--- /dev/null
+;;; image-file.el --- Support for visiting image files
+;;
+;; Copyright (C) 2000 Free Software Foundation, Inc.
+;;
+;; Author: Miles Bader <miles@gnu.org>
+;; Keywords: multimedia
+
+;; 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)
+;; any later version.
+
+;; 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.
+
+;;; Commentary:
+
+;; Defines a file-name-handler hook that transforms visited (or
+;; inserted) image files so that they are by displayed as emacs as
+;; images. This is done by putting a `display' text-property on the
+;; image data, with the image-data still present underneath; if the
+;; resulting buffer file is saved to another name it will correctly save
+;; the image data to the new file.
+
+;;; Code:
+
+(require 'image)
+
+;;;###autoload
+(defcustom image-file-handler-enabled nil
+ "True if visiting an image file will actually display the image.
+A file is considered an image file if its filename matches one of the
+regexps in `image-file-regexps'.
+
+Setting this variable directly does not take effect;
+use either \\[customize] or the function `set-image-file-handler-enabled'."
+ :type 'boolean
+ :set (lambda (sym val) (set-image-file-handler-enabled val))
+ :initialize 'custom-initialize-default
+ :require 'image-file
+ :group 'image)
+
+(defcustom image-file-regexps
+ '("\\.png$" "\\.jpeg$" "\\.jpg$" "\\.gif$" "\\.tiff$" "\\.x[bp]m$")
+ "*A list of regexps matching files that should be displayed as images.
+
+Setting this variable directly does not take effect until the next time
+`set-image-file-handler-enabled' is called (which happens automatically
+when using \\[customize]."
+ :type '(repeat regexp)
+ :set (lambda (sym val)
+ (set-default sym val)
+ (when image-file-handler-enabled
+ ;; Re-initialize the image-file handler
+ (set-image-file-handler-enabled t)))
+ :initialize 'custom-initialize-default
+ :group 'image)
+
+;;;###autoload
+(defun insert-image-file (file &optional visit beg end replace)
+ "Insert the image file FILE into the current buffer.
+Optional arguments VISIT, BEG, END, and REPLACE are interpreted as for
+the command `insert-file-contents'."
+ (let ((rval
+ (image-file-call-underlying #'insert-file-contents-literally
+ 'insert-file-contents
+ file visit beg end replace)))
+ (when (and image-file-handler-enabled (or (null beg) (zerop beg)) (null end))
+ ;; Make image into a picture, but only if the whole file was inserted
+ (let* ((ibeg (point))
+ (iend (+ (point) (cadr rval)))
+ (data
+ (string-make-unibyte (buffer-substring-no-properties ibeg iend)))
+ (image
+ (create-image data nil t))
+ (props
+ `(display ,image
+ intangible ,image
+ rear-nonsticky (display)
+ ;; This a cheap attempt to make the whole buffer
+ ;; read-only when we're visiting the file.
+ ,@(and visit
+ (= ibeg (point-min))
+ (= iend (point-max))
+ '(read-only t front-sticky (read-only))))))
+ (add-text-properties ibeg iend props)))
+ rval))
+
+(defun image-file-handler (operation &rest args)
+ "File name handler for inserting image files.
+OPERATION is the operation to perform, on ARGS.
+See `file-name-handler-alist' for details."
+ (if (eq operation 'insert-file-contents)
+ (apply #'insert-image-file args)
+ ;; We don't handle OPERATION, use another handler or the default
+ (apply #'image-file-call-underlying operation operation args)))
+
+(defun image-file-call-underlying (function operation &rest args)
+ "Call FUNCTION with `image-file-handler' and OPERATION inhibited.
+Optional argument ARGS are the arguments to call FUNCTION with."
+ (let ((inhibit-file-name-handlers
+ (cons 'image-file-handler
+ (and (eq inhibit-file-name-operation operation)
+ inhibit-file-name-handlers)))
+ (inhibit-file-name-operation operation))
+ (apply function args)))
+
+;;;###autoload
+(defun set-image-file-handler-enabled (enabled)
+ "Enable or disable visiting image files as real images, as per ENABLED.
+The regexp in `image-file-regexp' is used to determine which filenames are
+considered image files."
+ ;; Remove existing handler
+ (let ((existing-entry (rassq 'image-file-handler file-name-handler-alist)))
+ (when existing-entry
+ (setq file-name-handler-alist
+ (delq existing-entry file-name-handler-alist))))
+ ;; Add new handler
+ (when enabled
+ (let ((regexp
+ (concat "\\("
+ (mapconcat 'identity image-file-regexps "\\|")
+ "\\)")))
+ (setq file-name-handler-alist
+ (cons (cons regexp 'image-file-handler) file-name-handler-alist))))
+ (setq-default image-file-handler-enabled enabled))
+
+;;;###autoload
+(defun enable-image-file-handler ()
+ "Enable visiting image files as real images.
+The regexp in `image-file-regexp' is used to determine which filenames are
+considered image files."
+ (interactive)
+ (set-image-file-handler-enabled t))
+
+(defun disable-image-file-handler ()
+ "Disable visiting image files as real images."
+ (interactive)
+ (set-image-file-handler-enabled nil))
+
+(provide 'image-file)
+
+;;; image-file.el ends here