Merge from trunk.

[bpt/emacs.git] / lisp / gnus / shr.el

;;; shr.el --- Simple HTML Renderer

;; Copyright (C) 2010-2012 Free Software Foundation, Inc.

;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; Keywords: html

;; 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:

;; This package takes a HTML parse tree (as provided by
;; libxml-parse-html-region) and renders it in the current buffer.  It
;; does not do CSS, JavaScript or anything advanced: It's geared
;; towards rendering typical short snippets of HTML, like what you'd
;; find in HTML email and the like.

;;; Code:

(eval-when-compile (require 'cl))
(require 'browse-url)

(defgroup shr nil
  "Simple HTML Renderer"
  :version "24.1"
  :group 'mail)

(defcustom shr-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 'shr
  :type 'float)

(defcustom shr-blocked-images nil
  "Images that have URLs matching this regexp will be blocked."
  :version "24.1"
  :group 'shr
  :type 'regexp)

(defcustom shr-table-horizontal-line ?\s
  "Character used to draw horizontal table lines."
  :group 'shr
  :type 'character)

(defcustom shr-table-vertical-line ?\s
  "Character used to draw vertical table lines."
  :group 'shr
  :type 'character)

(defcustom shr-table-corner ?\s
  "Character used to draw table corners."
  :group 'shr
  :type 'character)

(defcustom shr-hr-line ?-
  "Character used to draw hr lines."
  :group 'shr
  :type 'character)

(defcustom shr-width fill-column
  "Frame width to use for rendering.
May either be an integer specifying a fixed width in characters,
or nil, meaning that the full width of the window should be
used."
  :type '(choice (integer :tag "Fixed width in characters")
		 (const   :tag "Use the width of the window" nil))
  :group 'shr)

(defvar shr-content-function nil
  "If bound, this should be a function that will return the content.
This is used for cid: URLs, and the function is called with the
cid: URL as the argument.")

(defvar shr-put-image-function 'shr-put-image
  "Function called to put image and alt string.")

(defface shr-strike-through '((t (:strike-through t)))
  "Font for <s> elements."
  :group 'shr)

(defface shr-link
  '((t (:inherit link)))
  "Font for link elements."
  :group 'shr)

;;; Internal variables.

(defvar shr-folding-mode nil)
(defvar shr-state nil)
(defvar shr-start nil)
(defvar shr-indentation 0)
(defvar shr-inhibit-images nil)
(defvar shr-list-mode nil)
(defvar shr-content-cache nil)
(defvar shr-kinsoku-shorten nil)
(defvar shr-table-depth 0)
(defvar shr-stylesheet nil)
(defvar shr-base nil)
(defvar shr-ignore-cache nil)

(defvar shr-map
  (let ((map (make-sparse-keymap)))
    (define-key map "a" 'shr-show-alt-text)
    (define-key map "i" 'shr-browse-image)
    (define-key map "z" 'shr-zoom-image)
    (define-key map "I" 'shr-insert-image)
    (define-key map "u" 'shr-copy-url)
    (define-key map "v" 'shr-browse-url)
    (define-key map "o" 'shr-save-contents)
    (define-key map "\r" 'shr-browse-url)
    map))

;; Public functions and commands.

(defun shr-render-buffer (buffer)
  "Display the HTML rendering of the current buffer."
  (interactive (list (current-buffer)))
  (pop-to-buffer "*html*")
  (erase-buffer)
  (shr-insert-document
   (with-current-buffer buffer
     (libxml-parse-html-region (point-min) (point-max))))
  (goto-char (point-min)))

(defun shr-visit-file (file)
  "Parse FILE as an HTML document, and render it in a new buffer."
  (interactive "fHTML file name: ")
  (with-temp-buffer
    (insert-file-contents file)
    (shr-render-buffer (current-buffer))))

;;;###autoload
(defun shr-insert-document (dom)
  "Render the parsed document DOM into the current buffer.
DOM should be a parse tree as generated by
`libxml-parse-html-region' or similar."
  (setq shr-content-cache nil)
  (let ((start (point))
	(shr-state nil)
	(shr-start nil)
	(shr-base nil)
	(shr-width (or shr-width (window-width))))
    (shr-descend (shr-transform-dom dom))
    (shr-remove-trailing-whitespace start (point))))

(defun shr-remove-trailing-whitespace (start end)
  (let ((width (window-width)))
    (save-restriction
      (narrow-to-region start end)
      (goto-char start)
      (while (not (eobp))
	(end-of-line)
	(when (> (shr-previous-newline-padding-width (current-column)) width)
	  (dolist (overlay (overlays-at (point)))
	    (when (overlay-get overlay 'before-string)
	      (overlay-put overlay 'before-string nil))))
	(forward-line 1)))))

(defun shr-copy-url ()
  "Copy the URL under point to the kill ring.
If called twice, then try to fetch the URL and see whether it
redirects somewhere else."
  (interactive)
  (let ((url (get-text-property (point) 'shr-url)))
    (cond
     ((not url)
      (message "No URL under point"))
     ;; Resolve redirected URLs.
     ((equal url (car kill-ring))
      (url-retrieve
       url
       (lambda (a)
	 (when (and (consp a)
		    (eq (car a) :redirect))
	   (with-temp-buffer
	     (insert (cadr a))
	     (goto-char (point-min))
	     ;; Remove common tracking junk from the URL.
	     (when (re-search-forward ".utm_.*" nil t)
	       (replace-match "" t t))
	     (message "Copied %s" (buffer-string))
	     (copy-region-as-kill (point-min) (point-max)))))
       nil t))
     ;; Copy the URL to the kill ring.
     (t
      (with-temp-buffer
	(insert url)
	(copy-region-as-kill (point-min) (point-max))
	(message "Copied %s" url))))))

(defun shr-show-alt-text ()
  "Show the ALT text of the image under point."
  (interactive)
  (let ((text (get-text-property (point) 'shr-alt)))
    (if (not text)
	(message "No image under point")
      (message "%s" text))))

(defun shr-browse-image (&optional copy-url)
  "Browse the image under point.
If COPY-URL (the prefix if called interactively) is non-nil, copy
the URL of the image to the kill buffer instead."
  (interactive "P")
  (let ((url (get-text-property (point) 'image-url)))
    (cond
     ((not url)
      (message "No image under point"))
     (copy-url
      (with-temp-buffer
	(insert url)
	(copy-region-as-kill (point-min) (point-max))
	(message "Copied %s" url)))
     (t
      (message "Browsing %s..." url)
      (browse-url url)))))

(defun shr-insert-image ()
  "Insert the image under point into the buffer."
  (interactive)
  (let ((url (get-text-property (point) 'image-url)))
    (if (not url)
	(message "No image under point")
      (message "Inserting %s..." url)
      (url-retrieve url 'shr-image-fetched
		    (list (current-buffer) (1- (point)) (point-marker))
		    t t))))

(defun shr-zoom-image ()
  "Toggle the image size.
The size will be rotated between the default size, the original
size, and full-buffer size."
  (interactive)
  (let ((url (get-text-property (point) 'image-url))
	(size (get-text-property (point) 'image-size))
	(buffer-read-only nil))
    (if (not url)
	(message "No image under point")
      ;; Delete the old picture.
      (while (get-text-property (point) 'image-url)
	(forward-char -1))
      (forward-char 1)
      (let ((start (point)))
	(while (get-text-property (point) 'image-url)
	  (forward-char 1))
	(forward-char -1)
	(put-text-property start (point) 'display nil)
	(when (> (- (point) start) 2)
	  (delete-region start (1- (point)))))
      (message "Inserting %s..." url)
      (url-retrieve url 'shr-image-fetched
		    (list (current-buffer) (1- (point)) (point-marker)
			  (list (cons 'size
				      (cond ((or (eq size 'default)
						 (null size))
					     'original)
					    ((eq size 'original)
					     'full)
					    ((eq size 'full)
					     'default)))))
		    t))))

;;; Utility functions.

(defun shr-transform-dom (dom)
  (let ((result (list (pop dom))))
    (dolist (arg (pop dom))
      (push (cons (intern (concat ":" (symbol-name (car arg))) obarray)
		  (cdr arg))
	    result))
    (dolist (sub dom)
      (if (stringp sub)
	  (push (cons 'text sub) result)
	(push (shr-transform-dom sub) result)))
    (nreverse result)))

(defun shr-descend (dom)
  (let ((function (intern (concat "shr-tag-" (symbol-name (car dom))) obarray))
	(style (cdr (assq :style (cdr dom))))
	(shr-stylesheet shr-stylesheet)
	(start (point)))
    (when style
      (if (string-match "color" style)
	  (setq shr-stylesheet (nconc (shr-parse-style style)
				      shr-stylesheet))
	(setq style nil)))
    (if (fboundp function)
	(funcall function (cdr dom))
      (shr-generic (cdr dom)))
    ;; If style is set, then this node has set the color.
    (when style
      (shr-colorize-region start (point)
			   (cdr (assq 'color shr-stylesheet))
			   (cdr (assq 'background-color shr-stylesheet))))))

(defun shr-generic (cont)
  (dolist (sub cont)
    (cond
     ((eq (car sub) 'text)
      (shr-insert (cdr sub)))
     ((listp (cdr sub))
      (shr-descend sub)))))

(defmacro shr-char-breakable-p (char)
  "Return non-nil if a line can be broken before and after CHAR."
  `(aref fill-find-break-point-function-table ,char))
(defmacro shr-char-nospace-p (char)
  "Return non-nil if no space is required before and after CHAR."
  `(aref fill-nospace-between-words-table ,char))

;; KINSOKU is a Japanese word meaning a rule that should not be violated.
;; In Emacs, it is a term used for characters, e.g. punctuation marks,
;; parentheses, and so on, that should not be placed in the beginning
;; of a line or the end of a line.
(defmacro shr-char-kinsoku-bol-p (char)
  "Return non-nil if a line ought not to begin with CHAR."
  `(aref (char-category-set ,char) ?>))
(defmacro shr-char-kinsoku-eol-p (char)
  "Return non-nil if a line ought not to end with CHAR."
  `(aref (char-category-set ,char) ?<))
(unless (shr-char-kinsoku-bol-p (make-char 'japanese-jisx0208 33 35))
  (load "kinsoku" nil t))

(defun shr-insert (text)
  (when (and (eq shr-state 'image)
	     (not (bolp))
	     (not (string-match "\\`[ \t\n]+\\'" text)))
    (insert "\n")
    (setq shr-state nil))
  (cond
   ((eq shr-folding-mode 'none)
    (insert text))
   (t