1;;; mwheel.el --- Wheel mouse support
2
3;; Copyright (C) 1998, 2000, 2001, 2002, 2002, 2004,
4;;   2005, 2006, 2007 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.
93The mouse wheel is typically on the mouse-2 button, so it may easily
94happen that text is accidentally yanked into the buffer when
95scrolling with the mouse wheel.  To prevent that, this variable can be
96set 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.
108This is an alist mapping the modifier key to the amount to scroll when
109the wheel is moved with the modifier key depressed.
110Elements of the list have the form (MODIFIERS . AMOUNT) or just AMOUNT if
111MODIFIERS is nil.
112
113AMOUNT should be the number of lines to scroll, or nil for near full
114screen.  It can also be a floating point number, specifying the fraction of
115a full screen to scroll.  A near full screen is `next-screen-context-lines'
116less 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.
143Note that this has no effect when `mouse-wheel-scroll-amount' specifies
144a \"near full screen\" scroll or when the mouse wheel sends key instead
145of 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.
151This 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.
187This 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.
239With prefix argument ARG, turn on if positive, otherwise off.
240Return 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
273