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+;;; gnus-html.el --- Render HTML in a buffer.
+
+;; Copyright (C) 2010 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))
+(eval-when-compile (require 'mm-decode))
+(require 'mm-url)
+
+(defcustom gnus-html-cache-directory (nnheader-concat gnus-directory "html-cache/")
+ "Where Gnus will cache images it downloads from the web."
+ :version "24.1"
+ :group 'gnus-art
+ :type 'directory)
+
+(defcustom gnus-html-cache-size 500000000
+ "The size of the Gnus image cache."
+ :version "24.1"
+ :group 'gnus-art
+ :type 'integer)
+
+(defcustom gnus-html-frame-width 70
+ "What width to use when rendering HTML."
+ :version "24.1"
+ :group 'gnus-art
+ :type 'integer)
+
+(defcustom gnus-blocked-images "."
+ "Images that have URLs matching this regexp will be blocked."
+ :version "24.1"
+ :group 'gnus-art
+ :type 'regexp)
+
+(defcustom gnus-max-image-proportion 0.7
+ "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)
+ 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))
+
+;;;###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" "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 ()
+ (let (tag parameters string start end images url)
+ (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)
+ (setq url (match-string 1 parameters))
+ (gnus-message 8 "gnus-html-wash-tags: fetching image URL %s" 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
+ (setq url (match-string 1 url))))
+ image)
+ (when handle
+ (mm-with-part handle
+ (setq image (gnus-create-image (buffer-string)
+ nil t))))
+ (when image
+ (let ((string (buffer-substring start end)))
+ (delete-region start end)
+ (gnus-put-image image (gnus-string-or string "*") 'cid)
+ (gnus-add-image 'cid image))))
+ ;; Normal, external URL.
+ (if (gnus-html-image-url-blocked-p
+ url
+ (if (buffer-live-p gnus-summary-buffer)
+ (with-current-buffer gnus-summary-buffer
+ gnus-blocked-images)
+ gnus-blocked-images))
+ (progn
+ (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)
+ (let ((overlay (gnus-make-overlay start end))
+ (spec (list url
+ (set-marker (make-marker) start)
+ (set-marker (make-marker) end))))
+ (gnus-overlay-put overlay 'local-map gnus-html-image-map)
+ (gnus-overlay-put overlay 'gnus-image spec)
+ (gnus-put-text-property
+ start end
+ 'gnus-image spec)))
+ (let ((file (gnus-html-image-id url))
+ width height alt-text)
+ (when (string-match "height=\"?\\([0-9]+\\)" parameters)
+ (setq height (string-to-number (match-string 1 parameters))))
+ (when (string-match "width=\"?\\([0-9]+\\)" parameters)
+ (setq width (string-to-number (match-string 1 parameters))))
+ (when (string-match "\\(alt\\|title\\)=\"\\([^\"]+\\)"
+ parameters)
+ (setq alt-text (match-string 2 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)))
+ (if (file-exists-p file)
+ ;; It's already cached, so just insert it.
+ (let ((string (buffer-substring start end)))
+ ;; Delete the IMG text.
+ (delete-region start end)
+ (gnus-html-put-image file (point) string url alt-text))
+ ;; We don't have it, so schedule it for fetching
+ ;; asynchronously.
+ (push (list url
+ (set-marker (make-marker) start)
+ (point-marker))
+ images))))))))
+ (when images
+ (gnus-html-schedule-image-fetching (current-buffer) (nreverse images)))))
+
+(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 (plusp (length parameters))
+ (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 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))
+ ;; 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 ()
+ "Fetch and insert the image under point."
+ (interactive)
+ (gnus-html-schedule-image-fetching
+ (current-buffer) (list (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) 'gnus-image)))
+
+(defun gnus-html-browse-url ()
+ "Browse the image under point."
+ (interactive)
+ (let ((url (get-text-property (point) 'gnus-string)))
+ (if (not url)
+ (message "No URL at point")
+ (browse-url url))))
+
+(defun gnus-html-schedule-image-fetching (buffer images)
+ (gnus-message 8 "gnus-html-schedule-image-fetching: buffer %s, images %s"
+ buffer images)
+ (let* ((url (caar images))
+ (process (start-process
+ "images" nil "curl"
+ "-s" "--create-dirs"
+ "--location"
+ "--max-time" "60"
+ "-o" (gnus-html-image-id url)
+ (mm-url-decode-entities-string url))))
+ (process-kill-without-query process)
+ (set-process-sentinel process 'gnus-html-curl-sentinel)
+ (gnus-set-process-plist process (list 'images images
+ 'buffer buffer))))
+
+(defun gnus-html-image-id (url)
+ (expand-file-name (sha1 url) gnus-html-cache-directory))
+
+(defun gnus-html-curl-sentinel (process event)
+ (when (string-match "finished" event)
+ (let* ((images (gnus-process-get process 'images))
+ (buffer (gnus-process-get process 'buffer))
+ (spec (pop images))
+ (file (gnus-html-image-id (car spec))))
+ (when (and (buffer-live-p buffer)
+ ;; If the position of the marker is 1, then that
+ ;; means that the text it was in has been deleted;
+ ;; i.e., that the user has selected a different
+ ;; article before the image arrived.
+ (not (= (marker-position (cadr spec)) (point-min))))
+ (with-current-buffer buffer
+ (let ((inhibit-read-only t)
+ (string (buffer-substring (cadr spec) (caddr spec))))
+ (delete-region (cadr spec) (caddr spec))
+ (gnus-html-put-image file (cadr spec) string))))
+ (when images
+ (gnus-html-schedule-image-fetching buffer images)))))
+
+(defun gnus-html-put-image (file point string &optional url alt-text)
+ (when (gnus-graphic-display-p)
+ (let* ((image (ignore-errors
+ (gnus-create-image file)))
+ (size (and image
+ (if (featurep 'xemacs)
+ (cons (glyph-width image) (glyph-height image))
+ (image-size image t)))))
+ (save-excursion
+ (goto-char point)
+ (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 ((data (cdadar (specifier-spec-list
+ (glyph-image image)))))
+ (and (vectorp data)
+ (aref data 0)))
+ (plist-get (cdr image) :type))
+ 'gif)
+ (= (car size) 30)
+ (= (cdr size) 30))))
+ (let ((start (point)))
+ (setq image (gnus-html-rescale-image image file size))
+ (gnus-put-image image
+ (gnus-string-or string "*")
+ 'external)
+ (let ((overlay (gnus-make-overlay start (point))))
+ (gnus-overlay-put overlay 'local-map
+ gnus-html-displayed-image-map)
+ (gnus-put-text-property start (point) 'gnus-alt-text alt-text)
+ (when url
+ (gnus-put-text-property start (point) 'gnus-image url)))
+ (gnus-add-image 'external image)
+ t)
+ (insert string)
+ (when (fboundp 'find-image)
+ (setq image (find-image '((:type xpm :file "lock-broken.xpm"))))
+ (gnus-put-image image
+ (gnus-string-or string "*")
+ 'internal)
+ (gnus-add-image 'internal image))
+ nil)))))
+
+(defun gnus-html-rescale-image (image file size)
+ (if (or (not (fboundp 'imagemagick-types))
+ (not (get-buffer-window (current-buffer))))
+ image
+ (let* ((width (car size))
+ (height (cdr size))
+ (edges (window-pixel-edges (get-buffer-window (current-buffer))))
+ (window-width (truncate (* gnus-max-image-proportion
+ (- (nth 2 edges) (nth 0 edges)))))
+ (window-height (truncate (* gnus-max-image-proportion
+ (- (nth 3 edges) (nth 1 edges)))))
+ scaled-image)
+ (when (> height window-height)
+ (setq image (or (create-image file 'imagemagick nil
+ :height window-height)
+ image))
+ (setq size (image-size image t)))
+ (when (> (car size) window-width)
+ (setq image (or
+ (create-image file 'imagemagick nil
+ :width window-width)
+ image)))
+ image)))
+
+(defun gnus-html-prune-cache ()
+ (let ((total-size 0)
+ files)
+ (dolist (file (directory-files gnus-html-cache-directory t nil t))
+ (let ((attributes (file-attributes file)))
+ (unless (nth 0 attributes)
+ (incf total-size (nth 7 attributes))
+ (push (list (time-to-seconds (nth 5 attributes))
+ (nth 7 attributes) file)
+ files))))
+ (when (> total-size gnus-html-cache-size)
+ (setq files (sort files (lambda (f1 f2)
+ (< (car f1) (car f2)))))
+ (dolist (file files)
+ (when (> total-size gnus-html-cache-size)
+ (decf total-size (cadr file))
+ (delete-file (nth 2 file)))))))
+
+(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))
+
+(defun gnus-html-show-images ()
+ "Show any images that are in the HTML-rendered article buffer.
+This only works if the article in question is HTML."
+ (interactive)
+ (gnus-with-article-buffer
+ (let ((overlays (overlays-in (point-min) (point-max)))
+ overlay images)
+ (while (setq overlay (pop overlays))
+ (when (overlay-get overlay 'gnus-image)
+ (push (overlay-get overlay 'gnus-image) images)))
+ (if (not images)
+ (message "No images to show")
+ (gnus-html-schedule-image-fetching (current-buffer) images)))))
+
+;;;###autoload
+(defun gnus-html-prefetch-images (summary)
+ (let (blocked-images urls)
+ (when (buffer-live-p summary)
+ (with-current-buffer summary
+ (setq blocked-images gnus-blocked-images))
+ (save-match-data
+ (while (re-search-forward "<img.*src=[\"']\\([^\"']+\\)" nil t)
+ (let ((url (match-string 1)))
+ (unless (gnus-html-image-url-blocked-p url blocked-images)
+ (unless (file-exists-p (gnus-html-image-id url))
+ (push (mm-url-decode-entities-string url) urls)
+ (push (gnus-html-image-id url) urls)
+ (push "-o" urls)))))
+ (let ((process
+ (apply 'start-process
+ "images" nil "curl"
+ "-s" "--create-dirs"
+ "--location"
+ "--max-time" "60"
+ urls)))
+ (process-kill-without-query process))))))
+
+(provide 'gnus-html)
+
+;;; gnus-html.el ends here
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