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113 lines
4.0 KiB
EmacsLisp
113 lines
4.0 KiB
EmacsLisp
;;; hl-line.el --- highlight the current line
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;; Copyright (C) 1998 Free Software Foundation, Inc.
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;; Author: Dave Love <fx@gnu.org>
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;; Created: 1998-09-13
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;; Keywords: faces, frames
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;; Hl-Line mode is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; Hl-Line mode is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to the
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;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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;; Boston, MA 02111-1307, USA.
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;;; Commentary:
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;; Provides a global minor mode (toggled by M-x hl-line-mode) to
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;; highlight, in a windowing system, the line on which point is
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;; (except in a minibuffer window) to satisfy a request for a feature
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;; of Lesser Editors.
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;; You probably don't really want this; if the cursor is difficult to
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;; spot, try changing its colour or using a cursor blinking
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;; <URL:http://www.wonderworks.com/download/blinking-cursor.el.gz> or
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;; jiggling <URL:http://www.eskimo.com/%7Eseldon> package. (Cursor
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;; blinking will be built in to Emacs 21.) The hookery involved here
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;; might slow Emacs noticeably on a slow machine.
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;; An overlay is used, active only on the selected window. Hooks are
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;; added to `pre-command-hook' and `post-command-hook' to activate and
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;; deactivate (by deleting) the overlay. `hl-line-unhighlight', on
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;; `pre-command-hook', deactivates it unconditionally in case the
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;; command changes the selected window. (It does so rather than
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;; keeping track of changes in the selected window).
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;; `hl-line-highlight', on `post-command-hook', activates it again
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;; across the window width.
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;;; Code:
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(defgroup hl-line nil
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"Highliight the current line."
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:version "21.1"
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:group 'editing)
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;;;###autoload
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(defcustom hl-line-mode nil
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"Non-nil if Hl-Line mode is enabled."
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:set (lambda (symbol value)
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(hl-line-mode (or value 0)))
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:initialize 'custom-initialize-default
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:type 'boolean
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:group 'hl-line
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:require 'hl-line)
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(defcustom hl-line-face 'highlight
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"Face with which to highlight the current line."
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:type 'face
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:group 'hl-line)
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(defvar hl-line-overlay nil)
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(make-variable-buffer-local 'hl-line-overlay)
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(defun hl-line-highlight ()
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"Active the Hl-Line overlay on the current line in the current window.
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\(Unless it's a minibuffer window.)"
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(unless (window-minibuffer-p (selected-window)) ; silly in minibuffer
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(unless hl-line-overlay ; new overlay for this buffer
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(setq hl-line-overlay (make-overlay 1 1)) ; to be moved
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(overlay-put hl-line-overlay 'face hl-line-face))
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(overlay-put hl-line-overlay 'window (selected-window))
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(move-overlay hl-line-overlay
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(line-beginning-position) (1+ (line-end-position)))))
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(defun hl-line-unhighlight ()
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"Deactivate the Hl-Line overlay on the current line in the current window."
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(if hl-line-overlay
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(delete-overlay hl-line-overlay)))
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;;;###autoload
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(defun hl-line-mode (&optional arg)
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"Global minor mode to highlight the line about point.
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With ARG, turn Hl-Line mode on if ARG is positive, off otherwise.
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Only useful with a windowing system.
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Uses functions `hl-line-unhighlight' and `hl-line-highlight' on
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`pre-command-hook' and `post-command-hook'."
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(interactive "P")
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(setq hl-line-mode (if (null arg)
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(not hl-line-mode)
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(> (prefix-numeric-value arg) 0)))
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(cond (hl-line-mode
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(add-hook 'pre-command-hook #'hl-line-unhighlight)
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(add-hook 'post-command-hook #'hl-line-highlight))
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(t
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(hl-line-unhighlight)
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(remove-hook 'pre-command-hook #'hl-line-unhighlight)
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(remove-hook 'post-command-hook #'hl-line-highlight)))
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(if (interactive-p)
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(message "Hl-Line mode %sabled" (if hl-line-mode "en" "dis"))))
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(provide 'hl-line)
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;;; hl-line.el ends here
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