lisp/mwheel.el

   1 ;;; mwheel.el --- Mouse support for MS intelli-mouse type mice
   2
   3 ;; Copyright (C) 1998, 2000, 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
  44 (defcustom mouse-wheel-scroll-amount '(5 . 1)
  45   "Amount to scroll windows by when spinning the mouse wheel.
  46 This is actually a cons cell, where the first item is the amount to scroll
  47 on a normal wheel event, and the second is the amount to scroll when the
  48 wheel is moved with the shift key depressed.
  49
  50 Each item should be the number of lines to scroll, or `nil' for near
  51 full screen.
  52 A near full screen is `next-screen-context-lines' less than a full screen."
  53   :group 'mouse
  54   :type '(cons
  55           (choice :tag "Normal"
  56                   (const :tag "Full screen" :value nil)
  57                   (integer :tag "Specific # of lines"))
  58           (choice :tag "Shifted"
  59                   (const :tag "Full screen" :value nil)
  60                   (integer :tag "Specific # of lines"))))
  61
  62 (defcustom mouse-wheel-follow-mouse nil
  63   "Whether the mouse wheel should scroll the window that the mouse is over.
  64 This can be slightly disconcerting, but some people may prefer it."
  65   :group 'mouse
  66   :type 'boolean)
  67
  68 (if (not (fboundp 'event-button))
  69     (defun mwheel-event-button (event)
  70       (let ((x (symbol-name (event-basic-type event))))
  71         (if (not (string-match "^mouse-\\([0-9]+\\)" x))
  72             (error "Not a button event: %S" event))
  73         (string-to-int (substring x (match-beginning 1) (match-end 1)))))
  74   (fset 'mwheel-event-button 'event-button))
  75
  76 (if (not (fboundp 'event-window))
  77     (defun mwheel-event-window (event)
  78       (posn-window (event-start event)))
  79   (fset 'mwheel-event-window 'event-window))
  80
  81 (defun mwheel-scroll (event)
  82   (interactive "e")
  83   (let ((curwin (if mouse-wheel-follow-mouse
  84                     (prog1
  85                         (selected-window)
  86                       (select-window (mwheel-event-window event)))))
  87         (amt (if (memq 'shift (event-modifiers event))
  88                  (cdr mouse-wheel-scroll-amount)
  89                (car mouse-wheel-scroll-amount))))
  90     (unwind-protect
  91         (let ((button (mwheel-event-button event)))
  92           (cond ((= button 4) (scroll-down amt))
  93                 ((= button 5) (scroll-up amt))
  94                 (t (error "Bad binding in mwheel-scroll"))))
  95       (if curwin (select-window curwin)))))
  96
  97
  98 ;;; Note this definition must be at the end of the file, because
  99 ;;; `define-minor-mode' actually calls the mode-function if the
 100 ;;; associated variable is non-nil, which requires that all needed
 101 ;;; functions be already defined.
 102 ;;;###autoload
 103 (define-minor-mode mouse-wheel-mode
 104   "Toggle mouse wheel support.
 105 With prefix argument ARG, turn on if positive, otherwise off.
 106 Returns non-nil if the new state is enabled."
 107   :global t
 108   :group 'mouse
 109   ;; In the latest versions of XEmacs, we could just use
 110   ;; (S-)*mouse-[45], since those are aliases for the button
 111   ;; equivalents in XEmacs, but I want this to work in as many
 112   ;; versions of XEmacs as it can.
 113   (let ((keys
 114          (if (featurep 'xemacs)
 115              '(button4 [(shift button4)] button5 [(shift button5)])
 116            '([mouse-4] [S-mouse-4] [mouse-5] [S-mouse-5]))))
 117     ;; This condition-case is here because Emacs 19 will throw an error
 118     ;; if you try to define a key that it does not know about.  I for one
 119     ;; prefer to just unconditionally do a mwheel-install in my .emacs, so
 120     ;; that if the wheeled-mouse is there, it just works, and this way it
 121     ;; doesn't yell at me if I'm on my laptop or another machine, etc.
 122     (condition-case ()
 123         (dolist (key keys)
 124           (cond (mouse-wheel-mode
 125                  (define-key global-map key 'mwheel-scroll))
 126                 ((eq (lookup-key global-map key) 'mwheel-scroll)
 127                  (define-key global-map key nil))))
 128       (error nil))))
 129
 130 ;;; Compatibility entry point
 131 ;;;###autoload
 132 (defun mwheel-install (&optional uninstall)
 133   "Enable mouse wheel support."
 134   (mouse-wheel-mode t))
 135
 136
 137 (provide 'mwheel)
 138
 139 ;;; mwheel.el ends here