emacs/lisp/avoid.el

;;; avoid.el --- make mouse pointer stay out of the way of editing  -*- lexical-binding: t -*-

;; Copyright (C) 1993-1994, 2000-2024 Free Software Foundation, Inc.

;; Author: Boris Goldowsky <boris@gnu.org>
;; Keywords: mouse

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; For those who are annoyed by the mouse pointer obscuring text,
;; this mode moves the mouse pointer - either just a little out of
;; the way, or all the way to the corner of the frame.
;;
;; To use, type `M-x mouse-avoidance-mode'.
;;
;; To set up permanently, put this in your .emacs:
;;
;; (if (display-mouse-p) (mouse-avoidance-mode 'animate))
;;
;; Other legitimate alternatives include
;; `banish', `exile', `jump', `cat-and-mouse', and `proteus'.
;; They do somewhat different things.
;; See the documentation for function `mouse-avoidance-mode' for
;; details of the different modes.
;;
;; For added silliness, make the animatee animate...
;; put something similar to the following into your .emacs:
;;
;; (if (eq window-system 'x)
;;     (mouse-avoidance-set-pointer-shape
;;	     (seq-random-elt
;;		  (list x-pointer-man x-pointer-spider
;;			x-pointer-gobbler x-pointer-gumby))))
;;
;; For completely random pointer shape, replace the setq above with:
;; (setq x-pointer-shape (mouse-avoidance-random-shape))

;; Credits:
;; This code was helped by all those who contributed suggestions,
;;   fixes, and additions
;; Joe Harrington (and his advisor), for the original inspiration.
;; Ken Manheimer, for dreaming up the Protean mode.
;; Richard Stallman, for the awful cat-and-mouse pun, among other things.
;; Mike Williams, Denis Howe, Bill Benedetto, Chris Moore, Don Morris,
;; Simon Marshall, and M.S. Ashton, for their feedback.

;;; Code:

(eval-when-compile (require 'cl-lib))

(defgroup avoid nil
  "Make mouse pointer stay out of the way of editing."
  :prefix "mouse-avoidance-"
  :group 'mouse)

;;;###autoload
(defcustom mouse-avoidance-mode nil
  "Activate Mouse Avoidance mode.
See function `mouse-avoidance-mode' for possible values.
Setting this variable directly does not take effect;
use either \\[customize] or \\[mouse-avoidance-mode]."
  :set (lambda (_symbol value)
	 ;; 'none below prevents toggling when value is nil.
	 (mouse-avoidance-mode (or value 'none)))
  :initialize 'custom-initialize-default
  :type '(choice (const :tag "none" nil) (const banish) (const jump)
		 (const animate) (const exile) (const proteus))
  :require 'avoid
  :version "20.3")


(defcustom mouse-avoidance-nudge-dist 15
  "Average distance that mouse will be moved when approached by cursor.
Only applies in Mouse Avoidance mode `jump' and its derivatives.
For best results make this larger than `mouse-avoidance-threshold'."
  :type 'integer)

(defcustom mouse-avoidance-nudge-var 10
  "Variability of `mouse-avoidance-nudge-dist' (which see)."
  :type 'integer)

(defcustom mouse-avoidance-animation-delay .01
  "Delay between animation steps, in seconds."
  :type 'number)

(defcustom mouse-avoidance-threshold 5
  "Mouse-pointer's flight distance.
If the cursor gets closer than this, the mouse pointer will move away.
Only applies in Mouse Avoidance modes `animate' and `jump'."
  :type 'integer)

(defcustom mouse-avoidance-banish-position '((frame-or-window . frame)
                                             (side . right)
                                             (side-pos . 3)
                                             (top-or-bottom . top)
                                             (top-or-bottom-pos . 0))
  "Position to which Mouse Avoidance mode `banish' moves the mouse.
An alist where keywords mean:
FRAME-OR-WINDOW: banish the mouse to corner of frame or window.
SIDE: banish the mouse on right or left corner of frame or window.
SIDE-POS: Distance from right or left edge of frame or window.
TOP-OR-BOTTOM: banish the mouse to top or bottom of frame or window.
TOP-OR-BOTTOM-POS: Distance from top or bottom edge of frame or window."
  :group   'avoid
  :version "24.3"
  :type    '(alist :key-type symbol :value-type (choice symbol integer))
  :options '((frame-or-window symbol) (side symbol) (side-pos integer)
             (top-or-bottom symbol) (top-or-bottom-pos integer)))

;; Internal variables
(defvar mouse-avoidance-state nil)
(defvar mouse-avoidance-pointer-shapes nil)
(defvar mouse-avoidance-old-pointer-shape nil)
(defvar mouse-avoidance-animating-pointer nil)

;; This timer is used to run something when Emacs is idle.
(defvar mouse-avoidance-timer nil)

;;; Functions:

(defsubst mouse-avoidance-set-pointer-shape (shape)
  "Set the shape of the mouse pointer to SHAPE."
  (when (boundp 'x-pointer-shape)
    (setq x-pointer-shape shape)
    (set-mouse-color nil)))

(defun mouse-avoidance-point-position ()
  "Return the position of point as (FRAME X . Y).
Analogous to `mouse-position'."
  (let* ((edges (window-inside-edges))
	 (posn-at-point (posn-at-point))
	 (x-y (and posn-at-point (posn-x-y posn-at-point))))
    (when x-y
      (cons (selected-frame)
	    (cons (+ (car edges)
		     (/ (car x-y) (frame-char-width)))
		  (+ (car (cdr edges))
		     (/ (cdr x-y) (frame-char-height))))))))

;(defun mouse-avoidance-point-position-test ()
;  (interactive)
;  (message "point=%s mouse=%s"
;	    (cdr (mouse-avoidance-point-position))
;	    (cdr (mouse-position))))

(defun mouse-avoidance-set-mouse-position (pos)
  ;; Carefully set mouse position to given position (X . Y)
  ;; Returns t if it moved the mouse.
  (let ((f (selected-frame)))
    (set-mouse-position f (car pos) (cdr pos))
    t))

(defun mouse-avoidance-too-close-p (mouse)
  "Return t if mouse pointer and point cursor are too close.
MOUSE is the current mouse position as returned by `mouse-position'.
Acceptable distance is defined by `mouse-avoidance-threshold'."
  (let* ((frame (car mouse))
	 (mouse-y (cdr (cdr mouse)))
	 (tool-bar-lines (frame-parameter nil 'tool-bar-lines))
	 point)
    (or tool-bar-lines
	(setq tool-bar-lines 0))
    (cond
     ((and mouse-y (< mouse-y tool-bar-lines))
      nil)
     ((setq point (mouse-avoidance-point-position))
      (let ((mouse-x (car (cdr mouse))))
	(and (eq frame (car point))
	     (not (null mouse-x))
	     (< (abs (- mouse-x (car (cdr point))))
		mouse-avoidance-threshold)
	     (< (abs (- mouse-y (cdr (cdr point))))
		mouse-avoidance-threshold)))))))

(defun mouse-avoidance-banish-destination ()
  "The position to which Mouse Avoidance mode `banish' moves the mouse.

If you want the mouse banished to a different corner set
`mouse-avoidance-banish-position' as you need."
  (let* ((fra-or-win         (assoc-default
                              'frame-or-window
                              mouse-avoidance-banish-position 'eq))
         (list-values        (pcase fra-or-win
                               ('frame (list 0 0 (frame-width) (frame-height)))
                               ('window (window-edges))))
         (alist              (cl-loop for v in list-values
                                      for k in '(left top right bottom)
                                      collect (cons k v)))
         (side               (assoc-default
                              'side
                              mouse-avoidance-banish-position #'eq))
         (side-dist          (assoc-default
                              'side-pos
                              mouse-avoidance-banish-position #'eq))
         (top-or-bottom      (assoc-default
                              'top-or-bottom
                              mouse-avoidance-banish-position #'eq))
         (top-or-bottom-dist (assoc-default
                              'top-or-bottom-pos
                              mouse-avoidance-banish-position #'eq))
         (side-fn            (pcase side
                               ('left '+)
                               ('right '-)))
         (top-or-bottom-fn   (pcase top-or-bottom
                               ('top '+)
                               ('bottom '-))))
    (cons (funcall side-fn                        ; -/+
                   (assoc-default side alist 'eq) ; right or left
                   side-dist)                     ; distance from side
	  (funcall top-or-bottom-fn                        ; -/+
                   (assoc-default top-or-bottom alist 'eq) ; top/bottom
                   top-or-bottom-dist)))) ; distance from top/bottom

(defun mouse-avoidance-banish-mouse ()
  "Put the mouse pointer to `mouse-avoidance-banish-position'."
  (mouse-avoidance-set-mouse-position (mouse-avoidance-banish-destination)))

(defsubst mouse-avoidance-delta (cur delta dist var min max)
  ;; Decide how far to move in either dimension.
  ;; Args are the CURRENT location, the desired DELTA for
  ;; warp-conservation, the DISTANCE we like to move, the VARIABILITY
  ;; in distance allowed, and the MIN and MAX possible window positions.
  ;; Returns something as close to DELTA as possible within the constraints.
  (let ((L1 (max (- min cur) (+ (- dist) (- var))))
	(R1                  (+ (- dist)    var ))
	(L2                  (+    dist  (- var)))
	(R2 (min (- max cur) (+    dist     var))))
    (if (< R1 (- min cur)) (setq L1 nil R1 nil))
    (if (> L2 (- max cur)) (setq L2 nil R2 nil))
    (cond ((and L1 (< delta L1)) L1)
	  ((and R1 (< delta R1)) delta)
	  ((and R1 (< delta 0)) R1)
	  ((and L2 (< delta L2)) L2)
	  ((and R2 (< delta R2)) delta)
	  (R2)
	  ((or R1 L2))
	  (t 0))))

(defun mouse-avoidance-nudge-mouse ()
  "Push the mouse a little way away, possibly animating the move.
For these modes, state keeps track of the total offset that we've
accumulated, and tries to keep it close to zero."
  (let* ((cur (mouse-position))
	 (cur-pos (cdr cur))
 	 (pos (window-edges))
 	 (wleft (pop pos))
 	 (wtop (pop pos))
 	 (wright (pop pos))
 	 (wbot (pop pos))
	 (deltax (mouse-avoidance-delta
		  (car cur-pos) (- (random mouse-avoidance-nudge-var)
				   (car mouse-avoidance-state))
		  mouse-avoidance-nudge-dist mouse-avoidance-nudge-var
		  wleft (1- wright)))
	 (deltay (mouse-avoidance-delta
		  (cdr cur-pos) (- (random mouse-avoidance-nudge-var)
				   (cdr mouse-avoidance-state))
		  mouse-avoidance-nudge-dist mouse-avoidance-nudge-var
		  wtop (1- wbot))))
    (setq mouse-avoidance-state
	  (cons (+ (car mouse-avoidance-state) deltax)
		(+ (cdr mouse-avoidance-state) deltay)))
    (if (or (eq mouse-avoidance-mode 'animate)
	    (eq mouse-avoidance-mode 'proteus))
	(let ((i 0.0)
	      (incr (max .1 (/ 1.0 mouse-avoidance-nudge-dist))))
	  (setq mouse-avoidance-animating-pointer t)
	  (while (<= i 1)
	    (mouse-avoidance-set-mouse-position
	     (cons (+ (car cur-pos) (round (* i deltax)))
		   (+ (cdr cur-pos) (round (* i deltay)))))
    	    (setq i (+ i incr))
	    (if (eq mouse-avoidance-mode 'proteus)
		(mouse-avoidance-set-pointer-shape
		 (mouse-avoidance-random-shape)))
	    (sit-for mouse-avoidance-animation-delay))
	  (setq mouse-avoidance-animating-pointer nil))
      (mouse-avoidance-set-mouse-position (cons (+ (car (cdr cur)) deltax)
						(+ (cdr (cdr cur)) deltay))))))

(defvar x-pointer-invisible) ; silence byte-compiler

(defun mouse-avoidance-random-shape ()
  "Return a random cursor shape.
This assumes that any variable whose name begins with x-pointer- and
has an integer value is a valid cursor shape.  You might want to
redefine this function to suit your own tastes."
  (if (null mouse-avoidance-pointer-shapes)
      (progn
	(dolist (i (all-completions "x-pointer-" obarray
				    (lambda (x)
				      (and (boundp x)
                                           (integerp (symbol-value x))))))
          (ignore-errors
            (let ((value (symbol-value (intern i))))
              (when (< value x-pointer-invisible)
                (push value mouse-avoidance-pointer-shapes)))))))
  (seq-random-elt mouse-avoidance-pointer-shapes))

(defun mouse-avoidance-ignore-p ()
  (let ((mp (mouse-position)))
    (or (not (frame-pointer-visible-p)) ; The pointer is hidden
        (not cursor-type)               ; There's no cursor
        executing-kbd-macro	       ; don't check inside macro
	(null (cadr mp))	       ; don't move unless in an Emacs frame
	(not (eq (car mp) (selected-frame)))
        ;; Don't interfere with ongoing `mouse-drag-and-drop-region'
        ;; (Bug#36269).
        (or (eq track-mouse 'dropping)
            (eq track-mouse 'drag-source))
	;; Don't do anything if last event was a mouse event.
	;; FIXME: this code fails in the case where the mouse was moved
	;; since the last key-press but without generating any event.
	(and (consp last-input-event)
	     (symbolp (car last-input-event))
	     (let ((modifiers (event-modifiers (car last-input-event))))
	       (or (memq (car last-input-event)
			 '(mouse-movement scroll-bar-movement
			   select-window focus-out))
		   (memq 'click modifiers)
		   (memq 'double modifiers)
		   (memq 'triple modifiers)
		   (memq 'drag modifiers)
		   (memq 'down modifiers)
		   (memq 'meta modifiers)
		   (memq 'control modifiers)
		   (memq 'shift modifiers)
		   (memq 'hyper modifiers)
		   (memq 'super modifiers)
		   (memq 'alt modifiers)))))))

(defun mouse-avoidance-banish ()
  (if (not (mouse-avoidance-ignore-p))
      (mouse-avoidance-banish-mouse)))

(defun mouse-avoidance-exile ()
  ;; For exile mode, the state is nil when the mouse is in its normal
  ;; position, and set to the old mouse-position when the mouse is in exile.
  (if (not (mouse-avoidance-ignore-p))
      (let ((mp (mouse-position)))
	(cond ((and (not mouse-avoidance-state)
		    (mouse-avoidance-too-close-p mp))
	       (setq mouse-avoidance-state mp)
	       (mouse-avoidance-banish-mouse))
	      ((and mouse-avoidance-state
		    (not (mouse-avoidance-too-close-p mouse-avoidance-state)))
	       (if (and (eq (car mp) (selected-frame))
			(equal (cdr mp) (mouse-avoidance-banish-destination)))
		   (mouse-avoidance-set-mouse-position
		    ;; move back only if user has not moved mouse
		    (cdr mouse-avoidance-state)))
	       ;; but clear state anyway, to be ready for another move
	       (setq mouse-avoidance-state nil))))))

(defun mouse-avoidance-fancy ()
  ;; Used for the "fancy" modes, i.e. jump et al.
  (if (and (not mouse-avoidance-animating-pointer)
	   (not (mouse-avoidance-ignore-p))
	   (mouse-avoidance-too-close-p (mouse-position)))
      (let ((old-pos (mouse-position)))
	(mouse-avoidance-nudge-mouse)
	(if (not (eq (selected-frame) (car old-pos)))
	    ;; This should never happen.
            (apply #'set-mouse-position old-pos)))))

;;;###autoload
(defun mouse-avoidance-mode (&optional mode)
  "Set Mouse Avoidance mode to MODE.
MODE should be one of the symbols `banish', `exile', `jump', `animate',
`cat-and-mouse', `proteus', or `none'.

If MODE is nil, toggle mouse avoidance between `none' and `banish'
modes.  Positive numbers and symbols other than the above are treated
as equivalent to `banish'; negative numbers and `-' are equivalent to `none'.

Effects of the different modes:
 * banish: Move the mouse to the upper-right corner on any keypress.
 * exile: Move the mouse to the corner only if the cursor gets too close,
     and allow it to return once the cursor is out of the way.
 * jump: If the cursor gets too close to the mouse, displace the mouse
     a random distance & direction.
 * animate: As `jump', but shows steps along the way for illusion of motion.
 * cat-and-mouse: Same as `animate'.
 * proteus: As `animate', but changes the shape of the mouse pointer too.

\(See `mouse-avoidance-threshold' for definition of \"too close\",
and `mouse-avoidance-nudge-dist' and `mouse-avoidance-nudge-var' for
definition of \"random distance\".)"
  (interactive
   (list (intern (completing-read
		  "Select cursor avoidance technique (SPACE for list): "
		  '(("banish") ("exile") ("jump") ("animate")
		    ("cat-and-mouse") ("proteus") ("none"))
		  nil t))))
  (if (eq mode 'cat-and-mouse)
      (setq mode 'animate))
  (if mouse-avoidance-timer
      (cancel-timer mouse-avoidance-timer))
  (setq mouse-avoidance-timer nil)

  ;; Restore pointer shape if necessary
  (if (eq mouse-avoidance-mode 'proteus)
      (mouse-avoidance-set-pointer-shape mouse-avoidance-old-pointer-shape))

  ;; Do additional setup depending on version of mode requested
  (cond	((eq mode 'none)
	 (setq mouse-avoidance-mode nil))
	((or (eq mode 'jump)
	     (eq mode 'animate)
	     (eq mode 'proteus))
	 (setq mouse-avoidance-timer
	       (run-with-idle-timer 0.1 t 'mouse-avoidance-fancy))
	 (setq mouse-avoidance-mode mode
	       mouse-avoidance-state (cons 0 0)
	       mouse-avoidance-old-pointer-shape
	       (and (boundp 'x-pointer-shape) x-pointer-shape)))
	((eq mode 'exile)
	 (setq mouse-avoidance-timer
	       (run-with-idle-timer 0.1 t 'mouse-avoidance-exile))
	 (setq mouse-avoidance-mode mode
	       mouse-avoidance-state nil))
	((or (eq mode 'banish)
	     (eq mode t)
	     (and (null mode) (null mouse-avoidance-mode))
	     (and mode (> (prefix-numeric-value mode) 0)))
	 (setq mouse-avoidance-timer
	       (run-with-idle-timer 0.1 t 'mouse-avoidance-banish))
	 (setq mouse-avoidance-mode 'banish))
	(t (setq mouse-avoidance-mode nil)))
  (force-mode-line-update))

;; Most people who use avoid mode leave it on all the time, so it's not
;; very informative to announce it in the mode line.
;;(or (assq 'mouse-avoidance-mode minor-mode-alist)
;;    (setq minor-mode-alist (cons '(mouse-avoidance-mode " Avoid")
;;				 minor-mode-alist)))

;; Needed for custom.
(if mouse-avoidance-mode
    (mouse-avoidance-mode mouse-avoidance-mode))

(provide 'avoid)

;;; avoid.el ends here