1 ;;; beacon.el --- Highlight the cursor whenever it moves long distances -*- lexical-binding: t; -*-
3 ;; Copyright (C) 2015 Artur Malabarba
5 ;; Author: Artur Malabarba <emacs@endlessparentheses.com>
6 ;; URL: https://github.com/Malabarba/beacon
7 ;; Keywords: convenience
9 ;; Package-Requires: ((cl-lib "0.5"))
11 ;; This program is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation, either version 3 of the License, or
14 ;; (at your option) any later version.
16 ;; This program is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with this program. If not, see <http://www.gnu.org/licenses/>.
26 ;; This is a global minor-mode. Turn it on everywhere with
34 "Customization group for beacon."
38 (defvar beacon--timer nil)
40 (defcustom beacon-push-mark nil
41 "Should the mark be pushed before long movements?
42 If nil, `beacon' will not push the mark.
43 Otherwise this should be a number, and `beacon' will push the
44 mark whenever point moves more than that many lines."
45 :type '(choice integer (const nil)))
47 (defcustom beacon-blink-when-point-moves nil
48 "Should the beacon blink when moving a long distance?
49 If nil, don't blink due to plain movement.
50 If non-nil, this should be an integer, which is the minimum
51 movement distance (in lines) that triggers a beacon blink."
52 :type '(choice integer (const nil)))
54 (defcustom beacon-blink-when-buffer-changes t
55 "Should the beacon blink when changing buffer?"
58 (defcustom beacon-blink-when-window-scrolls t
59 "Should the beacon blink when the window scrolls?"
62 (defcustom beacon-blink-duration 0.3
63 "Time, in seconds, that the blink should last."
66 (defcustom beacon-blink-delay 0.3
67 "Time, in seconds, before starting to fade the beacon."
70 (defcustom beacon-size 40
71 "Size of the beacon in characters."
74 (defcustom beacon-color 0.5
76 This can be a string or a number.
78 If it is a number, the color is taken to be white or
79 black (depending on the current theme's background) and this
80 number is a float between 0 and 1 specifing the brightness.
82 If it is a string, it is a color name or specification,
84 :type '(choice number color))
88 (defvar beacon--ovs nil)
90 (defun beacon--colored-overlay (color)
91 "Put an overlay at point with background COLOR."
92 (let ((ov (make-overlay (point) (1+ (point)))))
93 (overlay-put ov 'face (list :background color))
94 (overlay-put ov 'beacon t)
95 (push ov beacon--ovs)))
97 (defun beacon--ov-put-after-string (overlay colors)
98 "Add an after-string property to OVERLAY.
99 The property's value is a string of spaces with background
100 COLORS applied to each one."
101 (overlay-put overlay 'beacon-colors colors)
102 (overlay-put overlay 'after-string
103 (mapconcat (lambda (c) (propertize " " 'face (list :background c)))
107 (defun beacon--after-string-overlay (colors)
108 "Put an overlay at point with an after-string property.
109 The property's value is a string of spaces with background
110 COLORS applied to each one."
111 (let ((ov (make-overlay (point) (point))))
112 (beacon--ov-put-after-string ov colors)
113 (overlay-put ov 'beacon t)
114 (push ov beacon--ovs)))
116 (defun beacon--ov-at-point ()
117 (car (cl-member-if (lambda (o) (overlay-get o 'beacon))
118 (overlays-at (point)))))
120 (defun beacon--vanish ()
121 "Turn off the beacon."
122 (when (timerp beacon--timer)
123 (cancel-timer beacon--timer))
124 (mapc #'delete-overlay beacon--ovs)
125 (setq beacon--ovs nil))
129 (defun beacon--int-range (a b)
130 "Return a list of integers between A inclusive and B exclusive.
131 Only returns `beacon-size' elements."
132 (let ((d (/ (- b a) beacon-size))
134 (dotimes (_ (1- beacon-size))
135 (push (+ (car out) d) out))
138 (defun beacon--color-range ()
139 "Return a list of background colors for the beacon."
140 (let* ((bg (color-values (face-attribute 'default :background)))
142 ((stringp beacon-color) (color-values beacon-color))
143 ((< (color-distance "black" bg)
144 (color-distance "white" bg))
145 (make-list 3 (* beacon-color 65535)))
146 (t (make-list 3 (* (- 1 beacon-color) 65535))))))
147 (apply #'cl-mapcar (lambda (r g b) (format "#%04x%04x%04x" r g b))
148 (mapcar (lambda (n) (butlast (beacon--int-range (elt fg n) (elt bg n))))
153 (defun beacon--shine ()
154 "Shine a beacon at point."
155 (let ((colors (beacon--color-range)))
160 (beacon--after-string-overlay colors)
162 (beacon--colored-overlay (pop colors))
163 (forward-char 1))))))
165 (defun beacon--dec ()
166 "Decrease the beacon brightness by one."
167 (let ((o (beacon--ov-at-point)))
172 (while (progn (forward-char 1)
173 (setq o (beacon--ov-at-point)))
174 (let ((colors (overlay-get o 'beacon-colors)))
176 (move-overlay o (1- (point)) (point))
178 (beacon--colored-overlay (pop colors))
179 (beacon--ov-put-after-string o colors))))))))
181 (defun beacon-blink ()
182 "Blink the beacon at the position of the cursor."
187 (run-at-time beacon-blink-delay
188 (/ beacon-blink-duration 1.0 beacon-size)
192 ;;; Movement detection
193 (defvar beacon--previous-place nil)
194 (defvar beacon--previous-window-start nil)
195 (defvar beacon--previous-mark-head nil)
197 (defun beacon--movement-> (delta)
198 "Return non-nil if latest point movement is > DELTA.
199 If DELTA is nil, return nil."
201 (equal (marker-buffer beacon--previous-place)
203 (> (abs (- (point) beacon--previous-place))
205 (> (count-screen-lines (min (point) beacon--previous-place)
206 (max (point) beacon--previous-place))
209 (defun beacon--maybe-push-mark ()
210 "Push mark if it seems to be safe."
211 (when (and (not mark-active)
212 (beacon--movement-> beacon-push-mark))
213 (let ((head (car mark-ring)))
214 (when (and (eq beacon--previous-mark-head head)
215 (not (equal head beacon--previous-place)))
216 (push-mark beacon--previous-place)))))
218 (defun beacon--post-command ()
219 "Blink if point moved very far."
221 ((not (markerp beacon--previous-place))
223 ;; Blink because we changed buffer.
224 ((not (equal (marker-buffer beacon--previous-place)
226 (when beacon-blink-when-buffer-changes
227 (unless (window-minibuffer-p)
229 ;; Blink for scrolling.
230 ((and beacon-blink-when-window-scrolls
232 (not (equal beacon--previous-window-start (window-start)))))
234 ;; Blink for movement
235 ((beacon--movement-> beacon-blink-when-point-moves)
237 ;; Even if we don't blink, vanish any previous beacon.
238 (t (beacon--vanish)))
239 (beacon--maybe-push-mark)
240 (unless (window-minibuffer-p)
241 (setq beacon--previous-window-start (window-start))
242 (setq beacon--previous-mark-head (car mark-ring))
243 (setq beacon--previous-place (point-marker))))
247 (defcustom beacon-lighter (cond
248 ((char-displayable-p ?💡) "💡")
249 ((char-displayable-p ?Λ) "Λ")
251 "Lighter string used on the mode-line."
255 (define-minor-mode beacon-mode
256 nil nil beacon-lighter nil
259 (add-hook 'post-command-hook #'beacon--post-command)
260 (remove-hook 'post-command-hook #'beacon--post-command)))
263 ;;; beacon.el ends here