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1 | ;;; scrollbar.el -- window system-independent scrollbar support. |
2 | ||
3 | ;;; Copyright (C) 1993 Free Software Foundation, Inc. | |
4 | ||
5 | ;; Maintainer: FSF | |
6 | ;; Keywords: hardware | |
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 | |
22 | ;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
23 | ||
24 | \f | |
25 | ;;;; Utilities. | |
26 | ||
27 | (defun scrollbar-scale (num-denom whole) | |
28 | "Given a pair (NUM . DENOM) and WHOLE, return (/ (* NUM WHOLE) DENOM). | |
29 | This is handy for scaling a position on a scrollbar into real units, | |
30 | like buffer positions. If SCROLLBAR-POS is the (PORTION . WHOLE) pair | |
31 | from a scrollbar event, then (scrollbar-scale SCROLLBAR-POS | |
32 | \(buffer-size)) is the position in the current buffer corresponding to | |
33 | that scrollbar position." | |
34 | ;; We multiply before we divide to maintain precision. | |
35 | ;; We use floating point because the product of a large buffer size | |
36 | ;; with a large scrollbar portion can easily overflow a lisp int. | |
37 | (truncate (/ (* (float (car num-denom)) whole) (cdr num-denom)))) | |
38 | ||
39 | \f | |
40 | ;;;; Buffer navigation using the scrollbar. | |
41 | ||
42 | (defun scrollbar-set-window-start (event) | |
43 | "Set the window start according to where the scrollbar is dragged. | |
44 | EVENT should be a scrollbar click or drag event." | |
45 | (interactive "e") | |
46 | (let* ((end-position (nth (1- (length event)) event)) | |
47 | (window (nth 0 end-position)) | |
48 | (portion-whole (nth 2 end-position))) | |
49 | (save-excursion | |
50 | (set-buffer (window-buffer window)) | |
51 | (save-excursion | |
52 | (goto-char (scrollbar-scale portion-whole (buffer-size))) | |
53 | (beginning-of-line) | |
54 | (set-window-start window (point)))))) | |
55 | ||
56 | (defun scrollbar-scroll-down (event) | |
57 | "Scroll the window's top line down to the location of the scrollbar click. | |
58 | EVENT should be a scrollbar click." | |
59 | (interactive "e") | |
60 | (let ((old-selected-window (selected-window))) | |
61 | (unwind-protect | |
62 | (progn | |
63 | (let* ((end-position (nth (1- (length event)) event)) | |
64 | (window (nth 0 end-position)) | |
65 | (portion-whole (nth 2 end-position))) | |
66 | (select-window window) | |
67 | (scroll-down | |
68 | (scrollbar-scale portion-whole (1- (window-height)))))) | |
69 | (select-window old-selected-window)))) | |
70 | ||
71 | (defun scrollbar-scroll-up (event) | |
72 | "Scroll the line next to the scrollbar click to the top of the window. | |
73 | EVENT should be a scrollbar click." | |
74 | (interactive "e") | |
75 | (let ((old-selected-window (selected-window))) | |
76 | (unwind-protect | |
77 | (progn | |
78 | (let* ((end-position (nth (1- (length event)) event)) | |
79 | (window (nth 0 end-position)) | |
80 | (portion-whole (nth 2 end-position))) | |
81 | (select-window window) | |
82 | (scroll-up | |
83 | (scrollbar-scale portion-whole (1- (window-height)))))) | |
84 | (select-window old-selected-window)))) | |
85 | ||
86 | \f | |
87 | ;;;; Bindings. | |
88 | ||
89 | ;;; For now, we'll set things up to work like xterm. | |
90 | (global-set-key [vertical-scrollbar mouse-1] 'scrollbar-scroll-up) | |
91 | (global-set-key [vertical-scrollbar drag-mouse-1] 'scrollbar-scroll-up) | |
92 | ||
93 | (global-set-key [vertical-scrollbar mouse-2] 'scrollbar-set-window-start) | |
94 | (global-set-key [vertical-scrollbar drag-mouse-2] 'scrollbar-set-window-start) | |
95 | ||
96 | (global-set-key [vertical-scrollbar mouse-3] 'scrollbar-scroll-down) | |
97 | (global-set-key [vertical-scrollbar drag-mouse-3] 'scrollbar-scroll-down) | |
98 | ||
99 | \f | |
100 | (provide 'scrollbar) | |
101 | ||
102 | ;;; scrollbar.el ends here |