BTW, I just tried it out and it looks great! I like that meteor trail
effect :)

I now just need to figure out how to make it play nice with fci-mode.

If a beacon pre/post hook is available, I can disable/enable fci-mode in
there.

I have this to make fci-mode play nice with popup:

    ;; Turn off fci-mode when popups are activated
    ;;
https://github.com/alpaker/Fill-Column-Indicator/issues/21#issuecomment-6959718
    (with-eval-after-load 'popup
      (defvar sanityinc/fci-mode-suppressed nil)

      (defun sanityinc/suppress-fci-mode (&rest args)
        "Suspend fci-mode while popups are visible"
        (setq-local sanityinc/fci-mode-suppressed fci-mode)
        (when fci-mode
          (turn-off-fci-mode)))
      (advice-add 'popup-create :before #'sanityinc/suppress-fci-mode)

      (defun sanityinc/restore-fci-mode (&rest args)
        "Restore fci-mode when all popups have closed"
        (when (and sanityinc/fci-mode-suppressed
                   (null popup-instances))
          (setq-local sanityinc/fci-mode-suppressed nil)
          (turn-on-fci-mode)))
      (advice-add 'popup-delete :after #'sanityinc/restore-fci-mode))





--
Kaushal Modi

On Thu, Oct 15, 2015 at 1:26 PM, Kaushal Modi <kaushal.modi@gmail.com>
wrote:

> Of course pulse.el is a library which other packages might find useful and
> beacon.el is an end-user package. I was just curious if the technique used
> to set overlay on the current position was similar.
>
>
> --
> Kaushal Modi
>
> On Thu, Oct 15, 2015 at 1:24 PM, Kaushal Modi <kaushal.modi@gmail.com>
> wrote:
>
>> I haven't read either of the source codes, but is it similar to
>> lisp/cedet/pulse.el?
>>
>>
>> --
>> Kaushal Modi
>>
>> On Thu, Oct 15, 2015 at 1:02 PM, Artur Malabarba <
>> bruce.connor.am@gmail.com> wrote:
>>
>>> Whenever the window scrolls or the buffer changes a light will shine on
>>> top of your cursor so you know where it is.
>>>
>>> That’s it. See this gif for example:
>>> https://github.com/Malabarba/beacon/raw/master/example-beacon.gif
>>>
>>>
>>> ----------
>>>
>>>
>>> ;;; beacon.el --- Highlight the cursor when the window scrolls  -*-
>>> lexical-binding: t; -*-
>>>
>>> ;; Copyright (C) 2015 Free Software Foundation, Inc.
>>>
>>> ;; Author: Artur Malabarba <emacs@endlessparentheses.com>
>>> ;; URL: https://github.com/Malabarba/beacon
>>> ;; Keywords: convenience
>>> ;; Version: 0.1
>>> ;; Package-Requires: ((seq "1.9"))
>>>
>>> ;; This program 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.
>>>
>>> ;; This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
>>>
>>> ;;; Commentary:
>>>
>>> ;; This is a global minor-mode. Turn it on everywhere with:
>>> ;; ┌────
>>> ;; │ (beacon-mode 1)
>>> ;; └────
>>> ;;
>>> ;; Whenever the window scrolls or the buffer changes a light will shine
>>> on
>>> ;; top of your cursor so you know where it is.
>>> ;;
>>> ;; That’s it.
>>> ;;
>>> ;;
>>> ;; 1 Customizations
>>> ;; ════════════════
>>> ;;
>>> ;;   • To customize the appearance of the beacon, configure `beacon-size'
>>> ;;     and `beacon-color'.
>>> ;;
>>> ;;   • To customize how long it lasts, configure `beacon-blink-duration'
>>> ;;       and `beacon-blink-delay'.
>>> ;;
>>> ;;   • To customize /when/ it is used at all, configure
>>> ;;     `beacon-blink-when-window-scrolls',
>>> ;;     `beacon-blink-when-buffer-changes', and
>>> ;;     `beacon-blink-when-point-moves'.
>>>
>>> ;;; Code:
>>>
>>> (require 'seq)
>>>
>>> (defgroup beacon nil
>>>   "Customization group for beacon."
>>>   :group 'emacs
>>>   :prefix "beacon-")
>>>
>>> (defvar beacon--timer nil)
>>>
>>> (defcustom beacon-push-mark nil
>>>   "Should the mark be pushed before long movements?
>>> If nil, `beacon' will not push the mark.
>>> Otherwise this should be a number, and `beacon' will push the
>>> mark whenever point moves more than that many lines."
>>>   :type '(choice integer (const nil)))
>>>
>>> (defcustom beacon-blink-when-point-moves nil
>>>   "Should the beacon blink when moving a long distance?
>>> If nil, don't blink due to plain movement.
>>> If non-nil, this should be an integer, which is the minimum
>>> movement distance (in lines) that triggers a beacon blink."
>>>   :type '(choice integer (const nil)))
>>>
>>> (defcustom beacon-blink-when-buffer-changes t
>>>   "Should the beacon blink when changing buffer?"
>>>   :type 'boolean)
>>>
>>> (defcustom beacon-blink-when-window-scrolls t
>>>   "Should the beacon blink when the window scrolls?"
>>>   :type 'boolean)
>>>
>>> (defcustom beacon-blink-duration 0.3
>>>   "Time, in seconds, that the blink should last."
>>>   :type 'number)
>>>
>>> (defcustom beacon-blink-delay 0.3
>>>   "Time, in seconds, before starting to fade the beacon."
>>>   :type 'number)
>>>
>>> (defcustom beacon-size 40
>>>   "Size of the beacon in characters."
>>>   :type 'number)
>>>
>>> (defcustom beacon-color 0.5
>>>   "Color of the beacon.
>>> This can be a string or a number.
>>>
>>> If it is a number, the color is taken to be white or
>>> black (depending on the current theme's background) and this
>>> number is a float between 0 and 1 specifing the brightness.
>>>
>>> If it is a string, it is a color name or specification,
>>> e.g. \"#666600\"."
>>>   :type '(choice number color))
>>>
>>>
>>> ;;; Overlays
>>> (defvar beacon--ovs nil)
>>>
>>> (defun beacon--colored-overlay (color)
>>>   "Put an overlay at point with background COLOR."
>>>   (let ((ov (make-overlay (point) (1+ (point)))))
>>>     (overlay-put ov 'face (list :background color))
>>>     (overlay-put ov 'beacon t)
>>>     (push ov beacon--ovs)))
>>>
>>> (defun beacon--ov-put-after-string (overlay colors)
>>>   "Add an after-string property to OVERLAY.
>>> The property's value is a string of spaces with background
>>> COLORS applied to each one."
>>>   (if (not colors)
>>>       (delete-overlay overlay)
>>>     (overlay-put overlay 'beacon-colors colors)
>>>     (overlay-put overlay 'after-string
>>>                  (propertize
>>>                   (mapconcat (lambda (c) (propertize " " 'face (list
>>> :background c)))
>>>                              colors
>>>                              "")
>>>                   'cursor 1000))))
>>>
>>> (defun beacon--after-string-overlay (colors)
>>>   "Put an overlay at point with an after-string property.
>>> The property's value is a string of spaces with background
>>> COLORS applied to each one."
>>>   (let ((ov (make-overlay (point) (point)))
>>>         ;; The after-string must not be longer than the remaining
>>> columns from
>>>         ;; point to right window-end else it will be wrapped around
>>> (assuming
>>>         ;; truncate-lines is nil) introducing an ugly wrap-around for a
>>>         ;; fraction of a second.
>>>         (colors (seq-take colors (- (window-width) (current-column)))))
>>>     (beacon--ov-put-after-string ov colors)
>>>     (overlay-put ov 'beacon t)
>>>     (push ov beacon--ovs)))
>>>
>>> (defun beacon--ov-at-point ()
>>>   (car (or (seq-filter (lambda (o) (overlay-get o 'beacon))
>>>                      (overlays-in (point) (point)))
>>>            (seq-filter (lambda (o) (overlay-get o 'beacon))
>>>                      (overlays-at (point))))))
>>>
>>> (defun beacon--vanish ()
>>>   "Turn off the beacon."
>>>   (when (timerp beacon--timer)
>>>     (cancel-timer beacon--timer))
>>>   (mapc #'delete-overlay beacon--ovs)
>>>   (setq beacon--ovs nil))
>>>
>>>
>>> ;;; Colors
>>> (defun beacon--int-range (a b)
>>>   "Return a list of integers between A inclusive and B exclusive.
>>> Only returns `beacon-size' elements."
>>>   (let ((d (/ (- b a) beacon-size))
>>>         (out (list a)))
>>>     (dotimes (_ (1- beacon-size))
>>>       (push (+ (car out) d) out))
>>>     (nreverse out)))
>>>
>>> (defun beacon--color-range ()
>>>   "Return a list of background colors for the beacon."
>>>   (let* ((bg (color-values (face-attribute 'default :background)))
>>>          (fg (cond
>>>               ((stringp beacon-color) (color-values beacon-color))
>>>               ((< (color-distance "black" bg)
>>>                   (color-distance "white" bg))
>>>                (make-list 3 (* beacon-color 65535)))
>>>               (t (make-list 3 (* (- 1 beacon-color) 65535))))))
>>>     (apply #'cl-mapcar (lambda (r g b) (format "#%04x%04x%04x" r g b))
>>>            (mapcar (lambda (n) (butlast (beacon--int-range (elt fg n)
>>> (elt bg n))))
>>>                    [0 1 2]))))
>>>
>>>
>>> ;;; Blinking
>>> (defun beacon--shine ()
>>>   "Shine a beacon at point."
>>>   (let ((colors (beacon--color-range)))
>>>     (save-excursion
>>>       (while colors
>>>         (if (looking-at "$")
>>>             (progn
>>>               (beacon--after-string-overlay colors)
>>>               (setq colors nil))
>>>           (beacon--colored-overlay (pop colors))
>>>           (forward-char 1))))))
>>>
>>> (defun beacon--dec ()
>>>   "Decrease the beacon brightness by one."
>>>   (pcase (beacon--ov-at-point)
>>>     (`nil (beacon--vanish))
>>>     ((and o (let c (overlay-get o 'beacon-colors)) (guard c))
>>>      (beacon--ov-put-after-string o (cdr c)))
>>>     (o
>>>      (delete-overlay o)
>>>      (save-excursion
>>>        (while (progn (forward-char 1)
>>>                      (setq o (beacon--ov-at-point)))
>>>          (let ((colors (overlay-get o 'beacon-colors)))
>>>            (if (not colors)
>>>                (move-overlay o (1- (point)) (point))
>>>              (forward-char -1)
>>>              (beacon--colored-overlay (pop colors))
>>>              (beacon--ov-put-after-string o colors)
>>>              (forward-char 1))))))))
>>>
>>> (defun beacon-blink ()
>>>   "Blink the beacon at the position of the cursor."
>>>   (interactive)
>>>   (beacon--vanish)
>>>   (beacon--shine)
>>>   (setq beacon--timer
>>>         (run-at-time beacon-blink-delay
>>>                      (/ beacon-blink-duration 1.0 beacon-size)
>>>                      #'beacon--dec)))
>>>
>>>
>>> ;;; Movement detection
>>> (defvar beacon--window-scrolled nil)
>>> (defvar beacon--previous-place nil)
>>> (defvar beacon--previous-mark-head nil)
>>>
>>> (defun beacon--movement-> (delta)
>>>   "Return non-nil if latest point movement is > DELTA.
>>> If DELTA is nil, return nil."
>>>   (and delta
>>>        (markerp beacon--previous-place)
>>>        (equal (marker-buffer beacon--previous-place)
>>>               (current-buffer))
>>>        (> (abs (- (point) beacon--previous-place))
>>>           delta)
>>>        (> (count-screen-lines (min (point) beacon--previous-place)
>>>                               (max (point) beacon--previous-place))
>>>           delta)))
>>>
>>> (defun beacon--maybe-push-mark ()
>>>   "Push mark if it seems to be safe."
>>>   (when (and (not mark-active)
>>>              (beacon--movement-> beacon-push-mark))
>>>     (let ((head (car mark-ring)))
>>>       (when (and (eq beacon--previous-mark-head head)
>>>                  (not (equal head beacon--previous-place)))
>>>         (push-mark beacon--previous-place)))))
>>>
>>> (defun beacon--post-command ()
>>>   "Blink if point moved very far."
>>>   (cond
>>>    ((not (markerp beacon--previous-place))
>>>     (beacon--vanish))
>>>    ;; Blink because we changed buffer.
>>>    ((not (equal (marker-buffer beacon--previous-place)
>>>                 (current-buffer)))
>>>     (when beacon-blink-when-buffer-changes
>>>       (unless (window-minibuffer-p)
>>>         (beacon-blink))))
>>>    ;; Blink for scrolling.
>>>    ((and beacon-blink-when-window-scrolls
>>>          beacon--window-scrolled
>>>          (equal beacon--window-scrolled (selected-window)))
>>>     (beacon-blink)
>>>     (setq beacon--window-scrolled nil))
>>>    ;; Blink for movement
>>>    ((beacon--movement-> beacon-blink-when-point-moves)
>>>     (beacon-blink))
>>>    ;; Even if we don't blink, vanish any previous beacon.
>>>    (t (beacon--vanish)))
>>>   (beacon--maybe-push-mark)
>>>   (unless (window-minibuffer-p)
>>>     (setq beacon--previous-mark-head (car mark-ring))
>>>     (setq beacon--previous-place (point-marker))))
>>>
>>> (defun beacon--window-scroll-function (win _start-pos)
>>>   "Blink the beacon or record that window has been scrolled.
>>> If invoked during the command loop, record the current window so
>>> that it may be blinked on post-command.  This is because the
>>> scrolled window might not be active, but we only know that at
>>> `post-command-hook'.
>>>
>>> If invoked outside the command loop, `post-command-hook' would be
>>> unreliable, so just blink immediately."
>>>   (if this-command
>>>       (setq beacon--window-scrolled win)
>>>     (beacon-blink)))
>>>
>>>
>>> ;;; Minor-mode
>>> (defcustom beacon-lighter
>>>   (cond
>>>    ((char-displayable-p ?💡) " 💡")
>>>    ((char-displayable-p ?Λ) " Λ")
>>>    (t " *"))
>>>   "Lighter string used on the mode-line."
>>>   :type 'string)
>>>
>>> ;;;###autoload
>>> (define-minor-mode beacon-mode
>>>   nil nil beacon-lighter nil
>>>   :global t
>>>   (if beacon-mode
>>>       (progn
>>>         (add-hook 'window-scroll-functions
>>> #'beacon--window-scroll-function)
>>>         (add-hook 'post-command-hook #'beacon--post-command))
>>>     (remove-hook 'window-scroll-functions
>>> #'beacon--window-scroll-function)
>>>     (remove-hook 'post-command-hook #'beacon--post-command)))
>>>
>>> (provide 'beacon)
>>> ;;; beacon.el ends here
>>>
>>>
>>
>