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360 lines
12 KiB
EmacsLisp
360 lines
12 KiB
EmacsLisp
;;; scroll-bar.el --- window system-independent scroll bar support
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;; Copyright (C) 1993-1995, 1999-2012 Free Software Foundation, Inc.
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;; Maintainer: FSF
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;; Keywords: hardware
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;; Package: emacs
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:
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;; Window-system-independent bindings of mouse clicks on the scroll bar.
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;; Presently emulates the scroll-bar behavior of xterm.
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;;; Code:
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(require 'mouse)
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(eval-when-compile (require 'cl-lib))
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;;;; Utilities.
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(defun scroll-bar-event-ratio (event)
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"Given a scroll bar event EVENT, return the scroll bar position as a ratio.
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The value is a cons cell (PORTION . WHOLE) containing two integers
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whose ratio gives the event's vertical position in the scroll bar, with 0
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referring to the top and 1 to the bottom."
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(nth 2 event))
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(defun scroll-bar-scale (num-denom whole)
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"Given a pair (NUM . DENOM) and WHOLE, return (/ (* NUM WHOLE) DENOM).
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This is handy for scaling a position on a scroll bar into real units,
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like buffer positions. If SCROLL-BAR-POS is the (PORTION . WHOLE) pair
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from a scroll bar event, then (scroll-bar-scale SCROLL-BAR-POS
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\(buffer-size)) is the position in the current buffer corresponding to
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that scroll bar position."
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;; We multiply before we divide to maintain precision.
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;; We use floating point because the product of a large buffer size
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;; with a large scroll bar portion can easily overflow a lisp int.
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(truncate (/ (* (float (car num-denom)) whole) (cdr num-denom))))
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(defun scroll-bar-columns (side)
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"Return the width, measured in columns, of the vertical scrollbar on SIDE.
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SIDE must be the symbol `left' or `right'."
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(let* ((wsb (window-scroll-bars))
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(vtype (nth 2 wsb))
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(cols (nth 1 wsb)))
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(cond
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((not (memq side '(left right)))
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(error "`left' or `right' expected instead of %S" side))
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((and (eq vtype side) cols))
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((eq (frame-parameter nil 'vertical-scroll-bars) side)
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;; nil means it's a non-toolkit scroll bar, and its width in
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;; columns is 14 pixels rounded up.
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(ceiling (or (frame-parameter nil 'scroll-bar-width) 14)
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(frame-char-width)))
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(0))))
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;;;; Helpful functions for enabling and disabling scroll bars.
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(defvar scroll-bar-mode)
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(defvar previous-scroll-bar-mode nil)
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(defvar scroll-bar-mode-explicit nil
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"Non-nil means `set-scroll-bar-mode' should really do something.
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This is nil while loading `scroll-bar.el', and t afterward.")
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(defun set-scroll-bar-mode (value)
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"Set the scroll bar mode to VALUE and put the new value into effect.
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See the `scroll-bar-mode' variable for possible values to use."
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(if scroll-bar-mode
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(setq previous-scroll-bar-mode scroll-bar-mode))
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(setq scroll-bar-mode value)
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(when scroll-bar-mode-explicit
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(modify-all-frames-parameters (list (cons 'vertical-scroll-bars
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scroll-bar-mode)))))
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(defcustom scroll-bar-mode default-frame-scroll-bars
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"Specify whether to have vertical scroll bars, and on which side.
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Possible values are nil (no scroll bars), `left' (scroll bars on left)
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and `right' (scroll bars on right).
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To set this variable in a Lisp program, use `set-scroll-bar-mode'
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to make it take real effect.
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Setting the variable with a customization buffer also takes effect."
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:type '(choice (const :tag "none (nil)" nil)
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(const left)
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(const right))
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:group 'frames
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;; The default value for :initialize would try to use :set
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;; when processing the file in cus-dep.el.
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:initialize 'custom-initialize-default
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:set (lambda (_sym val) (set-scroll-bar-mode val)))
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;; We just set scroll-bar-mode, but that was the default.
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;; If it is set again, that is for real.
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(setq scroll-bar-mode-explicit t)
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(defun get-scroll-bar-mode ()
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(declare (gv-setter set-scroll-bar-mode))
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scroll-bar-mode)
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(define-minor-mode scroll-bar-mode
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"Toggle vertical scroll bars on all frames (Scroll Bar mode).
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With a prefix argument ARG, enable Scroll Bar mode if ARG is
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positive, and disable it otherwise. If called from Lisp, enable
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the mode if ARG is omitted or nil.
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This command applies to all frames that exist and frames to be
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created in the future."
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:variable ((get-scroll-bar-mode)
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. (lambda (v) (set-scroll-bar-mode
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(if v (or previous-scroll-bar-mode
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default-frame-scroll-bars))))))
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(defun toggle-scroll-bar (arg)
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"Toggle whether or not the selected frame has vertical scroll bars.
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With arg, turn vertical scroll bars on if and only if arg is positive.
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The variable `scroll-bar-mode' controls which side the scroll bars are on
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when they are turned on; if it is nil, they go on the left."
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(interactive "P")
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(if (null arg)
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(setq arg
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(if (cdr (assq 'vertical-scroll-bars
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(frame-parameters (selected-frame))))
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-1 1))
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(setq arg (prefix-numeric-value arg)))
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(modify-frame-parameters
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(selected-frame)
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(list (cons 'vertical-scroll-bars
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(if (> arg 0)
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(or scroll-bar-mode default-frame-scroll-bars))))))
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(defun toggle-horizontal-scroll-bar (_arg)
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"Toggle whether or not the selected frame has horizontal scroll bars.
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With arg, turn horizontal scroll bars on if and only if arg is positive.
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Horizontal scroll bars aren't implemented yet."
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(interactive "P")
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(error "Horizontal scroll bars aren't implemented yet"))
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;;;; Buffer navigation using the scroll bar.
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;; This was used for up-events on button 2, but no longer.
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(defun scroll-bar-set-window-start (event)
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"Set the window start according to where the scroll bar is dragged.
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EVENT should be a scroll bar click or drag event."
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(interactive "e")
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(portion-whole (nth 2 end-position)))
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(with-current-buffer (window-buffer window)
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(save-excursion
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(goto-char (+ (point-min)
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(scroll-bar-scale portion-whole
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(- (point-max) (point-min)))))
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(beginning-of-line)
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(set-window-start window (point))))))
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(defun scroll-bar-drag-position (portion-whole)
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"Calculate new window start for drag event."
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(save-excursion
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(goto-char (+ (point-min)
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(scroll-bar-scale portion-whole
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(- (point-max) (point-min)))))
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(beginning-of-line)
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(point)))
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(defun scroll-bar-maybe-set-window-start (event)
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"Set the window start according to where the scroll bar is dragged.
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Only change window start if the new start is substantially different.
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EVENT should be a scroll bar click or drag event."
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(interactive "e")
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(portion-whole (nth 2 end-position))
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(next-portion-whole (cons (1+ (car portion-whole))
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(cdr portion-whole)))
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portion-start
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next-portion-start
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(current-start (window-start window)))
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(with-current-buffer (window-buffer window)
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(setq portion-start (scroll-bar-drag-position portion-whole))
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(setq next-portion-start (max
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(scroll-bar-drag-position next-portion-whole)
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(1+ portion-start)))
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(if (or (>= current-start next-portion-start)
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(< current-start portion-start))
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(set-window-start window portion-start)
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;; Always set window start, to ensure scroll bar position is updated.
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(set-window-start window current-start)))))
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;; Scroll the window to the proper position for EVENT.
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(defun scroll-bar-drag-1 (event)
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(let* ((start-position (event-start event))
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(window (nth 0 start-position))
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(portion-whole (nth 2 start-position)))
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(save-excursion
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(with-current-buffer (window-buffer window)
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;; Calculate position relative to the accessible part of the buffer.
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(goto-char (+ (point-min)
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(scroll-bar-scale portion-whole
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(- (point-max) (point-min)))))
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(vertical-motion 0 window)
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(set-window-start window (point))))))
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(defun scroll-bar-drag (event)
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"Scroll the window by dragging the scroll bar slider.
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If you click outside the slider, the window scrolls to bring the slider there."
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(interactive "e")
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(let* (done
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(echo-keystrokes 0)
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(end-position (event-end event))
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(window (nth 0 end-position))
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(before-scroll))
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(with-current-buffer (window-buffer window)
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(setq before-scroll point-before-scroll))
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(save-selected-window
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(select-window window)
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(setq before-scroll
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(or before-scroll (point))))
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(scroll-bar-drag-1 event)
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(track-mouse
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(while (not done)
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(setq event (read-event))
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(if (eq (car-safe event) 'mouse-movement)
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(setq event (read-event)))
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(cond ((eq (car-safe event) 'scroll-bar-movement)
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(scroll-bar-drag-1 event))
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(t
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;; Exit when we get the drag event; ignore that event.
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(setq done t)))))
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(sit-for 0)
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(with-current-buffer (window-buffer window)
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(setq point-before-scroll before-scroll))))
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(defun scroll-bar-scroll-down (event)
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"Scroll the window's top line down to the location of the scroll bar click.
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EVENT should be a scroll bar click."
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(interactive "e")
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(before-scroll))
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(with-current-buffer (window-buffer window)
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(setq before-scroll point-before-scroll))
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(unwind-protect
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(save-selected-window
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(let ((portion-whole (nth 2 end-position)))
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(select-window window)
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(setq before-scroll
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(or before-scroll (point)))
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(scroll-down
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(scroll-bar-scale portion-whole (1- (window-height)))))
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(sit-for 0))
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(with-current-buffer (window-buffer window)
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(setq point-before-scroll before-scroll)))))
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(defun scroll-bar-scroll-up (event)
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"Scroll the line next to the scroll bar click to the top of the window.
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EVENT should be a scroll bar click."
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(interactive "e")
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(before-scroll))
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(with-current-buffer (window-buffer window)
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(setq before-scroll point-before-scroll))
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(unwind-protect
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(save-selected-window
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(let ((portion-whole (nth 2 end-position)))
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(select-window window)
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(setq before-scroll
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(or before-scroll (point)))
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(scroll-up
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(scroll-bar-scale portion-whole (1- (window-height)))))
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(sit-for 0))
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(with-current-buffer (window-buffer window)
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(setq point-before-scroll before-scroll)))))
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;;; Tookit scroll bars.
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(defun scroll-bar-toolkit-scroll (event)
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(interactive "e")
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(part (nth 4 end-position))
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before-scroll)
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(cond ((eq part 'end-scroll))
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(t
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(with-current-buffer (window-buffer window)
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(setq before-scroll point-before-scroll))
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(save-selected-window
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(select-window window)
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(setq before-scroll (or before-scroll (point)))
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(cond ((eq part 'above-handle)
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(scroll-up '-))
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((eq part 'below-handle)
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(scroll-up nil))
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((eq part 'ratio)
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(let* ((portion-whole (nth 2 end-position))
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(lines (scroll-bar-scale portion-whole
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(1- (window-height)))))
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(scroll-up (cond ((not (zerop lines)) lines)
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((< (car portion-whole) 0) -1)
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(t 1)))))
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((eq part 'up)
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(scroll-up -1))
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((eq part 'down)
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(scroll-up 1))
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((eq part 'top)
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(set-window-start window (point-min)))
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((eq part 'bottom)
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(goto-char (point-max))
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(recenter))
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((eq part 'handle)
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(scroll-bar-drag-1 event))))
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(sit-for 0)
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(with-current-buffer (window-buffer window)
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(setq point-before-scroll before-scroll))))))
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;;;; Bindings.
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;; For now, we'll set things up to work like xterm.
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(cond ((and (boundp 'x-toolkit-scroll-bars) x-toolkit-scroll-bars)
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(global-set-key [vertical-scroll-bar mouse-1]
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'scroll-bar-toolkit-scroll))
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(t
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(global-set-key [vertical-scroll-bar mouse-1]
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'scroll-bar-scroll-up)
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(global-set-key [vertical-scroll-bar drag-mouse-1]
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'scroll-bar-scroll-up)
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(global-set-key [vertical-scroll-bar down-mouse-2]
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'scroll-bar-drag)
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(global-set-key [vertical-scroll-bar mouse-3]
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'scroll-bar-scroll-down)
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(global-set-key [vertical-scroll-bar drag-mouse-3]
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'scroll-bar-scroll-down)))
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(provide 'scroll-bar)
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;;; scroll-bar.el ends here
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