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.
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Kaushal ModiOn 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?
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Kaushal ModiOn 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