lisp/image-file.el

   1 ;;; image-file.el --- support for visiting image files
   2 ;;
   3 ;; Copyright (C) 2000, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006, 2007, 2008 Free Software Foundation, Inc.
   5 ;;
   6 ;; Author: Miles Bader <miles@gnu.org>
   7 ;; Keywords: multimedia
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 3, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  24 ;; Boston, MA 02110-1301, USA.
  25
  26 ;;; Commentary:
  27
  28 ;; Defines a file-name-handler hook that transforms visited (or
  29 ;; inserted) image files so that they are displayed by Emacs as
  30 ;; images.  This is done by putting a `display' text-property on the
  31 ;; image data, with the image-data still present underneath; if the
  32 ;; resulting buffer file is saved to another name it will correctly save
  33 ;; the image data to the new file.
  34
  35 ;;; Code:
  36
  37 (require 'image)
  38
  39
  40 ;;;###autoload
  41 (defcustom image-file-name-extensions
  42   '("png" "jpeg" "jpg" "gif" "tiff" "tif" "xbm" "xpm" "pbm" "pgm" "ppm" "pnm" "svg")
  43   "*A list of image-file filename extensions.
  44 Filenames having one of these extensions are considered image files,
  45 in addition to those matching `image-file-name-regexps'.
  46
  47 See `auto-image-file-mode'; if `auto-image-file-mode' is enabled,
  48 setting this variable directly does not take effect unless
  49 `auto-image-file-mode' is re-enabled; this happens automatically when
  50 the variable is set using \\[customize]."
  51   :type '(repeat string)
  52   :set (lambda (sym val)
  53          (set-default sym val)
  54          (when auto-image-file-mode
  55            ;; Re-initialize the image-file handler
  56            (auto-image-file-mode t)))
  57   :initialize 'custom-initialize-default
  58   :group 'image)
  59
  60 ;;;###autoload
  61 (defcustom image-file-name-regexps nil
  62   "*List of regexps matching image-file filenames.
  63 Filenames matching one of these regexps are considered image files,
  64 in addition to those with an extension in `image-file-name-extensions'.
  65
  66 See function `auto-image-file-mode'; if `auto-image-file-mode' is
  67 enabled, setting this variable directly does not take effect unless
  68 `auto-image-file-mode' is re-enabled; this happens automatically when
  69 the variable is set using \\[customize]."
  70   :type '(repeat regexp)
  71   :set (lambda (sym val)
  72          (set-default sym val)
  73          (when auto-image-file-mode
  74            ;; Re-initialize the image-file handler
  75            (auto-image-file-mode t)))
  76   :initialize 'custom-initialize-default
  77   :group 'image)
  78
  79
  80 ;;;###autoload
  81 (defun image-file-name-regexp ()
  82   "Return a regular expression matching image-file filenames."
  83   (let ((exts-regexp
  84          (and image-file-name-extensions
  85               (concat "\\."
  86                       (regexp-opt (nconc (mapcar #'upcase
  87                                                  image-file-name-extensions)
  88                                          image-file-name-extensions)
  89                                   t)
  90                       "\\'"))))
  91     (if image-file-name-regexps
  92         (mapconcat 'identity
  93                    (if exts-regexp
  94                        (cons exts-regexp image-file-name-regexps)
  95                      image-file-name-regexps)
  96                    "\\|")
  97       exts-regexp)))
  98
  99
 100 ;;;###autoload
 101 (defun insert-image-file (file &optional visit beg end replace)
 102   "Insert the image file FILE into the current buffer.
 103 Optional arguments VISIT, BEG, END, and REPLACE are interpreted as for
 104 the command `insert-file-contents'."
 105   (let ((rval
 106          (image-file-call-underlying #'insert-file-contents-literally
 107                                      'insert-file-contents
 108                                      file visit beg end replace)))
 109     ;; Turn the image data into a real image, but only if the whole file
 110     ;; was inserted
 111     (when (and (or (null beg) (zerop beg)) (null end))
 112       (let* ((ibeg (point))
 113              (iend (+ (point) (cadr rval)))
 114              (visitingp (and visit (= ibeg (point-min)) (= iend (point-max))))
 115              (data
 116               (string-make-unibyte
 117                (buffer-substring-no-properties ibeg iend)))
 118              (image
 119               (create-image data nil t))
 120              (props
 121               `(display ,image
 122                         yank-handler
 123                         (image-file-yank-handler nil t)
 124                         intangible ,image
 125                         rear-nonsticky (display intangible)
 126                         ;; This a cheap attempt to make the whole buffer
 127                         ;; read-only when we're visiting the file (as
 128                         ;; opposed to just inserting it).
 129                         ,@(and visitingp
 130                                '(read-only t front-sticky (read-only))))))
 131         (add-text-properties ibeg iend props)
 132         (when visitingp
 133           ;; Inhibit the cursor when the buffer contains only an image,
 134           ;; because cursors look very strange on top of images.
 135           (setq cursor-type nil)
 136           ;; This just makes the arrow displayed in the right fringe
 137           ;; area look correct when the image is wider than the window.
 138           (setq truncate-lines t))))
 139     rval))
 140
 141 ;; We use a yank-handler to make yanked images unique, so that
 142 ;; yanking two copies of the same image next to each other are
 143 ;; recognized as two different images.
 144 (defun image-file-yank-handler (string)
 145   "Yank handler for inserting an image into a buffer."
 146   (let ((len (length string))
 147         (image (get-text-property 0 'display string)))
 148     (remove-text-properties 0 len yank-excluded-properties string)
 149     (if (consp image)
 150         (add-text-properties 0
 151                              (or (next-single-property-change 0 'image-counter string)
 152                                  (length string))
 153                              `(display
 154                                ,(cons (car image) (cdr image))
 155                                yank-handler
 156                                ,(cons 'image-file-yank-handler '(nil t)))
 157                              string))
 158     (insert string)))
 159
 160 (put 'image-file-handler 'safe-magic t)
 161 (defun image-file-handler (operation &rest args)
 162   "Filename handler for inserting image files.
 163 OPERATION is the operation to perform, on ARGS.
 164 See `file-name-handler-alist' for details."
 165   (if (and (eq operation 'insert-file-contents)
 166            auto-image-file-mode)
 167       (apply #'insert-image-file args)
 168     ;; We don't handle OPERATION, use another handler or the default
 169     (apply #'image-file-call-underlying operation operation args)))
 170
 171 (defun image-file-call-underlying (function operation &rest args)
 172   "Call FUNCTION with `image-file-handler' and OPERATION inhibited.
 173 Optional argument ARGS are the arguments to call FUNCTION with."
 174   (let ((inhibit-file-name-handlers
 175          (cons 'image-file-handler
 176                (and (eq inhibit-file-name-operation operation)
 177                     inhibit-file-name-handlers)))
 178         (inhibit-file-name-operation operation))
 179     (apply function args)))
 180
 181
 182 ;;;###autoload
 183 (define-minor-mode auto-image-file-mode
 184   "Toggle visiting of image files as images.
 185 With prefix argument ARG, turn on if positive, otherwise off.
 186 Returns non-nil if the new state is enabled.
 187
 188 Image files are those whose name has an extension in
 189 `image-file-name-extensions', or matches a regexp in
 190 `image-file-name-regexps'."
 191   :global t
 192   :group 'image
 193   ;; Remove existing handler
 194   (let ((existing-entry
 195          (rassq 'image-file-handler file-name-handler-alist)))
 196     (when existing-entry
 197       (setq file-name-handler-alist
 198             (delq existing-entry file-name-handler-alist))))
 199   ;; Add new handler, if enabled
 200   (when auto-image-file-mode
 201     (push (cons (image-file-name-regexp) 'image-file-handler)
 202           file-name-handler-alist)))
 203
 204
 205 (provide 'image-file)
 206
 207 ;;; arch-tag: 04cafe36-f7ba-4c80-9f47-4cb656520ce1
 208 ;;; image-file.el ends here