RE: [PATCH] Add idle-cursor-morph.

[Drew Adams <drew.adams@oracle.com>]

> This is for ELPA.
> 
> Admittedly this is pretty hacky, but it has worked for me since ages.
> 
> It also has a bug I have no idea how to chase: every once in a blue moon
> it will fail to restore the cursor color.  I'm guessing it's probably a
> bug in Emacs since the implementation is so simple and restoring the
> style works, but don't know really.

FWIW, this has been in my code (in `oneonone.el') since 2006.
(I haven't come across that blue-moon problem, BTW.)

---

(defun 1on1-toggle-box-cursor-when-idle (&optional arg)
  "Turn on or off automatically changing to a box cursor when idle.
When on, the cursor is changed to a box whenever Emacs is idle.
With prefix argument, turn on if ARG > 0; else turn off."
  (interactive "P")
  (setq 1on1-box-cursor-when-idle-p
        (if arg
            (> (prefix-numeric-value arg) 0)
          (not 1on1-box-cursor-when-idle-p)))
  (cond (1on1-box-cursor-when-idle-p
         (timer-activate-when-idle 1on1-box-cursor-when-idle-timer)
         (add-hook 'pre-command-hook '1on1-box-cursor-when-idle-off)
         (message "Turned ON making cursor a box when Emacs is idle."))
        (t
         (cancel-timer 1on1-box-cursor-when-idle-timer)
         (remove-hook 'pre-command-hook '1on1-box-cursor-when-idle-off)
         (message "Turned OFF making cursor a box when Emacs is idle."))))

(defun 1on1-set-cursor-type (cursor-type)
  "Set the cursor type of the selected frame to CURSOR-TYPE.
When called interactively, prompt for the type to use.
To get the frame's current cursor type, use `frame-parameters'."
  (interactive
   (list (intern (completing-read
                   "Cursor type: "
                   (mapcar 'list '("box" "hollow" "bar" "hbar" nil))))))
  (modify-frame-parameters (selected-frame)
                           (list (cons 'cursor-type cursor-type))))

(defun 1on1-box-cursor-when-idle ()
  "Change the cursor to a box cursor when Emacs is idle."
  (let ((type  (cdr (assoc 'cursor-type (frame-parameters)))))
    (unless (eq type 'box)
      (setq 1on1-last-cursor-type  type)
      (1on1-set-cursor-type 'box))))

(defun 1on1-box-cursor-when-idle-off ()
  "Turn off changing the cursor to a box cursor when Emacs is idle."
  (when 1on1-last-cursor-type
    (1on1-set-cursor-type 1on1-last-cursor-type)))

(defvar 1on1-box-cursor-when-idle-p t
  "Non-nil means to use a box cursor whenever Emacs is idle.
Do NOT change this yourself; instead, use \
`\\[1on1-toggle-box-cursor-when-idle]'.")

(defvar 1on1-box-cursor-when-idle-interval 2
  "Number of seconds to wait before changing cursor type to box.
Do NOT change this yourself to change the wait period; instead, use
`\\[1on1-set-box-cursor-when-idle-interval]'.")

(defvar 1on1-box-cursor-when-idle-timer
  (progn 
    (when (boundp '1on1-box-cursor-when-idle-timer)
      (cancel-timer 1on1-box-cursor-when-idle-timer))
    (run-with-idle-timer 1on1-box-cursor-when-idle-interval t
                         '1on1-box-cursor-when-idle))
  "Timer used to change the cursor to a box cursor when Emacs is idle.")

(cancel-timer 1on1-box-cursor-when-idle-timer)