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spacemacs/layers/+spacemacs/spacemacs-navigation/local/centered-cursor/centered-cursor-mode.el
syl20bnr 30d7beb277 Refactor spacemacs-ui and spacemacs-ui-visual layers 
Create new layers:
- spacemacs-navigation: contains packages whose principal goal is navigation
- spacemacs-modeline: contains packages about mode line

Merge spacemacs-ui and spacemacs-ui-visual into layer spacemacs-visual.
2017-04-11 23:09:35 -04:00

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