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image-file.el
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image-file.el
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;;; image-file.el --- Support for visiting image files
;;
;; Copyright (C) 2000, 2001 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 displayed by 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-name-extensions
'("png" "jpeg" "jpg" "gif" "tiff" "tif" "xbm" "xpm" "pbm" "pgm" "ppm")
"*A list of image-file filename extensions.
Filenames having one of these extensions are considered image files,
in addition to those matching `image-file-name-regexps'.
See `auto-image-file-mode'; if `auto-image-file-mode' is enabled,
setting this variable directly does not take effect unless
`auto-image-file-mode' is re-enabled; this happens automatically the
variable is set using \\[customize]."
:type '(repeat string)
:set (lambda (sym val)
(set-default sym val)
(when auto-image-file-mode
;; Re-initialize the image-file handler
(auto-image-file-mode t)))
:initialize 'custom-initialize-default
:group 'image)
;;;###autoload
(defcustom image-file-name-regexps nil
"*List of regexps matching image-file filenames.
Filenames matching one of these regexps are considered image files,
in addition to those with an extension in `image-file-name-extensions'.
See function `auto-image-file-mode'; if `auto-image-file-mode' is
enabled, setting this variable directly does not take effect unless
`auto-image-file-mode' is re-enabled; this happens automatically the
variable is set using \\[customize]."
:type '(repeat regexp)
:set (lambda (sym val)
(set-default sym val)
(when auto-image-file-mode
;; Re-initialize the image-file handler
(auto-image-file-mode t)))
:initialize 'custom-initialize-default
:group 'image)
;;;###autoload
(defun image-file-name-regexp ()
"Return a regular expression matching image-file filenames."
(let ((exts-regexp
(and image-file-name-extensions
(concat "\\."
(regexp-opt (nconc (mapcar #'upcase
image-file-name-extensions)
image-file-name-extensions)
t)
"\\'"))))
(if image-file-name-regexps
(mapconcat 'identity
(if exts-regexp
(cons exts-regexp image-file-name-regexps)
image-file-name-regexps)
"\\|")
exts-regexp)))
;;;###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)))
;; Turn the image data into a real image, but only if the whole file
;; was inserted
(when (and (or (null beg) (zerop beg)) (null end))
(let* ((ibeg (point))
(iend (+ (point) (cadr rval)))
(visitingp (and visit (= ibeg (point-min)) (= iend (point-max))))
(data
(string-make-unibyte
(buffer-substring-no-properties ibeg iend)))
(image
(create-image data nil t))
(props
`(display ,image
intangible ,image
rear-nonsticky (display intangible)
;; This a cheap attempt to make the whole buffer
;; read-only when we're visiting the file (as
;; opposed to just inserting it).
,@(and visitingp
'(read-only t front-sticky (read-only))))))
(add-text-properties ibeg iend props)
(when visitingp
;; Inhibit the cursor when the buffer contains only an image,
;; because cursors look very strange on top of images.
(setq cursor-type nil)
;; This just makes the arrow displayed in the right fringe
;; area look correct when the image is wider than the window.
(setq truncate-lines t))))
rval))
(defun image-file-handler (operation &rest args)
"Filename handler for inserting image files.
OPERATION is the operation to perform, on ARGS.
See `file-name-handler-alist' for details."
(if (and (eq operation 'insert-file-contents)
auto-image-file-mode)
(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)))
;;; Note this definition must be at the end of the file, because
;;; `define-minor-mode' actually calls the mode-function if the
;;; associated variable is non-nil, which requires that all needed
;;; functions be already defined. [This is arguably a bug in d-m-m]
;;;###autoload
(define-minor-mode auto-image-file-mode
"Toggle visiting of image files as images.
With prefix argument ARG, turn on if positive, otherwise off.
Returns non-nil if the new state is enabled.
Image files are those whose name has an extension in
`image-file-name-extensions', or matches a regexp in
`image-file-name-regexps'."
:global t
:group 'image
;; 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, if enabled
(when auto-image-file-mode
(push (cons (image-file-name-regexp) 'image-file-handler)
file-name-handler-alist)))
(provide 'image-file)
;;; image-file.el ends here