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;;; markdown-preview-mode.el --- markdown realtime preview minor mode.
;; Copyright (C) 2014 <>
;; Author: Igor Shymko <>
;; URL:
;; Keywords: markdown, preview
;; Version: 0.6
;; Package-Requires: ((websocket "1.6") (markdown-mode "2.1") (cl-lib "0.5"))
;; This file is not part of GNU Emacs.
;; This program 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, or (at your option)
;; any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; 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 <>.
;;; Commentary:
;; This package makes use of websockets to deliver rendered markdown to a web browser.
;; Updates happen upon buffer save or on idle.
;;; Code:
(require 'cl-lib)
(require 'websocket)
(require 'markdown-mode)
(defgroup markdown-preview nil
"Markdown preview mode."
:group 'text
:prefix "markdown-preview-"
:link '(url-link ""))
(defcustom markdown-preview-host 'local
"Markdown preview websocket server address."
:group 'markdown-preview
:type '(choice (const :tag "localhost" local)
(string :tag "Custom host")))
(defcustom markdown-preview-port 7379
"Markdown preview websocket server port."
:group 'markdown-preview
:type 'integer)
(defcustom markdown-preview-style
"Markdown preview style URI."
:group 'markdown-preview
:type 'string)
(defcustom markdown-preview-file-name ".markdown-preview.html"
"Markdown preview file name."
:group 'markdown-preview
:type 'string)
(defvar markdown-preview--websocket-server nil
"`markdown-preview' Websocket server.")
(defvar markdown-preview--local-client nil
"`markdown-preview' local client.")
(defvar markdown-preview--remote-clients nil
"List of `markdown-preview' websocket remote clients.")
(defvar markdown-preview--preview-url
(concat (file-name-directory load-file-name) "preview.html")
"Location of `markdown-preview' html.")
(defvar markdown-preview--idle-timer nil
"Preview idle timer.")
(defun markdown-preview--stop-idle-timer ()
"Stop the `markdown-preview' idle timer."
(when (timerp markdown-preview--idle-timer)
(cancel-timer markdown-preview--idle-timer)))
(defun markdown-preview--open-browser-preview ()
"Open the markdown preview in the browser."
(let* ((dir-of-buffer-to-preview (file-name-directory (buffer-file-name)))
(preview-file (concat dir-of-buffer-to-preview markdown-preview-file-name)))
(if (not (file-exists-p preview-file))
(copy-file markdown-preview--preview-url preview-file))
(browse-url preview-file)))
(defun markdown-preview--stop-websocket-server ()
"Stop the `markdown-preview' websocket server."
(when markdown-preview--local-client
(websocket-close markdown-preview--local-client))
(when markdown-preview--websocket-server
(delete-process markdown-preview--websocket-server)
(setq markdown-preview--websocket-server nil
markdown-preview--remote-clients nil)))
(defun markdown-preview--drop-closed-clients ()
"Clean closed clients in `markdown-preview--remote-clients' list."
(setq markdown-preview--remote-clients
(cl-remove-if-not #'websocket-openp markdown-preview--remote-clients)))
(defun markdown-preview--start-websocket-server ()
"Start `markdown-preview' websocket server."
(when (not markdown-preview--websocket-server)
(setq markdown-preview--websocket-server
:host markdown-preview-host
:on-message (lambda (websocket frame)
(mapc (lambda (ws) (websocket-send ws frame))
:on-open (lambda (websocket)
(push websocket markdown-preview--remote-clients)
(markdown-preview--send-preview-to websocket))
:on-error (lambda (websocket type err) (message (concat "====> Error:" err)))
:on-close (lambda (websocket) (markdown-preview--drop-closed-clients))))
(add-hook 'kill-emacs-hook 'markdown-preview--stop-websocket-server)
(defun markdown-preview--start-local-client ()
"Start the `markdown-preview' local client."
(when (not markdown-preview--local-client)
(setq markdown-preview--local-client
(format "ws://localhost:%d" markdown-preview-port)
:on-error (lambda (ws type err)
(message "error connecting"))
:on-close (lambda (websocket)
(setq markdown-preview--local-client nil))))))
(defun markdown-preview--send-preview ()
"Send the `markdown-preview' preview to clients."
(when (bound-and-true-p markdown-preview-mode)
(markdown-preview--send-preview-to markdown-preview--local-client)))
(defun markdown-preview--send-preview-to (websocket)
"Send the `markdown-preview' to a specific WEBSOCKET."
(let ((mark-position-percent
(* 100
(float (- (line-number-at-pos) (/ (count-screen-lines (window-start) (point)) 2)))
(count-lines (point-min) (point-max))))))))
(markdown markdown-output-buffer-name)
(with-current-buffer (get-buffer markdown-output-buffer-name)
(websocket-send-text websocket
"<span id='style'>"
"<span id='position-percentage'>"
"<div id='content'>"
(buffer-substring-no-properties (point-min) (point-max))
(defun markdown-preview--start ()
"Start `markdown-preview' mode."
(setq markdown-preview--idle-timer
(run-with-idle-timer 2 t (lambda () (markdown-preview--send-preview))))
(add-hook 'after-save-hook 'markdown-preview--send-preview nil t))
(defun markdown-preview--stop ()
"Stop `markdown-preview' mode."
(remove-hook 'after-save-hook 'markdown-preview--send-preview t)
(let ((preview-file (concat (file-name-directory (buffer-file-name)) markdown-preview-file-name)))
(if (file-exists-p preview-file)
(delete-file preview-file)))
(defun markdown-preview-open-browser ()
"Open the `markdown-preview' in the browser."
(defun markdown-preview-cleanup ()
"Cleanup `markdown-preview' mode."
(define-minor-mode markdown-preview-mode
"Markdown preview mode."
:group 'markdown-preview
:init-value nil
(when (not (or
(equal major-mode 'markdown-mode)
(equal major-mode 'gfm-mode)))
(if markdown-preview-mode
(provide 'markdown-preview-mode)
;;; markdown-preview-mode.el ends here