-;;; beacon.el --- Highlight the cursor whenever it moves long distances -*- lexical-binding: t; -*-
+;;; beacon.el --- Highlight the cursor whenever the window scrolls -*- lexical-binding: t; -*-
-;; Copyright (C) 2015 Artur Malabarba
+;; 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: ((cl-lib "0.5"))
+;; Version: 0.1.1
+;; 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
;;; Commentary:
-;; This is a global minor-mode. Turn it on everywhere with
-;; (beacon-mode 1)
+;; This is a global minor-mode. Turn it on everywhere with:
+;; ┌────
+;; │ (beacon-mode 1)
+;; └────
+;;
+;; Whenever the window scrolls a light will shine on top of your cursor so
+;; you know where it is.
+;;
+;; That’s it.
+;;
+;; See the accompanying Readme.org for configuration details.
;;; Code:
-(require 'cl-lib)
+(require 'seq)
(defgroup beacon nil
"Customization group for beacon."
(defvar beacon--timer nil)
-(defcustom beacon-minimum-distance 15
- "Minimum movement distance in lines to blink the beacon."
- :type 'integer)
+(defcustom beacon-push-mark 35
+ "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-push-mark nil
- "Should the mark be pushed before long movements?"
- :type 'boolean)
+(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-when-window-changes t
+ "Should the beacon blink when the window changes?"
+ :type 'boolean)
+
(defcustom beacon-blink-duration 0.3
"Time, in seconds, that the blink should last."
:type 'number)
"Time, in seconds, before starting to fade the beacon."
:type 'number)
-(defcustom beacon-size 30
+(defcustom beacon-size 40
"Size of the beacon in characters."
:type 'number)
-(defcustom beacon-brightness 0.5
- "Brightness as a float between 0 and 1."
- :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))
+
+(defvar beacon-dont-blink-predicates nil
+ "A list of predicates that prevent the beacon blink.
+These predicate functions are called in order, with no
+arguments, before blinking the beacon. If any returns
+non-nil, the beacon will not blink.
+
+For instance, if you want to disable beacon on buffers where
+`hl-line-mode' is on, you can do:
+
+ (add-hook \\='beacon-dont-blink-predicates
+ (lambda () (bound-and-true-p hl-line-mode)))")
+
+(add-hook 'beacon-dont-blink-predicates #'window-minibuffer-p)
+
+(defcustom beacon-dont-blink-major-modes '(magit-status-mode)
+ "A list of major-modes where the beacon won't blink.
+Whenever the current buffer satisfies `derived-mode-p' for
+one of the major-modes on this list, the beacon will not
+blink."
+ :type '(repeat symbol))
+
+(defcustom beacon-dont-blink-commands '(recenter-top-bottom)
+ "A list of commands that should not make the beacon blink.
+Use this for commands that scroll the window in very
+predictable ways, when the blink would be more distracting
+than helpful.."
+ :type '(repeat symbol))
\f
;;; Overlays
(defvar beacon--ovs nil)
-(defun beacon--colored-overlay (color)
+(defconst beacon-overlay-priority (/ most-positive-fixnum 2)
+ "Priotiy used on all of our overlays.")
+
+(defun beacon--make-overlay (length &rest properties)
"Put an overlay at point with background COLOR."
- (let ((ov (make-overlay (point) (1+ (point)))))
- (overlay-put ov 'face (list :background color))
+ (let ((ov (make-overlay (point) (+ length (point)))))
(overlay-put ov 'beacon t)
- (push ov beacon--ovs)))
+ ;; Our overlay is very temporary, so we take the liberty of giving
+ ;; it a high priority.
+ (overlay-put ov 'priority beacon-overlay-priority)
+ (overlay-put ov 'window (selected-window))
+ (while properties
+ (overlay-put ov (pop properties) (pop properties)))
+ (push ov beacon--ovs)
+ ov))
+
+(defun beacon--colored-overlay (color)
+ "Put an overlay at point with background COLOR."
+ (beacon--make-overlay 1 'face (list :background color)))
+
+(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 COLORS is nil, OVERLAY is deleted!"
+ (if (not colors)
+ (when (overlayp overlay)
+ (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."
+ ;; The after-string must not be longer than the remaining columns
+ ;; from point to right window-end else it will be wrapped around.
+ (let ((colors (seq-take colors (- (window-width) (current-column)))))
+ (beacon--ov-put-after-string (beacon--make-overlay 0) colors)))
(defun beacon--ov-at-point ()
- (car (cl-member-if (lambda (o) (overlay-get o 'beacon))
- (overlays-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."
(defun beacon--color-range ()
"Return a list of background colors for the beacon."
- (let ((bg (color-values (face-attribute 'default :background))))
- (apply #'cl-mapcar (lambda (r g b) (format "#%04x%04x%04x" r g b))
- (if (< (color-distance "black" bg)
+ (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))
- (mapcar (lambda (n) (butlast (beacon--int-range (* beacon-brightness 65535) n))) bg)
- (mapcar (lambda (n) (cdr (beacon--int-range (* (- 1 beacon-brightness) 65535) n))) 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]))))
\f
;;; Blinking
(while colors
(if (looking-at "$")
(progn
- ;; (beacon--after-string)
+ (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."
- (let ((o (beacon--ov-at-point)))
- (if (not o)
- (beacon--vanish)
- (delete-overlay o)
- (save-excursion
- (while (progn (forward-char 1)
- (setq o (beacon--ov-at-point)))
- (move-overlay o (1- (point)) (point)))))))
+ (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)))
+ (unless (or (not beacon-mode)
+ (run-hook-with-args-until-success 'beacon-dont-blink-predicates)
+ (seq-find #'derived-mode-p beacon-dont-blink-major-modes)
+ (memq (or this-command last-command) beacon-dont-blink-commands))
+ (beacon--shine)
+ (setq beacon--timer
+ (run-at-time beacon-blink-delay
+ (/ beacon-blink-duration 1.0 beacon-size)
+ #'beacon--dec))))
\f
;;; Movement detection
+(defvar beacon--window-scrolled nil)
(defvar beacon--previous-place nil)
(defvar beacon--previous-mark-head nil)
+(defvar beacon--previous-window nil)
+
+(defun beacon--pos-on-current-line-p (pos)
+ "Return non-nil if POS is on the current line."
+ (<= (save-excursion (beginning-of-line) (point))
+ pos
+ (save-excursion (end-of-line) (point))))
+
+(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)
+ ;; Check if the movement was larger than DELTA lines by testing if
+ ;; `point' is still on the same line or on any line DELTA lines up or
+ ;; down. This is much cheaper than computing the actual number of lines
+ ;; moved using `count-screen-lines'.
+ (let ((prev-pos (marker-position beacon--previous-place)))
+ (catch 'movement
+ (when (beacon--pos-on-current-line-p (point))
+ (throw 'movement nil))
+ (dolist (inc '(1 -1))
+ (save-excursion
+ (dotimes (i delta)
+ (vertical-motion inc)
+ (when (beacon--pos-on-current-line-p (point))
+ (throw 'movement nil)))))
+ (throw 'movement t)))))
(defun beacon--maybe-push-mark ()
"Push mark if it seems to be safe."
- (when (and beacon-push-mark
- (not mark-active))
+ (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)))
(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 distance movement
- ((and (> (abs (- (point) beacon--previous-place))
- beacon-minimum-distance)
- (> (count-screen-lines (min (point) beacon--previous-place)
- (max (point) beacon--previous-place))
- beacon-minimum-distance))
- (beacon--maybe-push-mark)
+ ;; Blink for switching windows.
+ ((and beacon-blink-when-window-changes
+ (not (eq beacon--previous-window (selected-window))))
+ (beacon-blink))
+ ;; Blink for scrolling.
+ ((and beacon-blink-when-window-scrolls
+ beacon--window-scrolled
+ (equal beacon--window-scrolled (selected-window)))
+ (beacon-blink))
+ ;; 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)
+ (setq beacon--window-scrolled nil)
(unless (window-minibuffer-p)
(setq beacon--previous-mark-head (car mark-ring))
- (setq beacon--previous-place (point-marker))))
+ (setq beacon--previous-place (point-marker))
+ (setq beacon--previous-window (selected-window))))
+
+(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)
+ (setq beacon--window-scrolled nil)
+ (beacon-blink)))
\f
;;; Minor-mode
-(defcustom beacon-lighter (cond
- ((char-displayable-p ?💡) "💡")
- ((char-displayable-p ?Λ) "Λ")
- (t "*"))
+(defcustom beacon-lighter
+ (cond
+ ((char-displayable-p ?💡) " 💡")
+ ((char-displayable-p ?Λ) " Λ")
+ (t " *"))
"Lighter string used on the mode-line."
:type 'string)
nil nil beacon-lighter nil
:global t
(if beacon-mode
- (add-hook 'post-command-hook #'beacon--post-command)
- (remove-hook 'post-command-hook #'beacon--post-command)))
+ (progn
+ (add-hook 'window-scroll-functions #'beacon--window-scroll-function)
+ (add-hook 'post-command-hook #'beacon--post-command)
+ (add-hook 'pre-command-hook #'beacon--vanish))
+ (remove-hook 'window-scroll-functions #'beacon--window-scroll-function)
+ (remove-hook 'post-command-hook #'beacon--post-command)
+ (remove-hook 'pre-command-hook #'beacon--vanish)))
(provide 'beacon)
;;; beacon.el ends here