lisp/mwheel.el

   1 ;;; mwheel.el --- Wheel mouse support
   2
   3 ;; Copyright (C) 1998, 2000, 2001, 2002, 2002, 2004,
   4 ;;   2005, 2006 Free Software Foundation, Inc.
   5 ;; Maintainer: William M. Perry <wmperry@gnu.org>
   6 ;; Keywords: mouse
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  22 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  23 ;; Boston, MA 02110-1301, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; This code will enable the use of the infamous 'wheel' on the new
  28 ;; crop of mice.  Under XFree86 and the XSuSE X Servers, the wheel
  29 ;; events are sent as button4/button5 events.
  30
  31 ;; I for one would prefer some way of converting the button4/button5
  32 ;; events into different event types, like 'mwheel-up' or
  33 ;; 'mwheel-down', but I cannot find a way to do this very easily (or
  34 ;; portably), so for now I just live with it.
  35
  36 ;; To enable this code, simply put this at the top of your .emacs
  37 ;; file:
  38 ;;
  39 ;; (mouse-wheel-mode 1)
  40
  41 ;;; Code:
  42
  43 (require 'custom)
  44 (require 'timer)
  45
  46 ;; Setter function for mouse-button user-options.  Switch Mouse Wheel
  47 ;; mode off and on again so that the old button is unbound and
  48 ;; new button is bound to mwheel-scroll.
  49
  50 (defun mouse-wheel-change-button (var button)
  51   (let ((active mouse-wheel-mode))
  52     ;; Deactivate before changing the setting.
  53     (when active (mouse-wheel-mode -1))
  54     (set-default var button)
  55     (when active (mouse-wheel-mode 1))))
  56
  57 (defvar mouse-wheel-down-button 4)
  58 (make-obsolete-variable 'mouse-wheel-down-button
  59                         'mouse-wheel-down-event)
  60 (defcustom mouse-wheel-down-event
  61   ;; In the latest versions of XEmacs, we could just use mouse-%s as well.
  62   (if (memq window-system '(w32 mac))
  63       'wheel-up
  64     (intern (format (if (featurep 'xemacs) "button%s" "mouse-%s")
  65                     mouse-wheel-down-button)))
  66   "Event used for scrolling down."
  67   :group 'mouse
  68   :type 'symbol
  69   :set 'mouse-wheel-change-button)
  70
  71 (defvar mouse-wheel-up-button 5)
  72 (make-obsolete-variable 'mouse-wheel-up-button
  73                         'mouse-wheel-up-event)
  74 (defcustom mouse-wheel-up-event
  75   ;; In the latest versions of XEmacs, we could just use mouse-%s as well.
  76   (if (memq window-system '(w32 mac))
  77       'wheel-down
  78     (intern (format (if (featurep 'xemacs) "button%s" "mouse-%s")
  79                     mouse-wheel-up-button)))
  80   "Event used for scrolling up."
  81   :group 'mouse
  82   :type 'symbol
  83   :set 'mouse-wheel-change-button)
  84
  85 (defvar mouse-wheel-click-button 2)
  86 (make-obsolete-variable 'mouse-wheel-click-button
  87                         'mouse-wheel-click-event)
  88 (defcustom mouse-wheel-click-event
  89   ;; In the latest versions of XEmacs, we could just use mouse-%s as well.
  90   (intern (format (if (featurep 'xemacs) "button%s" "mouse-%s")
  91                   mouse-wheel-click-button))
  92   "Event that should be temporarily inhibited after mouse scrolling.
  93 The mouse wheel is typically on the mouse-2 button, so it may easily
  94 happen that text is accidentally yanked into the buffer when
  95 scrolling with the mouse wheel.  To prevent that, this variable can be
  96 set to the event sent when clicking on the mouse wheel button."
  97   :group 'mouse
  98   :type 'symbol
  99   :set 'mouse-wheel-change-button)
 100
 101 (defcustom mouse-wheel-inhibit-click-time 0.35
 102   "Time in seconds to inhibit clicking on mouse wheel button after scroll."
 103   :group 'mouse
 104   :type 'number)
 105
 106 (defcustom mouse-wheel-scroll-amount '(5 ((shift) . 1) ((control) . nil))
 107   "Amount to scroll windows by when spinning the mouse wheel.
 108 This is an alist mapping the modifier key to the amount to scroll when
 109 the wheel is moved with the modifier key depressed.
 110 Elements of the list have the form (MODIFIERS . AMOUNT) or just AMOUNT if
 111 MODIFIERS is nil.
 112
 113 AMOUNT should be the number of lines to scroll, or nil for near full
 114 screen.  It can also be a floating point number, specifying the fraction of
 115 a full screen to scroll.  A near full screen is `next-screen-context-lines'
 116 less than a full screen."
 117   :group 'mouse
 118   :type '(cons
 119           (choice :tag "Normal"
 120                   (const :tag "Full screen" :value nil)
 121                   (integer :tag "Specific # of lines")
 122                   (float :tag "Fraction of window")
 123                   (cons
 124                    (repeat (choice :tag "modifier"
 125                                    (const alt) (const control) (const hyper)
 126                                    (const meta) (const shift) (const super)))
 127                    (choice :tag "scroll amount"
 128                            (const :tag "Full screen" :value nil)
 129                            (integer :tag "Specific # of lines")
 130                            (float :tag "Fraction of window"))))
 131           (repeat
 132            (cons
 133             (repeat (choice :tag "modifier"
 134                             (const alt) (const control) (const hyper)
 135                             (const meta) (const shift) (const super)))
 136             (choice :tag "scroll amount"
 137                     (const :tag "Full screen" :value nil)
 138                     (integer :tag "Specific # of lines")
 139                     (float :tag "Fraction of window"))))))
 140
 141 (defcustom mouse-wheel-progressive-speed t
 142   "If non-nil, the faster the user moves the wheel, the faster the scrolling.
 143 Note that this has no effect when `mouse-wheel-scroll-amount' specifies
 144 a \"near full screen\" scroll or when the mouse wheel sends key instead
 145 of button events."
 146   :group 'mouse
 147   :type 'boolean)
 148
 149 (defcustom mouse-wheel-follow-mouse t
 150   "Whether the mouse wheel should scroll the window that the mouse is over.
 151 This can be slightly disconcerting, but some people prefer it."
 152   :group 'mouse
 153   :type 'boolean)
 154
 155 (if (not (fboundp 'event-button))
 156     (defun mwheel-event-button (event)
 157       (let ((x (event-basic-type event)))
 158         ;; Map mouse-wheel events to appropriate buttons
 159         (if (eq 'mouse-wheel x)
 160             (let ((amount (car (cdr (cdr (cdr event))))))
 161               (if (< amount 0)
 162                   mouse-wheel-up-event
 163                 mouse-wheel-down-event))
 164           x)))
 165   (fset 'mwheel-event-button 'event-button))
 166
 167 (if (not (fboundp 'event-window))
 168     (defun mwheel-event-window (event)
 169       (posn-window (event-start event)))
 170   (fset 'mwheel-event-window 'event-window))
 171
 172 (defvar mwheel-inhibit-click-event-timer nil
 173   "Timer running while mouse wheel click event is inhibited.")
 174
 175 (defun mwheel-inhibit-click-timeout ()
 176   "Handler for `mwheel-inhibit-click-event-timer'."
 177   (setq mwheel-inhibit-click-event-timer nil)
 178   (remove-hook 'pre-command-hook 'mwheel-filter-click-events))
 179
 180 (defun mwheel-filter-click-events ()
 181   "Discard `mouse-wheel-click-event' while scrolling the mouse."
 182   (if (eq (event-basic-type last-input-event) mouse-wheel-click-event)
 183       (setq this-command 'ignore)))
 184
 185 (defun mwheel-scroll (event)
 186   "Scroll up or down according to the EVENT.
 187 This should only be bound to mouse buttons 4 and 5."
 188   (interactive (list last-input-event))
 189   (let* ((curwin (if mouse-wheel-follow-mouse
 190                      (prog1
 191                          (selected-window)
 192                        (select-window (mwheel-event-window event)))))
 193          (mods
 194           (delq 'click (delq 'double (delq 'triple (event-modifiers event)))))
 195          (amt (assoc mods mouse-wheel-scroll-amount)))
 196     ;; Extract the actual amount or find the element that has no modifiers.
 197     (if amt (setq amt (cdr amt))
 198       (let ((list-elt mouse-wheel-scroll-amount))
 199         (while (consp (setq amt (pop list-elt))))))
 200     (if (floatp amt) (setq amt (1+ (truncate (* amt (window-height))))))
 201     (when (and mouse-wheel-progressive-speed (numberp amt))
 202       ;; When the double-mouse-N comes in, a mouse-N has been executed already,
 203       ;; So by adding things up we get a squaring up (1, 3, 6, 10, 15, ...).
 204       (setq amt (* amt (event-click-count event))))
 205     (unwind-protect
 206         (let ((button (mwheel-event-button event)))
 207           (cond ((eq button mouse-wheel-down-event)
 208                  (condition-case nil (scroll-down amt)
 209                    ;; Make sure we do indeed scroll to the beginning of
 210                    ;; the buffer.
 211                    (beginning-of-buffer
 212                     (unwind-protect
 213                         (scroll-down)
 214                       ;; If the first scroll succeeded, then some scrolling
 215                       ;; is possible: keep scrolling til the beginning but
 216                       ;; do not signal an error.  For some reason, we have
 217                       ;; to do it even if the first scroll signalled an
 218                       ;; error, because otherwise the window is recentered
 219                       ;; for a reason that escapes me.  This problem seems
 220                       ;; to only affect scroll-down.  --Stef
 221                       (set-window-start (selected-window) (point-min))))))
 222                 ((eq button mouse-wheel-up-event)
 223                  (condition-case nil (scroll-up amt)
 224                    ;; Make sure we do indeed scroll to the end of the buffer.
 225                    (end-of-buffer (while t (scroll-up)))))
 226                 (t (error "Bad binding in mwheel-scroll"))))
 227       (if curwin (select-window curwin))))
 228   (when (and mouse-wheel-click-event mouse-wheel-inhibit-click-time)
 229     (if mwheel-inhibit-click-event-timer
 230         (cancel-timer mwheel-inhibit-click-event-timer)
 231       (add-hook 'pre-command-hook 'mwheel-filter-click-events))
 232     (setq mwheel-inhibit-click-event-timer
 233           (run-with-timer mouse-wheel-inhibit-click-time nil
 234                           'mwheel-inhibit-click-timeout))))
 235
 236 ;;;###autoload
 237 (define-minor-mode mouse-wheel-mode
 238   "Toggle mouse wheel support.
 239 With prefix argument ARG, turn on if positive, otherwise off.
 240 Return non-nil if the new state is enabled."
 241   :global t
 242   :group 'mouse
 243   (let* ((dn mouse-wheel-down-event)
 244          (up mouse-wheel-up-event)
 245          (keys
 246           (nconc (mapcar (lambda (amt) `[(,@(if (consp amt) (car amt)) ,up)])
 247                          mouse-wheel-scroll-amount)
 248                  (mapcar (lambda (amt) `[(,@(if (consp amt) (car amt)) ,dn)])
 249                          mouse-wheel-scroll-amount))))
 250     ;; This condition-case is here because Emacs 19 will throw an error
 251     ;; if you try to define a key that it does not know about.  I for one
 252     ;; prefer to just unconditionally do a mwheel-install in my .emacs, so
 253     ;; that if the wheeled-mouse is there, it just works, and this way it
 254     ;; doesn't yell at me if I'm on my laptop or another machine, etc.
 255     (condition-case ()
 256         (dolist (key keys)
 257           (cond (mouse-wheel-mode
 258                  (global-set-key key 'mwheel-scroll))
 259                 ((eq (lookup-key (current-global-map) key) 'mwheel-scroll)
 260                  (global-unset-key key))))
 261       (error nil))))
 262
 263 ;;; Compatibility entry point
 264 ;;;###autoload
 265 (defun mwheel-install (&optional uninstall)
 266   "Enable mouse wheel support."
 267   (mouse-wheel-mode (if uninstall -1 1)))
 268
 269 (provide 'mwheel)
 270
 271 ;; arch-tag: 50ed00e7-3686-4b7a-8037-fb31aa5c237f
 272 ;;; mwheel.el ends here