421 lines
17 KiB
EmacsLisp
421 lines
17 KiB
EmacsLisp
;;; centered-cursor-mode.el --- cursor stays vertically centered
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;; Copyright (C) 2007 André Riemann
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;; Author: André Riemann <andre.riemann@web.de>
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;; Maintainer: André Riemann <andre.riemann@web.de>
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;; Created: 2007-09-14
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;; Keywords: convenience
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;; URL: http://www.emacswiki.org/cgi-bin/wiki/centered-cursor-mode.el
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;; Compatibility: only tested with GNU Emacs 23.0
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;; Version: 0.5.2
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;; Last-Updated: 2009-08-31
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;; This file 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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;; This file is distributed in the hope that it will be useful, but
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;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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;; 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 Free
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;; Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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;; MA 02110-1301, USA.
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;;; Commentary:
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;; Makes the cursor stay vertically in a defined position (usually
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;; centered). The vertical position can be altered, see key definition
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;; below.
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;; To load put that in .emacs:
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;; (require 'centered-cursor-mode)
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;; To activate do:
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;; M-x centered-cursor-mode
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;; for buffer local or
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;; M-x global-centered-cursor-mode
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;; for global minor mode.
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;; Also possible: put that in .emacs
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;; (and
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;; (require 'centered-cursor-mode)
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;; (global-centered-cursor-mode +1))
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;; to always have centered-cursor-mode on in all buffers.
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;;; TODO:
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;; - the code is a mess
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;; - ccm-vpos-inverted doesn't work with ccm-vpos == 0, because first
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;; position from top is 0 and from bottom -1
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;; - interactive first start isn't animated when calling global-...
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;; because it starts the modes for each buffer and interactive-p fails
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;; for that
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;; - more bugs?
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;;; Change Log:
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;; 2009-08-31 andre-r
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;; * replaced window-body-height with window-text-height
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;; (partially visible lines are not counted in window-text-height)
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;; * bug fixed in ccm-vpos-recenter
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;; (some parentheses where wrong after the last update)
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;; 2009-02-23 andre-r
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;; * some simplifications
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;; 2009-02-22 andre-r
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;; * some tips from Drew Adams:
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;; - new local variable coding:utf-8
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;; - made recenter-sequence a defvar
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;; - added groups scrolling and convenience
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;; - replaced mouse-4 and mouse-5 with
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;; mouse-wheel-up-event and mouse-wheel-down-event
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;; - added scroll-bar-toolkit-scroll to ccm-ignored-commands
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;; - made ccm-ignored-commands customisable
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;; * removed a bug where it didn't work with more than one window
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;; displaying the same buffer
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;; * added function for page up and down scrolling
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;; (standard ones didn't work well with this mode)
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;; * made the animation delay customisable
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;; * made the initial vertical position customisable
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;; * made the behaviour at the end of the file customisable
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;; 2008-02-02 andre-r
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;; * fixed bug that led to wrong-type-argument
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;; when opening a new buffer
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;; * some other minor stuff
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;; 2007-09-24 andre-r
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;; * added global minor mode
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;; 2007-09-21 andre-r
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;; * not recentering at end of buffer
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;; * defvar animate-first-start-p
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;; 2007-09-14 andre-r
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;; * inital release
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;; This file is *NOT* part of GNU Emacs.
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;;; Code:
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(defgroup centered-cursor nil
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"Makes the cursor stay vertically in a defined position (usually centered).
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Instead the cursor the text moves around the cursor."
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:group 'scrolling
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:group 'convenience
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:link '(emacs-library-link :tag "Source Lisp File" "centered-cursor-mode.el")
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:link '(url-link "http://www.emacswiki.org/cgi-bin/wiki/centered-cursor-mode.el"))
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(defcustom ccm-step-size 2
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"Step size when animated recentering."
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:group 'centered-cursor
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:tag "Animation step size"
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:type 'integer)
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(defcustom ccm-step-delay 0.02
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"Delay between animation steps.
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If you want a different animation speed."
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:group 'centered-cursor
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:tag "Animation step delay"
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:type 'number)
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(defcustom ccm-ignored-commands '(mouse-drag-region
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mouse-set-point
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widget-button-click
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scroll-bar-toolkit-scroll)
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"After these commands recentering is ignored.
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This is to prevent unintentional jumping (especially when mouse
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clicking). Following commands (except the ignored ones) will
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cause an animated recentering to give a feedback and not just
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jumping to the center."
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:group 'centered-cursor
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:tag "Ignored commands"
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:type '(repeat (symbol :tag "Command")))
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(defcustom ccm-vpos-init '(round (window-text-height) 2)
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"This is the screen line position where the cursor initially stays."
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:group 'centered-cursor
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:tag "Vertical cursor position"
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:type '(choice (const :tag "Center" (round (window-text-height) 2))
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(const :tag "Golden ratio" (round (* 21 (window-text-height)) 34))
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(integer :tag "Lines from top" :value 10)))
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(make-variable-buffer-local 'ccm-vpos-init)
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(defcustom ccm-vpos-inverted 1
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"Inverted vertical cursor position.
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Defines if the initial vertical position `ccm-vpos-init' is
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measured from the bottom instead from the top."
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:group 'centered-cursor
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:tag "Inverted cursor position"
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:type '(choice (const :tag "Inverted" -1)
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(const :tag "Not inverted" 1)))
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(make-variable-buffer-local 'ccm-vpos-inverted)
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(defcustom ccm-recenter-at-end-of-file nil
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"Recenter at the end of the file.
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If non-nil the end of the file is recentered. If nil the end of
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the file stays at the end of the window."
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:group 'centered-cursor
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:tag "Recenter at EOF"
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:type '(choice (const :tag "Don't recenter at the end of the file" nil)
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(const :tag "Recenter at the end of the file" t)))
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(make-variable-buffer-local 'ccm-recenter-end-of-file)
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(defvar ccm-vpos nil
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"This is the screen line position where the cursor stays.")
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(make-variable-buffer-local 'ccm-vpos)
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(defvar animate-first-start-p nil
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"Whether or not to animate at first start. It is set to nil, if
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centered-cursor-mode is called non-interactively.")
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(make-variable-buffer-local 'animate-first-start-p)
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(defvar recenter-sequence nil
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"Before animated recentering a list is generated first with positions
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to successively recenter to")
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(make-variable-buffer-local 'recenter-sequence)
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(defvar ccm-map
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(let ((ccm-map (make-sparse-keymap)))
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(define-key ccm-map [(control meta -)] 'ccm-vpos-up)
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(define-key ccm-map [(control meta +)] 'ccm-vpos-down)
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(define-key ccm-map [(control meta =)] 'ccm-vpos-down)
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(define-key ccm-map [(control meta ?0)] 'ccm-vpos-recenter)
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(when (bound-and-true-p mouse-wheel-mode)
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(mapc (lambda (key)
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(define-key ccm-map key 'ccm-mwheel-scroll))
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(list (vector mouse-wheel-up-event)
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(vector mouse-wheel-down-event)
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(vector (list 'control mouse-wheel-up-event))
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(vector (list 'control mouse-wheel-down-event))
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(vector (list 'shift mouse-wheel-up-event))
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(vector (list 'shift mouse-wheel-down-event)))))
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(define-key ccm-map [(meta v)] 'ccm-scroll-down)
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(define-key ccm-map [(control v)] 'ccm-scroll-up)
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(define-key ccm-map [prior] 'ccm-scroll-down)
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(define-key ccm-map [next] 'ccm-scroll-up)
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ccm-map)
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"Keymap used in centered-cursor-mode.")
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(defun ccm-mwheel-scroll (event)
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"Very similar to `mwheel-scroll', but does not use `scroll-down'
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and `scroll-up' but `previous-line' and `next-line', that is, the
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cursor is moved and thus the text in the window is scrolled
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due to `recenter'.
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The customizable variable `mouse-wheel-scroll-amount' is used to
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determine how much to scroll, where nil instead of a number means
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the same as in mwheel-scroll, scroll by a near full screen.
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This command exists, because mwheel-scroll caused strange
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behaviour with automatic recentering."
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;; (interactive (list last-input-event))
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(interactive "e")
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(let* ((mods (delq 'click (delq 'double (delq 'triple (event-modifiers event)))))
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(amt (assoc mods mouse-wheel-scroll-amount)))
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;;(message "%S" mods)
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(if amt
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(setq amt (or (cdr amt)
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(- (window-text-height)
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next-screen-context-lines)))
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(let ((list-elt mouse-wheel-scroll-amount))
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(while (consp (setq amt (pop list-elt))))))
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(if mouse-wheel-follow-mouse
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(select-window (posn-window (event-start event))))
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(let ((button (mwheel-event-button event)))
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(cond
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((eq button mouse-wheel-down-event)
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(forward-line (- amt)))
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;;(princ amt))
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((eq button mouse-wheel-up-event)
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(forward-line amt))
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;;(princ amt))
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(t (error "Bad binding in ccm-mwheel-scroll"))))))
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(defun ccm-scroll-down (&optional arg)
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"Replaces `scroll-down' because with scroll-down
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`centered-cursor-mode' sometimes doesn't reach the top of the
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buffer. This version actually moves the cursor with
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`previous-line'. Since with centered-cursor-mode the cursor is in
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a fixed position the movement appears as page up."
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(interactive "P")
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(let ((amt (or arg (- (window-text-height)
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next-screen-context-lines))))
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(forward-line (- amt))))
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(defun ccm-scroll-up (&optional arg)
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"Replaces `scroll-up' to be consistent with `ccm-scroll-down'.
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This version actually moves the cursor with `previous-line'.
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Since with centered-cursor-mode the cursor is in a fixed position
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the movement appears as page up."
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(interactive "P")
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(let ((amt (or arg (- (window-text-height)
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next-screen-context-lines))))
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(forward-line amt)))
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(defun ccm-vpos-down (arg)
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"Adjust the value of the screen line (where the cursor stays) by arg.
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Negative values for arg are possible. Just the variable ccm-vpos
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is set."
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(interactive "p")
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(or arg (setq arg 1))
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(let ((new-pos (if (< ccm-vpos 0)
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(- ccm-vpos arg)
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(+ ccm-vpos arg)))
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;; see pos-visible-in-window-p
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(vpos-max (if (< ccm-vpos 0)
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-1
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(- (window-text-height) 1)))
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(vpos-min (if (< ccm-vpos 0)
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(- (window-text-height))
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0)))
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(setq ccm-vpos
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(cond
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((< new-pos vpos-min)
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vpos-min)
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((> new-pos vpos-max)
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vpos-max)
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(t
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new-pos)))))
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(defun ccm-vpos-up (arg)
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"See `ccm-vpos-down'."
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(interactive "p")
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(or arg (setq arg 1))
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(ccm-vpos-down (- arg)))
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(defun ccm-vpos-recenter ()
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"Set the value of the screen line (where the cursor stays) in
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the center. Just the variable ccm-vpos is set."
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(interactive)
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(if (equal (current-buffer)
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(window-buffer (selected-window)))
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(setq ccm-vpos (* (eval ccm-vpos-init)
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ccm-vpos-inverted))))
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(defun ccm-position-cursor ()
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"Do the actual recentering at the position `ccm-vpos'."
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(unless (member this-command ccm-ignored-commands)
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(unless ccm-vpos
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(ccm-vpos-recenter))
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(unless (minibufferp (current-buffer))
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(if (equal (current-buffer)
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(window-buffer (selected-window)))
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(let* ((current-line
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(if (< ccm-vpos 0)
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;; one-based, from bottom, negative
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(- (count-lines (point)
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;; window-end is sometimes < 0
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;; when opening a help buffer
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(if (> (window-end) 0)
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(window-end)
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1)))
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;; zero-based, from top, positive
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(+ (count-lines (window-start) (point))
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;; count-lines returns different value in column 0
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(if (= (current-column) 0) 0 -1))))
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(diff (- ccm-vpos current-line))
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(step-size ccm-step-size)
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(step-delay ccm-step-delay)
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(vpos-inverted ccm-vpos-inverted)
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(recenter-at-end-of-file ccm-recenter-at-end-of-file))
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(let* ((bottom-vpos (if (< ccm-vpos 0)
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(- ccm-vpos)
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(- (window-text-height) ccm-vpos)))
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(correction (save-excursion
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(if (or (= (point) (point-max))
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(progn
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(goto-char (point-max))
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(zerop (current-column))))
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1 0)))
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;; lines from point to end of buffer
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(bottom-lines (+ (count-lines (point) (point-max))
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correction)))
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;; only animate if point was moved rather far away
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;; before by a mouseclick (see ccm-ignored-commands)
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;; or if minor mode is just entered interactively
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(if (not (and (> (abs diff) 4)
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(or (member last-command ccm-ignored-commands)
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animate-first-start-p)))
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(recenter (if (and (< bottom-lines bottom-vpos)
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(not recenter-at-end-of-file))
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;; if near the bottom, recenter in the
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;; negative screen line that equals the
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;; bottom buffer line, i.e. if we are in
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;; the second last line (-2) of the
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;; buffer, the cursor will be recentered
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;; in -2
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(- bottom-lines)
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ccm-vpos))
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(setq animate-first-start-p nil)
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;; first build a list with positions to successively recenter to
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(setq recenter-sequence
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;; reverse: because we build the list not FROM -> TO but
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;; TO -> FROM because if step size in number-sequence is
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;; bigger than one, TO might not included, that means the
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;; ccm-vpos would not be reached
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;; cdr: don't recenter the current-line
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(if (and (< bottom-lines bottom-vpos)
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(not recenter-at-end-of-file))
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;; this one is for animation near the bottom
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(cdr (reverse (number-sequence
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(- bottom-lines)
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(if (< ccm-vpos 0)
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current-line
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(- (- (window-text-height) current-line)))
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(* (/ diff (abs diff)) (- step-size)))))
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(cdr (reverse (number-sequence
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ccm-vpos
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current-line
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(* (/ diff (abs diff)) (- step-size)))))))
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;; (message "%d %d %d (%d): %S" current-line ccm-vpos bottom-lines diff recenter-sequence)
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(while recenter-sequence
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;; actual animation
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(recenter (pop recenter-sequence))
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(if (car recenter-sequence) (sit-for step-delay t))))))))))
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(defun ccm-first-start (animate)
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"Called from centered-cursor-mode. Animate at first start, if
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centered-cursor-mode is called interactively."
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(let ((animate-first-start-p animate))
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(ccm-vpos-recenter)
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(ccm-position-cursor)))
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;;(defalias 'ccm 'centered-cursor-mode)
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(define-minor-mode centered-cursor-mode
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"Makes the cursor stay vertically in a defined
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position (usually centered)."
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:init-value nil
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;; :lighter nil
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:lighter " ¢"
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:keymap ccm-map
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(cond
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(centered-cursor-mode
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(ccm-first-start (interactive-p))
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(add-hook 'post-command-hook 'ccm-position-cursor t t)
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(add-hook 'window-configuration-change-hook 'ccm-vpos-recenter t t))
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(t
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(remove-hook 'post-command-hook 'ccm-position-cursor t)
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(remove-hook 'window-configuration-change-hook 'ccm-vpos-recenter t))))
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(define-global-minor-mode global-centered-cursor-mode centered-cursor-mode
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centered-cursor-mode)
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(provide 'centered-cursor-mode)
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;;; Help:
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;; (info "(elisp)Defining Minor Modes")
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;; (info "(elisp)Screen Lines")
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;; (info "(elisp)Hooks")
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;; (info "(elisp)Customization")
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;; (find-function 'mwheel-scroll)
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;; Local Variables:
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;; coding: utf-8
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;; End:
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;;; centered-cursor-mode.el ends here
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