1 ;;; gnus-html.el --- Render HTML in a buffer.
3 ;; Copyright (C) 2010-2011 Free Software Foundation, Inc.
5 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software: you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation, either version 3 of the License, or
13 ;; (at your option) any later version.
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
25 ;; The idea is to provide a simple, fast and pretty minimal way to
26 ;; render HTML (including links and images) in a buffer, based on an
27 ;; external HTML renderer (i.e., w3m).
31 (eval-when-compile (require 'cl
))
34 (eval-when-compile (require 'mm-decode
))
41 (eval-and-compile (unless (featurep 'xemacs
) (require 'help-fns
)))
43 (defcustom gnus-html-image-cache-ttl
(days-to-time 7)
44 "Time used to determine if we should use images from the cache."
49 (defcustom gnus-html-image-automatic-caching t
50 "Whether automatically cache retrieve images."
55 (defcustom gnus-html-frame-width
70
56 "What width to use when rendering HTML."
61 (defcustom gnus-max-image-proportion
0.9
62 "How big pictures displayed are in relation to the window they're in.
63 A value of 0.7 means that they are allowed to take up 70% of the
64 width and height of the window. If they are larger than this,
65 and Emacs supports it, then the images will be rescaled down to
71 (defvar gnus-html-image-map
72 (let ((map (make-sparse-keymap)))
73 (define-key map
"u" 'gnus-article-copy-string
)
74 (define-key map
"i" 'gnus-html-insert-image
)
75 (define-key map
"v" 'gnus-html-browse-url
)
78 (defvar gnus-html-displayed-image-map
79 (let ((map (make-sparse-keymap)))
80 (define-key map
"a" 'gnus-html-show-alt-text
)
81 (define-key map
"i" 'gnus-html-browse-image
)
82 (define-key map
"\r" 'gnus-html-browse-url
)
83 (define-key map
"u" 'gnus-article-copy-string
)
84 (define-key map
[tab] 'widget-forward)
88 (defalias 'gnus-html-encode-url-chars
89 (if (fboundp 'browse-url-url-encode-chars)
90 'browse-url-url-encode-chars
92 "URL-encode the chars in TEXT that match CHARS.
93 CHARS is a regexp-like character alternative (e.g., \"[)$]\")."
94 (let ((encoded-text (copy-sequence text))
96 (while (setq s (string-match chars encoded-text s))
98 (replace-match (format "%%%x"
100 (match-string 0 encoded-text)))
105 (defun gnus-html-encode-url (url)
107 (gnus-html-encode-url-chars url "[)$ ]"))
109 (defun gnus-html-cache-expired (url ttl)
110 "Check if URL is cached for more than TTL."
111 (cond (url-standalone-mode
112 (not (file-exists-p (url-cache-create-filename url))))
113 (t (let ((cache-time (url-is-cached url)))
123 (defun gnus-article-html (&optional handle)
124 (let ((article-buffer (current-buffer)))
126 (setq handle (mm-dissect-buffer t)))
128 (narrow-to-region (point) (point))
131 (let* ((coding-system-for-read 'utf-8)
132 (coding-system-for-write 'utf-8)
133 (default-process-coding-system
134 (cons coding-system-for-read coding-system-for-write))
135 (charset (mail-content-type-get (mm-handle-type handle)
138 (setq charset (mm-charset-to-coding-system charset))
139 (not (eq charset 'ascii)))
141 (mm-decode-coding-string (buffer-string) charset)
143 (mm-enable-multibyte))))
144 (call-process-region (point-min) (point-max)
146 nil article-buffer nil
151 "-o" "ext_halfdump=1"
152 "-o" "display_ins_del=2"
154 "-t" (format "%s" tab-width)
155 "-cols" (format "%s" gnus-html-frame-width)
156 "-o" "display_image=on"
158 (gnus-html-wash-tags))))
160 (defvar gnus-article-mouse-face)
162 (defun gnus-html-pre-wash ()
163 (goto-char (point-min))
164 (while (re-search-forward " *<pre_int> *</pre_int> *\n" nil t)
165 (replace-match "" t t))
166 (goto-char (point-min))
167 (while (re-search-forward "<a name[^\n>]+>" nil t)
168 (replace-match "" t t)))
170 (defun gnus-html-wash-images ()
171 "Run through current buffer and replace img tags by images."
172 (let (tag parameters string start end images url alt-text
173 inhibit-images blocked-images)
174 (if (buffer-live-p gnus-summary-buffer)
175 (with-current-buffer gnus-summary-buffer
176 (setq inhibit-images gnus-inhibit-images
177 blocked-images (gnus-blocked-images)))
178 (setq inhibit-images gnus-inhibit-images
179 blocked-images (gnus-blocked-images)))
180 (goto-char (point-min))
181 ;; Search for all the images first.
182 (while (re-search-forward "<img_alt \\([^>]*\\)>" nil t)
183 (setq parameters (match-string 1)
184 start (match-beginning 0))
185 (delete-region start (point))
186 (when (search-forward "</img_alt>" (line-end-position) t)
187 (delete-region (match-beginning 0) (match-end 0)))
189 (when (string-match "src=\"\\([^\"]+\\)" parameters)
190 (gnus-message 8 "gnus-html-wash-tags: fetching image URL %s" url)
191 (setq url (gnus-html-encode-url (match-string 1 parameters))
192 alt-text (when (string-match "\\(alt\\|title\\)=\"\\([^\"]+\\)"
194 (xml-substitute-special (match-string 2 parameters))))
195 (gnus-add-text-properties
198 'image-displayer `(lambda (url start end)
199 (gnus-html-display-image url start end
201 'gnus-image (list url start end alt-text)))
202 (widget-convert-button
203 'url-link start (point)
205 :keymap gnus-html-image-map
207 (if (string-match "\\`cid:" url)
208 ;; URLs with cid: have their content stashed in other
209 ;; parts of the MIME structure, so just insert them
211 (let* ((handle (mm-get-content-id (substring url (match-end 0))))
212 (image (when (and handle
213 (not inhibit-images))
215 (mm-with-part handle (buffer-string))
222 image (gnus-html-maximum-image-size))
223 (gnus-string-or (prog1
224 (buffer-substring start end)
225 (delete-region start end))
228 (widget-convert-button
230 :action 'gnus-html-insert-image
232 :keymap gnus-html-image-map
233 :button-keymap gnus-html-image-map)))
234 ;; Normal, external URL.
235 (if (or inhibit-images
236 (gnus-html-image-url-blocked-p url blocked-images))
237 (widget-convert-button
239 :action 'gnus-html-insert-image
241 :keymap gnus-html-image-map
242 :button-keymap gnus-html-image-map)
245 (when (string-match "width=\"?\\([0-9]+\\)" parameters)
246 (string-to-number (match-string 1 parameters))))
248 (when (string-match "height=\"?\\([0-9]+\\)" parameters)
249 (string-to-number (match-string 1 parameters)))))
250 ;; Don't fetch images that are really small. They're
251 ;; probably tracking pictures.
252 (when (and (or (null height)
256 (gnus-html-display-image url start end alt-text)))))))))
258 (defun gnus-html-display-image (url start end &optional alt-text)
259 "Display image at URL on text from START to END.
260 Use ALT-TEXT for the image string."
261 (or alt-text (setq alt-text "*"))
262 (if (string-match "\\`cid:" url)
263 (let ((handle (mm-get-content-id (substring url (match-end 0)))))
265 (gnus-html-put-image (mm-with-part handle (buffer-string))
267 (if (gnus-html-cache-expired url gnus-html-image-cache-ttl)
268 ;; We don't have it, so schedule it for fetching
270 (gnus-html-schedule-image-fetching
273 ;; It's already cached, so just insert it.
274 (gnus-html-put-image (gnus-html-get-image-data url) url alt-text))))
276 (defun gnus-html-wash-tags ()
277 (let (tag parameters string start end images url)
279 (gnus-html-wash-images)
281 (goto-char (point-min))
282 ;; Then do the other tags.
283 (while (re-search-forward "<\\([^ />]+\\)\\([^>]*\\)>" nil t)
284 (setq tag (match-string 1)
285 parameters (match-string 2)
286 start (match-beginning 0))
287 (when (> (length parameters) 0)
288 (set-text-properties 0 (1- (length parameters)) nil parameters))
289 (delete-region start (point))
290 (when (search-forward (concat "</" tag ">") nil t)
291 (delete-region (match-beginning 0) (match-end 0)))
294 ;; Fetch and insert a picture.
295 ((equal tag "img_alt"))
299 (when (string-match "href=\"\\([^\"]+\\)" parameters)
300 (setq url (match-string 1 parameters))
301 (gnus-message 8 "gnus-html-wash-tags: fetching link URL %s" url)
302 (gnus-article-add-button start end
303 'browse-url (mm-url-decode-entities-string url)
305 (let ((overlay (gnus-make-overlay start end)))
306 (gnus-overlay-put overlay 'evaporate t)
307 (gnus-overlay-put overlay 'gnus-button-url url)
308 (gnus-put-text-property start end 'gnus-string url)
309 (when gnus-article-mouse-face
310 (gnus-overlay-put overlay 'mouse-face gnus-article-mouse-face)))))
311 ;; The upper-case IMG_ALT is apparently just an artifact that
312 ;; should be deleted.
313 ((equal tag "IMG_ALT")
314 (delete-region start end))
315 ;; w3m does not normalize the case
318 (gnus-overlay-put (gnus-make-overlay start end) 'face 'gnus-emphasis-bold))
321 (gnus-overlay-put (gnus-make-overlay start end) 'face 'gnus-emphasis-underline))
324 (gnus-overlay-put (gnus-make-overlay start end) 'face 'gnus-emphasis-italic))
327 (gnus-overlay-put (gnus-make-overlay start end) 'face 'gnus-emphasis-strikethru))
328 ((or (equal tag "ins")
330 (gnus-overlay-put (gnus-make-overlay start end) 'face 'gnus-emphasis-underline))
331 ;; Handle different UL types
332 ((equal tag "_SYMBOL")
333 (when (string-match "TYPE=\\(.+\\)" parameters)
334 (let ((type (string-to-number (match-string 1 parameters))))
335 (delete-region start end)
336 (cond ((= type 33) (insert " "))
337 ((= type 34) (insert " "))
338 ((= type 35) (insert " "))
339 ((= type 36) (insert " "))
340 ((= type 37) (insert " "))
341 ((= type 38) (insert " "))
342 ((= type 39) (insert " "))
343 ((= type 40) (insert " "))
344 ((= type 42) (insert " "))
345 ((= type 43) (insert " "))
347 ;; Whatever. Just ignore the tag.
351 (goto-char (point-min))
352 ;; The output from -halfdump isn't totally regular, so strip
353 ;; off any </pre_int>s that were left over.
354 (while (re-search-forward "</pre_int>\\|</internal>" nil t)
355 (replace-match "" t t))
356 (mm-url-decode-entities)))
358 (defun gnus-html-insert-image (&rest args)
359 "Fetch and insert the image under point."
361 (apply 'gnus-html-display-image (get-text-property (point) 'gnus-image)))
363 (defun gnus-html-show-alt-text ()
364 "Show the ALT text of the image under point."
366 (message "%s" (get-text-property (point) 'gnus-alt-text)))
368 (defun gnus-html-browse-image ()
369 "Browse the image under point."
371 (browse-url (get-text-property (point) 'image-url)))
373 (defun gnus-html-browse-url ()
374 "Browse the image under point."
376 (let ((url (get-text-property (point) 'gnus-string)))
379 (message "No link under point"))
380 ((string-match "^mailto:" url)
381 (gnus-url-mailto url))
385 (defun gnus-html-schedule-image-fetching (buffer image)
386 "Retrieve IMAGE, and place it into BUFFER on arrival."
387 (gnus-message 8 "gnus-html-schedule-image-fetching: buffer %s, image %s"
389 (if (fboundp 'url-queue-retrieve)
390 (url-queue-retrieve (car image)
391 'gnus-html-image-fetched
392 (list buffer image) t)
394 (url-retrieve (car image)
395 'gnus-html-image-fetched
396 (list buffer image)))))
398 (defun gnus-html-image-fetched (status buffer image)
399 "Callback function called when image has been fetched."
400 (unless (plist-get status :error)
401 (when gnus-html-image-automatic-caching
402 (url-store-in-cache (current-buffer)))
403 (when (and (or (search-forward "\n\n" nil t)
404 (search-forward "\r\n\r\n" nil t))
405 (buffer-live-p buffer))
406 (let ((data (buffer-substring (point) (point-max))))
407 (with-current-buffer buffer
408 (let ((inhibit-read-only t))
409 (gnus-html-put-image data (car image) (cadr image)))))))
410 (kill-buffer (current-buffer)))
412 (defun gnus-html-get-image-data (url)
413 "Get image data for URL.
414 Return a string with image data."
416 (mm-disable-multibyte)
417 (url-cache-extract (url-cache-create-filename url))
418 (when (or (search-forward "\n\n" nil t)
419 (search-forward "\r\n\r\n" nil t))
420 (buffer-substring (point) (point-max)))))
422 (defun gnus-html-maximum-image-size ()
423 "Return the maximum size of an image according to `gnus-max-image-proportion'."
424 (let ((edges (gnus-window-inside-pixel-edges
425 (get-buffer-window (current-buffer)))))
430 (* gnus-max-image-proportion
431 (- (nth 2 edges) (nth 0 edges))))
433 (truncate (* gnus-max-image-proportion
434 (- (nth 3 edges) (nth 1 edges)))))))
436 (defun gnus-html-put-image (data url &optional alt-text)
437 "Put an image with DATA from URL and optional ALT-TEXT."
438 (when (gnus-graphic-display-p)
439 (let* ((start (text-property-any (point-min) (point-max)
442 (next-single-property-change start 'image-url))))
447 (gnus-create-image data nil t)))
449 (if (featurep 'xemacs)
450 (cons (glyph-width image) (glyph-height image))
451 (image-size image t)))))
454 (let ((alt-text (or alt-text
455 (buffer-substring-no-properties start end)))
456 (inhibit-read-only t))
458 ;; Kludge to avoid displaying 30x30 gif images, which
459 ;; seems to be a signal of a broken image.
460 (not (and (if (featurep 'xemacs)
463 (eq (if (featurep 'xemacs)
466 (glyph-image image)))))
469 (plist-get (cdr image) :type))
473 ;; Good image, add it!
474 (let ((image (gnus-rescale-image image (gnus-html-maximum-image-size))))
475 (delete-region start end)
476 (gnus-put-image image alt-text 'external)
477 (widget-convert-button
478 'url-link start (point)
480 :keymap gnus-html-displayed-image-map
482 (gnus-put-text-property start (point)
483 'gnus-alt-text alt-text)
485 (gnus-add-text-properties
490 (lambda (url start end)
491 (gnus-html-display-image url start end
493 (gnus-add-image 'external image)
495 ;; Bad image, try to show something else
496 (when (fboundp 'find-image)
497 (delete-region start end)
498 (setq image (find-image
499 '((:type xpm :file "lock-broken.xpm"))))
500 (gnus-put-image image alt-text 'internal)
501 (gnus-add-image 'internal image))
504 (defun gnus-html-image-url-blocked-p (url blocked-images)
505 "Find out if URL is blocked by BLOCKED-IMAGES."
506 (let ((ret (and blocked-images
507 (string-match blocked-images url))))
509 (gnus-message 8 "gnus-html-image-url-blocked-p: %s blocked by regex %s"
511 (gnus-message 9 "gnus-html-image-url-blocked-p: %s passes regex %s"
516 (defun gnus-html-prefetch-images (summary)
517 (when (buffer-live-p summary)
518 (let (inhibit-images blocked-images)
519 (with-current-buffer summary
520 (setq inhibit-images gnus-inhibit-images
521 blocked-images (gnus-blocked-images)))
523 (while (re-search-forward "<img[^>]+src=[\"']\\(http[^\"']+\\)" nil t)
524 (let ((url (gnus-html-encode-url
525 (mm-url-decode-entities-string (match-string 1)))))
526 (unless (or inhibit-images
527 (gnus-html-image-url-blocked-p url blocked-images))
528 (when (gnus-html-cache-expired url gnus-html-image-cache-ttl)
529 (gnus-html-schedule-image-fetching nil
534 ;;; gnus-html.el ends here