1;;; scroll-bar.el --- window system-independent scroll bar support. 2 3;;; Copyright (C) 1993, 1994 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;;; Code: 25 26;;; Commentary: 27 28;; Window-system-independent bindings of mouse clicks on the scroll bar. 29;; Presently emulates the scroll-bar behavior of xterm. 30;;; Code: 31 32(require 'mouse) 33 34 35;;;; Utilities. 36 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 44(defun scroll-bar-scale (num-denom whole) 45 "Given a pair (NUM . DENOM) and WHOLE, return (/ (* NUM WHOLE) DENOM). 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 49\(buffer-size)) is the position in the current buffer corresponding to 50that scroll bar position." 51 ;; We multiply before we divide to maintain precision. 52 ;; We use floating point because the product of a large buffer size 53 ;; with a large scroll bar portion can easily overflow a lisp int. 54 (truncate (/ (* (float (car num-denom)) whole) (cdr num-denom)))) 55 56 57;;;; Helpful functions for enabling and disabling scroll bars. 58 59(defun scroll-bar-mode (flag) 60 "Toggle display of vertical scroll bars on each frame. 61This command applies to all frames that exist and frames to be 62created in the future. 63With a numeric argument, if the argument is negative, 64turn off scroll bars; otherwise, turn on scroll bars." 65 (interactive "P") 66 (if flag (setq flag (prefix-numeric-value flag))) 67 68 ;; Obtain the current setting by looking at default-frame-alist. 69 (let ((scroll-bar-mode 70 (let ((assq (assq 'vertical-scroll-bars default-frame-alist))) 71 (if assq (cdr assq) t)))) 72 73 ;; Tweedle it according to the argument. 74 (setq scroll-bar-mode (if (null flag) (not scroll-bar-mode) 75 (or (not (numberp flag)) (>= flag 0)))) 76 77 ;; Apply it to default-frame-alist. 78 (mapcar 79 (function 80 (lambda (param-name) 81 (let ((parameter (assq param-name default-frame-alist))) 82 (if (consp parameter) 83 (setcdr parameter scroll-bar-mode) 84 (setq default-frame-alist 85 (cons (cons param-name scroll-bar-mode) 86 default-frame-alist)))))) 87 '(vertical-scroll-bars horizontal-scroll-bars)) 88 89 ;; Apply it to existing frames. 90 (let ((frames (frame-list))) 91 (while frames 92 (modify-frame-parameters 93 (car frames) 94 (list (cons 'vertical-scroll-bars scroll-bar-mode) 95 (cons 'horizontal-scroll-bars scroll-bar-mode))) 96 (setq frames (cdr frames)))))) 97 98;;;; Buffer navigation using the scroll bar. 99 100;;; This was used for up-events on button 2, but no longer. 101(defun scroll-bar-set-window-start (event) 102 "Set the window start according to where the scroll bar is dragged. 103EVENT should be a scroll bar click or drag event." 104 (interactive "e") 105 (let* ((end-position (event-end event)) 106 (window (nth 0 end-position)) 107 (portion-whole (nth 2 end-position))) 108 (save-excursion 109 (set-buffer (window-buffer window)) 110 (save-excursion 111 (goto-char (+ (point-min) 112 (scroll-bar-scale portion-whole 113 (- (point-max) (point-min))))) 114 (beginning-of-line) 115 (set-window-start window (point)))))) 116 117;; Scroll the window to the proper position for EVENT. 118(defun scroll-bar-drag-1 (event) 119 (let* ((start-position (event-start event)) 120 (window (nth 0 start-position)) 121 (portion-whole (nth 2 start-position))) 122 (save-excursion 123 (set-buffer (window-buffer window)) 124 ;; Calculate position relative to the accessible part of the buffer. 125 (goto-char (+ (point-min) 126 (scroll-bar-scale portion-whole 127 (- (point-max) (point-min))))) 128 (beginning-of-line) 129 (set-window-start window (point))))) 130 131(defun scroll-bar-drag (event) 132 "Scroll the window by dragging the scroll bar slider. 133If you click outside the slider, the window scrolls to bring the slider there." 134 (interactive "e") 135 (let* (done) 136 (scroll-bar-drag-1 event) 137 (track-mouse 138 (while (not done) 139 (setq event (read-event)) 140 (if (eq (car-safe event) 'mouse-movement) 141 (setq event (read-event))) 142 (cond ((eq (car-safe event) 'scroll-bar-movement) 143 (scroll-bar-drag-1 event)) 144 (t 145 ;; Exit when we get the drag event; ignore that event. 146 (setq done t))))))) 147 148(defun scroll-bar-scroll-down (event) 149 "Scroll the window's top line down to the location of the scroll bar click. 150EVENT should be a scroll bar click." 151 (interactive "e") 152 (let ((old-selected-window (selected-window))) 153 (unwind-protect 154 (progn 155 (let* ((end-position (event-end event)) 156 (window (nth 0 end-position)) 157 (portion-whole (nth 2 end-position))) 158 (select-window window) 159 (scroll-down 160 (scroll-bar-scale portion-whole (1- (window-height)))))) 161 (select-window old-selected-window)))) 162 163(defun scroll-bar-scroll-up (event) 164 "Scroll the line next to the scroll bar click to the top of the window. 165EVENT should be a scroll bar click." 166 (interactive "e") 167 (let ((old-selected-window (selected-window))) 168 (unwind-protect 169 (progn 170 (let* ((end-position (event-end event)) 171 (window (nth 0 end-position)) 172 (portion-whole (nth 2 end-position))) 173 (select-window window) 174 (scroll-up 175 (scroll-bar-scale portion-whole (1- (window-height)))))) 176 (select-window old-selected-window)))) 177 178 179;;;; Bindings. 180 181;;; For now, we'll set things up to work like xterm. 182(global-set-key [vertical-scroll-bar mouse-1] 'scroll-bar-scroll-up) 183(global-set-key [vertical-scroll-bar drag-mouse-1] 'scroll-bar-scroll-up) 184 185(global-set-key [vertical-scroll-bar down-mouse-2] 'scroll-bar-drag) 186 187(global-set-key [vertical-scroll-bar mouse-3] 'scroll-bar-scroll-down) 188(global-set-key [vertical-scroll-bar drag-mouse-3] 'scroll-bar-scroll-down) 189 190 191(provide 'scroll-bar) 192 193;;; scroll-bar.el ends here 194