Commit 798330fe authored by Dave Love's avatar Dave Love
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Initial revision

parent b98e5762
;;; hl-line.el --- highlight the current line
;; Copyright (C) 1998 Free Software Foundation, Inc.
;; Author: Dave Love <>
;; Created: 1998-09-13
;; Keywords: faces, frames
;; Hl-Line mode 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 2, or (at your option)
;; any later version.
;; Hl-Line mode is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Commentary:
;; Provides a global minor mode (toggled by M-x hl-line-mode) to
;; highlight, in a windowing system, the line on which point is
;; (except in a minibuffer window) to satisfy a request for a feature
;; of Lesser Editors.
;; You probably don't really want this; if the cursor is difficult to
;; spot, try changing its colour or using a cursor blinking
;; <URL:> or
;; jiggling <URL:> package. (Cursor
;; blinking will be built in to Emacs 21.) The hookery involved here
;; might slow Emacs noticeably on a slow machine.
;; An overlay is used, active only on the selected window. Hooks are
;; added to `pre-command-hook' and `post-command-hook' to activate and
;; deactivate (by deleting) the overlay. `hl-line-unhighlight', on
;; `pre-command-hook', deactivates it unconditionally in case the
;; command changes the selected window. (It does so rather than
;; keeping track of changes in the selected window).
;; `hl-line-highlight', on `post-command-hook', activates it again
;; across the window width.
;;; Code:
(defgroup hl-line nil
"Highliight the current line."
:group 'editing)
(defcustom hl-line-mode nil
"Non-nil if Hl-Line mode is enabled."
:set (lambda (symbol value)
(hl-line-mode (or value 0)))
:initialize 'custom-initialize-default
:type 'boolean
:group 'hl-line
:require 'hl-line)
(defcustom hl-line-face 'highlight
"Face with which to highlight the current line."
:type 'face
:group 'hl-line)
(defvar hl-line-overlay nil)
(make-variable-buffer-local 'hl-line-overlay)
(defun hl-line-highlight ()
"Active the Hl-Line overlay on the current line in the current window.
\(Unless it's a minibuffer window.)"
(unless (window-minibuffer-p (selected-window)) ; silly in minibuffer
(unless hl-line-overlay ; new overlay for this buffer
(setq hl-line-overlay (make-overlay 1 1)) ; to be moved
(overlay-put hl-line-overlay 'face hl-line-face))
(overlay-put hl-line-overlay 'window (selected-window))
(move-overlay hl-line-overlay
(line-beginning-position) (1+ (line-end-position)))))
(defun hl-line-unhighlight ()
"Deactivate the Hl-Line overlay on the current line in the current window."
(if hl-line-overlay
(delete-overlay hl-line-overlay)))
(defun hl-line-mode (&optional arg)
"Global minor mode to highlight the line about point.
With ARG, turn Hl-Line mode on if ARG is positive, off otherwise.
Only useful with a windowing system.
Uses functions `hl-line-unhighlight' and `hl-line-highlight' on
`pre-command-hook' and `post-command-hook'."
(interactive "P")
(setq hl-line-mode (if (null arg)
(not hl-line-mode)
(> (prefix-numeric-value arg) 0)))
(cond (hl-line-mode
(add-hook 'pre-command-hook #'hl-line-unhighlight)
(add-hook 'post-command-hook #'hl-line-highlight))
(remove-hook 'pre-command-hook #'hl-line-unhighlight)
(remove-hook 'post-command-hook #'hl-line-highlight)))
(if (interactive-p)
(message "Hl-Line mode %sabled" (if hl-line-mode "en" "dis"))))
(provide 'hl-line)
;;; hl-line.el ends here
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