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, 2008 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 3 of the License, or
  16 ;; (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.
  25
  26 ;;; Commentary:
  27
  28 ;; Provides a local minor mode (toggled by M-x hl-line-mode) and
  29 ;; a global minor mode (toggled by M-x global-hl-line-mode) to
  30 ;; highlight, on a suitable terminal, the line on which point is.  The
  31 ;; global mode highlights the current line in the selected window only
  32 ;; (except when the minibuffer window is selected).  This was
  33 ;; implemented to satisfy a request for a feature of Lesser Editors.
  34 ;; The local mode is sticky: it highlights the line about the buffer's
  35 ;; point even if the buffer's window is not selected.  Caveat: the
  36 ;; buffer's point might be different from the point of a non-selected
  37 ;; window.  Set the variable `hl-line-sticky-flag' to nil to make the
  38 ;; local mode behave like the global mode.
  39
  40 ;; You probably don't really want to use the global mode; if the
  41 ;; cursor is difficult to spot, try changing its colour, relying on
  42 ;; `blink-cursor-mode' or both.  The hookery used might affect
  43 ;; response noticeably on a slow machine.  The local mode may be
  44 ;; useful in non-editing buffers such as Gnus or PCL-CVS though.
  45
  46 ;; An overlay is used.  In the non-sticky cases, this overlay is
  47 ;; active only on the selected window.  A hook is added to
  48 ;; `post-command-hook' to activate the overlay and move it to the line
  49 ;; about point.  To get the non-sticky behavior, `hl-line-unhighlight'
  50 ;; is added to `pre-command-hook' as well.  This function deactivates
  51 ;; the overlay unconditionally in case the command changes the
  52 ;; selected window.  (It does so rather than keeping track of changes
  53 ;; in the selected window).
  54
  55 ;; You could make variable `global-hl-line-mode' buffer-local and set
  56 ;; it to nil to avoid highlighting specific buffers, when the global
  57 ;; mode is used.
  58
  59 ;; By default the whole line is highlighted.  The range of highlighting
  60 ;; can be changed by defining an appropriate function as the
  61 ;; buffer-local value of `hl-line-range-function'.
  62
  63 ;;; Code:
  64
  65 (defvar hl-line-overlay nil
  66   "Overlay used by Hl-Line mode to highlight the current line.")
  67 (make-variable-buffer-local 'hl-line-overlay)
  68
  69 (defvar global-hl-line-overlay nil
  70   "Overlay used by Global-Hl-Line mode to highlight the current line.")
  71
  72 (defgroup hl-line nil
  73   "Highlight the current line."
  74   :version "21.1"
  75   :group 'editing)
  76
  77 (defface hl-line
  78   '((t :inherit highlight))
  79   "Default face for highlighting the current line in Hl-Line mode."
  80   :version "22.1"
  81   :group 'hl-line)
  82
  83 (defcustom hl-line-face 'hl-line
  84   "Face with which to highlight the current line in Hl-Line mode."
  85   :type 'face
  86   :group 'hl-line
  87   :set (lambda (symbol value)
  88          (set symbol value)
  89          (dolist (buffer (buffer-list))
  90            (with-current-buffer buffer
  91              (when hl-line-overlay
  92                (overlay-put hl-line-overlay 'face hl-line-face))))
  93          (when global-hl-line-overlay
  94            (overlay-put global-hl-line-overlay 'face hl-line-face))))
  95
  96 (defcustom hl-line-sticky-flag t
  97   "*Non-nil means highlight the current line in all windows.
  98 Otherwise Hl-Line mode will highlight only in the selected
  99 window.  Setting this variable takes effect the next time you use
 100 the command `hl-line-mode' to turn Hl-Line mode on."
 101   :type 'boolean
 102   :version "22.1"
 103   :group 'hl-line)
 104
 105 (defvar hl-line-range-function nil
 106   "If non-nil, function to call to return highlight range.
 107 The function of no args should return a cons cell; its car value
 108 is the beginning position of highlight and its cdr value is the
 109 end position of highlight in the buffer.
 110 It should return nil if there's no region to be highlighted.
 111
 112 This variable is expected to be made buffer-local by modes.")
 113
 114 ;;;###autoload
 115 (define-minor-mode hl-line-mode
 116   "Buffer-local minor mode to highlight the line about point.
 117 With ARG, turn Hl-Line mode on if ARG is positive, off otherwise.
 118
 119 If `hl-line-sticky-flag' is non-nil, Hl-Line mode highlights the
 120 line about the buffer's point in all windows.  Caveat: the
 121 buffer's point might be different from the point of a
 122 non-selected window.  Hl-Line mode uses the function
 123 `hl-line-highlight' on `post-command-hook' in this case.
 124
 125 When `hl-line-sticky-flag' is nil, Hl-Line mode highlights the
 126 line about point in the selected window only.  In this case, it
 127 uses the function `hl-line-unhighlight' on `pre-command-hook' in
 128 addition to `hl-line-highlight' on `post-command-hook'."
 129   :group 'hl-line
 130   (if hl-line-mode
 131       (progn
 132         ;; In case `kill-all-local-variables' is called.
 133         (add-hook 'change-major-mode-hook #'hl-line-unhighlight nil t)
 134         (if hl-line-sticky-flag
 135             (remove-hook 'pre-command-hook #'hl-line-unhighlight t)
 136           (add-hook 'pre-command-hook #'hl-line-unhighlight nil t))
 137         (hl-line-highlight)
 138         (add-hook 'post-command-hook #'hl-line-highlight nil t))
 139     (remove-hook 'post-command-hook #'hl-line-highlight t)
 140     (hl-line-unhighlight)
 141     (remove-hook 'change-major-mode-hook #'hl-line-unhighlight t)
 142     (remove-hook 'pre-command-hook #'hl-line-unhighlight t)))
 143
 144 (defun hl-line-highlight ()
 145   "Activate the Hl-Line overlay on the current line."
 146   (if hl-line-mode      ; Might be changed outside the mode function.
 147       (progn
 148         (unless hl-line-overlay
 149           (setq hl-line-overlay (make-overlay 1 1)) ; to be moved
 150           (overlay-put hl-line-overlay 'face hl-line-face))
 151         (overlay-put hl-line-overlay
 152                      'window (unless hl-line-sticky-flag (selected-window)))
 153         (hl-line-move hl-line-overlay))
 154     (hl-line-unhighlight)))
 155
 156 (defun hl-line-unhighlight ()
 157   "Deactivate the Hl-Line overlay on the current line."
 158   (if hl-line-overlay
 159       (delete-overlay hl-line-overlay)))
 160
 161 ;;;###autoload
 162 (define-minor-mode global-hl-line-mode
 163   "Global minor mode to highlight the line about point in the current window.
 164 With ARG, turn Global-Hl-Line mode on if ARG is positive, off otherwise.
 165
 166 Global-Hl-Line mode uses the functions `global-hl-line-unhighlight' and
 167 `global-hl-line-highlight' on `pre-command-hook' and `post-command-hook'."
 168   :global t
 169   :group 'hl-line
 170   (if global-hl-line-mode
 171       (progn
 172         (add-hook 'pre-command-hook #'global-hl-line-unhighlight)
 173         (add-hook 'post-command-hook #'global-hl-line-highlight))
 174     (global-hl-line-unhighlight)
 175     (remove-hook 'pre-command-hook #'global-hl-line-unhighlight)
 176     (remove-hook 'post-command-hook #'global-hl-line-highlight)))
 177
 178 (defun global-hl-line-highlight ()
 179   "Active the Global-Hl-Line overlay on the current line in the current window."
 180   (when global-hl-line-mode     ; Might be changed outside the mode function.
 181     (unless (window-minibuffer-p (selected-window))
 182       (unless global-hl-line-overlay
 183         (setq global-hl-line-overlay (make-overlay 1 1)) ; to be moved
 184         (overlay-put global-hl-line-overlay 'face hl-line-face))
 185       (overlay-put global-hl-line-overlay 'window (selected-window))
 186       (hl-line-move global-hl-line-overlay))))
 187
 188 (defun global-hl-line-unhighlight ()
 189   "Deactivate the Global-Hl-Line overlay on the current line."
 190   (if global-hl-line-overlay
 191       (delete-overlay global-hl-line-overlay)))
 192
 193 (defun hl-line-move (overlay)
 194   "Move the Hl-Line overlay.
 195 If `hl-line-range-function' is non-nil, move the OVERLAY to the position
 196 where the function returns.  If `hl-line-range-function' is nil, fill
 197 the line including the point by OVERLAY."
 198   (let (tmp b e)
 199     (if hl-line-range-function
 200         (setq tmp (funcall hl-line-range-function)
 201               b   (car tmp)
 202               e   (cdr tmp))
 203       (setq tmp t
 204             b (line-beginning-position)
 205             e (line-beginning-position 2)))
 206     (if tmp
 207         (move-overlay overlay b e)
 208       (move-overlay overlay 1 1))))
 209
 210 (provide 'hl-line)
 211
 212 ;; arch-tag: ac806940-0876-4959-8c89-947563ee2833
 213 ;;; hl-line.el ends here