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, 2009, 2010, 2011 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 of the License, or
  14 ;; (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;; Defines a file-name-handler hook that transforms visited (or
  27 ;; inserted) image files so that they are displayed by Emacs as
  28 ;; images.  This is done by putting a `display' text-property on the
  29 ;; image data, with the image-data still present underneath; if the
  30 ;; resulting buffer file is saved to another name it will correctly save
  31 ;; the image data to the new file.
  32
  33 ;;; Code:
  34
  35 (require 'image)
  36
  37
  38 ;;;###autoload
  39 (defcustom image-file-name-extensions
  40   (purecopy '("png" "jpeg" "jpg" "gif" "tiff" "tif" "xbm" "xpm" "pbm" "pgm" "ppm" "pnm" "svg"))
  41   "A list of image-file filename extensions.
  42 Filenames having one of these extensions are considered image files,
  43 in addition to those matching `image-file-name-regexps'.
  44
  45 See `auto-image-file-mode'; if `auto-image-file-mode' is enabled,
  46 setting this variable directly does not take effect unless
  47 `auto-image-file-mode' is re-enabled; this happens automatically when
  48 the variable is set using \\[customize]."
  49   :type '(repeat string)
  50   :set (lambda (sym val)
  51          (set-default sym val)
  52          (when auto-image-file-mode
  53            ;; Re-initialize the image-file handler
  54            (auto-image-file-mode t)))
  55   :initialize 'custom-initialize-default
  56   :group 'image)
  57
  58 ;;;###autoload
  59 (defcustom image-file-name-regexps nil
  60   "List of regexps matching image-file filenames.
  61 Filenames matching one of these regexps are considered image files,
  62 in addition to those with an extension in `image-file-name-extensions'.
  63
  64 See function `auto-image-file-mode'; if `auto-image-file-mode' is
  65 enabled, setting this variable directly does not take effect unless
  66 `auto-image-file-mode' is re-enabled; this happens automatically when
  67 the variable is set using \\[customize]."
  68   :type '(repeat regexp)
  69   :set (lambda (sym val)
  70          (set-default sym val)
  71          (when auto-image-file-mode
  72            ;; Re-initialize the image-file handler
  73            (auto-image-file-mode t)))
  74   :initialize 'custom-initialize-default
  75   :group 'image)
  76
  77
  78 ;;;###autoload
  79 (defun image-file-name-regexp ()
  80   "Return a regular expression matching image-file filenames."
  81   (let ((exts-regexp
  82          (and image-file-name-extensions
  83               (concat "\\."
  84                       (regexp-opt (nconc (mapcar #'upcase
  85                                                  image-file-name-extensions)
  86                                          image-file-name-extensions)
  87                                   t)
  88                       "\\'"))))
  89     (if image-file-name-regexps
  90         (mapconcat 'identity
  91                    (if exts-regexp
  92                        (cons exts-regexp image-file-name-regexps)
  93                      image-file-name-regexps)
  94                    "\\|")
  95       exts-regexp)))
  96
  97
  98 ;;;###autoload
  99 (defun insert-image-file (file &optional visit beg end replace)
 100   "Insert the image file FILE into the current buffer.
 101 Optional arguments VISIT, BEG, END, and REPLACE are interpreted as for
 102 the command `insert-file-contents'."
 103   (let ((rval
 104          (image-file-call-underlying #'insert-file-contents-literally
 105                                      'insert-file-contents
 106                                      file visit beg end replace)))
 107     ;; Turn the image data into a real image, but only if the whole file
 108     ;; was inserted
 109     (when (and (or (null beg) (zerop beg)) (null end))
 110       (let* ((ibeg (point))
 111              (iend (+ (point) (cadr rval)))
 112              (visitingp (and visit (= ibeg (point-min)) (= iend (point-max))))
 113              (data
 114               (string-make-unibyte
 115                (buffer-substring-no-properties ibeg iend)))
 116              (image
 117               (create-image data nil t))
 118              (props
 119               `(display ,image
 120                         yank-handler
 121                         (image-file-yank-handler nil t)
 122                         intangible ,image
 123                         rear-nonsticky (display intangible)
 124                         ;; This a cheap attempt to make the whole buffer
 125                         ;; read-only when we're visiting the file (as
 126                         ;; opposed to just inserting it).
 127                         ,@(and visitingp
 128                                '(read-only t front-sticky (read-only))))))
 129         (add-text-properties ibeg iend props)
 130         (when visitingp
 131           ;; Inhibit the cursor when the buffer contains only an image,
 132           ;; because cursors look very strange on top of images.
 133           (setq cursor-type nil)
 134           ;; This just makes the arrow displayed in the right fringe
 135           ;; area look correct when the image is wider than the window.
 136           (setq truncate-lines t))))
 137     rval))
 138
 139 ;; We use a yank-handler to make yanked images unique, so that
 140 ;; yanking two copies of the same image next to each other are
 141 ;; recognized as two different images.
 142 (defun image-file-yank-handler (string)
 143   "Yank handler for inserting an image into a buffer."
 144   (let ((len (length string))
 145         (image (get-text-property 0 'display string)))
 146     (remove-text-properties 0 len yank-excluded-properties string)
 147     (if (consp image)
 148         (add-text-properties 0
 149                              (or (next-single-property-change 0 'image-counter string)
 150                                  (length string))
 151                              `(display
 152                                ,(cons (car image) (cdr image))
 153                                yank-handler
 154                                ,(cons 'image-file-yank-handler '(nil t)))
 155                              string))
 156     (insert string)))
 157
 158 (put 'image-file-handler 'safe-magic t)
 159 (defun image-file-handler (operation &rest args)
 160   "Filename handler for inserting image files.
 161 OPERATION is the operation to perform, on ARGS.
 162 See `file-name-handler-alist' for details."
 163   (if (and (eq operation 'insert-file-contents)
 164            auto-image-file-mode)
 165       (apply #'insert-image-file args)
 166     ;; We don't handle OPERATION, use another handler or the default
 167     (apply #'image-file-call-underlying operation operation args)))
 168
 169 (defun image-file-call-underlying (function operation &rest args)
 170   "Call FUNCTION with `image-file-handler' and OPERATION inhibited.
 171 Optional argument ARGS are the arguments to call FUNCTION with."
 172   (let ((inhibit-file-name-handlers
 173          (cons 'image-file-handler
 174                (and (eq inhibit-file-name-operation operation)
 175                     inhibit-file-name-handlers)))
 176         (inhibit-file-name-operation operation))
 177     (apply function args)))
 178
 179
 180 ;;;###autoload
 181 (define-minor-mode auto-image-file-mode
 182   "Toggle visiting of image files as images.
 183 With prefix argument ARG, turn on if positive, otherwise off.
 184 Returns non-nil if the new state is enabled.
 185
 186 Image files are those whose name has an extension in
 187 `image-file-name-extensions', or matches a regexp in
 188 `image-file-name-regexps'."
 189   :global t
 190   :group 'image
 191   ;; Remove existing handler
 192   (let ((existing-entry
 193          (rassq 'image-file-handler file-name-handler-alist)))
 194     (when existing-entry
 195       (setq file-name-handler-alist
 196             (delq existing-entry file-name-handler-alist))))
 197   ;; Add new handler, if enabled
 198   (when auto-image-file-mode
 199     (push (cons (image-file-name-regexp) 'image-file-handler)
 200           file-name-handler-alist)))
 201
 202
 203 (provide 'image-file)
 204
 205 ;; arch-tag: 04cafe36-f7ba-4c80-9f47-4cb656520ce1
 206 ;;; image-file.el ends here