-;; LCD Archive Entry:
-;; auto-show|Pete Ware|ware@cis.ohio-state.edu|
-;; Automatically scroll horizontally|
-;; 95-02-24|1.9|~/misc/auto-show.el|
-;;
-;;;
-;;; Author:
-;;;
-;;; Pete Ware ware@cis.ohio-state.edu
-;;; CIS Dept, Ohio State University w/ (614) 292-8501
-;;; 774 Dreese, 2015 Neil Ave. h/ (614) 791-1347
-;;; Columbus, OH 43210 http://www.cis.ohio-state.edu/~ware
-;;;
-;;;
-;;; Modification history:
-;;; 02/24/95 Added auto-show-show-left-margin-threshold so that if
-;;; there is anyway for the left margin to be displayed it is.
-;;; 02/24/95 Only scroll window if it matches current buffer. Added
-;;; function for enabeling scrolling in comint buffers on output.
-;;; 02/13/95 Aded Kevin Broadey <KevinB@bartley.demon.co.uk> fix so that
-;;; it doesn't scroll if we are at window border and at the
-;;; end of the line (i.e. newline character)
-;;; 02/10/95 jeff.dwork@amd.com added auto-show-toggle function.
-;;; 02/08/95 Added auto-show-enable as per
-;;; jeff.dwork@amd.com (Jeff Dwork)'s suggestion. Cleaned up
-;;; documentation.
-;;; 02/07/95 Rewrote for emacs 19: much, much cleaner. Renamed auto-show
-;;; 8/6/90 Make next-line/previous-line do better job following movement.
-;;; 3/21/90 better calculation of w-width in e-make-point-visible
-;;; test for truncated windows
-;;; added substitute-in-keymap
-;;; renamed to auto-horizontal
-;;; added backward-delete-char
-;;; 8/13/88 Created
-
-;;;
-;;; This is a rewrite of auto-horizontal. It is comparable in
-;;; functionality to hscroll.el except it is not a minor mode and does
-;;; not use any timers. This file provides functions that
-;;; automatically scroll the window horizontally when the point moves
-;;; off the left or right side of the window. To load it just add:
-;;; (require 'auto-show)
-;;; to your .emacs.
-;;;
-;;; Setting the variable ``truncate-lines'' to non-nil causes long
-;;; lines to disappear off the end of the screen instead of wrapping
-;;; to the beginning of the next line. To make this the default for
-;;; all buffers add the following line to your .emacs (sans ;;;):
-;;;
-;;; (set-default 'truncate-lines t)
-;;;
-
-;;; However, I've found that I only want this when I'm editing C code.
-;;; Accordingly I have something like the following in my .emacs:
-;;;
-;;; (set-default 'truncate-lines nil) ; this is the original value
-;;; (defun my-c-mode-hook ()
-;;; "Run when C-mode starts up. Changes ..."
-;;; ... set various personal preferences ...
-;;; (setq truncate-lines t))
-;;; (add-hook 'c-mode-hook 'my-c-mode-hook)
-;;;
-;;;
-;;; As a finer level of control, one can still have truncated lines but
-;;; without the automatic left and right scrolling by setting the buffer
-;;; local variable ``auto-show-enable'' to nil. The default value is t.
-;;; The command ``auto-show-toggle'' will toggle the value of
-;;; ``auto-show-enable''.
-;;;
-;;;
-;;; I also like the output from my shell's (and other comint.el based commands)
-;;; to scroll on output. One can call:
-;;;
-;;; (auto-show-comint-make-point-visible)
-;;;
-;;; which adds auto-show-make-point-visible to comint-output-filter-functions.
-
-(provide 'auto-show)
-
-;;;************************************************************
-;;;*
-;;;* Define Automatic Horizontal Scrolling Functions
-;;;*
-;;;************************************************************
-
-(add-hook 'post-command-hook 'auto-show-make-point-visible)
-
-(defvar auto-show-enable t
- "*Allows one to turn off automatic horizontal scrolling on a per buffer
-basis independent of whether truncate-lines is t. The default value is t.
-To change the default:
- (set-default 'auto-show-enable nil)
-Any time auto-show-enable is changed it is only in the current buffer:
- (setq auto-show-enable nil)
-turns it on for this buffer.
-See also command `auto-show-toggle'.")
-
-(make-variable-buffer-local 'auto-show-enable)
-
-(defvar auto-show-shift-amount 8
- "*Extra amount to shift a line when point is not visible.")
-
-(defvar auto-show-show-left-margin-threshold 50
- "*Point must be before this column for us to try and make the left margin
-visible. Setting this to 0 disables this feature.")
-
-(defun auto-show-truncationp ()
- "True if truncation is on for current window."
- (or truncate-lines
- (and truncate-partial-width-windows
- (< (window-width) (frame-width)))))
-
-(defun auto-show-toggle ()
- "Toggle value of auto-show-enable."
- (interactive)
- (setq auto-show-enable (not auto-show-enable)))
-
-(defun auto-show-make-point-visible (&optional ignore-arg)
- "Scrolls the screen horizontally to make point visible but only if
-auto-show-enable is non-nil and lines are truncated. See also variable
-`auto-show-enable' and command `auto-show-toggle'."
- (interactive)
- (if (and auto-show-enable (auto-show-truncationp)
- (equal (window-buffer) (current-buffer)))
- (let* ((col (current-column)) ;column on line point is at
- (scroll (window-hscroll)) ;how far window is scrolled
- (w-width (- (window-width)
- (if (> scroll 0)
- 2 1))) ;how wide window is on the screen
- (right-col (+ scroll w-width)))
- (if (and (< col auto-show-show-left-margin-threshold)
- (< col (window-width))
- (> scroll 0))
- (scroll-right scroll)
- (if (< col scroll) ;to the left of the screen
- (scroll-right (+ (- scroll col) auto-show-shift-amount))
- (if (or (> col right-col) ;to the right of the screen
- (and (= col right-col)
- (not (eolp))))
- (scroll-left (+ auto-show-shift-amount
- (- col (+ scroll w-width))))
- )
- )
- )
- )
- )
- )
-
-(defun auto-show-comint-make-point-visible ()
- "Add a function to comint-output-filter-functions that auto-scrolls
-left or right on output to the buffer.
-
-NOTE: you should load comint mode before this as comint.el uses a
-defvar to initialize comint-output-filter-functions to the default value."
- (interactive)
- (add-hook 'comint-output-filter-functions 'auto-show-make-point-visible t)
- )
-
-;; end of auto-show.el
-
+;;; auto-show.el --- perform automatic horizontal scrolling as point moves
+;;; This file is in the public domain.
+
+;;; Keywords: scroll display minor-mode
+;;; Author: Pete Ware <ware@cis.ohio-state.edu>
+;;; Maintainer: FSF
+
+;;; Commentary:
+
+;;; This file provides functions that
+;;; automatically scroll the window horizontally when the point moves
+;;; off the left or right side of the window.
+
+;;; Once this library is loaded, automatic horizontal scrolling
+;;; occurs whenever long lines are being truncated.
+;;; To request truncation of long lines, set the variable
+;;; Setting the variable `truncate-lines' to non-nil.
+;;; You can do this for all buffers as follows:
+;;;
+;;; (set-default 'truncate-lines t)
+
+;;; Here is how to do it for C mode only:
+;;;
+;;; (set-default 'truncate-lines nil) ; this is the original value
+;;; (defun my-c-mode-hook ()
+;;; "Run when C-mode starts up. Changes ..."
+;;; ... set various personal preferences ...
+;;; (setq truncate-lines t))
+;;; (add-hook 'c-mode-hook 'my-c-mode-hook)
+;;;
+;;;
+;;; As a finer level of control, you can still have truncated lines but
+;;; without the automatic horizontal scrolling by setting the buffer
+;;; local variable `auto-show-mode' to nil. The default value is t.
+;;; The command `auto-show-mode' toggles the value of the variable
+;;; `auto-show-mode'.
+
+;;; Code:
+
+(defgroup auto-show nil
+ "Perform automatic horizontal scrolling as point moves."
+ :group 'editing)
+
+(defcustom auto-show-mode t
+ "*Non-nil enables automatic horizontal scrolling, when lines are truncated.
+The default value is t. To change the default, do this:
+ (set-default 'auto-show-mode nil)
+See also command `auto-show-mode'.
+This variable has no effect when lines are not being truncated.
+This variable is automatically local in each buffer where it is set."
+ :type 'boolean
+ :group 'auto-show)
+
+(make-variable-buffer-local 'auto-show-mode)
+
+(defcustom auto-show-shift-amount 8
+ "*Extra columns to scroll. for automatic horizontal scrolling."
+ :type 'integer
+ :group 'auto-show)
+
+(defcustom auto-show-show-left-margin-threshold 50
+ "*Threshold column for automatic horizontal scrolling to the right.
+If point is before this column, we try to scroll to make the left margin
+visible. Setting this to 0 disables this feature."
+ :type 'integer
+ :group 'auto-show)
+
+(defun auto-show-truncationp ()
+ "True if line truncation is enabled for the selected window."
+ (or truncate-lines
+ (and truncate-partial-width-windows
+ (< (window-width) (frame-width)))))
+
+;;;###autoload
+(defun auto-show-mode (arg)
+ "Turn automatic horizontal scroll mode on or off.
+With arg, turn auto scrolling on if arg is positive, off otherwise.
+This mode is enabled or disabled for each buffer individually.
+It takes effect only when `truncate-lines' is non-nil."
+ (interactive "P")
+ (setq auto-show-mode
+ (if (null arg)
+ (not auto-show-mode)
+ (> (prefix-numeric-value arg) 0))))
+
+(defun auto-show-make-point-visible (&optional ignore-arg)
+ "Scroll horizontally to make point visible, if that is enabled.
+This function only does something if `auto-show-mode' is non-nil
+and longlines are being truncated in the selected window.
+See also the command `auto-show-mode'."
+ (interactive)
+ (if (and auto-show-mode (auto-show-truncationp)
+ (equal (window-buffer) (current-buffer)))
+ (let* ((col (current-column)) ;column on line point is at
+ (scroll (window-hscroll)) ;how far window is scrolled
+ (w-width (- (window-width)
+ (if (> scroll 0)
+ 2 1))) ;how wide window is on the screen
+ (right-col (+ scroll w-width)))
+ (if (and (< col auto-show-show-left-margin-threshold)
+ (< col (window-width))
+ (> scroll 0))
+ (scroll-right scroll)
+ (if (< col scroll) ;to the left of the screen
+ (scroll-right (+ (- scroll col) auto-show-shift-amount))
+ (if (or (> col right-col) ;to the right of the screen
+ (and (= col right-col)
+ (not (eolp))))
+ (scroll-left (+ auto-show-shift-amount
+ (- col (+ scroll w-width))))
+ )
+ )
+ )
+ )
+ )
+ )
+
+;; Do auto-scrolling after commands.
+(add-hook 'post-command-hook 'auto-show-make-point-visible)
+
+;; Do auto-scrolling in comint buffers after process output also.
+(add-hook 'comint-output-filter-functions 'auto-show-make-point-visible t)
+
+(provide 'auto-show)
+
+;; auto-show.el ends here
+
HCoop / bpt / emacs.git / blobdiff