lisp/mwheel.el

   1 ;;; mwheel.el --- Wheel mouse support
   2
   3 ;; Copyright (C) 1998,2000,2001,2002  Free Software Foundation, Inc.
   4 ;; Maintainer: William M. Perry <wmperry@gnu.org>
   5 ;; Keywords: mouse
   6
   7 ;; This file is part of GNU Emacs.
   8
   9 ;; GNU Emacs is free software; you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation; either version 2, or (at your option)
  12 ;; any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  21 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  22 ;; Boston, MA 02111-1307, USA.
  23
  24 ;;; Commentary:
  25
  26 ;; This code will enable the use of the infamous 'wheel' on the new
  27 ;; crop of mice.  Under XFree86 and the XSuSE X Servers, the wheel
  28 ;; events are sent as button4/button5 events.
  29
  30 ;; I for one would prefer some way of converting the button4/button5
  31 ;; events into different event types, like 'mwheel-up' or
  32 ;; 'mwheel-down', but I cannot find a way to do this very easily (or
  33 ;; portably), so for now I just live with it.
  34
  35 ;; To enable this code, simply put this at the top of your .emacs
  36 ;; file:
  37 ;;
  38 ;; (mwheel-install)
  39
  40 ;;; Code:
  41
  42 (require 'custom)
  43 (require 'timer)
  44
  45 ;; Setter function for mouse-button user-options.  Switch Mouse Wheel
  46 ;; mode off and on again so that the old button is unbound and
  47 ;; new button is bound to mwheel-scroll.
  48
  49 (defun mouse-wheel-change-button (var button)
  50   (let ((active mouse-wheel-mode))
  51     ;; Deactivate before changing the setting.
  52     (when active (mouse-wheel-mode -1))
  53     (set-default var button)
  54     (when active (mouse-wheel-mode 1))))
  55
  56 (defvar mouse-wheel-down-button 4)
  57 (make-obsolete-variable 'mouse-wheel-down-button
  58                         'mouse-wheel-down-event)
  59 (defcustom mouse-wheel-down-event
  60   ;; In the latest versions of XEmacs, we could just use mouse-%s as well.
  61   (intern (format (if (featurep 'xemacs) "button%s" "mouse-%s")
  62                   mouse-wheel-down-button))
  63   "Event used for scrolling down."
  64   :group 'mouse
  65   :type 'symbol
  66   :set 'mouse-wheel-change-button)
  67
  68 (defvar mouse-wheel-up-button 5)
  69 (make-obsolete-variable 'mouse-wheel-up-button
  70                         'mouse-wheel-up-event)
  71 (defcustom mouse-wheel-up-event
  72   ;; In the latest versions of XEmacs, we could just use mouse-%s as well.
  73   (intern (format (if (featurep 'xemacs) "button%s" "mouse-%s")
  74                   mouse-wheel-up-button))
  75   "Event used for scrolling down."
  76   :group 'mouse
  77   :type 'symbol
  78   :set 'mouse-wheel-change-button)
  79
  80 (defvar mouse-wheel-click-button 2)
  81 (make-obsolete-variable 'mouse-wheel-click-button
  82                         'mouse-wheel-click-event)
  83 (defcustom mouse-wheel-click-event
  84   ;; In the latest versions of XEmacs, we could just use mouse-%s as well.
  85   (intern (format (if (featurep 'xemacs) "button%s" "mouse-%s")
  86                   mouse-wheel-click-button))
  87   "Event that should be temporarily inhibited after mouse scrolling.
  88 The mouse wheel is typically on the mouse-2 button, so it may easily
  89 happen that text is accidentially yanked into the buffer when
  90 scrolling with the mouse wheel.  To prevent that, this variable can be
  91 set to the event sent when clicking on the mouse wheel button."
  92   :group 'mouse
  93   :type 'symbol
  94   :set 'mouse-wheel-change-button)
  95
  96 (defcustom mouse-wheel-inhibit-click-time 0.35
  97   "Time in seconds to inhibit clicking on mouse wheel button after scroll."
  98   :group 'mouse
  99   :type 'number)
 100
 101 (defcustom mouse-wheel-scroll-amount '(5 ((shift) . 1) ((control) . nil))
 102   "Amount to scroll windows by when spinning the mouse wheel.
 103 This is an alist mapping the modifier key to the amount to scroll when
 104 the wheel is moved with the modifier key depressed.
 105 Elements of the list have the form (MODIFIERS . AMOUNT) or just AMOUNT if
 106 MODIFIERS is nil.
 107
 108 AMOUNT should be the number of lines to scroll, or nil for near full
 109 screen.  It can also be a floating point number, specifying the fraction of
 110 a full screen to scroll.  A near full screen is `next-screen-context-lines'
 111 less than a full screen."
 112   :group 'mouse
 113   :type '(cons
 114           (choice :tag "Normal"
 115                   (const :tag "Full screen" :value nil)
 116                   (integer :tag "Specific # of lines")
 117                   (float :tag "Fraction of window")
 118                   (cons
 119                    (repeat (choice :tag "modifier"
 120                                    (const alt) (const control) (const hyper)
 121                                    (const meta) (const shift) (const super)))
 122                    (choice :tag "scroll amount"
 123                            (const :tag "Full screen" :value nil)
 124                            (integer :tag "Specific # of lines")
 125                            (float :tag "Fraction of window"))))
 126           (repeat
 127            (cons
 128             (repeat (choice :tag "modifier"
 129                             (const alt) (const control) (const hyper)
 130                             (const meta) (const shift) (const super)))
 131             (choice :tag "scroll amount"
 132                     (const :tag "Full screen" :value nil)
 133                     (integer :tag "Specific # of lines")
 134                     (float :tag "Fraction of window"))))))
 135
 136 (defcustom mouse-wheel-progessive-speed t
 137   "If non-nil, the faster the user moves the wheel, the faster the scrolling.
 138 Note that this has no effect when `mouse-wheel-scroll-amount' specifies
 139 a \"near full screen\" scroll or when the mouse wheel sends key instead
 140 of button events."
 141   :group 'mouse
 142   :type 'boolean)
 143
 144 (defcustom mouse-wheel-follow-mouse t
 145   "Whether the mouse wheel should scroll the window that the mouse is over.
 146 This can be slightly disconcerting, but some people prefer it."
 147   :group 'mouse
 148   :type 'boolean)
 149
 150 (if (not (fboundp 'event-button))
 151     (defun mwheel-event-button (event)
 152       (let ((x (event-basic-type event)))
 153         ;; Map mouse-wheel events to appropriate buttons
 154         (if (eq 'mouse-wheel x)
 155             (let ((amount (car (cdr (cdr (cdr event))))))
 156               (if (< amount 0)
 157                   mouse-wheel-up-event
 158                 mouse-wheel-down-event))
 159           x)))
 160   (fset 'mwheel-event-button 'event-button))
 161
 162 (if (not (fboundp 'event-window))
 163     (defun mwheel-event-window (event)
 164       (posn-window (event-start event)))
 165   (fset 'mwheel-event-window 'event-window))
 166
 167 (defvar mwheel-inhibit-click-event-timer nil
 168   "Timer running while mouse wheel click event is inhibited.")
 169
 170 (defun mwheel-inhibit-click-timeout ()
 171   "Handler for `mwheel-inhibit-click-event-timer'."
 172   (setq mwheel-inhibit-click-event-timer nil)
 173   (remove-hook 'pre-command-hook 'mwheel-filter-click-events))
 174
 175 (defun mwheel-filter-click-events ()
 176   "Discard `mouse-wheel-click-event' while scrolling the mouse."
 177   (if (eq (event-basic-type last-input-event) mouse-wheel-click-event)
 178       (setq this-command 'ignore)))
 179
 180 (defun mwheel-scroll (event)
 181   "Scroll up or down according to the EVENT.
 182 This should only be bound to mouse buttons 4 and 5."
 183   (interactive (list last-input-event))
 184   (let* ((curwin (if mouse-wheel-follow-mouse
 185                      (prog1
 186                          (selected-window)
 187                        (select-window (mwheel-event-window event)))))
 188          (mods
 189           (delq 'click (delq 'double (delq 'triple (event-modifiers event)))))
 190          (amt (assoc mods mouse-wheel-scroll-amount)))
 191     ;; Extract the actual amount or find the element that has no modifiers.
 192     (if amt (setq amt (cdr amt))
 193       (let ((list-elt mouse-wheel-scroll-amount))
 194         (while (consp (setq amt (pop list-elt))))))
 195     (if (floatp amt) (setq amt (1+ (truncate (* amt (window-height))))))
 196     (when (and mouse-wheel-progessive-speed (numberp amt))
 197       ;; When the double-mouse-N comes in, a mouse-N has been executed already,
 198       ;; So by adding things up we get a squaring up (1, 3, 6, 10, 15, ...).
 199       (setq amt (* amt (event-click-count event))))
 200     (unwind-protect
 201         (let ((button (mwheel-event-button event)))
 202           (cond ((eq button mouse-wheel-down-event) (scroll-down amt))
 203                 ((eq button mouse-wheel-up-event) (scroll-up amt))
 204                 (t (error "Bad binding in mwheel-scroll"))))
 205       (if curwin (select-window curwin))))
 206   (when (and mouse-wheel-click-event mouse-wheel-inhibit-click-time)
 207     (if mwheel-inhibit-click-event-timer
 208         (cancel-timer mwheel-inhibit-click-event-timer)
 209       (add-hook 'pre-command-hook 'mwheel-filter-click-events))
 210     (setq mwheel-inhibit-click-event-timer
 211           (run-with-timer mouse-wheel-inhibit-click-time nil
 212                           'mwheel-inhibit-click-timeout))))
 213
 214 ;;;###autoload
 215 (define-minor-mode mouse-wheel-mode
 216   "Toggle mouse wheel support.
 217 With prefix argument ARG, turn on if positive, otherwise off.
 218 Returns non-nil if the new state is enabled."
 219   :global t
 220   :group 'mouse
 221   (let* ((dn mouse-wheel-down-event)
 222          (up mouse-wheel-up-event)
 223          (keys
 224           (nconc (mapcar (lambda (amt) `[(,@(if (consp amt) (car amt)) ,up)])
 225                          mouse-wheel-scroll-amount)
 226                  (mapcar (lambda (amt) `[(,@(if (consp amt) (car amt)) ,dn)])
 227                          mouse-wheel-scroll-amount))))
 228     ;; This condition-case is here because Emacs 19 will throw an error
 229     ;; if you try to define a key that it does not know about.  I for one
 230     ;; prefer to just unconditionally do a mwheel-install in my .emacs, so
 231     ;; that if the wheeled-mouse is there, it just works, and this way it
 232     ;; doesn't yell at me if I'm on my laptop or another machine, etc.
 233     (condition-case ()
 234         (dolist (key keys)
 235           (cond (mouse-wheel-mode
 236                  (global-set-key key 'mwheel-scroll))
 237                 ((eq (lookup-key (current-global-map) key) 'mwheel-scroll)
 238                  (global-unset-key key))))
 239       (error nil))))
 240
 241 ;;; Compatibility entry point
 242 ;;;###autoload
 243 (defun mwheel-install (&optional uninstall)
 244   "Enable mouse wheel support."
 245   (mouse-wheel-mode (if uninstall -1 1)))
 246
 247 (provide 'mwheel)
 248
 249 ;;; mwheel.el ends here