lisp/hl-line.el

   1 ;;; hl-line.el --- highlight the current line
   2
   3 ;; Copyright (C) 1998, 2000, 2001, 2002, 2003, 2004,
   4 ;;   2005 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 ;; In default whole the 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 (defgroup hl-line nil
  68   "Highlight the current line."
  69   :version "21.1"
  70   :group 'editing)
  71
  72 (defcustom hl-line-face 'highlight
  73   "Face with which to highlight the current line."
  74   :type 'face
  75   :group 'hl-line)
  76
  77 (defcustom hl-line-sticky-flag t
  78   "*Non-nil means highlight the current line in all windows.
  79 Otherwise Hl-Line mode will highlight only in the selected
  80 window.  Setting this variable takes effect the next time you use
  81 the command `hl-line-mode' to turn Hl-Line mode on."
  82   :type 'boolean
  83   :version "22.1"
  84   :group 'hl-line)
  85
  86 (defvar hl-line-range-function nil
  87   "If non-nil, function to call to return highlight range.
  88 The function of no args should return a cons cell; its car value
  89 is the beginning position of highlight and its cdr value is the
  90 end position of highlight in the buffer.
  91 It should return nil if there's no region to be highlighted.
  92
  93 This variable is expected to be made buffer-local by modes.")
  94
  95 (defvar hl-line-overlay nil
  96   "Overlay used by Hl-Line mode to highlight the current line.")
  97 (make-variable-buffer-local 'hl-line-overlay)
  98
  99 (defvar global-hl-line-overlay nil
 100   "Overlay used by Global-Hl-Line mode to highlight the current line.")
 101
 102 ;;;###autoload
 103 (define-minor-mode hl-line-mode
 104   "Buffer-local minor mode to highlight the line about point.
 105 With ARG, turn Hl-Line mode on if ARG is positive, off otherwise.
 106
 107 If `hl-line-sticky-flag' is non-nil, Hl-Line mode highlights the
 108 line about the buffer's point in all windows.  Caveat: the
 109 buffer's point might be different from the point of a
 110 non-selected window.  Hl-Line mode uses the function
 111 `hl-line-highlight' on `post-command-hook' in this case.
 112
 113 When `hl-line-sticky-flag' is nil, Hl-Line mode highlights the
 114 line about point in the selected window only.  In this case, it
 115 uses the function `hl-line-unhighlight' on `pre-command-hook' in
 116 addition to `hl-line-highlight' on `post-command-hook'."
 117   :group 'hl-line
 118   (if hl-line-mode
 119       (progn
 120         ;; In case `kill-all-local-variables' is called.
 121         (add-hook 'change-major-mode-hook #'hl-line-unhighlight nil t)
 122         (if hl-line-sticky-flag
 123             (remove-hook 'pre-command-hook #'hl-line-unhighlight t)
 124           (add-hook 'pre-command-hook #'hl-line-unhighlight nil t))
 125         (hl-line-highlight)
 126         (add-hook 'post-command-hook #'hl-line-highlight nil t))
 127     (remove-hook 'post-command-hook #'hl-line-highlight t)
 128     (hl-line-unhighlight)
 129     (remove-hook 'change-major-mode-hook #'hl-line-unhighlight t)
 130     (remove-hook 'pre-command-hook #'hl-line-unhighlight t)))
 131
 132 (defun hl-line-highlight ()
 133   "Active the Hl-Line overlay on the current line."
 134   (if hl-line-mode      ; Might be changed outside the mode function.
 135       (progn
 136         (unless hl-line-overlay
 137           (setq hl-line-overlay (make-overlay 1 1)) ; to be moved
 138           (overlay-put hl-line-overlay 'face hl-line-face))
 139         (overlay-put hl-line-overlay
 140                      'window (unless hl-line-sticky-flag (selected-window)))
 141         (hl-line-move hl-line-overlay))
 142     (hl-line-unhighlight)))
 143
 144 (defun hl-line-unhighlight ()
 145   "Deactivate the Hl-Line overlay on the current line."
 146   (if hl-line-overlay
 147       (delete-overlay hl-line-overlay)))
 148
 149 ;;;###autoload
 150 (define-minor-mode global-hl-line-mode
 151   "Global minor mode to highlight the line about point in the current window.
 152 With ARG, turn Global-Hl-Line mode on if ARG is positive, off otherwise.
 153
 154 Global-Hl-Line mode uses the functions `global-hl-line-unhighlight' and
 155 `global-hl-line-highlight' on `pre-command-hook' and `post-command-hook'."
 156   :global t
 157   :group 'hl-line
 158   (if global-hl-line-mode
 159       (progn
 160         (add-hook 'pre-command-hook #'global-hl-line-unhighlight)
 161         (add-hook 'post-command-hook #'global-hl-line-highlight))
 162     (global-hl-line-unhighlight)
 163     (remove-hook 'pre-command-hook #'global-hl-line-unhighlight)
 164     (remove-hook 'post-command-hook #'global-hl-line-highlight)))
 165
 166 (defun global-hl-line-highlight ()
 167   "Active the Global-Hl-Line overlay on the current line in the current window."
 168   (when global-hl-line-mode     ; Might be changed outside the mode function.
 169     (unless (window-minibuffer-p (selected-window))
 170       (unless global-hl-line-overlay
 171         (setq global-hl-line-overlay (make-overlay 1 1)) ; to be moved
 172         (overlay-put global-hl-line-overlay 'face hl-line-face))
 173       (overlay-put global-hl-line-overlay 'window (selected-window))
 174       (hl-line-move global-hl-line-overlay))))
 175
 176 (defun global-hl-line-unhighlight ()
 177   "Deactivate the Global-Hl-Line overlay on the current line."
 178   (if global-hl-line-overlay
 179       (delete-overlay global-hl-line-overlay)))
 180
 181 (defun hl-line-move (overlay)
 182   "Move the hl-line-mode overlay.
 183 If `hl-line-range-function' is non-nil, move the OVERLAY to the position
 184 where the function returns. If `hl-line-range-function' is nil, fill
 185 the line including the point by OVERLAY."
 186   (let (tmp b e)
 187     (if hl-line-range-function
 188         (setq tmp (funcall hl-line-range-function)
 189               b   (car tmp)
 190               e   (cdr tmp))
 191       (setq tmp t
 192             b (line-beginning-position)
 193             e (line-beginning-position 2)))
 194     (if tmp
 195         (move-overlay overlay b e)
 196       (move-overlay overlay 1 1))))
 197
 198 (provide 'hl-line)
 199
 200 ;;; arch-tag: ac806940-0876-4959-8c89-947563ee2833
 201 ;;; hl-line.el ends here