lisp/image-mode.el

   1 ;;; image-mode.el --- support for visiting image files  -*- lexical-binding: t -*-
   2 ;;
   3 ;; Copyright (C) 2005-2013 Free Software Foundation, Inc.
   4 ;;
   5 ;; Author: Richard Stallman <rms@gnu.org>
   6 ;; Keywords: multimedia
   7 ;; Package: emacs
   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 major mode for visiting image files
  27 ;; that allows conversion between viewing the text of the file
  28 ;; and viewing the file as an image.  Viewing the image
  29 ;; works by putting a `display' text-property on the
  30 ;; image data, with the image-data still present underneath; if the
  31 ;; resulting buffer file is saved to another name it will correctly save
  32 ;; the image data to the new file.
  33
  34 ;; Todo:
  35
  36 ;; Consolidate with doc-view to make them work on directories of images or on
  37 ;; image files containing various "pages".
  38
  39 ;;; Code:
  40
  41 (require 'image)
  42 (eval-when-compile (require 'cl-lib))
  43
  44 ;;; Image mode window-info management.
  45
  46 (defvar-local image-mode-winprops-alist t)
  47
  48 (defvar image-mode-new-window-functions nil
  49   "Special hook run when image data is requested in a new window.
  50 It is called with one argument, the initial WINPROPS.")
  51
  52 (defun image-mode-winprops (&optional window cleanup)
  53   "Return winprops of WINDOW.
  54 A winprops object has the shape (WINDOW . ALIST).
  55 WINDOW defaults to `selected-window' if it displays the current buffer, and
  56 otherwise it defaults to t, used for times when the buffer is not displayed."
  57   (cond ((null window)
  58          (setq window
  59                (if (eq (current-buffer) (window-buffer)) (selected-window) t)))
  60         ((eq window t))
  61         ((not (windowp window))
  62          (error "Not a window: %s" window)))
  63   (when cleanup
  64     (setq image-mode-winprops-alist
  65           (delq nil (mapcar (lambda (winprop)
  66                               (if (window-live-p (car-safe winprop))
  67                                   winprop))
  68                             image-mode-winprops-alist))))
  69   (let ((winprops (assq window image-mode-winprops-alist)))
  70     ;; For new windows, set defaults from the latest.
  71     (unless winprops
  72       (setq winprops (cons window
  73                            (copy-alist (cdar image-mode-winprops-alist))))
  74       (run-hook-with-args 'image-mode-new-window-functions winprops))
  75     ;; Move window to front.
  76     (setq image-mode-winprops-alist
  77           (cons winprops (delq winprops image-mode-winprops-alist)))
  78     winprops))
  79
  80 (defun image-mode-window-get (prop &optional winprops)
  81   (declare (gv-setter (lambda (val)
  82                         `(image-mode-window-put ,prop ,val ,winprops))))
  83   (unless (consp winprops) (setq winprops (image-mode-winprops winprops)))
  84   (cdr (assq prop (cdr winprops))))
  85
  86 (defun image-mode-window-put (prop val &optional winprops)
  87   (unless (consp winprops) (setq winprops (image-mode-winprops winprops)))
  88   (setcdr winprops (cons (cons prop val)
  89                          (delq (assq prop (cdr winprops)) (cdr winprops)))))
  90
  91 (defun image-set-window-vscroll (vscroll)
  92   (setf (image-mode-window-get 'vscroll) vscroll)
  93   (set-window-vscroll (selected-window) vscroll))
  94
  95 (defun image-set-window-hscroll (ncol)
  96   (setf (image-mode-window-get 'hscroll) ncol)
  97   (set-window-hscroll (selected-window) ncol))
  98
  99 (defun image-mode-reapply-winprops ()
 100   ;; When set-window-buffer, set hscroll and vscroll to what they were
 101   ;; last time the image was displayed in this window.
 102   (when (and (image-get-display-property)
 103              (listp image-mode-winprops-alist))
 104     (let* ((winprops (image-mode-winprops nil t))
 105            (hscroll (image-mode-window-get 'hscroll winprops))
 106            (vscroll (image-mode-window-get 'vscroll winprops)))
 107       (if hscroll (set-window-hscroll (selected-window) hscroll))
 108       (if vscroll (set-window-vscroll (selected-window) vscroll)))))
 109
 110 (defun image-mode-setup-winprops ()
 111   ;; Record current scroll settings.
 112   (unless (listp image-mode-winprops-alist)
 113     (setq image-mode-winprops-alist nil))
 114   (add-hook 'window-configuration-change-hook
 115             'image-mode-reapply-winprops nil t))
 116
 117 ;;; Image scrolling functions
 118
 119 (defun image-get-display-property ()
 120   (get-char-property (point-min) 'display
 121                      ;; There might be different images for different displays.
 122                      (if (eq (window-buffer) (current-buffer))
 123                          (selected-window))))
 124
 125 (declare-function image-size "image.c" (spec &optional pixels frame))
 126
 127 (defun image-display-size (spec &optional pixels frame)
 128   "Wrapper around `image-size', handling slice display properties.
 129 Like `image-size', the return value is (WIDTH . HEIGHT).
 130 WIDTH and HEIGHT are in canonical character units if PIXELS is
 131 nil, and in pixel units if PIXELS is non-nil.
 132
 133 If SPEC is an image display property, this function is equivalent
 134 to `image-size'.  If SPEC is a list of properties containing
 135 `image' and `slice' properties, return the display size taking
 136 the slice property into account.  If the list contains `image'
 137 but not `slice', return the `image-size' of the specified image."
 138   (if (eq (car spec) 'image)
 139       (image-size spec pixels frame)
 140     (let ((image (assoc 'image spec))
 141           (slice (assoc 'slice spec)))
 142       (cond ((and image slice)
 143              (if pixels
 144                  (cons (nth 3 slice) (nth 4 slice))
 145                (cons (/ (float (nth 3 slice)) (frame-char-width frame))
 146                      (/ (float (nth 4 slice)) (frame-char-height frame)))))
 147             (image
 148              (image-size image pixels frame))
 149             (t
 150              (error "Invalid image specification: %s" spec))))))
 151
 152 (defun image-forward-hscroll (&optional n)
 153   "Scroll image in current window to the left by N character widths.
 154 Stop if the right edge of the image is reached."
 155   (interactive "p")
 156   (cond ((= n 0) nil)
 157         ((< n 0)
 158          (image-set-window-hscroll (max 0 (+ (window-hscroll) n))))
 159         (t
 160          (let* ((image (image-get-display-property))
 161                 (edges (window-inside-edges))
 162                 (win-width (- (nth 2 edges) (nth 0 edges)))
 163                 (img-width (ceiling (car (image-display-size image)))))
 164            (image-set-window-hscroll (min (max 0 (- img-width win-width))
 165                                           (+ n (window-hscroll))))))))
 166
 167 (defun image-backward-hscroll (&optional n)
 168   "Scroll image in current window to the right by N character widths.
 169 Stop if the left edge of the image is reached."
 170   (interactive "p")
 171   (image-forward-hscroll (- n)))
 172
 173 (defun image-next-line (n)
 174   "Scroll image in current window upward by N lines.
 175 Stop if the bottom edge of the image is reached."
 176   (interactive "p")
 177   (cond ((= n 0) nil)
 178         ((< n 0)
 179          (image-set-window-vscroll (max 0 (+ (window-vscroll) n))))
 180         (t
 181          (let* ((image (image-get-display-property))
 182                 (edges (window-inside-edges))
 183                 (win-height (- (nth 3 edges) (nth 1 edges)))
 184                 (img-height (ceiling (cdr (image-display-size image)))))
 185            (image-set-window-vscroll (min (max 0 (- img-height win-height))
 186                                           (+ n (window-vscroll))))))))
 187
 188 (defun image-previous-line (&optional n)
 189   "Scroll image in current window downward by N lines.
 190 Stop if the top edge of the image is reached."
 191   (interactive "p")
 192   (image-next-line (- n)))
 193
 194 (defun image-scroll-up (&optional n)
 195   "Scroll image in current window upward by N lines.
 196 Stop if the bottom edge of the image is reached.
 197 If ARG is omitted or nil, scroll upward by a near full screen.
 198 A near full screen is `next-screen-context-lines' less than a full screen.
 199 Negative ARG means scroll downward.
 200 If ARG is the atom `-', scroll downward by nearly full screen.
 201 When calling from a program, supply as argument a number, nil, or `-'."
 202   (interactive "P")
 203   (cond ((null n)
 204          (let* ((edges (window-inside-edges))
 205                 (win-height (- (nth 3 edges) (nth 1 edges))))
 206            (image-next-line
 207             (max 0 (- win-height next-screen-context-lines)))))
 208         ((eq n '-)
 209          (let* ((edges (window-inside-edges))
 210                 (win-height (- (nth 3 edges) (nth 1 edges))))
 211            (image-next-line
 212             (min 0 (- next-screen-context-lines win-height)))))
 213         (t (image-next-line (prefix-numeric-value n)))))
 214
 215 (defun image-scroll-down (&optional n)
 216   "Scroll image in current window downward by N lines.
 217 Stop if the top edge of the image is reached.
 218 If ARG is omitted or nil, scroll downward by a near full screen.
 219 A near full screen is `next-screen-context-lines' less than a full screen.
 220 Negative ARG means scroll upward.
 221 If ARG is the atom `-', scroll upward by nearly full screen.
 222 When calling from a program, supply as argument a number, nil, or `-'."
 223   (interactive "P")
 224   (cond ((null n)
 225          (let* ((edges (window-inside-edges))
 226                 (win-height (- (nth 3 edges) (nth 1 edges))))
 227            (image-next-line
 228             (min 0 (- next-screen-context-lines win-height)))))
 229         ((eq n '-)
 230          (let* ((edges (window-inside-edges))
 231                 (win-height (- (nth 3 edges) (nth 1 edges))))
 232            (image-next-line
 233             (max 0 (- win-height next-screen-context-lines)))))
 234         (t (image-next-line (- (prefix-numeric-value n))))))
 235
 236 (defun image-bol (arg)
 237   "Scroll horizontally to the left edge of the image in the current window.
 238 With argument ARG not nil or 1, move forward ARG - 1 lines first,
 239 stopping if the top or bottom edge of the image is reached."
 240   (interactive "p")
 241   (and arg
 242        (/= (setq arg (prefix-numeric-value arg)) 1)
 243        (image-next-line (- arg 1)))
 244   (image-set-window-hscroll 0))
 245
 246 (defun image-eol (arg)
 247   "Scroll horizontally to the right edge of the image in the current window.
 248 With argument ARG not nil or 1, move forward ARG - 1 lines first,
 249 stopping if the top or bottom edge of the image is reached."
 250   (interactive "p")
 251   (and arg
 252        (/= (setq arg (prefix-numeric-value arg)) 1)
 253        (image-next-line (- arg 1)))
 254   (let* ((image (image-get-display-property))
 255          (edges (window-inside-edges))
 256          (win-width (- (nth 2 edges) (nth 0 edges)))
 257          (img-width (ceiling (car (image-display-size image)))))
 258     (image-set-window-hscroll (max 0 (- img-width win-width)))))
 259
 260 (defun image-bob ()
 261   "Scroll to the top-left corner of the image in the current window."
 262   (interactive)
 263   (image-set-window-hscroll 0)
 264   (image-set-window-vscroll 0))
 265
 266 (defun image-eob ()
 267   "Scroll to the bottom-right corner of the image in the current window."
 268   (interactive)
 269   (let* ((image (image-get-display-property))
 270          (edges (window-inside-edges))
 271          (win-width (- (nth 2 edges) (nth 0 edges)))
 272          (img-width (ceiling (car (image-display-size image))))
 273          (win-height (- (nth 3 edges) (nth 1 edges)))
 274          (img-height (ceiling (cdr (image-display-size image)))))
 275     (image-set-window-hscroll (max 0 (- img-width win-width)))
 276     (image-set-window-vscroll (max 0 (- img-height win-height)))))
 277
 278 ;; Adjust frame and image size.
 279
 280 (defun image-mode-fit-frame ()
 281   "Toggle whether to fit the frame to the current image.
 282 This function assumes the current frame has only one window."
 283   ;; FIXME: This does not take into account decorations like mode-line,
 284   ;; minibuffer, header-line, ...
 285   (interactive)
 286   (let* ((saved (frame-parameter nil 'image-mode-saved-size))
 287          (display (image-get-display-property))
 288          (size (image-display-size display)))
 289     (if (and saved
 290              (eq (caar saved) (frame-width))
 291              (eq (cdar saved) (frame-height)))
 292         (progn ;; Toggle back to previous non-fitted size.
 293           (set-frame-parameter nil 'image-mode-saved-size nil)
 294           (setq size (cdr saved)))
 295       ;; Round up size, and save current size so we can toggle back to it.
 296       (setcar size (ceiling (car size)))
 297       (setcdr size (ceiling (cdr size)))
 298       (set-frame-parameter nil 'image-mode-saved-size
 299                            (cons size (cons (frame-width) (frame-height)))))
 300     (set-frame-width  (selected-frame) (car size))
 301     (set-frame-height (selected-frame) (cdr size))))
 302
 303 ;;; Image Mode setup
 304
 305 (defvar image-type nil
 306   "The image type for the current Image mode buffer.")
 307 (make-variable-buffer-local 'image-type)
 308
 309 (defvar image-mode-previous-major-mode nil
 310   "Internal variable to keep the previous non-image major mode.")
 311
 312 (defvar image-mode-map
 313   (let ((map (make-sparse-keymap)))
 314     (set-keymap-parent map special-mode-map)
 315     (define-key map "\C-c\C-c" 'image-toggle-display)
 316     (define-key map (kbd "SPC")       'image-scroll-up)
 317     (define-key map (kbd "DEL")       'image-scroll-down)
 318     (define-key map (kbd "RET")       'image-toggle-animation)
 319     (define-key map [remap forward-char] 'image-forward-hscroll)
 320     (define-key map [remap backward-char] 'image-backward-hscroll)
 321     (define-key map [remap right-char] 'image-forward-hscroll)
 322     (define-key map [remap left-char] 'image-backward-hscroll)
 323     (define-key map [remap previous-line] 'image-previous-line)
 324     (define-key map [remap next-line] 'image-next-line)
 325     (define-key map [remap scroll-up] 'image-scroll-up)
 326     (define-key map [remap scroll-down] 'image-scroll-down)
 327     (define-key map [remap scroll-up-command] 'image-scroll-up)
 328     (define-key map [remap scroll-down-command] 'image-scroll-down)
 329     (define-key map [remap move-beginning-of-line] 'image-bol)
 330     (define-key map [remap move-end-of-line] 'image-eol)
 331     (define-key map [remap beginning-of-buffer] 'image-bob)
 332     (define-key map [remap end-of-buffer] 'image-eob)
 333     map)
 334   "Mode keymap for `image-mode'.")
 335
 336 (defvar image-minor-mode-map
 337   (let ((map (make-sparse-keymap)))
 338     (define-key map "\C-c\C-c" 'image-toggle-display)
 339     map)
 340   "Mode keymap for `image-minor-mode'.")
 341
 342 (defvar bookmark-make-record-function)
 343
 344 (put 'image-mode 'mode-class 'special)
 345
 346 ;;;###autoload
 347 (defun image-mode ()
 348   "Major mode for image files.
 349 You can use \\<image-mode-map>\\[image-toggle-display]
 350 to toggle between display as an image and display as text."
 351   (interactive)
 352   (condition-case err
 353       (progn
 354         (unless (display-images-p)
 355           (error "Display does not support images"))
 356
 357         (kill-all-local-variables)
 358         (setq major-mode 'image-mode)
 359
 360         (if (not (image-get-display-property))
 361             (progn
 362               (image-toggle-display-image)
 363               ;; If attempt to display the image fails.
 364               (if (not (image-get-display-property))
 365                   (error "Invalid image")))
 366           ;; Set next vars when image is already displayed but local
 367           ;; variables were cleared by kill-all-local-variables
 368           (setq cursor-type nil truncate-lines t
 369                 image-type (plist-get (cdr (image-get-display-property)) :type)))
 370
 371         (setq mode-name (if image-type (format "Image[%s]" image-type) "Image"))
 372         (use-local-map image-mode-map)
 373
 374         ;; Use our own bookmarking function for images.
 375         (set (make-local-variable 'bookmark-make-record-function)
 376              'image-bookmark-make-record)
 377
 378         ;; Keep track of [vh]scroll when switching buffers
 379         (image-mode-setup-winprops)
 380
 381         (add-hook 'change-major-mode-hook 'image-toggle-display-text nil t)
 382         (add-hook 'after-revert-hook 'image-after-revert-hook nil t)
 383         (run-mode-hooks 'image-mode-hook)
 384         (let ((image (image-get-display-property))
 385               (msg1 (substitute-command-keys
 386                      "Type \\[image-toggle-display] to view the image as ")))
 387           (cond
 388            ((null image)
 389             (message "%s" (concat msg1 "an image.")))
 390            ((image-animated-p image)
 391             (message "%s"
 392                      (concat msg1 "text, or "
 393                              (substitute-command-keys
 394                               "\\[image-toggle-animation] to animate."))))
 395            (t
 396             (message "%s" (concat msg1 "text."))))))
 397
 398     (error
 399      (image-mode-as-text)
 400      (funcall
 401       (if (called-interactively-p 'any) 'error 'message)
 402       "Cannot display image: %s" (cdr err)))))
 403
 404 ;;;###autoload
 405 (define-minor-mode image-minor-mode
 406   "Toggle Image minor mode in this buffer.
 407 With a prefix argument ARG, enable Image minor mode if ARG is
 408 positive, and disable it otherwise.  If called from Lisp, enable
 409 the mode if ARG is omitted or nil.
 410
 411 Image minor mode provides the key \\<image-mode-map>\\[image-toggle-display],
 412 to switch back to `image-mode' and display an image file as the
 413 actual image."
 414   nil (:eval (if image-type (format " Image[%s]" image-type) " Image"))
 415   image-minor-mode-map
 416   :group 'image
 417   :version "22.1"
 418   (if image-minor-mode
 419       (add-hook 'change-major-mode-hook (lambda () (image-minor-mode -1)) nil t)))
 420
 421 ;;;###autoload
 422 (defun image-mode-as-text ()
 423   "Set a non-image mode as major mode in combination with image minor mode.
 424 A non-image major mode found from `auto-mode-alist' or Fundamental mode
 425 displays an image file as text.  `image-minor-mode' provides the key
 426 \\<image-mode-map>\\[image-toggle-display] to switch back to `image-mode'
 427 to display an image file as the actual image.
 428
 429 You can use `image-mode-as-text' in `auto-mode-alist' when you want
 430 to display an image file as text initially.
 431
 432 See commands `image-mode' and `image-minor-mode' for more information
 433 on these modes."
 434   (interactive)
 435   ;; image-mode-as-text = normal-mode + image-minor-mode
 436   (let ((previous-image-type image-type)) ; preserve `image-type'
 437     (if image-mode-previous-major-mode
 438         ;; Restore previous major mode that was already found by this
 439         ;; function and cached in `image-mode-previous-major-mode'
 440         (funcall image-mode-previous-major-mode)
 441       (let ((auto-mode-alist
 442              (delq nil (mapcar
 443                         (lambda (elt)
 444                           (unless (memq (or (car-safe (cdr elt)) (cdr elt))
 445                                         '(image-mode image-mode-maybe image-mode-as-text))
 446                             elt))
 447                         auto-mode-alist)))
 448             (magic-fallback-mode-alist
 449              (delq nil (mapcar
 450                         (lambda (elt)
 451                           (unless (memq (or (car-safe (cdr elt)) (cdr elt))
 452                                         '(image-mode image-mode-maybe image-mode-as-text))
 453                             elt))
 454                         magic-fallback-mode-alist))))
 455         (normal-mode)
 456         (set (make-local-variable 'image-mode-previous-major-mode) major-mode)))
 457     ;; Restore `image-type' after `kill-all-local-variables' in `normal-mode'.
 458     (setq image-type previous-image-type)
 459     ;; Enable image minor mode with `C-c C-c'.
 460     (image-minor-mode 1)
 461     ;; Show the image file as text.
 462     (image-toggle-display-text)
 463     (message "%s" (concat
 464                    (substitute-command-keys
 465                     "Type \\[image-toggle-display] to view the image as ")
 466                    (if (image-get-display-property)
 467                        "text" "an image") "."))))
 468
 469 (define-obsolete-function-alias 'image-mode-maybe 'image-mode "23.2")
 470
 471 (defun image-toggle-display-text ()
 472   "Show the image file as text.
 473 Remove text properties that display the image."
 474   (let ((inhibit-read-only t)
 475         (buffer-undo-list t)
 476         (modified (buffer-modified-p)))
 477     (remove-list-of-text-properties (point-min) (point-max)
 478                                     '(display read-nonsticky ;; intangible
 479                                               read-only front-sticky))
 480     (set-buffer-modified-p modified)
 481     (if (called-interactively-p 'any)
 482         (message "Repeat this command to go back to displaying the image"))))
 483
 484 (defvar archive-superior-buffer)
 485 (defvar tar-superior-buffer)
 486 (declare-function image-flush "image.c" (spec &optional frame))
 487
 488 (defun image-toggle-display-image ()
 489   "Show the image of the image file.
 490 Turn the image data into a real image, but only if the whole file
 491 was inserted."
 492   (unless (derived-mode-p 'image-mode)
 493     (error "The buffer is not in Image mode"))
 494   (let* ((filename (buffer-file-name))
 495          (data-p (not (and filename
 496                            (file-readable-p filename)
 497                            (not (file-remote-p filename))
 498                            (not (buffer-modified-p))
 499                            (not (and (boundp 'archive-superior-buffer)
 500                                      archive-superior-buffer))
 501                            (not (and (boundp 'tar-superior-buffer)
 502                                      tar-superior-buffer)))))
 503          (file-or-data (if data-p
 504                            (string-make-unibyte
 505                             (buffer-substring-no-properties (point-min) (point-max)))
 506                          filename))
 507          (type (image-type file-or-data nil data-p))
 508          (image (create-image file-or-data type data-p))
 509          (inhibit-read-only t)
 510          (buffer-undo-list t)
 511          (modified (buffer-modified-p))
 512          props)
 513
 514     ;; Discard any stale image data before looking it up again.
 515     (image-flush image)
 516     (setq image (append image (image-transform-properties image)))
 517     (setq props
 518           `(display ,image
 519                     ;; intangible ,image
 520                     rear-nonsticky (display) ;; intangible
 521                     read-only t front-sticky (read-only)))
 522
 523     (let ((buffer-file-truename nil)) ; avoid changing dir mtime by lock_file
 524       (add-text-properties (point-min) (point-max) props)
 525       (restore-buffer-modified-p modified))
 526     ;; Inhibit the cursor when the buffer contains only an image,
 527     ;; because cursors look very strange on top of images.
 528     (setq cursor-type nil)
 529     ;; This just makes the arrow displayed in the right fringe
 530     ;; area look correct when the image is wider than the window.
 531     (setq truncate-lines t)
 532     ;; Disable adding a newline at the end of the image file when it
 533     ;; is written with, e.g., C-x C-w.
 534     (if (coding-system-equal (coding-system-base buffer-file-coding-system)
 535                              'no-conversion)
 536         (set (make-local-variable 'find-file-literally) t))
 537     ;; Allow navigation of large images
 538     (set (make-local-variable 'auto-hscroll-mode) nil)
 539     (setq image-type type)
 540     (if (eq major-mode 'image-mode)
 541         (setq mode-name (format "Image[%s]" type)))
 542     (image-transform-check-size)
 543     (if (called-interactively-p 'any)
 544         (message "Repeat this command to go back to displaying the file as text"))))
 545
 546 (defun image-toggle-display ()
 547   "Toggle between image and text display.
 548 If the current buffer is displaying an image file as an image,
 549 call `image-mode-as-text' to switch to text.  Otherwise, display
 550 the image by calling `image-mode'."
 551   (interactive)
 552   (if (image-get-display-property)
 553       (image-mode-as-text)
 554     (image-mode)))
 555
 556 (defun image-after-revert-hook ()
 557   (when (image-get-display-property)
 558     (image-toggle-display-text)
 559     ;; Update image display.
 560     (mapc (lambda (window) (redraw-frame (window-frame window)))
 561           (get-buffer-window-list (current-buffer) 'nomini 'visible))
 562     (image-toggle-display-image)))
 563
 564 \f
 565 ;;; Animated images
 566
 567 (defcustom image-animate-loop nil
 568   "Non-nil means animated images loop forever, rather than playing once."
 569   :type 'boolean
 570   :version "24.1"
 571   :group 'image)
 572
 573 (defun image-toggle-animation ()
 574   "Start or stop animating the current image.
 575 If `image-animate-loop' is non-nil, animation loops forever.
 576 Otherwise it plays once, then stops."
 577   (interactive)
 578   (let ((image (image-get-display-property))
 579         animation)
 580     (cond
 581      ((null image)
 582       (error "No image is present"))
 583      ((null (setq animation (image-animated-p image)))
 584       (message "No image animation."))
 585      (t
 586       (let ((timer (image-animate-timer image)))
 587         (if timer
 588             (cancel-timer timer)
 589           (let ((index (plist-get (cdr image) :index)))
 590             ;; If we're at the end, restart.
 591             (and index
 592                  (>= index (1- (car animation)))
 593                  (setq index nil))
 594             (image-animate image index
 595                            (if image-animate-loop t)))))))))
 596
 597 \f
 598 ;;; Support for bookmark.el
 599 (declare-function bookmark-make-record-default
 600                   "bookmark" (&optional no-file no-context posn))
 601 (declare-function bookmark-prop-get "bookmark" (bookmark prop))
 602 (declare-function bookmark-default-handler "bookmark" (bmk))
 603
 604 (defun image-bookmark-make-record ()
 605   `(,@(bookmark-make-record-default nil 'no-context 0)
 606       (image-type . ,image-type)
 607       (handler    . image-bookmark-jump)))
 608
 609 ;;;###autoload
 610 (defun image-bookmark-jump (bmk)
 611   ;; This implements the `handler' function interface for record type
 612   ;; returned by `bookmark-make-record-function', which see.
 613   (prog1 (bookmark-default-handler bmk)
 614     (when (not (string= image-type (bookmark-prop-get bmk 'image-type)))
 615       (image-toggle-display))))
 616 \f
 617
 618 ;; Not yet implemented.
 619 ;; (defvar image-transform-minor-mode-map
 620 ;;   (let ((map (make-sparse-keymap)))
 621 ;;     ;; (define-key map  [(control ?+)] 'image-scale-in)
 622 ;;     ;; (define-key map  [(control ?-)] 'image-scale-out)
 623 ;;     ;; (define-key map  [(control ?=)] 'image-scale-none)
 624 ;;     ;; (define-key map "c f h" 'image-scale-fit-height)
 625 ;;     ;; (define-key map "c ]" 'image-rotate-right)
 626 ;;     map)
 627 ;;   "Minor mode keymap `image-transform-mode'.")
 628 ;;
 629 ;; (define-minor-mode image-transform-mode
 630 ;;   "Minor mode for scaling and rotating images.
 631 ;; With a prefix argument ARG, enable the mode if ARG is positive,
 632 ;; and disable it otherwise.  If called from Lisp, enable the mode
 633 ;; if ARG is omitted or nil.  This minor mode requires Emacs to have
 634 ;; been compiled with ImageMagick support."
 635 ;;   nil "image-transform" image-transform-minor-mode-map)
 636
 637
 638 ;; FIXME this doesn't seem mature yet. Document in manual when it is.
 639 (defvar image-transform-resize nil
 640   "The image resize operation.
 641 Its value should be one of the following:
 642  - nil, meaning no resizing.
 643  - `fit-height', meaning to fit the image to the window height.
 644  - `fit-width', meaning to fit the image to the window width.
 645  - A number, which is a scale factor (the default size is 1).")
 646
 647 (defvar image-transform-scale 1.0
 648   "The scale factor of the image being displayed.")
 649
 650 (defvar image-transform-rotation 0.0
 651   "Rotation angle for the image in the current Image mode buffer.")
 652
 653 (defvar image-transform-right-angle-fudge 0.0001
 654   "Snap distance to a multiple of a right angle.
 655 There's no deep theory behind the default value, it should just
 656 be somewhat larger than ImageMagick's MagickEpsilon.")
 657
 658 (defsubst image-transform-width (width height)
 659   "Return the bounding box width of a rotated WIDTH x HEIGHT rectangle.
 660 The rotation angle is the value of `image-transform-rotation' in degrees."
 661   (let ((angle (degrees-to-radians image-transform-rotation)))
 662     ;; Assume, w.l.o.g., that the vertices of the rectangle have the
 663     ;; coordinates (+-w/2, +-h/2) and that (0, 0) is the center of the
 664     ;; rotation by the angle A.  The projections onto the first axis
 665     ;; of the vertices of the rotated rectangle are +- (w/2) cos A +-
 666     ;; (h/2) sin A, and the difference between the largest and the
 667     ;; smallest of the four values is the expression below.
 668     (+ (* width (abs (cos angle))) (* height (abs (sin angle))))))
 669
 670 ;; The following comment and code snippet are from
 671 ;; ImageMagick-6.7.4-4/magick/distort.c
 672
 673 ;;    /* Set the output image geometry to calculated 'best fit'.
 674 ;;       Yes this tends to 'over do' the file image size, ON PURPOSE!
 675 ;;       Do not do this for DePolar which needs to be exact for virtual tiling.
 676 ;;    */
 677 ;;    if ( fix_bounds ) {
 678 ;;      geometry.x = (ssize_t) floor(min.x-0.5);
 679 ;;      geometry.y = (ssize_t) floor(min.y-0.5);
 680 ;;      geometry.width=(size_t) ceil(max.x-geometry.x+0.5);
 681 ;;      geometry.height=(size_t) ceil(max.y-geometry.y+0.5);
 682 ;;    }
 683
 684 ;; Other parts of the same file show that here the origin is in the
 685 ;; left lower corner of the image rectangle, the center of the
 686 ;; rotation is the center of the rectangle and min.x and max.x
 687 ;; (resp. min.y and max.y) are the smallest and the largest of the
 688 ;; projections of the vertices onto the first (resp. second) axis.
 689
 690 (defun image-transform-fit-width (width height length)
 691   "Return (w . h) so that a rotated w x h image has exactly width LENGTH.
 692 The rotation angle is the value of `image-transform-rotation'.
 693 Write W for WIDTH and H for HEIGHT.  Then the w x h rectangle is
 694 an \"approximately uniformly\" scaled W x H rectangle, which
 695 currently means that w is one of floor(s W) + {0, 1, -1} and h is
 696 floor(s H), where s can be recovered as the value of `image-transform-scale'.
 697 The value of `image-transform-rotation' may be replaced by
 698 a slightly different angle.  Currently this is done for values
 699 close to a multiple of 90, see `image-transform-right-angle-fudge'."
 700   (cond ((< (abs (- (mod (+ image-transform-rotation 90) 180) 90))
 701             image-transform-right-angle-fudge)
 702          (cl-assert (not (zerop width)) t)
 703          (setq image-transform-rotation
 704                (float (round image-transform-rotation))
 705                image-transform-scale (/ (float length) width))
 706          (cons length nil))
 707         ((< (abs (- (mod (+ image-transform-rotation 45) 90) 45))
 708             image-transform-right-angle-fudge)
 709          (cl-assert (not (zerop height)) t)
 710          (setq image-transform-rotation
 711                (float (round image-transform-rotation))
 712                image-transform-scale (/ (float length) height))
 713          (cons nil length))
 714         (t
 715          (cl-assert (not (and (zerop width) (zerop height))) t)
 716          (setq image-transform-scale
 717                (/ (float (1- length)) (image-transform-width width height)))
 718          ;; Assume we have a w x h image and an angle A, and let l =
 719          ;; l(w, h) = w |cos A| + h |sin A|, which is the actual width
 720          ;; of the bounding box of the rotated image, as calculated by
 721          ;; `image-transform-width'.  The code snippet quoted above
 722          ;; means that ImageMagick puts the rotated image in
 723          ;; a bounding box of width L = 2 ceil((w+l+1)/2) - w.
 724          ;; Elementary considerations show that this is equivalent to
 725          ;; L - w being even and L-3 < l(w, h) <= L-1.  In our case, L is
 726          ;; the given `length' parameter and our job is to determine
 727          ;; reasonable values for w and h which satisfy these
 728          ;; conditions.
 729          (let ((w (floor (* image-transform-scale width)))
 730                (h (floor (* image-transform-scale height))))
 731            ;; Let w and h as bound above.  Then l(w, h) <= l(s W, s H)
 732            ;; = L-1 < l(w+1, h+1) = l(w, h) + l(1, 1) <= l(w, h) + 2,
 733            ;; hence l(w, h) > (L-1) - 2 = L-3.
 734            (cons
 735             (cond ((= (mod w 2) (mod length 2))
 736                    w)
 737                   ;; l(w+1, h) >= l(w, h) > L-3, but does l(w+1, h) <=
 738                   ;; L-1 hold?
 739                   ((<= (image-transform-width (1+ w) h) (1- length))
 740                    (1+ w))
 741                   ;; No, it doesn't, but this implies that l(w-1, h) =
 742                   ;; l(w+1, h) - l(2, 0) >= l(w+1, h) - 2 > (L-1) -
 743                   ;; 2 = L-3.  Clearly, l(w-1, h) <= l(w, h) <= L-1.
 744                   (t
 745                    (1- w)))
 746             h)))))
 747
 748 (defun image-transform-check-size ()
 749   "Check that the image exactly fits the width/height of the window.
 750
 751 Do this for an image of type `imagemagick' to make sure that the
 752 elisp code matches the way ImageMagick computes the bounding box
 753 of a rotated image."
 754   (when (and (not (numberp image-transform-resize))
 755              (boundp 'image-type)
 756              (eq image-type 'imagemagick))
 757     (let ((size (image-display-size (image-get-display-property) t)))
 758       (cond ((eq image-transform-resize 'fit-width)
 759              (cl-assert (= (car size)
 760                         (- (nth 2 (window-inside-pixel-edges))
 761                            (nth 0 (window-inside-pixel-edges))))
 762                      t))
 763             ((eq image-transform-resize 'fit-height)
 764              (cl-assert (= (cdr size)
 765                         (- (nth 3 (window-inside-pixel-edges))
 766                            (nth 1 (window-inside-pixel-edges))))
 767                      t))))))
 768
 769 (defun image-transform-properties (spec)
 770   "Return rescaling/rotation properties for image SPEC.
 771 These properties are determined by the Image mode variables
 772 `image-transform-resize' and `image-transform-rotation'.  The
 773 return value is suitable for appending to an image spec.
 774
 775 Rescaling and rotation properties only take effect if Emacs is
 776 compiled with ImageMagick support."
 777   (setq image-transform-scale 1.0)
 778   (when (or image-transform-resize
 779             (/= image-transform-rotation 0.0))
 780     ;; Note: `image-size' looks up and thus caches the untransformed
 781     ;; image.  There's no easy way to prevent that.
 782     (let* ((size (image-size spec t))
 783            (resized
 784             (cond
 785              ((numberp image-transform-resize)
 786               (unless (= image-transform-resize 1)
 787                 (setq image-transform-scale image-transform-resize)
 788                 (cons nil (floor (* image-transform-resize (cdr size))))))
 789              ((eq image-transform-resize 'fit-width)
 790               (image-transform-fit-width
 791                (car size) (cdr size)
 792                (- (nth 2 (window-inside-pixel-edges))
 793                   (nth 0 (window-inside-pixel-edges)))))
 794              ((eq image-transform-resize 'fit-height)
 795               (let ((res (image-transform-fit-width
 796                           (cdr size) (car size)
 797                           (- (nth 3 (window-inside-pixel-edges))
 798                              (nth 1 (window-inside-pixel-edges))))))
 799                 (cons (cdr res) (car res)))))))
 800       `(,@(when (car resized)
 801             (list :width (car resized)))
 802         ,@(when (cdr resized)
 803             (list :height (cdr resized)))
 804         ,@(unless (= 0.0 image-transform-rotation)
 805             (list :rotation image-transform-rotation))))))
 806
 807 (defun image-transform-set-scale (scale)
 808   "Prompt for a number, and resize the current image by that amount.
 809 This command has no effect unless Emacs is compiled with
 810 ImageMagick support."
 811   (interactive "nScale: ")
 812   (setq image-transform-resize scale)
 813   (image-toggle-display-image))
 814
 815 (defun image-transform-fit-to-height ()
 816   "Fit the current image to the height of the current window.
 817 This command has no effect unless Emacs is compiled with
 818 ImageMagick support."
 819   (interactive)
 820   (setq image-transform-resize 'fit-height)
 821   (image-toggle-display-image))
 822
 823 (defun image-transform-fit-to-width ()
 824   "Fit the current image to the width of the current window.
 825 This command has no effect unless Emacs is compiled with
 826 ImageMagick support."
 827   (interactive)
 828   (setq image-transform-resize 'fit-width)
 829   (image-toggle-display-image))
 830
 831 (defun image-transform-set-rotation (rotation)
 832   "Prompt for an angle ROTATION, and rotate the image by that amount.
 833 ROTATION should be in degrees.  This command has no effect unless
 834 Emacs is compiled with ImageMagick support."
 835   (interactive "nRotation angle (in degrees): ")
 836   (setq image-transform-rotation (float (mod rotation 360)))
 837   (image-toggle-display-image))
 838
 839 (provide 'image-mode)
 840
 841 ;;; image-mode.el ends here