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[bpt/emacs.git] / lisp / scroll-bar.el
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aae56ea7 1;;; scroll-bar.el --- window system-independent scroll bar support.
6d62a90e 2
b578f267 3;; Copyright (C) 1993, 1994, 1995 Free Software Foundation, Inc.
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4
5;; Maintainer: FSF
6;; Keywords: hardware
7
b578f267 8;; This file is part of GNU Emacs.
6d62a90e 9
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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.
6d62a90e 14
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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.
6d62a90e 19
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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.
76550a57 24
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25;;; Commentary:
26
27;; Window-system-independent bindings of mouse clicks on the scroll bar.
28;; Presently emulates the scroll-bar behavior of xterm.
b578f267 29
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30;;; Code:
31
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32(require 'mouse)
33
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34\f
35;;;; Utilities.
36
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37(defun scroll-bar-event-ratio (event)
38 "Given a scroll bar event EVENT, return the scroll bar position as a ratio.
39The value is a cons cell (PORTION . WHOLE) containing two integers
40whose ratio gives the event's vertical position in the scroll bar, with 0
41referring to the top and 1 to the bottom."
42 (nth 2 event))
43
bf3c8a70 44(defun scroll-bar-scale (num-denom whole)
6d62a90e 45 "Given a pair (NUM . DENOM) and WHOLE, return (/ (* NUM WHOLE) DENOM).
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46This is handy for scaling a position on a scroll bar into real units,
47like buffer positions. If SCROLL-BAR-POS is the (PORTION . WHOLE) pair
48from a scroll bar event, then (scroll-bar-scale SCROLL-BAR-POS
6d62a90e 49\(buffer-size)) is the position in the current buffer corresponding to
bf3c8a70 50that scroll bar position."
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51 ;; We multiply before we divide to maintain precision.
52 ;; We use floating point because the product of a large buffer size
bf3c8a70 53 ;; with a large scroll bar portion can easily overflow a lisp int.
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54 (truncate (/ (* (float (car num-denom)) whole) (cdr num-denom))))
55
56\f
fe48f821 57;;;; Helpful functions for enabling and disabling scroll bars.
fe48f821 58
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59(defvar scroll-bar-mode)
60
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61(defvar scroll-bar-mode-explicit nil
62 "Non-nil means `set-scroll-bar-mode' should really do something.
63This is nil while loading `scroll-bar.el', and t afterward.")
64
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65(defun set-scroll-bar-mode-1 (ignore value)
66 (set-scroll-bar-mode value))
67
68(defun set-scroll-bar-mode (value)
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69 "Set `scroll-bar-mode' to VALUE and put the new value into effect."
70 (setq scroll-bar-mode value)
71
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72 (when scroll-bar-mode-explicit
73 ;; Apply it to default-frame-alist.
74 (let ((parameter (assq 'vertical-scroll-bars default-frame-alist)))
75 (if (consp parameter)
76 (setcdr parameter scroll-bar-mode)
77 (setq default-frame-alist
78 (cons (cons 'vertical-scroll-bars scroll-bar-mode)
79 default-frame-alist))))
80
81 ;; Apply it to existing frames.
82 (let ((frames (frame-list)))
83 (while frames
84 (modify-frame-parameters
85 (car frames)
86 (list (cons 'vertical-scroll-bars scroll-bar-mode)))
87 (setq frames (cdr frames))))))
04c34f2e 88
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89(defcustom scroll-bar-mode
90 (if (eq system-type 'windows-nt) 'right 'left)
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91 "*Specify whether to have vertical scroll bars, and on which side.
92Possible values are nil (no scroll bars), `left' (scroll bars on left)
93and `right' (scroll bars on right).
94When you set the variable in a Lisp program, it takes effect for new frames,
95and for existing frames when `toggle-scroll-bar' is used.
96When you set this with the customization buffer,
97it takes effect immediately for all frames."
98 :type '(choice (const :tag "none (nil)")
99 (const left)
100 (const right))
101 :group 'frames
e4b201bb 102 :set 'set-scroll-bar-mode-1)
04c34f2e 103
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104;; We just set scroll-bar-mode, but that was the default.
105;; If it is set again, that is for real.
106(setq scroll-bar-mode-explicit t)
107
fe48f821 108(defun scroll-bar-mode (flag)
04c34f2e 109 "Toggle display of vertical scroll bars on all frames.
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110This command applies to all frames that exist and frames to be
111created in the future.
112With a numeric argument, if the argument is negative,
113turn off scroll bars; otherwise, turn on scroll bars."
114 (interactive "P")
6ee9f953 115 (if flag (setq flag (prefix-numeric-value flag)))
ada464a7 116
04c34f2e 117 ;; Tweedle the variable according to the argument.
e4b201bb 118 (set-scroll-bar-mode (if (null flag) (not scroll-bar-mode)
04c34f2e 119 (and (or (not (numberp flag)) (>= flag 0))
1032e793 120 (if (eq system-type 'windows-nt) 'right 'left)))))
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121
122(defun toggle-scroll-bar (arg)
123 "Toggle whether or not the selected frame has vertical scroll bars.
124With arg, turn vertical scroll bars on if and only if arg is positive.
125The variable `scroll-bar-mode' controls which side the scroll bars are on
126when they are turned on; if it is nil, they go on the left."
127 (interactive "P")
128 (if (null arg)
129 (setq arg
130 (if (cdr (assq 'vertical-scroll-bars
131 (frame-parameters (selected-frame))))
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132 -1 1))
133 (setq arg (prefix-numeric-value arg)))
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134 (modify-frame-parameters
135 (selected-frame)
136 (list (cons 'vertical-scroll-bars
137 (if (> arg 0)
138 (or scroll-bar-mode
139 (if (eq system-type 'windows-nt) 'right 'left)))))))
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140
141(defun toggle-horizontal-scroll-bar (arg)
142 "Toggle whether or not the selected frame has horizontal scroll bars.
143With arg, turn horizontal scroll bars on if and only if arg is positive.
144Horizontal scroll bars aren't implemented yet."
145 (interactive "P")
146 (error "Horizontal scroll bars aren't implemented yet"))
fe48f821 147\f
bf3c8a70 148;;;; Buffer navigation using the scroll bar.
6d62a90e 149
e532b016 150;;; This was used for up-events on button 2, but no longer.
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151(defun scroll-bar-set-window-start (event)
152 "Set the window start according to where the scroll bar is dragged.
153EVENT should be a scroll bar click or drag event."
6d62a90e 154 (interactive "e")
dbc4e1c1 155 (let* ((end-position (event-end event))
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156 (window (nth 0 end-position))
157 (portion-whole (nth 2 end-position)))
158 (save-excursion
159 (set-buffer (window-buffer window))
160 (save-excursion
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161 (goto-char (+ (point-min)
162 (scroll-bar-scale portion-whole
163 (- (point-max) (point-min)))))
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164 (beginning-of-line)
165 (set-window-start window (point))))))
166
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167(defun scroll-bar-drag-position (portion-whole)
168 "Calculate new window start for drag event."
169 (save-excursion
170 (goto-char (+ (point-min)
171 (scroll-bar-scale portion-whole
172 (- (point-max) (point-min)))))
173 (beginning-of-line)
174 (point)))
175
176(defun scroll-bar-maybe-set-window-start (event)
177 "Set the window start according to where the scroll bar is dragged.
178Only change window start if the new start is substantially different.
179EVENT should be a scroll bar click or drag event."
180 (interactive "e")
181 (let* ((end-position (event-end event))
182 (window (nth 0 end-position))
183 (portion-whole (nth 2 end-position))
184 (next-portion-whole (cons (1+ (car portion-whole))
185 (cdr portion-whole)))
186 portion-start
187 next-portion-start
188 (current-start (window-start window)))
189 (save-excursion
190 (set-buffer (window-buffer window))
191 (setq portion-start (scroll-bar-drag-position portion-whole))
192 (setq next-portion-start (max
193 (scroll-bar-drag-position next-portion-whole)
194 (1+ portion-start)))
15655694 195 (if (or (>= current-start next-portion-start)
aeee66be 196 (< current-start portion-start))
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197 (set-window-start window portion-start)
198 ;; Always set window start, to ensure scroll bar position is updated.
199 (set-window-start window current-start)))))
aeee66be 200
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201;; Scroll the window to the proper position for EVENT.
202(defun scroll-bar-drag-1 (event)
203 (let* ((start-position (event-start event))
204 (window (nth 0 start-position))
205 (portion-whole (nth 2 start-position)))
206 (save-excursion
207 (set-buffer (window-buffer window))
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208 ;; Calculate position relative to the accessible part of the buffer.
209 (goto-char (+ (point-min)
210 (scroll-bar-scale portion-whole
211 (- (point-max) (point-min)))))
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212 (beginning-of-line)
213 (set-window-start window (point)))))
214
215(defun scroll-bar-drag (event)
216 "Scroll the window by dragging the scroll bar slider.
217If you click outside the slider, the window scrolls to bring the slider there."
218 (interactive "e")
c782bea5 219 (let* (done
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220 (echo-keystrokes 0)
221 (end-position (event-end event))
222 (window (nth 0 end-position))
223 (before-scroll))
224 (with-current-buffer (window-buffer window)
225 (setq before-scroll point-before-scroll))
226 (save-selected-window
227 (select-window window)
228 (setq before-scroll
229 (or before-scroll (point))))
230 (scroll-bar-drag-1 event)
231 (track-mouse
232 (while (not done)
233 (setq event (read-event))
234 (if (eq (car-safe event) 'mouse-movement)
235 (setq event (read-event)))
236 (cond ((eq (car-safe event) 'scroll-bar-movement)
237 (scroll-bar-drag-1 event))
238 (t
239 ;; Exit when we get the drag event; ignore that event.
240 (setq done t)))))
241 (sit-for 0)
242 (with-current-buffer (window-buffer window)
243 (setq point-before-scroll before-scroll))))
e532b016 244
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245(defun scroll-bar-scroll-down (event)
246 "Scroll the window's top line down to the location of the scroll bar click.
247EVENT should be a scroll bar click."
6d62a90e 248 (interactive "e")
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249 (let* ((end-position (event-end event))
250 (window (nth 0 end-position))
251 (before-scroll))
252 (with-current-buffer (window-buffer window)
253 (setq before-scroll point-before-scroll))
254 (save-selected-window
255 (let ((portion-whole (nth 2 end-position)))
256 (select-window window)
257 (setq before-scroll
258 (or before-scroll (point)))
259 (scroll-down
260 (scroll-bar-scale portion-whole (1- (window-height))))))
261 (sit-for 0)
262 (with-current-buffer (window-buffer window)
263 (setq point-before-scroll before-scroll))))
6d62a90e 264
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265(defun scroll-bar-scroll-up (event)
266 "Scroll the line next to the scroll bar click to the top of the window.
267EVENT should be a scroll bar click."
6d62a90e 268 (interactive "e")
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269 (let* ((end-position (event-end event))
270 (window (nth 0 end-position))
271 (before-scroll))
272 (with-current-buffer (window-buffer window)
273 (setq before-scroll point-before-scroll))
274 (save-selected-window
275 (let ((portion-whole (nth 2 end-position)))
276 (select-window window)
277 (setq before-scroll
278 (or before-scroll (point)))
279 (scroll-up
280 (scroll-bar-scale portion-whole (1- (window-height))))))
281 (sit-for 0)
282 (with-current-buffer (window-buffer window)
283 (setq point-before-scroll before-scroll))))
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284
285\f
286;;;; Bindings.
287
288;;; For now, we'll set things up to work like xterm.
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289(global-set-key [vertical-scroll-bar mouse-1] 'scroll-bar-scroll-up)
290(global-set-key [vertical-scroll-bar drag-mouse-1] 'scroll-bar-scroll-up)
6d62a90e 291
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292(global-set-key [vertical-scroll-bar down-mouse-2] 'scroll-bar-drag)
293
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294(global-set-key [vertical-scroll-bar mouse-3] 'scroll-bar-scroll-down)
295(global-set-key [vertical-scroll-bar drag-mouse-3] 'scroll-bar-scroll-down)
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296
297\f
dc14eed2 298(provide 'scroll-bar)
6d62a90e 299
bf3c8a70 300;;; scroll-bar.el ends here