v2e4lisp/show-your-colors.el

## show-your-colors.el
;;; show-your-colours --- an HTTP server showing the current buffer fontified

;; Author: Wilfred Hughes <me@wilfred.me.uk>
;; Version: 0.1
;; Package-Requires: ((s "1.3.0"))

;;; Commentary:

;; Allow others to see what you're editing in Emacs. For live
;; screencasts, or general Emacs advocacy. If you have multiple
;; buffers open, this will show the currently focused buffer.

;; FIXME: Crashes with rainbow-delimeters.

;; UPDATE:
;; * We don't need `syc--buffer' any more. Because in fact
;;   we can get the `current-buffer' by a liitle trick. (see the syc--buffer-as-html)
;; * syc--buffer-as-html is modified a little bit to make it simple and clear
;; * show-your-colours-buffer is deleted for not being used.
;; * advises are all deleted . We don't need them any more.

(require 'elnode)
(require 's)

(defvar syc--port 9000)

;; todo: is there a way we can just activate our advice?
;; DONE: Yes, you can put `activate' as an arg in defadvice.
;; e.g :
;; (defadvice ido-switch-buffer (after set-syc--buffer activate)
;;   "Set `syc--buffer' to the current buffer.
;; Since `switch-to-buffer' is very low-level and used everywhere,
;; we assume a buffer change by a user always uses `ido-switch-buffer"
;;   (setq syc--buffer (current-buffer)))


;; todo: automatic reload
;; DONE.
(defun syc--buffer-as-html ()
  "Get the current buffer and return a string of HTML.
The HTML is styled according to the buffer's fontification."
  (condition-case nil
      ;; While you cannot use `current-buffer' to actually get the current buffer,
      ;; since the elnode will automatically create a temp buffer for http connection.
      ;; What you can do is something like this: `(car (buffer-list))', this will return
      ;; the buffer you're editing or viewing, that's what we want.
      ;; Little trick, Done!
      (with-current-buffer (car (buffer-list))
        (with-current-buffer (htmlize-region (window-start) (window-end))
          (buffer-substring-no-properties (point-min) (point-max))))
    (error "<html><body>Could not fontify buffer.</body></html>")))

(defun syc--append-reload (html)
  "Given a piece of HTML, return a new string with
a JS automatic reload script appended."
  (s-replace
   "</body>"
   "<script type=\"text/javascript\">setTimeout(function() { location.reload(true); }, 100);</script>
</body>"
   html))

;; todo: why can't I let-bind this inside syc--handler?
(setq elnode-error-log-to-messages nil)

(defun syc--handler (httpcon)
    (elnode-http-start httpcon 200 '("Content-Type" . "text/html"))
    (elnode-http-return httpcon (syc--append-reload
                                 (syc--buffer-as-html))))

(elnode-start 'syc--handler :port 9000 :host "localhost")
	;;; show-your-colours --- an HTTP server showing the current buffer fontified

	;; Author: Wilfred Hughes <me@wilfred.me.uk>
	;; Version: 0.1
	;; Package-Requires: ((s "1.3.0"))

	;;; Commentary:

	;; Allow others to see what you're editing in Emacs. For live
	;; screencasts, or general Emacs advocacy. If you have multiple
	;; buffers open, this will show the currently focused buffer.

	;; FIXME: Crashes with rainbow-delimeters.

	;; UPDATE:
	;; * We don't need `syc--buffer' any more. Because in fact
	;; we can get the `current-buffer' by a liitle trick. (see the syc--buffer-as-html)
	;; * syc--buffer-as-html is modified a little bit to make it simple and clear
	;; * show-your-colours-buffer is deleted for not being used.
	;; * advises are all deleted . We don't need them any more.

	(require 'elnode)
	(require 's)

	(defvar syc--port 9000)

	;; todo: is there a way we can just activate our advice?
	;; DONE: Yes, you can put `activate' as an arg in defadvice.
	;; e.g :
	;; (defadvice ido-switch-buffer (after set-syc--buffer activate)
	;; "Set `syc--buffer' to the current buffer.
	;; Since `switch-to-buffer' is very low-level and used everywhere,
	;; we assume a buffer change by a user always uses `ido-switch-buffer"
	;; (setq syc--buffer (current-buffer)))


	;; todo: automatic reload
	;; DONE.
	(defun syc--buffer-as-html ()
	"Get the current buffer and return a string of HTML.
	The HTML is styled according to the buffer's fontification."
	(condition-case nil
	;; While you cannot use `current-buffer' to actually get the current buffer,
	;; since the elnode will automatically create a temp buffer for http connection.
	;; What you can do is something like this: `(car (buffer-list))', this will return
	;; the buffer you're editing or viewing, that's what we want.
	;; Little trick, Done!
	(with-current-buffer (car (buffer-list))
	(with-current-buffer (htmlize-region (window-start) (window-end))
	(buffer-substring-no-properties (point-min) (point-max))))
	(error "<html><body>Could not fontify buffer.</body></html>")))

	(defun syc--append-reload (html)
	"Given a piece of HTML, return a new string with
	a JS automatic reload script appended."
	(s-replace
	"</body>"
	"<script type=\"text/javascript\">setTimeout(function() { location.reload(true); }, 100);</script>
	</body>"
	html))

	;; todo: why can't I let-bind this inside syc--handler?
	(setq elnode-error-log-to-messages nil)

	(defun syc--handler (httpcon)
	(elnode-http-start httpcon 200 '("Content-Type" . "text/html"))
	(elnode-http-return httpcon (syc--append-reload
	(syc--buffer-as-html))))

	(elnode-start 'syc--handler :port 9000 :host "localhost")