;;; hl-line.el --- highlight the current line
;; Copyright (C) 1998, 2000, 2001, 2003 Free Software Foundation, Inc.
;; Author: Dave Love <email@example.com>
;; Created: 1998-09-13
;; Keywords: faces, frames, emulation
;; This file is part of GNU Emacs.
;; GNU Emacs 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.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; 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.
;; Provides a buffer-local minor mode (toggled by M-x hl-line-mode)
;; and a global minor mode (toggled by M-x global-hl-line-mode) to
;; highlight, on a suitable terminal, the line on which point is. The
;; global mode highlights the current line in the selected window only
;; (except when the minibuffer window is selected). This was
;; implemented to satisfy a request for a feature of Lesser Editors.
;; The local mode is sticky: it highlights the line about the buffer's
;; point even if the buffer's window is not selected. Caveat: the
;; buffer's point might be different from the point of a non-selected
;; window. Set the variable `hl-line-sticky-flag' to nil to make the
;; local mode behave like the global mode.
;; You probably don't really want to use the global mode; if the
;; cursor is difficult to spot, try changing its colour, relying on
;; `blink-cursor-mode' or both. The hookery used might affect
;; response noticeably on a slow machine. The local mode may be
;; useful in non-editing buffers such as Gnus or PCL-CVS though.
;; An overlay is used. In the non-sticky cases, this overlay is
;; active only on the selected window. A hook is added to
;; `post-command-hook' to activate the overlay and move it to the line
;; about point. To get the non-sticky behavior, `hl-line-unhighlight'
;; is added to `pre-command-hook' as well. This function deactivates
;; the overlay unconditionally in case the command changes the
;; selected window. (It does so rather than keeping track of changes
;; in the selected window).
;; You could make variable `global-hl-line-mode' buffer-local and set
;; it to nil to avoid highlighting specific buffers, when the global
;; mode is used.
(defgroup hl-line nil
"Highlight the current line."
(defcustom hl-line-face 'highlight
"Face with which to highlight the current line."
(defcustom hl-line-sticky-flag t
"*Non-nil means highlight the current line in all windows.
Otherwise Hl-Line mode will highlight only in the selected
window. Setting this variable takes effect the next time you use
the command `hl-line-mode' to turn Hl-Line mode on."
(defvar hl-line-overlay nil
"Overlay used by Hl-Line mode to highlight the current line.")
(defvar global-hl-line-overlay nil
"Overlay used by Global-Hl-Line mode to highlight the current line.")
"Buffer-local minor mode to highlight the line about point.
With ARG, turn Hl-Line mode on if ARG is positive, off otherwise.
If `hl-line-sticky-flag' is non-nil, Hl-Line mode highlights the
line about the buffer's point in all windows. Caveat: the
buffer's point might be different from the point of a
non-selected window. Hl-Line mode uses the function
`hl-line-highlight' on `post-command-hook' in this case.
When `hl-line-sticky-flag' is nil, Hl-Line mode highlights the
line about point in the selected window only. In this case, it
uses the function `hl-line-unhighlight' on `pre-command-hook' in
addition to `hl-line-highlight' on `post-command-hook'."
nil nil nil
;; In case `kill-all-local-variables' is called.
(add-hook 'change-major-mode-hook #'hl-line-unhighlight nil t)
(remove-hook 'pre-command-hook #'hl-line-unhighlight t)
(add-hook 'pre-command-hook #'hl-line-unhighlight nil t))
(add-hook 'post-command-hook #'hl-line-highlight nil t))
(remove-hook 'post-command-hook #'hl-line-highlight t)
(remove-hook 'change-major-mode-hook #'hl-line-unhighlight t)
(remove-hook 'pre-command-hook #'hl-line-unhighlight t)))
(defun hl-line-highlight ()
"Active the Hl-Line overlay on the current line."
(if hl-line-mode ; Might be changed outside the mode function.
(setq hl-line-overlay (make-overlay 1 1)) ; to be moved
(overlay-put hl-line-overlay 'face hl-line-face))
'window (unless hl-line-sticky-flag (selected-window)))
(line-beginning-position) (line-beginning-position 2)))
(defun hl-line-unhighlight ()
"Deactivate the Hl-Line overlay on the current line."
"Global minor mode to highlight the line about point in the current window.
With ARG, turn Global-Hl-Line mode on if ARG is positive, off otherwise.
Global-Hl-Line mode uses the functions `global-hl-line-unhighlight' and
`global-hl-line-highlight' on `pre-command-hook' and `post-command-hook'."
(add-hook 'pre-command-hook #'global-hl-line-unhighlight)
(add-hook 'post-command-hook #'global-hl-line-highlight))
(remove-hook 'pre-command-hook #'global-hl-line-unhighlight)
(remove-hook 'post-command-hook #'global-hl-line-highlight)))
(defun global-hl-line-highlight ()
"Active the Global-Hl-Line overlay on the current line in the current window."
(when global-hl-line-mode ; Might be changed outside the mode function.
(unless (window-minibuffer-p (selected-window))
(setq global-hl-line-overlay (make-overlay 1 1)) ; to be moved
(overlay-put global-hl-line-overlay 'face hl-line-face))
(overlay-put global-hl-line-overlay 'window (selected-window))
(line-beginning-position) (line-beginning-position 2)))))
(defun global-hl-line-unhighlight ()
"Deactivate the Global-Hl-Line overlay on the current line."
;;; hl-line.el ends here