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+ − 1 ;;; auto-show.el --- perform automatic horizontal scrolling as point moves
+ − 2
+ − 3 ;; Copyright (C) 1997 Free Software Foundation, Inc.
+ − 4 ;; This file is in the public domain.
+ − 5
+ − 6 ;; Author: Pete Ware <ware@cis.ohio-state.edu>
+ − 7 ;; Maintainer: XEmacs Development Team
+ − 8 ;; Keywords: extensions, internal, dumped
+ − 9
+ − 10 ;; This file is part of XEmacs.
+ − 11
+ − 12 ;; XEmacs is free software; you can redistribute it and/or modify it
+ − 13 ;; under the terms of the GNU General Public License as published by
+ − 14 ;; the Free Software Foundation; either version 2, or (at your option)
+ − 15 ;; any later version.
+ − 16
+ − 17 ;; XEmacs is distributed in the hope that it will be useful, but
+ − 18 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
+ − 19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ − 20 ;; General Public License for more details.
+ − 21
+ − 22 ;; You should have received a copy of the GNU General Public License
+ − 23 ;; along with XEmacs; see the file COPYING. If not, write to the Free
+ − 24 ;; Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ − 25 ;; 02111-1307, USA.
+ − 26
+ − 27 ;;; Synched up with: Emacs/Mule zeta.
+ − 28
+ − 29 ;;; Commentary:
+ − 30
+ − 31 ;; This file is dumped with XEmacs.
+ − 32
+ − 33 ;; Modified by: Ben Wing <ben@xemacs.org>
+ − 34
+ − 35 ;; This file provides functions that
+ − 36 ;; automatically scroll the window horizontally when the point moves
+ − 37 ;; off the left or right side of the window.
+ − 38
+ − 39 ;; Once this library is loaded, automatic horizontal scrolling
+ − 40 ;; occurs whenever long lines are being truncated.
+ − 41 ;; To request truncation of long lines, set the variable
+ − 42 ;; Setting the variable `truncate-lines' to non-nil.
+ − 43 ;; You can do this for all buffers as follows:
+ − 44 ;;
+ − 45 ;; (set-default 'truncate-lines t)
+ − 46
+ − 47 ;; Here is how to do it for C mode only:
+ − 48 ;;
+ − 49 ;; (set-default 'truncate-lines nil) ; this is the original value
+ − 50 ;; (defun my-c-mode-hook ()
+ − 51 ;; "Run when C-mode starts up. Changes ..."
+ − 52 ;; ... set various personal preferences ...
+ − 53 ;; (setq truncate-lines t))
+ − 54 ;; (add-hook 'c-mode-hook 'my-c-mode-hook)
+ − 55 ;;
+ − 56 ;;
+ − 57 ;; As a finer level of control, you can still have truncated lines but
+ − 58 ;; without the automatic horizontal scrolling by setting the buffer
+ − 59 ;; local variable `auto-show-mode' to nil. The default value is t.
+ − 60 ;; The command `auto-show-mode' toggles the value of the variable
+ − 61 ;; `auto-show-mode'.
+ − 62
+ − 63 ;;; Code:
+ − 64
+ − 65 (defgroup auto-show nil
+ − 66 "Perform automatic horizontal scrolling as point moves."
+ − 67 :group 'display
+ − 68 :group 'extensions)
+ − 69
+ − 70 ;; This is preloaded, so we don't need special :set, :require, etc.
+ − 71 (defcustom auto-show-mode t
+ − 72 "*Non-nil enables automatic horizontal scrolling, when lines are truncated.
+ − 73 The default value is t. To change the default, do this:
+ − 74 (set-default 'auto-show-mode nil)
+ − 75 See also command `auto-show-mode'.
+ − 76 This variable has no effect when lines are not being truncated.
+ − 77 This variable is automatically local in each buffer where it is set."
+ − 78 :type 'boolean
+ − 79 :group 'auto-show)
+ − 80
+ − 81 (make-variable-buffer-local 'auto-show-mode)
+ − 82
+ − 83 (defcustom auto-show-shift-amount 8
+ − 84 "*Extra columns to scroll. for automatic horizontal scrolling."
+ − 85 :type 'integer
+ − 86 :group 'auto-show)
+ − 87
+ − 88 (defcustom auto-show-show-left-margin-threshold 50
+ − 89 "*Threshold column for automatic horizontal scrolling to the right.
+ − 90 If point is before this column, we try to scroll to make the left margin
+ − 91 visible. Setting this to 0 disables this feature."
+ − 92 :type 'number
+ − 93 :group 'auto-show)
+ − 94
+ − 95 (defun auto-show-mode (arg)
+ − 96 "Turn automatic horizontal scroll mode on or off.
+ − 97 With arg, turn auto scrolling on if arg is positive, off otherwise.
+ − 98 This mode is enabled or disabled for each buffer individually.
+ − 99 It takes effect only when `truncate-lines' is non-nil."
+ − 100 (interactive "P")
+ − 101 (setq auto-show-mode
+ − 102 (if (null arg)
+ − 103 (not auto-show-mode)
+ − 104 (> (prefix-numeric-value arg) 0))))
+ − 105
+ − 106 ;; XEmacs addition:
+ − 107 (defvar auto-show-inhibiting-commands
+ − 108 '(scrollbar-char-left
+ − 109 scrollbar-char-right
+ − 110 scrollbar-page-left
+ − 111 scrollbar-page-right
+ − 112 scrollbar-to-left
+ − 113 scrollbar-to-right
+ − 114 scrollbar-horizontal-drag)
+ − 115 "Commands that inhibit auto-show behavior.
+ − 116 This normally includes the horizontal scrollbar commands.")
+ − 117
+ − 118 ;; XEmacs addition:
+ − 119 (defun auto-show-should-take-action-p ()
+ − 120 (and auto-show-mode (window-truncated-p)
+ − 121 (equal (window-buffer) (current-buffer))
+ − 122 (not (memq this-command auto-show-inhibiting-commands))))
+ − 123
+ − 124 ;; XEmacs addition:
+ − 125 (defun auto-show-make-region-visible (start end)
+ − 126 "Move point in such a way that the region (START, END) is visible.
+ − 127 This only does anything if auto-show-mode is enabled, and it doesn't
+ − 128 actually do any horizontal scrolling; rather, it just sets things up so
+ − 129 that the region will be visible when `auto-show-make-point-visible'
+ − 130 is next called (this happens after every command)."
+ − 131 (if (auto-show-should-take-action-p)
+ − 132 (let* ((scroll (window-hscroll)) ;how far window is scrolled
+ − 133 (w-width (- (window-width)
+ − 134 (if (> scroll 0)
+ − 135 2 1))) ;how wide window is on the screen
+ − 136 (right-col (+ scroll w-width))
+ − 137 (start-col (save-excursion (goto-char start) (current-column)))
+ − 138 (end-col (save-excursion (goto-char end) (current-column))))
+ − 139 (cond ((and (>= start-col scroll)
+ − 140 (<= end-col right-col))
+ − 141 ;; already completely visible
+ − 142 nil)
+ − 143 ((< start-col scroll)
+ − 144 (scroll-right (- scroll start-col)))
+ − 145 (t
+ − 146 (scroll-left (- end-col right-col)))))))
+ − 147
+ − 148 (defun auto-show-make-point-visible (&optional ignore-arg)
+ − 149 "Scroll horizontally to make point visible, if that is enabled.
+ − 150 This function only does something if `auto-show-mode' is non-nil
+ − 151 and longlines are being truncated in the selected window.
+ − 152 See also the command `auto-show-mode'."
+ − 153 (interactive)
+ − 154 ;; XEmacs change
+ − 155 (if (auto-show-should-take-action-p)
+ − 156 (let* ((col (current-column)) ;column on line point is at
+ − 157 (scroll (window-hscroll)) ;how far window is scrolled
+ − 158 (w-width (- (window-width)
+ − 159 (if (> scroll 0)
+ − 160 2 1))) ;how wide window is on the screen
+ − 161 (right-col (+ scroll w-width)))
+ − 162 (if (and (< col auto-show-show-left-margin-threshold)
+ − 163 (< col (window-width))
+ − 164 (> scroll 0))
+ − 165 (scroll-right scroll)
+ − 166 (if (< col scroll) ;to the left of the screen
+ − 167 (scroll-right (+ (- scroll col) auto-show-shift-amount))
+ − 168 (if (or (> col right-col) ;to the right of the screen
+ − 169 (and (= col right-col)
+ − 170 (not (eolp))))
+ − 171 (scroll-left (+ auto-show-shift-amount
+ − 172 (- col (+ scroll w-width))))))))))
+ − 173
+ − 174 ;; XEmacs change:
+ − 175 ;; #### instead of this, we kludgily call it from the C code, to make sure
+ − 176 ;; that it's done after any other things on post-command-hook (which might
+ − 177 ;; move point).
+ − 178 ;; Do auto-scrolling after commands.
+ − 179 ;;(add-hook 'post-command-hook 'auto-show-make-point-visible)
+ − 180
+ − 181 ;; If being dumped, turn it on right away.
+ − 182 (when (boundp 'pureload)
+ − 183 (auto-show-mode 1))
+ − 184
+ − 185 ;; Do auto-scrolling in comint buffers after process output also.
+ − 186 ; XEmacs -- don't do this now, it messes up comint.
+ − 187 ;(add-hook 'comint-output-filter-functions 'auto-show-make-point-visible t)
+ − 188
+ − 189 (provide 'auto-show)
+ − 190
+ − 191 ;;; auto-show.el ends here
