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emacs/lisp/gnus/gnus-html.el

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;;; gnus-html.el --- Render HTML in a buffer.
;; Copyright (C) 2010-2011 Free Software Foundation, Inc.
;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; Keywords: html, web
;; 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 3 of the License, 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. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;; The idea is to provide a simple, fast and pretty minimal way to
;; render HTML (including links and images) in a buffer, based on an
;; external HTML renderer (i.e., w3m).
;;; Code:
(eval-when-compile (require 'cl))
(require 'gnus-art)
(eval-when-compile (require 'mm-decode))
(require 'mm-url)
(require 'url)
(require 'url-cache)
(require 'xml)
(require 'browse-url)
(eval-and-compile (unless (featurep 'xemacs) (require 'help-fns)))
(defcustom gnus-html-image-cache-ttl (days-to-time 7)
"Time used to determine if we should use images from the cache."
:version "24.1"
:group 'gnus-art
:type 'integer)
(defcustom gnus-html-image-automatic-caching t
"Whether automatically cache retrieve images."
:version "24.1"
:group 'gnus-art
:type 'boolean)
(defcustom gnus-html-frame-width 70
"What width to use when rendering HTML."
:version "24.1"
:group 'gnus-art
:type 'integer)
(defcustom gnus-max-image-proportion 0.9
"How big pictures displayed are in relation to the window they're in.
A value of 0.7 means that they are allowed to take up 70% of the
width and height of the window. If they are larger than this,
and Emacs supports it, then the images will be rescaled down to
fit these criteria."
:version "24.1"
:group 'gnus-art
:type 'float)
(defvar gnus-html-image-map
(let ((map (make-sparse-keymap)))
(define-key map "u" 'gnus-article-copy-string)
(define-key map "i" 'gnus-html-insert-image)
(define-key map "v" 'gnus-html-browse-url)
map))
(defvar gnus-html-displayed-image-map
(let ((map (make-sparse-keymap)))
(define-key map "a" 'gnus-html-show-alt-text)
(define-key map "i" 'gnus-html-browse-image)
(define-key map "\r" 'gnus-html-browse-url)
(define-key map "u" 'gnus-article-copy-string)
(define-key map [tab] 'widget-forward)
map))
(eval-and-compile
(defalias 'gnus-html-encode-url-chars
(if (fboundp 'browse-url-url-encode-chars)
'browse-url-url-encode-chars
(lambda (text chars)
"URL-encode the chars in TEXT that match CHARS.
CHARS is a regexp-like character alternative (e.g., \"[)$]\")."
(let ((encoded-text (copy-sequence text))
(s 0))
(while (setq s (string-match chars encoded-text s))
(setq encoded-text
(replace-match (format "%%%x"
(string-to-char
(match-string 0 encoded-text)))
t t encoded-text)
s (1+ s)))
encoded-text)))))
(defun gnus-html-encode-url (url)
"Encode URL."
(gnus-html-encode-url-chars url "[)$ ]"))
(defun gnus-html-cache-expired (url ttl)
"Check if URL is cached for more than TTL."
(cond (url-standalone-mode
(not (file-exists-p (url-cache-create-filename url))))
(t (let ((cache-time (url-is-cached url)))
(if cache-time
(time-less-p
(time-add
cache-time
ttl)
(current-time))
t)))))
;;;###autoload
(defun gnus-article-html (&optional handle)
(let ((article-buffer (current-buffer)))
(unless handle
(setq handle (mm-dissect-buffer t)))
(save-restriction
(narrow-to-region (point) (point))
(save-excursion
(mm-with-part handle
(let* ((coding-system-for-read 'utf-8)
(coding-system-for-write 'utf-8)
(default-process-coding-system
(cons coding-system-for-read coding-system-for-write))
(charset (mail-content-type-get (mm-handle-type handle)
'charset)))
(when (and charset
(setq charset (mm-charset-to-coding-system charset))
(not (eq charset 'ascii)))
(insert (prog1
(mm-decode-coding-string (buffer-string) charset)
(erase-buffer)
(mm-enable-multibyte))))
(call-process-region (point-min) (point-max)
"w3m"
nil article-buffer nil
"-halfdump"
"-no-cookie"
"-I" "UTF-8"
"-O" "UTF-8"
"-o" "ext_halfdump=1"
"-o" "display_ins_del=2"
"-o" "pre_conv=1"
"-t" (format "%s" tab-width)
"-cols" (format "%s" gnus-html-frame-width)
"-o" "display_image=on"
"-T" "text/html"))))
(gnus-html-wash-tags))))
(defvar gnus-article-mouse-face)
(defun gnus-html-pre-wash ()
(goto-char (point-min))
(while (re-search-forward " *<pre_int> *</pre_int> *\n" nil t)
(replace-match "" t t))
(goto-char (point-min))
(while (re-search-forward "<a name[^\n>]+>" nil t)
(replace-match "" t t)))
(defun gnus-html-wash-images ()
"Run through current buffer and replace img tags by images."
(let (tag parameters string start end images url alt-text
inhibit-images blocked-images)
(if (buffer-live-p gnus-summary-buffer)
(with-current-buffer gnus-summary-buffer
(setq inhibit-images gnus-inhibit-images
blocked-images (gnus-blocked-images)))
(setq inhibit-images gnus-inhibit-images
blocked-images (gnus-blocked-images)))
(goto-char (point-min))
;; Search for all the images first.
(while (re-search-forward "<img_alt \\([^>]*\\)>" nil t)
(setq parameters (match-string 1)
start (match-beginning 0))
(delete-region start (point))
(when (search-forward "</img_alt>" (line-end-position) t)
(delete-region (match-beginning 0) (match-end 0)))
(setq end (point))
(when (string-match "src=\"\\([^\"]+\\)" parameters)
(gnus-message 8 "gnus-html-wash-tags: fetching image URL %s" url)
(setq url (gnus-html-encode-url (match-string 1 parameters))
alt-text (when (string-match "\\(alt\\|title\\)=\"\\([^\"]+\\)"
parameters)
(xml-substitute-special (match-string 2 parameters))))
(gnus-add-text-properties
start end
(list 'image-url url
'image-displayer `(lambda (url start end)
(gnus-html-display-image url start end
,alt-text))
'gnus-image (list url start end alt-text)))
(widget-convert-button
'url-link start (point)
:help-echo alt-text
:keymap gnus-html-image-map
url)
(if (string-match "\\`cid:" url)
;; URLs with cid: have their content stashed in other
;; parts of the MIME structure, so just insert them
;; immediately.
(let* ((handle (mm-get-content-id (substring url (match-end 0))))
(image (when (and handle
(not inhibit-images))
(gnus-create-image
(mm-with-part handle (buffer-string))
nil t))))
(if image
(progn
(gnus-put-image
(gnus-rescale-image
image (gnus-html-maximum-image-size))
(gnus-string-or (prog1
(buffer-substring start end)
(delete-region start end))
"*")
'cid)
(gnus-add-image 'cid image))
(widget-convert-button
'link start end
:action 'gnus-html-insert-image
:help-echo url
:keymap gnus-html-image-map
:button-keymap gnus-html-image-map)))
;; Normal, external URL.
(if (or inhibit-images
(gnus-html-image-url-blocked-p url blocked-images))
(widget-convert-button
'link start end
:action 'gnus-html-insert-image
:help-echo url
:keymap gnus-html-image-map
:button-keymap gnus-html-image-map)
;; Non-blocked url
(let ((width
(when (string-match "width=\"?\\([0-9]+\\)" parameters)
(string-to-number (match-string 1 parameters))))
(height
(when (string-match "height=\"?\\([0-9]+\\)" parameters)
(string-to-number (match-string 1 parameters)))))
;; Don't fetch images that are really small. They're
;; probably tracking pictures.
(when (and (or (null height)
(> height 4))
(or (null width)
(> width 4)))
(gnus-html-display-image url start end alt-text)))))))))
(defun gnus-html-display-image (url start end &optional alt-text)
"Display image at URL on text from START to END.
Use ALT-TEXT for the image string."
(or alt-text (setq alt-text "*"))
(if (string-match "\\`cid:" url)
(let ((handle (mm-get-content-id (substring url (match-end 0)))))
(when handle
(gnus-html-put-image (mm-with-part handle (buffer-string))
url alt-text)))
(if (gnus-html-cache-expired url gnus-html-image-cache-ttl)
;; We don't have it, so schedule it for fetching
;; asynchronously.
(gnus-html-schedule-image-fetching
(current-buffer)
(list url alt-text))
;; It's already cached, so just insert it.
(gnus-html-put-image (gnus-html-get-image-data url) url alt-text))))
(defun gnus-html-wash-tags ()
(let (tag parameters string start end images url)
(gnus-html-pre-wash)
(gnus-html-wash-images)
(goto-char (point-min))
;; Then do the other tags.
(while (re-search-forward "<\\([^ />]+\\)\\([^>]*\\)>" nil t)
(setq tag (match-string 1)
parameters (match-string 2)
start (match-beginning 0))
(when (> (length parameters) 0)
(set-text-properties 0 (1- (length parameters)) nil parameters))
(delete-region start (point))
(when (search-forward (concat "</" tag ">") nil t)
(delete-region (match-beginning 0) (match-end 0)))
(setq end (point))
(cond
;; Fetch and insert a picture.
((equal tag "img_alt"))
;; Add a link.
((or (equal tag "a")
(equal tag "A"))
(when (string-match "href=\"\\([^\"]+\\)" parameters)
(setq url (match-string 1 parameters))
(gnus-message 8 "gnus-html-wash-tags: fetching link URL %s" url)
(gnus-article-add-button start end
'browse-url (mm-url-decode-entities-string url)
url)
(let ((overlay (gnus-make-overlay start end)))
(gnus-overlay-put overlay 'evaporate t)
(gnus-overlay-put overlay 'gnus-button-url url)
(gnus-put-text-property start end 'gnus-string url)
(when gnus-article-mouse-face
(gnus-overlay-put overlay 'mouse-face gnus-article-mouse-face)))))
;; The upper-case IMG_ALT is apparently just an artifact that
;; should be deleted.
((equal tag "IMG_ALT")
(delete-region start end))
;; w3m does not normalize the case
((or (equal tag "b")
(equal tag "B"))
(gnus-overlay-put (gnus-make-overlay start end) 'face 'gnus-emphasis-bold))
((or (equal tag "u")
(equal tag "U"))
(gnus-overlay-put (gnus-make-overlay start end) 'face 'gnus-emphasis-underline))
((or (equal tag "i")
(equal tag "I"))
(gnus-overlay-put (gnus-make-overlay start end) 'face 'gnus-emphasis-italic))
((or (equal tag "s")
(equal tag "S"))
(gnus-overlay-put (gnus-make-overlay start end) 'face 'gnus-emphasis-strikethru))
((or (equal tag "ins")
(equal tag "INS"))
(gnus-overlay-put (gnus-make-overlay start end) 'face 'gnus-emphasis-underline))
;; Handle different UL types
((equal tag "_SYMBOL")
(when (string-match "TYPE=\\(.+\\)" parameters)
(let ((type (string-to-number (match-string 1 parameters))))
(delete-region start end)
(cond ((= type 33) (insert " "))
((= type 34) (insert " "))
((= type 35) (insert " "))
((= type 36) (insert " "))
((= type 37) (insert " "))
((= type 38) (insert " "))
((= type 39) (insert " "))
((= type 40) (insert " "))
((= type 42) (insert " "))
((= type 43) (insert " "))
(t (insert " "))))))
;; Whatever. Just ignore the tag.
(t
))
(goto-char start))
(goto-char (point-min))
;; The output from -halfdump isn't totally regular, so strip
;; off any </pre_int>s that were left over.
(while (re-search-forward "</pre_int>\\|</internal>" nil t)
(replace-match "" t t))
(mm-url-decode-entities)))
(defun gnus-html-insert-image (&rest args)
"Fetch and insert the image under point."
(interactive)
(apply 'gnus-html-display-image (get-text-property (point) 'gnus-image)))
(defun gnus-html-show-alt-text ()
"Show the ALT text of the image under point."
(interactive)
(message "%s" (get-text-property (point) 'gnus-alt-text)))
(defun gnus-html-browse-image ()
"Browse the image under point."
(interactive)
(browse-url (get-text-property (point) 'image-url)))
(defun gnus-html-browse-url ()
"Browse the image under point."
(interactive)
(let ((url (get-text-property (point) 'gnus-string)))
(cond
((not url)
(message "No link under point"))
((string-match "^mailto:" url)
(gnus-url-mailto url))
(t
(browse-url url)))))
(defun gnus-html-schedule-image-fetching (buffer image)
"Retrieve IMAGE, and place it into BUFFER on arrival."
(gnus-message 8 "gnus-html-schedule-image-fetching: buffer %s, image %s"
buffer image)
(let ((args (list (car image)
'gnus-html-image-fetched
(list buffer image))))
(when (> (length (if (featurep 'xemacs)
(cdr (split-string (function-arglist 'url-retrieve)))
(help-function-arglist 'url-retrieve)))
4)
(setq args (nconc args (list t))))
(ignore-errors
(push (apply #'url-retrieve args) gnus-buffers))))
(defun gnus-html-image-fetched (status buffer image)
"Callback function called when image has been fetched."
(unless (plist-get status :error)
(when gnus-html-image-automatic-caching
(url-store-in-cache (current-buffer)))
(when (and (or (search-forward "\n\n" nil t)
(search-forward "\r\n\r\n" nil t))
(buffer-live-p buffer))
(let ((data (buffer-substring (point) (point-max))))
(with-current-buffer buffer
(let ((inhibit-read-only t))
(gnus-html-put-image data (car image) (cadr image)))))))
(kill-buffer (current-buffer)))
(defun gnus-html-get-image-data (url)
"Get image data for URL.
Return a string with image data."
(with-temp-buffer
(mm-disable-multibyte)
(url-cache-extract (url-cache-create-filename url))
(when (or (search-forward "\n\n" nil t)
(search-forward "\r\n\r\n" nil t))
(buffer-substring (point) (point-max)))))
(defun gnus-html-maximum-image-size ()
"Return the maximum size of an image according to `gnus-max-image-proportion'."
(let ((edges (gnus-window-inside-pixel-edges
(get-buffer-window (current-buffer)))))
;; (width . height)
(cons
;; Aimed width
(truncate
(* gnus-max-image-proportion
(- (nth 2 edges) (nth 0 edges))))
;; Aimed height
(truncate (* gnus-max-image-proportion
(- (nth 3 edges) (nth 1 edges)))))))
(defun gnus-html-put-image (data url &optional alt-text)
"Put an image with DATA from URL and optional ALT-TEXT."
(when (gnus-graphic-display-p)
(let* ((start (text-property-any (point-min) (point-max)
'image-url url))
(end (when start
(next-single-property-change start 'image-url))))
;; Image found?
(when start
(let* ((image
(ignore-errors
(gnus-create-image data nil t)))
(size (and image
(if (featurep 'xemacs)
(cons (glyph-width image) (glyph-height image))
(image-size image t)))))
(save-excursion
(goto-char start)
(let ((alt-text (or alt-text
(buffer-substring-no-properties start end)))
(inhibit-read-only t))
(if (and image
;; Kludge to avoid displaying 30x30 gif images, which
;; seems to be a signal of a broken image.
(not (and (if (featurep 'xemacs)
(glyphp image)
(listp image))
(eq (if (featurep 'xemacs)
(let ((d (cdadar
(specifier-spec-list
(glyph-image image)))))
(and (vectorp d)
(aref d 0)))
(plist-get (cdr image) :type))
'gif)
(= (car size) 30)
(= (cdr size) 30))))
;; Good image, add it!
(let ((image (gnus-rescale-image image (gnus-html-maximum-image-size))))
(delete-region start end)
(gnus-put-image image alt-text 'external)
(widget-convert-button
'url-link start (point)
:help-echo alt-text
:keymap gnus-html-displayed-image-map
url)
(gnus-put-text-property start (point)
'gnus-alt-text alt-text)
(when url
(gnus-put-text-property start (point)
'image-url url))
(gnus-add-image 'external image)
t)
;; Bad image, try to show something else
(when (fboundp 'find-image)
(delete-region start end)
(setq image (find-image
'((:type xpm :file "lock-broken.xpm"))))
(gnus-put-image image alt-text 'internal)
(gnus-add-image 'internal image))
nil))))))))
(defun gnus-html-image-url-blocked-p (url blocked-images)
"Find out if URL is blocked by BLOCKED-IMAGES."
(let ((ret (and blocked-images
(string-match blocked-images url))))
(if ret
(gnus-message 8 "gnus-html-image-url-blocked-p: %s blocked by regex %s"
url blocked-images)
(gnus-message 9 "gnus-html-image-url-blocked-p: %s passes regex %s"
url blocked-images))
ret))
;;;###autoload
(defun gnus-html-prefetch-images (summary)
(when (buffer-live-p summary)
(let (inhibit-images blocked-images)
(with-current-buffer summary
(setq inhibit-images gnus-inhibit-images
blocked-images (gnus-blocked-images)))
(save-match-data
(while (re-search-forward "<img[^>]+src=[\"']\\(http[^\"']+\\)" nil t)
(let ((url (gnus-html-encode-url
(mm-url-decode-entities-string (match-string 1)))))
(unless (or inhibit-images
(gnus-html-image-url-blocked-p url blocked-images))
(when (gnus-html-cache-expired url gnus-html-image-cache-ttl)
(gnus-html-schedule-image-fetching nil
(list url))))))))))
(provide 'gnus-html)
;;; gnus-html.el ends here
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