My comments are inline below, with a formatted patch at the end of this email.
Here is a slightly optimized version of the same patch that results in lesser save-excursion and remove-text-properties calls in nlinum--current-line-update function:
I would like to optimize this even more.. I feel lag when I keep C-n/C-p pressed with nlinum-highlight-current-line set to t vs nil. Any pointers? You mentioned the use of markers instead of line numbers. How to use those if that could improve the performance?
From 7eb48b322578cc199eaa45de6bfe778e2b5f63de Mon Sep 17 00:00:00 2001
Date: Mon, 18 Jul 2016 17:42:45 -0400
Subject: [PATCH] Add ability to highlight current line number
* nlinum.el (nlinum-highlight-current-line): New defcustom to enable
highlighting current line number when non-nil (default is nil).
(nlinum-current-line): New face for highlighting the current
line number.
---
packages/nlinum/nlinum.el | 88 +++++++++++++++++++++++++++++++++++++++++------
1 file changed, 78 insertions(+), 10 deletions(-)
diff --git a/packages/nlinum/nlinum.el b/packages/nlinum/nlinum.el
index 98c9cbc..093d217 100644
--- a/packages/nlinum/nlinum.el
+++ b/packages/nlinum/nlinum.el
@@ -36,11 +36,27 @@
;;; Code:
-(require 'linum) ;For its face.
+(require 'linum) ; For its face.
+
+(defcustom nlinum-highlight-current-line nil
+ "Whether the current line number should be highlighted.
+When non-nil, the current line number is highlighted in `nlinum-current-line'
+face. "
+ :group 'nlinum
+ :type 'boolean)
(defvar nlinum--width 2)
(make-variable-buffer-local 'nlinum--width)
+(defface nlinum-current-line
+ '((t :inherit linum :weight bold))
+ "Face for displaying current line."
+ :group 'nlinum)
+
+(defvar nlinum--current-line 0
+ "Store current line number.")
+(make-variable-buffer-local 'nlinum--current-line)
+
;; (defvar nlinum--desc "")
;;;###autoload
@@ -53,9 +69,10 @@ if ARG is omitted or nil.
Linum mode is a buffer-local minor mode."
:lighter nil ;; (" NLinum" nlinum--desc)
(jit-lock-unregister #'nlinum--region)
- (remove-hook 'window-configuration-change-hook #'nlinum--setup-window t)
- (remove-hook 'text-scale-mode-hook #'nlinum--setup-window t)
- (remove-hook 'after-change-functions #'nlinum--after-change t)
+ (remove-hook 'window-configuration-change-hook #'nlinum--setup-window :local)
+ (remove-hook 'text-scale-mode-hook #'nlinum--setup-window :local)
+ (remove-hook 'after-change-functions #'nlinum--after-change :local)
+ (remove-hook 'post-command-hook #'nlinum--current-line-update :local)
(kill-local-variable 'nlinum--line-number-cache)
(remove-overlays (point-min) (point-max) 'nlinum t)
;; (kill-local-variable 'nlinum--ol-counter)
@@ -64,10 +81,13 @@ Linum mode is a buffer-local minor mode."
;; FIXME: Another approach would be to make the mode permanent-local,
;; which might indeed be preferable.
(add-hook 'change-major-mode-hook (lambda () (nlinum-mode -1)))
- (add-hook 'text-scale-mode-hook #'nlinum--setup-window nil t)
- (add-hook 'window-configuration-change-hook #'nlinum--setup-window nil t)
- (add-hook 'after-change-functions #'nlinum--after-change nil t)
- (jit-lock-register #'nlinum--region t))
+ (add-hook 'text-scale-mode-hook #'nlinum--setup-window nil :local)
+ (add-hook 'window-configuration-change-hook #'nlinum--setup-window nil :local)
+ (add-hook 'after-change-functions #'nlinum--after-change nil :local)
+ (if nlinum-highlight-current-line
+ (add-hook 'post-command-hook #'nlinum--current-line-update nil :local)
+ (remove-hook 'post-command-hook #'nlinum--current-line-update :local))
+ (jit-lock-register #'nlinum--region :contextual))
(nlinum--setup-windows))
(defun nlinum--face-height (face)
@@ -131,6 +151,48 @@ Linum mode is a buffer-local minor mode."
(point-min) (point-max) '(fontified)))))
(current-buffer)))
+(defun nlinum--current-line-update ()
+ "Update current line number."
+ (let ((last-line nlinum--current-line))
+ (setq nlinum--current-line (save-excursion
+ (unless (bolp)
+ (forward-line 0))
+ (nlinum--line-number-at-pos)))
+
+ (let ((line-diff (- last-line nlinum--current-line))
+ beg end rm-text-prop)
+ (cond
+ ;; If point is moving upwards, set BEG to be the line-beginning of
+ ;; the current line, and END to be the line-beginning of the next
+ ;; line after the last line.
+ ((> line-diff 0)
+ (setq beg (line-beginning-position)) ; beginning of the current line
+ ;; Handle the case of blank lines too.
+ ;; Using the beginning of the next line ensures that the
+ ;; BEG and END are never equal.
+ (setq end (save-excursion ; beginning of the line after the last line
+ (forward-line (1+ line-diff))
+ (line-beginning-position)))
+ (setq rm-text-prop 1))
+
+ ;; If point is moving downwards, set BEG to be the line-beginning of
+ ;; the last line, and END to be the line-beginning of the next
+ ;; line after the current line.
+ ((< line-diff 0)
+ (setq beg (save-excursion ; beginning of the last line
+ (forward-line line-diff)
+ (line-beginning-position)))
+ (setq end (save-excursion ; beginning of the line after the current line
+ (forward-line 1)
+ (line-beginning-position)))
+ (setq rm-text-prop 1)))
+
+ ;; Remove the text properties only if the current line has changed,
+ ;; i.e. line-diff != 0
+ (when rm-text-prop
+ (with-silent-modifications
+ (remove-text-properties beg end '(fontified)))))))
+
;; (defun nlinum--ol-count ()
;; (let ((i 0))
;; (dolist (ol (overlays-in (point-min) (point-max)))
@@ -215,11 +277,17 @@ Used by the default `nlinum-format-function'."
(defvar nlinum-format-function
(lambda (line width)
- (let ((str (format nlinum-format line)))
+ (let* ((is-current-line (= line nlinum--current-line))
+ (str (format nlinum-format line)))
(when (< (length str) width)
;; Left pad to try and right-align the line-numbers.
(setq str (concat (make-string (- width (length str)) ?\ ) str)))
- (put-text-property 0 width 'face 'linum str)
+ (put-text-property 0 width 'face
+ (if (and nlinum-highlight-current-line
+ is-current-line)
+ 'nlinum-current-line
+ 'linum)
+ str)
str))
"Function to build the string representing the line number.
Takes 2 arguments LINE and WIDTH, both of them numbers, and should return
--
2.6.0.rc0.24.gec371ff