is already bound to toggle-frame-maximized
<f11> is assigned to toggle-frame-fullscreen (On macOS this is used by
the OS so I have changed it to M-<f11>

So I have a three key-bidings M-<f9>, M-<f10>, M-<f11>.

--8<---------------cut here---------------start------------->8---
(defvar looks--frame-size 0)

(defun looks-cycle-frame-size ()
  "Cycle frame-size among default, small and big.

0) default - 80x38 (built-in).
1) small - 100x48
2) big - 174x58"

  (interactive)

  (pcase looks--frame-size
    (0 (set-frame-size (next-frame) 100 48)
       (setq looks--frame-size 1))
    (1 (set-frame-size (next-frame) 174 58)
       (setq looks--frame-size 2))
    (2 (set-frame-size (next-frame) 80 38)
       (setq looks--frame-size 0))))
  
(global-set-key (kbd "M-<f9>") 'looks-cycle-frame-size)
--8<---------------cut here---------------end--------------->8---