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;;; 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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;; Package-Version: 20150302.831 |
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;; URL: http://www.emacswiki.org/cgi-bin/wiki/centered-cursor-mode.el |
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;; Compatibility: tested with GNU Emacs 23.0, 24 |
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;; Version: 0.5.4 |
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;; Last-Updated: 2015-10-01 |
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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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;; 2015-10-01 Hinrik Örn Sigurðsson <hinrik.sig@gmail.com> |
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;; * Avoided calling count-lines when unnecessary, which |
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;; fixes slow scrolling in large files |
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;; 2015-03-01 andre-r |
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;; * fixed bug where Emacs without X support (emacs-nox) didn't find mouse-wheel-mode |
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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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(require 'mouse-wheel-mode nil 'noerror) |
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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 (and (boundp 'mouse-wheel-mode) 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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(window-is-at-bottom (= (window-end) (point-max))) |
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;; lines from point to end of buffer |
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(bottom-lines (if window-is-at-bottom |
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(+ (count-lines (point) (point-max)) |
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correction)))) |
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;; only animate if the 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 window-is-at-bottom |
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(< 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 window-is-at-bottom |
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(< 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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;;;###autoload |
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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 |
