code.delx.au - gnu-emacs-elpa/blob - beacon.el

   1 ;;; beacon.el --- Highlight the cursor whenever it moves long distances  -*- lexical-binding: t; -*-
   2
   3 ;; Copyright (C) 2015  Artur Malabarba
   4
   5 ;; Author: Artur Malabarba <emacs@endlessparentheses.com>
   6 ;; URL: https://github.com/Malabarba/beacon
   7 ;; Keywords: convenience
   8 ;; Version: 0.1
   9 ;; Package-Requires: ((seq "1.9"))
  10
  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.
  15
  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.
  20
  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/>.
  23
  24 ;;; Commentary:
  25
  26 ;; This is a global minor-mode.  Turn it on everywhere with
  27 ;;     (beacon-mode 1)
  28
  29 ;;; Code:
  30
  31 (require 'seq)
  32
  33 (defgroup beacon nil
  34   "Customization group for beacon."
  35   :group 'emacs
  36   :prefix "beacon-")
  37
  38 (defvar beacon--timer nil)
  39
  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)))
  46
  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)))
  53
  54 (defcustom beacon-blink-when-buffer-changes t
  55   "Should the beacon blink when changing buffer?"
  56   :type 'boolean)
  57
  58 (defcustom beacon-blink-when-window-scrolls t
  59   "Should the beacon blink when the window scrolls?"
  60   :type 'boolean)
  61
  62 (defcustom beacon-blink-duration 0.3
  63   "Time, in seconds, that the blink should last."
  64   :type 'number)
  65
  66 (defcustom beacon-blink-delay 0.3
  67   "Time, in seconds, before starting to fade the beacon."
  68   :type 'number)
  69
  70 (defcustom beacon-size 40
  71   "Size of the beacon in characters."
  72   :type 'number)
  73
  74 (defcustom beacon-color 0.5
  75   "Color of the beacon.
  76 This can be a string or a number.
  77
  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.
  81
  82 If it is a string, it is a color name or specification,
  83 e.g. \"#666600\"."
  84   :type '(choice number color))
  85
  86 \f
  87 ;;; Overlays
  88 (defvar beacon--ovs nil)
  89
  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)))
  96
  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   (if (not colors)
 102       (delete-overlay overlay)
 103     (overlay-put overlay 'beacon-colors colors)
 104     (overlay-put overlay 'after-string
 105                  (propertize
 106                   (mapconcat (lambda (c) (propertize " " 'face (list :background c)))
 107                              colors
 108                              "")
 109                   'cursor 1000))))
 110
 111 (defun beacon--after-string-overlay (colors)
 112   "Put an overlay at point with an after-string property.
 113 The property's value is a string of spaces with background
 114 COLORS applied to each one."
 115   (let ((ov (make-overlay (point) (point)))
 116         ;; The after-string must not be longer than the remaining columns from
 117         ;; point to right window-end else it will be wrapped around (assuming
 118         ;; truncate-lines is nil) introducing an ugly wrap-around for a
 119         ;; fraction of a second.
 120         (colors (seq-take colors (- (window-width) (current-column)))))
 121     (beacon--ov-put-after-string ov colors)
 122     (overlay-put ov 'beacon t)
 123     (push ov beacon--ovs)))
 124
 125 (defun beacon--ov-at-point ()
 126   (car (or (seq-filter (lambda (o) (overlay-get o 'beacon))
 127                      (overlays-in (point) (point)))
 128            (seq-filter (lambda (o) (overlay-get o 'beacon))
 129                      (overlays-at (point))))))
 130
 131 (defun beacon--vanish ()
 132   "Turn off the beacon."
 133   (when (timerp beacon--timer)
 134     (cancel-timer beacon--timer))
 135   (mapc #'delete-overlay beacon--ovs)
 136   (setq beacon--ovs nil))
 137
 138 \f
 139 ;;; Colors
 140 (defun beacon--int-range (a b)
 141   "Return a list of integers between A inclusive and B exclusive.
 142 Only returns `beacon-size' elements."
 143   (let ((d (/ (- b a) beacon-size))
 144         (out (list a)))
 145     (dotimes (_ (1- beacon-size))
 146       (push (+ (car out) d) out))
 147     (nreverse out)))
 148
 149 (defun beacon--color-range ()
 150   "Return a list of background colors for the beacon."
 151   (let* ((bg (color-values (face-attribute 'default :background)))
 152          (fg (cond
 153               ((stringp beacon-color) (color-values beacon-color))
 154               ((< (color-distance "black" bg)
 155                   (color-distance "white" bg))
 156                (make-list 3 (* beacon-color 65535)))
 157               (t (make-list 3 (* (- 1 beacon-color) 65535))))))
 158     (apply #'cl-mapcar (lambda (r g b) (format "#%04x%04x%04x" r g b))
 159            (mapcar (lambda (n) (butlast (beacon--int-range (elt fg n) (elt bg n))))
 160                    [0 1 2]))))
 161
 162 \f
 163 ;;; Blinking
 164 (defun beacon--shine ()
 165   "Shine a beacon at point."
 166   (let ((colors (beacon--color-range)))
 167     (save-excursion
 168       (while colors
 169         (if (looking-at "$")
 170             (progn
 171               (beacon--after-string-overlay colors)
 172               (setq colors nil))
 173           (beacon--colored-overlay (pop colors))
 174           (forward-char 1))))))
 175
 176 (defun beacon--dec ()
 177   "Decrease the beacon brightness by one."
 178   (pcase (beacon--ov-at-point)
 179     (`nil (beacon--vanish))
 180     ((and o (let c (overlay-get o 'beacon-colors)) (guard c))
 181      (beacon--ov-put-after-string o (cdr c)))
 182     (o
 183      (delete-overlay o)
 184      (save-excursion
 185        (while (progn (forward-char 1)
 186                      (setq o (beacon--ov-at-point)))
 187          (let ((colors (overlay-get o 'beacon-colors)))
 188            (if (not colors)
 189                (move-overlay o (1- (point)) (point))
 190              (forward-char -1)
 191              (beacon--colored-overlay (pop colors))
 192              (beacon--ov-put-after-string o colors)
 193              (forward-char 1))))))))
 194
 195 (defun beacon-blink ()
 196   "Blink the beacon at the position of the cursor."
 197   (interactive)
 198   (beacon--vanish)
 199   (beacon--shine)
 200   (setq beacon--timer
 201         (run-at-time beacon-blink-delay
 202                      (/ beacon-blink-duration 1.0 beacon-size)
 203                      #'beacon--dec)))
 204
 205 \f
 206 ;;; Movement detection
 207 (defvar beacon--previous-place nil)
 208 (defvar beacon--previous-window-start nil)
 209 (defvar beacon--previous-mark-head nil)
 210
 211 (defun beacon--movement-> (delta)
 212   "Return non-nil if latest point movement is > DELTA.
 213 If DELTA is nil, return nil."
 214   (and delta
 215        (markerp beacon--previous-place)
 216        (equal (marker-buffer beacon--previous-place)
 217               (current-buffer))
 218        (> (abs (- (point) beacon--previous-place))
 219           delta)
 220        (> (count-screen-lines (min (point) beacon--previous-place)
 221                               (max (point) beacon--previous-place))
 222           delta)))
 223
 224 (defun beacon--maybe-push-mark ()
 225   "Push mark if it seems to be safe."
 226   (when (and (not mark-active)
 227              (beacon--movement-> beacon-push-mark))
 228     (let ((head (car mark-ring)))
 229       (when (and (eq beacon--previous-mark-head head)
 230                  (not (equal head beacon--previous-place)))
 231         (push-mark beacon--previous-place)))))
 232
 233 (defun beacon--post-command ()
 234   "Blink if point moved very far."
 235   (cond
 236    ((not (markerp beacon--previous-place))
 237     (beacon--vanish))
 238    ;; Blink because we changed buffer.
 239    ((not (equal (marker-buffer beacon--previous-place)
 240                 (current-buffer)))
 241     (when beacon-blink-when-buffer-changes
 242       (unless (window-minibuffer-p)
 243         (beacon-blink))))
 244    ;; Blink for scrolling.
 245    ((and beacon-blink-when-window-scrolls
 246          (progn (redisplay)
 247                 (not (equal beacon--previous-window-start (window-start)))))
 248     (beacon-blink))
 249    ;; Blink for movement
 250    ((beacon--movement-> beacon-blink-when-point-moves)
 251     (beacon-blink))
 252    ;; Even if we don't blink, vanish any previous beacon.
 253    (t (beacon--vanish)))
 254   (beacon--maybe-push-mark)
 255   (unless (window-minibuffer-p)
 256     (setq beacon--previous-window-start (window-start))
 257     (setq beacon--previous-mark-head (car mark-ring))
 258     (setq beacon--previous-place (point-marker))))
 259
 260 \f
 261 ;;; Minor-mode
 262 (defcustom beacon-lighter (cond
 263                      ((char-displayable-p ?💡) " 💡")
 264                      ((char-displayable-p ?Λ) " Λ")
 265                      (t " *"))
 266   "Lighter string used on the mode-line."
 267   :type 'string)
 268
 269 ;;;###autoload
 270 (define-minor-mode beacon-mode
 271   nil nil beacon-lighter nil
 272   :global t
 273   (if beacon-mode
 274       (add-hook 'post-command-hook #'beacon--post-command)
 275     (remove-hook 'post-command-hook #'beacon--post-command)))
 276
 277 (provide 'beacon)
 278 ;;; beacon.el ends here