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[emacs.git] / lisp / hl-line.el
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1 ;;; hl-line.el --- highlight the current line
3 ;; Copyright (C) 1998, 2000 Free Software Foundation, Inc.
5 ;; Author: Dave Love <fx@gnu.org>
6 ;; Created: 1998-09-13
7 ;; Keywords: faces, frames, emulation
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
14 ;; any later version.
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
24 ;; Boston, MA 02111-1307, USA.
26 ;;; Commentary:
28 ;; Provides a global minor mode (toggled by M-x hl-line-mode) to
29 ;; highlight, on a suitable terminal, the line in the current window
30 ;; on which point is (except in a minibuffer window). Done to satisfy
31 ;; a request for a feature of Lesser Editors.
33 ;; You probably don't really want this; if the cursor is difficult to
34 ;; spot, try changing its colour, relying on `blink-cursor-mode' or
35 ;; both. The hookery used might affect response noticeably on a slow
36 ;; machine.
38 ;; An overlay is used, active only on the selected window. Hooks are
39 ;; added to `pre-command-hook' and `post-command-hook' to activate and
40 ;; deactivate (by deleting) the overlay. `hl-line-unhighlight', on
41 ;; `pre-command-hook', deactivates it unconditionally in case the
42 ;; command changes the selected window. (It does so rather than
43 ;; keeping track of changes in the selected window).
44 ;; `hl-line-highlight', on `post-command-hook', activates it again
45 ;; across the window width.
47 ;; You could make variable `hl-line-mode' buffer-local to avoid
48 ;; highlighting specific buffers.
50 ;;; Code:
52 (defgroup hl-line nil
53 "Highlight the current line."
54 :version "21.1"
55 :group 'editing)
57 (defcustom hl-line-face 'highlight
58 "Face with which to highlight the current line."
59 :type 'face
60 :group 'hl-line)
62 (defvar hl-line-overlay nil)
64 (defun hl-line-highlight ()
65 "Active the Hl-Line overlay on the current line in the current window.
66 \(Unless it's a minibuffer window.)"
67 (when hl-line-mode ; Could be made buffer-local.
68 (unless (window-minibuffer-p (selected-window)) ; silly in minibuffer
69 (unless hl-line-overlay
70 (setq hl-line-overlay (make-overlay 1 1)) ; to be moved
71 (overlay-put hl-line-overlay 'face hl-line-face))
72 (overlay-put hl-line-overlay 'window (selected-window))
73 (move-overlay hl-line-overlay
74 (line-beginning-position) (1+ (line-end-position))
75 (current-buffer)))))
77 (defun hl-line-unhighlight ()
78 "Deactivate the Hl-Line overlay on the current line in the current window."
79 (if hl-line-overlay
80 (delete-overlay hl-line-overlay)))
82 ;;;###autoload
83 (define-minor-mode hl-line-mode
84 "Global minor mode to highlight the line about point in the current window.
85 With ARG, turn Hl-Line mode on if ARG is positive, off otherwise.
86 Uses functions `hl-line-unhighlight' and `hl-line-highlight' on
87 `pre-command-hook' and `post-command-hook'."
88 :global t
89 (if hl-line-mode
90 (progn
91 (add-hook 'pre-command-hook #'hl-line-unhighlight)
92 (add-hook 'post-command-hook #'hl-line-highlight))
93 (hl-line-unhighlight)
94 (remove-hook 'pre-command-hook #'hl-line-unhighlight)
95 (remove-hook 'post-command-hook #'hl-line-highlight)))
97 (provide 'hl-line)
99 ;;; hl-line.el ends here