lisp/hl-line.el

   1 ;;; hl-line.el --- highlight the current line
   2
   3 ;; Copyright (C) 1998, 2000, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006, 2007 Free Software Foundation, Inc.
   5
   6 ;; Author:  Dave Love <fx@gnu.org>
   7 ;; Maintainer: FSF
   8 ;; Created: 1998-09-13
   9 ;; Keywords: faces, frames, emulation
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software; you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation; either version 2, or (at your option)
  16 ;; any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  25 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  26 ;; Boston, MA 02110-1301, USA.
  27
  28 ;;; Commentary:
  29
  30 ;; Provides a local minor mode (toggled by M-x hl-line-mode) and
  31 ;; a global minor mode (toggled by M-x global-hl-line-mode) to
  32 ;; highlight, on a suitable terminal, the line on which point is.  The
  33 ;; global mode highlights the current line in the selected window only
  34 ;; (except when the minibuffer window is selected).  This was
  35 ;; implemented to satisfy a request for a feature of Lesser Editors.
  36 ;; The local mode is sticky: it highlights the line about the buffer's
  37 ;; point even if the buffer's window is not selected.  Caveat: the
  38 ;; buffer's point might be different from the point of a non-selected
  39 ;; window.  Set the variable `hl-line-sticky-flag' to nil to make the
  40 ;; local mode behave like the global mode.
  41
  42 ;; You probably don't really want to use the global mode; if the
  43 ;; cursor is difficult to spot, try changing its colour, relying on
  44 ;; `blink-cursor-mode' or both.  The hookery used might affect
  45 ;; response noticeably on a slow machine.  The local mode may be
  46 ;; useful in non-editing buffers such as Gnus or PCL-CVS though.
  47
  48 ;; An overlay is used.  In the non-sticky cases, this overlay is
  49 ;; active only on the selected window.  A hook is added to
  50 ;; `post-command-hook' to activate the overlay and move it to the line
  51 ;; about point.  To get the non-sticky behavior, `hl-line-unhighlight'
  52 ;; is added to `pre-command-hook' as well.  This function deactivates
  53 ;; the overlay unconditionally in case the command changes the
  54 ;; selected window.  (It does so rather than keeping track of changes
  55 ;; in the selected window).
  56
  57 ;; You could make variable `global-hl-line-mode' buffer-local and set
  58 ;; it to nil to avoid highlighting specific buffers, when the global
  59 ;; mode is used.
  60
  61 ;; By default the whole line is highlighted.  The range of highlighting
  62 ;; can be changed by defining an appropriate function as the
  63 ;; buffer-local value of `hl-line-range-function'.
  64
  65 ;;; Code:
  66
  67 (defvar hl-line-overlay nil
  68   "Overlay used by Hl-Line mode to highlight the current line.")
  69 (make-variable-buffer-local 'hl-line-overlay)
  70
  71 (defvar global-hl-line-overlay nil
  72   "Overlay used by Global-Hl-Line mode to highlight the current line.")
  73
  74 (defgroup hl-line nil
  75   "Highlight the current line."
  76   :version "21.1"
  77   :group 'editing)
  78
  79 (defface hl-line
  80   '((t :inherit highlight))
  81   "Default face for highlighting the current line in Hl-Line mode."
  82   :version "22.1"
  83   :group 'hl-line)
  84
  85 (defcustom hl-line-face 'hl-line
  86   "Face with which to highlight the current line in Hl-Line mode."
  87   :type 'face
  88   :group 'hl-line
  89   :set (lambda (symbol value)
  90          (set symbol value)
  91          (dolist (buffer (buffer-list))
  92            (with-current-buffer buffer
  93              (when hl-line-overlay
  94                (overlay-put hl-line-overlay 'face hl-line-face))))
  95          (when global-hl-line-overlay
  96            (overlay-put global-hl-line-overlay 'face hl-line-face))))
  97
  98 (defcustom hl-line-sticky-flag t
  99   "*Non-nil means highlight the current line in all windows.
 100 Otherwise Hl-Line mode will highlight only in the selected
 101 window.  Setting this variable takes effect the next time you use
 102 the command `hl-line-mode' to turn Hl-Line mode on."
 103   :type 'boolean
 104   :version "22.1"
 105   :group 'hl-line)
 106
 107 (defvar hl-line-range-function nil
 108   "If non-nil, function to call to return highlight range.
 109 The function of no args should return a cons cell; its car value
 110 is the beginning position of highlight and its cdr value is the
 111 end position of highlight in the buffer.
 112 It should return nil if there's no region to be highlighted.
 113
 114 This variable is expected to be made buffer-local by modes.")
 115
 116 ;;;###autoload
 117 (define-minor-mode hl-line-mode
 118   "Buffer-local minor mode to highlight the line about point.
 119 With ARG, turn Hl-Line mode on if ARG is positive, off otherwise.
 120
 121 If `hl-line-sticky-flag' is non-nil, Hl-Line mode highlights the
 122 line about the buffer's point in all windows.  Caveat: the
 123 buffer's point might be different from the point of a
 124 non-selected window.  Hl-Line mode uses the function
 125 `hl-line-highlight' on `post-command-hook' in this case.
 126
 127 When `hl-line-sticky-flag' is nil, Hl-Line mode highlights the
 128 line about point in the selected window only.  In this case, it
 129 uses the function `hl-line-unhighlight' on `pre-command-hook' in
 130 addition to `hl-line-highlight' on `post-command-hook'."
 131   :group 'hl-line
 132   (if hl-line-mode
 133       (progn
 134         ;; In case `kill-all-local-variables' is called.
 135         (add-hook 'change-major-mode-hook #'hl-line-unhighlight nil t)
 136         (if hl-line-sticky-flag
 137             (remove-hook 'pre-command-hook #'hl-line-unhighlight t)
 138           (add-hook 'pre-command-hook #'hl-line-unhighlight nil t))
 139         (hl-line-highlight)
 140         (add-hook 'post-command-hook #'hl-line-highlight nil t))
 141     (remove-hook 'post-command-hook #'hl-line-highlight t)
 142     (hl-line-unhighlight)
 143     (remove-hook 'change-major-mode-hook #'hl-line-unhighlight t)
 144     (remove-hook 'pre-command-hook #'hl-line-unhighlight t)))
 145
 146 (defun hl-line-highlight ()
 147   "Activate the Hl-Line overlay on the current line."
 148   (if hl-line-mode      ; Might be changed outside the mode function.
 149       (progn
 150         (unless hl-line-overlay
 151           (setq hl-line-overlay (make-overlay 1 1)) ; to be moved
 152           (overlay-put hl-line-overlay 'face hl-line-face))
 153         (overlay-put hl-line-overlay
 154                      'window (unless hl-line-sticky-flag (selected-window)))
 155         (hl-line-move hl-line-overlay))
 156     (hl-line-unhighlight)))
 157
 158 (defun hl-line-unhighlight ()
 159   "Deactivate the Hl-Line overlay on the current line."
 160   (if hl-line-overlay
 161       (delete-overlay hl-line-overlay)))
 162
 163 ;;;###autoload
 164 (define-minor-mode global-hl-line-mode
 165   "Global minor mode to highlight the line about point in the current window.
 166 With ARG, turn Global-Hl-Line mode on if ARG is positive, off otherwise.
 167
 168 Global-Hl-Line mode uses the functions `global-hl-line-unhighlight' and
 169 `global-hl-line-highlight' on `pre-command-hook' and `post-command-hook'."
 170   :global t
 171   :group 'hl-line
 172   (if global-hl-line-mode
 173       (progn
 174         (add-hook 'pre-command-hook #'global-hl-line-unhighlight)
 175         (add-hook 'post-command-hook #'global-hl-line-highlight))
 176     (global-hl-line-unhighlight)
 177     (remove-hook 'pre-command-hook #'global-hl-line-unhighlight)
 178     (remove-hook 'post-command-hook #'global-hl-line-highlight)))
 179
 180 (defun global-hl-line-highlight ()
 181   "Active the Global-Hl-Line overlay on the current line in the current window."
 182   (when global-hl-line-mode     ; Might be changed outside the mode function.
 183     (unless (window-minibuffer-p (selected-window))
 184       (unless global-hl-line-overlay
 185         (setq global-hl-line-overlay (make-overlay 1 1)) ; to be moved
 186         (overlay-put global-hl-line-overlay 'face hl-line-face))
 187       (overlay-put global-hl-line-overlay 'window (selected-window))
 188       (hl-line-move global-hl-line-overlay))))
 189
 190 (defun global-hl-line-unhighlight ()
 191   "Deactivate the Global-Hl-Line overlay on the current line."
 192   (if global-hl-line-overlay
 193       (delete-overlay global-hl-line-overlay)))
 194
 195 (defun hl-line-move (overlay)
 196   "Move the Hl-Line overlay.
 197 If `hl-line-range-function' is non-nil, move the OVERLAY to the position
 198 where the function returns.  If `hl-line-range-function' is nil, fill
 199 the line including the point by OVERLAY."
 200   (let (tmp b e)
 201     (if hl-line-range-function
 202         (setq tmp (funcall hl-line-range-function)
 203               b   (car tmp)
 204               e   (cdr tmp))
 205       (setq tmp t
 206             b (line-beginning-position)
 207             e (line-beginning-position 2)))
 208     (if tmp
 209         (move-overlay overlay b e)
 210       (move-overlay overlay 1 1))))
 211
 212 (provide 'hl-line)
 213
 214 ;;; arch-tag: ac806940-0876-4959-8c89-947563ee2833
 215 ;;; hl-line.el ends here