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[emacs.git] / lisp / mouse-drag.el
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1 ;;; mouse-drag.el --- use mouse-2 to do a new style of scrolling
3 ;; Copyright (C) 1996, 1997 Free Software Foundation, Inc.
5 ;; Author: John Heidemann <johnh@ISI.EDU>
6 ;; Keywords: mouse
8 ;; This file is part of GNU Emacs.
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.
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.
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., 59 Temple Place - Suite 330,
23 ;; Boston, MA 02111-1307, USA.
25 ;;; Commentary:
27 ;;; What is ``mouse-drag.el''?
28 ;;;
29 ;;; Doesn't that scroll bar seem far away when you want to scroll?
30 ;;; This module overloads mouse-2 to do ``throw'' scrolling. You
31 ;;; click and drag. The distance you move from your original click
32 ;;; turns into a scroll amount. The scroll amount is scaled
33 ;;; exponentially to make both large moves and short adjustments easy.
34 ;;; What this boils down to is that you can easily scroll around the
35 ;;; buffer without much mouse movement. Finally, clicks which aren't
36 ;;; drags are passed off to the old mouse-2 binding, so old mouse-2
37 ;;; operations (find-file in dired-mode, yanking in most other modes)
38 ;;; still work.
39 ;;;
40 ;;; There is an alternative way to scroll, ``drag'' scrolling. You
41 ;;; can click on a character and then drag it around, scrolling the
42 ;;; buffer with you. The character always stays under the mouse.
43 ;;; Compared to throw-scrolling, this approach provides direct
44 ;;; manipulation (nice) but requires more mouse movement
45 ;;; (unfortunate). It is offered as an alternative for those who
46 ;;; prefer it.
47 ;;;
48 ;;; If you like mouse-drag, you should also check out mouse-copy
49 ;;; for ``one-click text copy and move''.
50 ;;;
51 ;;; To use mouse-drag, place the following in your .emacs file:
52 ;;; (require 'mouse-drag)
53 ;;; -and either-
54 ;;; (global-set-key [down-mouse-2] 'mouse-drag-throw)
55 ;;; -or-
56 ;;; (global-set-key [down-mouse-2] 'mouse-drag-drag)
57 ;;;
58 ;;;
59 ;;;
60 ;;; Options:
61 ;;;
62 ;;; - reverse the throw-scroll direction with \\[mouse-throw-with-scroll-bar]
63 ;;; - work around a bug with \\[mouse-extras-work-around-drag-bug]
64 ;;; - auto-enable horizontal scrolling with
65 ;;; \\[mouse-drag-electric-col-scrolling]
66 ;;;
67 ;;;
68 ;;; History and related work:
69 ;;;
70 ;;; One-click copying and moving was inspired by lemacs-19.8.
71 ;;; Throw-scrolling was inspired by MacPaint's ``hand'' and by Tk's
72 ;;; mouse-2 scrolling. The package mouse-scroll.el by Tom Wurgler
73 ;;; <twurgler@goodyear.com> is similar to mouse-drag-throw, but
74 ;;; doesn't pass clicks through.
75 ;;;
76 ;;; These functions have been tested in emacs version 19.30,
77 ;;; and this package has run in the past on 19.25-19.29.
78 ;;;
79 ;;; Originally mouse-drag was part of a larger package.
80 ;;; As of 11 July 96 the scrolling functions were split out
81 ;;; in preparation for incorporation into (the future) emacs-19.32.
82 ;;;
83 ;;;
84 ;;; Thanks:
85 ;;;
86 ;;; Thanks to Kai Grossjohann
87 ;;; <grossjoh@dusty.informatik.uni-dortmund.de> for reporting bugs, to
88 ;;; Tom Wurgler <twurgler@goodyear.com> for reporting bugs and
89 ;;; suggesting fixes, and to Joel Graber <jgraber@ti.com> for
90 ;;; prompting me to do drag-scrolling and for an initial
91 ;;; implementation of horizontal drag-scrolling.
92 ;;;
93 ;;; -johnh@isi.edu, 11-Jul-96
94 ;;;
95 ;;;
96 ;;; What's new with mouse-drag 2.24?
97 ;;;
98 ;;; - mouse-drag-electric-col-scrolling (default: on)
99 ;;; auto-enables horizontal scrolling when clicks on wrapped
100 ;;; lines occur
102 ;;; Code:
105 ;; scrolling code
108 (defun mouse-drag-safe-scroll (row-delta &optional col-delta)
109 "Scroll down ROW-DELTA lines and right COL-DELTA, ignoring buffer edge errors.
110 Keep the cursor on the screen as needed."
111 (if (and row-delta
112 (/= 0 row-delta))
113 (condition-case nil ;; catch and ignore movement errors
114 (scroll-down row-delta)
115 (beginning-of-buffer (message "Beginning of buffer"))
116 (end-of-buffer (message "End of buffer"))))
117 (if (and col-delta
118 (/= 0 col-delta))
119 (progn
120 (scroll-right col-delta)
121 ;; Make sure that the point stays on the visible screen
122 ;; (if truncation-lines in set).
123 ;; This code mimics the behavior we automatically get
124 ;; when doing vertical scrolling.
125 ;; Problem identified and a fix suggested by Tom Wurgler.
126 (cond
127 ((< (current-column) (window-hscroll))
128 (move-to-column (window-hscroll))) ; make on left column
129 ((> (- (current-column) (window-hscroll) (window-width) -2) 0)
130 (move-to-column (+ (window-width) (window-hscroll) -3)))))))
132 (defun mouse-drag-repeatedly-safe-scroll (row-delta &optional col-delta)
133 "Scroll ROW-DELTA rows and COL-DELTA cols until an event happens."
134 (while (sit-for mouse-scroll-delay)
135 (mouse-drag-safe-scroll row-delta col-delta)))
137 (defun mouse-drag-events-are-point-events-p (start-posn end-posn)
138 "Determine if START-POSN and END-POSN are \"close\"."
139 (let*
140 ((start-col-row (posn-col-row start-posn))
141 (end-col-row (posn-col-row end-posn)))
142 (and
143 ;; We no longer exclude things by time.
144 ;; (< (- (posn-timestamp end-posn) (posn-timestamp start-posn))
145 ;; (if (numberp double-click-time)
146 ;; (* 2 double-click-time) ;; stretch it a little
147 ;; 999999)) ;; non-numeric => check by position alone
148 (= (car start-col-row) (car end-col-row))
149 (= (cdr start-col-row) (cdr end-col-row)))))
151 (defvar mouse-drag-electric-col-scrolling t
152 "If non-nil, mouse-drag on a long line enables truncate-lines.")
154 (defun mouse-drag-should-do-col-scrolling ()
155 "Determine if it's wise to enable col-scrolling for the current window.
156 Basically, we check for existing horizontal scrolling."
157 (or truncate-lines
158 (> (window-hscroll (selected-window)) 0)
159 (< (window-width) (screen-width))
160 (and
161 mouse-drag-electric-col-scrolling
162 (save-excursion ;; on a long line?
163 (let
164 ((beg (progn (beginning-of-line) (point)))
165 (end (progn (end-of-line) (point))))
166 (if (> (- end beg) (window-width))
167 (setq truncate-lines t)
168 nil))))))
170 (defvar mouse-throw-with-scroll-bar nil
171 "*Set direction of mouse-throwing.
172 If nil, the text moves in the direction the mouse moves.
173 If t, the scroll bar moves in the direction the mouse moves.")
174 (defconst mouse-throw-magnifier-with-scroll-bar
175 [-16 -8 -4 -2 -1 0 0 0 1 2 4 8 16])
176 (defconst mouse-throw-magnifier-with-mouse-movement
177 [ 16 8 4 2 1 0 0 0 -1 -2 -4 -8 -16])
178 (defconst mouse-throw-magnifier-min -6)
179 (defconst mouse-throw-magnifier-max 6)
181 (defun mouse-drag-throw (start-event)
182 "\"Throw\" the page according to a mouse drag.
184 A \"throw\" is scrolling the page at a speed relative to the distance
185 from the original mouse click to the current mouse location. Try it;
186 you'll like it. It's easier to observe than to explain.
188 If the mouse is clicked and released in the same place of time we
189 assume that the user didn't want to scdebugroll but wanted to whatever
190 mouse-2 used to do, so we pass it through.
192 Throw scrolling was inspired (but is not identical to) the \"hand\"
193 option in MacPaint, or the middle button in Tk text widgets.
195 If `mouse-throw-with-scroll-bar' is non-nil, then this command scrolls
196 in the opposite direction. (Different people have different ideas
197 about which direction is natural. Perhaps it has to do with which
198 hemisphere you're in.)
200 To test this function, evaluate:
201 (global-set-key [down-mouse-2] 'mouse-drag-throw)"
202 (interactive "e")
203 ;; we want to do save-selected-window, but that requires 19.29
204 (let* ((start-posn (event-start start-event))
205 (start-window (posn-window start-posn))
206 (start-row (cdr (posn-col-row start-posn)))
207 (start-col (car (posn-col-row start-posn)))
208 (old-selected-window (selected-window))
209 event end row mouse-delta scroll-delta
210 have-scrolled point-event-p old-binding
211 window-last-row
212 col mouse-col-delta window-last-col
213 (scroll-col-delta 0)
214 adjusted-mouse-col-delta
215 adjusted-mouse-delta
216 ;; be conservative about allowing horizontal scrolling
217 (col-scrolling-p (mouse-drag-should-do-col-scrolling)))
218 (select-window start-window)
219 (track-mouse
220 (while (progn
221 (setq event (read-event)
222 end (event-end event)
223 row (cdr (posn-col-row end))
224 col (car (posn-col-row end)))
225 (or (mouse-movement-p event)
226 (eq (car-safe event) 'switch-frame)))
227 (if (eq start-window (posn-window end))
228 (progn
229 (setq mouse-delta (- start-row row)
230 adjusted-mouse-delta
231 (- (cond
232 ((<= mouse-delta mouse-throw-magnifier-min)
233 mouse-throw-magnifier-min)
234 ((>= mouse-delta mouse-throw-magnifier-max)
235 mouse-throw-magnifier-max)
236 (t mouse-delta))
237 mouse-throw-magnifier-min)
238 scroll-delta (aref (if mouse-throw-with-scroll-bar
239 mouse-throw-magnifier-with-scroll-bar
240 mouse-throw-magnifier-with-mouse-movement)
241 adjusted-mouse-delta))
242 (if col-scrolling-p
243 (setq mouse-col-delta (- start-col col)
244 adjusted-mouse-col-delta
245 (- (cond
246 ((<= mouse-col-delta mouse-throw-magnifier-min)
247 mouse-throw-magnifier-min)
248 ((>= mouse-col-delta mouse-throw-magnifier-max)
249 mouse-throw-magnifier-max)
250 (t mouse-col-delta))
251 mouse-throw-magnifier-min)
252 scroll-col-delta (aref (if mouse-throw-with-scroll-bar
253 mouse-throw-magnifier-with-scroll-bar
254 mouse-throw-magnifier-with-mouse-movement)
255 adjusted-mouse-col-delta)))))
256 (if (or (/= 0 scroll-delta)
257 (/= 0 scroll-col-delta))
258 (progn
259 (setq have-scrolled t)
260 (mouse-drag-safe-scroll scroll-delta scroll-col-delta)
261 (mouse-drag-repeatedly-safe-scroll scroll-delta scroll-col-delta))))) ;xxx
262 ;; If it was a click and not a drag, prepare to pass the event on.
263 ;; Note: We must determine the pass-through event before restoring
264 ;; the window, but invoke it after. Sigh.
265 (if (and (not have-scrolled)
266 (mouse-drag-events-are-point-events-p start-posn end))
267 (setq point-event-p t
268 old-binding (key-binding
269 (vector (event-basic-type start-event)))))
270 ;; Now restore the old window.
271 (select-window old-selected-window)
272 ;; For clicks, call the old function.
273 (if point-event-p
274 (call-interactively old-binding))))
276 (defun mouse-drag-drag (start-event)
277 "\"Drag\" the page according to a mouse drag.
279 Drag scrolling moves the page according to the movement of the mouse.
280 You \"grab\" the character under the mouse and move it around.
282 If the mouse is clicked and released in the same place of time we
283 assume that the user didn't want to scroll but wanted to whatever
284 mouse-2 used to do, so we pass it through.
286 Drag scrolling is identical to the \"hand\" option in MacPaint, or the
287 middle button in Tk text widgets.
289 To test this function, evaluate:
290 (global-set-key [down-mouse-2] 'mouse-drag-drag)"
291 (interactive "e")
292 ;; we want to do save-selected-window, but that requires 19.29
293 (let* ((start-posn (event-start start-event))
294 (start-window (posn-window start-posn))
295 (start-row (cdr (posn-col-row start-posn)))
296 (start-col (car (posn-col-row start-posn)))
297 (old-selected-window (selected-window))
298 event end row mouse-delta scroll-delta
299 have-scrolled point-event-p old-binding
300 window-last-row
301 col mouse-col-delta window-last-col
302 (scroll-col-delta 0)
303 ;; be conservative about allowing horizontal scrolling
304 (col-scrolling-p (mouse-drag-should-do-col-scrolling)))
305 (select-window start-window)
306 (setq window-last-row (- (window-height) 2)
307 window-last-col (- (window-width) 2))
308 (track-mouse
309 (while (progn
310 (setq event (read-event)
311 end (event-end event)
312 row (cdr (posn-col-row end))
313 col (car (posn-col-row end)))
314 (or (mouse-movement-p event)
315 (eq (car-safe event) 'switch-frame)))
316 ;; Scroll if see if we're on the edge.
317 ;; NEEDSWORK: should handle mouse-in-other window.
318 (cond
319 ((not (eq start-window (posn-window end)))
320 t) ; wait for return to original window
321 ((<= row 0) (mouse-drag-repeatedly-safe-scroll -1 0))
322 ((>= row window-last-row) (mouse-drag-repeatedly-safe-scroll 1 0))
323 ((and col-scrolling-p (<= col 1)) (mouse-drag-repeatedly-safe-scroll 0 -1))
324 ((and col-scrolling-p (>= col window-last-col)) (mouse-drag-repeatedly-safe-scroll 0 1))
326 (setq scroll-delta (- row start-row)
327 start-row row)
328 (if col-scrolling-p
329 (setq scroll-col-delta (- col start-col)
330 start-col col))
331 (if (or (/= 0 scroll-delta)
332 (/= 0 scroll-col-delta))
333 (progn
334 (setq have-scrolled t)
335 (mouse-drag-safe-scroll scroll-delta scroll-col-delta)))))))
336 ;; If it was a click and not a drag, prepare to pass the event on.
337 ;; Note: We must determine the pass-through event before restoring
338 ;; the window, but invoke it after. Sigh.
339 (if (and (not have-scrolled)
340 (mouse-drag-events-are-point-events-p start-posn end))
341 (setq point-event-p t
342 old-binding (key-binding
343 (vector (event-basic-type start-event)))))
344 ;; Now restore the old window.
345 (select-window old-selected-window)
346 ;; For clicks, call the old function.
347 (if point-event-p
348 (call-interactively old-binding))))
350 (provide 'mouse-drag)
352 ;;; mouse-drag.el ends here