+;;; rot13.el --- display a buffer in rot13.
+;; Copyright (C) 1988 Free Software Foundation, Inc.
+;; Author: Howard Gayle:
+;; This file is part of GNU Emacs.
+;; GNU Emacs is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 2, or (at your option)
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; GNU General Public License for more details.
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING. If not, write to the
+;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+;; The single entry point, `rot13-other-window', performs a Caesar cipher
+;; encrypt/decrypt on the current buffer and displays the result in another
+;; window. Rot13 encryption is sometimes used on USENET as a read-at-your-
+;; own-risk wrapper for material some might consider offensive, such as
+;; Written by Howard Gayle.
+;; This hack is mainly to show off the char table stuff.
+ (let ((table (make-display-table))
+ (aset table (+ i ?a) (vector (+ (% (+ i 13) 26) ?a)))
+ (aset table (+ i ?A) (vector (+ (% (+ i 13) 26) ?A)))
+ "Char table for rot 13 display.")
+(defun rot13-other-window ()
+ "Display current buffer in rot 13 in another window.
+To terminate the rot13 display, delete that window."
+ (let ((w (display-buffer (current-buffer) t)))
+ (set-window-display-table w rot13-display-table)))
+(defun toggle-rot13-mode ()
+ "Toggle the use of rot 13 encoding for the current window."
+ (if (eq (window-display-table (selected-window)) rot13-display-table)
+ (set-window-display-table (selected-window) nil)
+ (if (null (window-display-table (selected-window)))
+ (set-window-display-table (selected-window) rot13-display-table))))