[clinton/parenscript.git] / docs / tutorial.lisp

;;;# ParenScript Tutorial

;;; This chapter is a short introductory tutorial to ParenScript. It
;;; hopefully will give you an idea how ParenScript can be used in a
;;; Lisp web application.

;;;# Setting up the ParenScript environment

;;; In this tutorial, we will use the Portable Allegroserve webserver
;;; to serve the tutorial web application. We use the ASDF system to
;;; load both Allegroserve and ParenScript. I assume you have
;;; installed and downloaded Allegroserve and Parenscript, and know
;;; how to setup the central registry for ASDF.

(asdf:oos 'asdf:load-op :aserve)

; ... lots of compiler output ...

(asdf:oos 'asdf:load-op :parenscript)

; ... lots of compiler output ...

;;; The tutorial will be placed in its own package, which we first
;;; have to define.

(defpackage :js-tutorial
  (:use :common-lisp :net.aserve :net.html.generator :parenscript))

(in-package :js-tutorial)

;;; The next command starts the webserver on the port 8000.

(start :port 8000)

;;; We are now ready to generate the first JavaScript-enabled webpages
;;; using ParenScript.

;;;# A simple embedded example

;;; The first document we will generate is a simple HTML document,
;;; which features a single hyperlink. When clicking the hyperlink, a
;;; JavaScript handler opens a popup alert window with the string
;;; "Hello world". To facilitate the development, we will factor out
;;; the HTML generation to a separate function, and setup a handler
;;; for the url "/tutorial1", which will generate HTTP headers and
;;; call the function `TUTORIAL1'. At first, our function does nothing.

(defun tutorial1 (req ent)
  (declare (ignore req ent))
  nil)

(publish :path "/tutorial1"
         :content-type "text/html; charset=ISO-8859-1"
         :function #'(lambda (req ent)
                       (with-http-response (req ent)
                         (with-http-body (req ent)
                           (tutorial1 req ent)))))

;;; Browsing "http://localhost:8000/tutorial1" should return an empty
;;; HTML page. It's now time to fill this rather page with
;;; content. ParenScript features a macro that generates a string that
;;; can be used as an attribute value of HTML nodes.

(defun tutorial1 (req ent)
  (declare (ignore req ent))
  (html
   (:html
    (:head (:title "ParenScript tutorial: 1st example"))
    (:body (:h1 "ParenScript tutorial: 1st example")
           (:p "Please click the link below." :br
               ((:a :href "#" :onclick (js-inline
                                        (alert "Hello World")))
                "Hello World"))))))

;;; Browsing "http://localhost:8000/tutorial1" should return the
;;; following HTML:

<html><head><title>ParenScript tutorial: 1st example</title>
</head>
<body><h1>ParenScript tutorial: 1st example</h1>
<p>Please click the link below.<br/>
<a href="#"
   onclick="javascript:alert(&quot;Hello World&quot;);">Hello World</a>
</p>
</body>
</html>

;;;# Adding an inline ParenScript

;;; Suppose we now want to have a general greeting function. One way
;;; to do this is to add the javascript in a `SCRIPT' element at the
;;; top of the HTML page. This is done using the `JS-SCRIPT' macro
;;; which will generate the necessary XML and comment tricks to
;;; cleanly embed JavaScript. We will redefine our `TUTORIAL1'
;;; function and add a few links:

(defun tutorial1 (req ent)
  (declare (ignore req ent))
  (html
   (:html
    (:head
     (:title "ParenScript tutorial: 2nd example")
     (js-script
      (defun greeting-callback ()
        (alert "Hello World"))))
    (:body
     (:h1 "ParenScript tutorial: 2nd example")
     (:p "Please click the link below." :br
         ((:a :href "#" :onclick (js-inline (greeting-callback)))
          "Hello World")
         :br "And maybe this link too." :br
         ((:a :href "#" :onclick (js-inline (greeting-callback)))
          "Knock knock")
         :br "And finally a third link." :br
         ((:a :href "#" :onclick (js-inline (greeting-callback)))
          "Hello there"))))))

;;; This will generate the following HTML page, with the embedded
;;; JavaScript nicely sitting on top. Take note how
;;; `GREETING-CALLBACK' was converted to camelcase, and how the lispy
;;; `DEFUN' was converted to a JavaScript function declaration.

<html><head><title>ParenScript tutorial: 2nd example</title>
<script type="text/javascript">
// <![CDATA[
function greetingCallback() {
  alert("Hello World");
}
// ]]>
</script>
</head>
<body><h1>ParenScript tutorial: 2nd example</h1>
<p>Please click the link below.<br/>
<a href="#"
   onclick="javascript:greetingCallback();">Hello World</a>
<br/>
And maybe this link too.<br/>
<a href="#"
   onclick="javascript:greetingCallback();">Knock knock</a>
<br/>

And finally a third link.<br/>
<a href="#"
   onclick="javascript:greetingCallback();">Hello there</a>
</p>
</body>
</html>

;;;# Generating a JavaScript file

;;; The best way to integrate ParenScript into a Lisp application is
;;; to generate a JavaScript file from ParenScript code. This file can
;;; be cached by intermediate proxies, and webbrowsers won't have to
;;; reload the javascript code on each pageview. A standalone
;;; JavaScript can be generated using the macro `JS-FILE'. We will
;;; publish the tutorial JavaScript under "/tutorial.js".

(defun tutorial1-file (req ent)
  (declare (ignore req ent))
  (js-file
   (defun greeting-callback ()
     (alert "Hello World"))))

(publish :path "/tutorial1.js"
         :content-type "text/javascript; charset=ISO-8859-1"
         :function #'(lambda (req ent)
                       (with-http-response (req ent)
                         (with-http-body (req ent)
                           (tutorial1-file req ent)))))

(defun tutorial1 (req ent)
  (declare (ignore req ent))
  (html
   (:html
    (:head
     (:title "ParenScript tutorial: 3rd example")
     ((:script :language "JavaScript" :src "/tutorial1.js")))
    (:body
     (:h1 "ParenScript tutorial: 3rd example")
     (:p "Please click the link below." :br
         ((:a :href "#" :onclick (js-inline (greeting-callback)))
          "Hello World")
         :br "And maybe this link too." :br
         ((:a :href "#" :onclick (js-inline (greeting-callback)))
          "Knock knock")
         :br "And finally a third link." :br
         ((:a :href "#" :onclick (js-inline (greeting-callback)))
          "Hello there"))))))

;;; This will generate the following JavaScript code under
;;; "/tutorial1.js":

function greetingCallback() {
  alert("Hello World");
}

;;; and the following HTML code:

<html><head><title>ParenScript tutorial: 3rd example</title>
<script language="JavaScript" src="/tutorial1.js"></script>
</head>
<body><h1>ParenScript tutorial: 3rd example</h1>
<p>Please click the link below.<br/>
<a href="#" onclick="javascript:greetingCallback();">Hello World</a>
<br/>
And maybe this link too.<br/>
<a href="#" onclick="javascript:greetingCallback();">Knock knock</a>
<br/>

And finally a third link.<br/>
<a href="#" onclick="javascript:greetingCallback();">Hello there</a>
</p>
</body>
</html>

;;;# A ParenScript slideshow

;;; While developing ParenScript, I used JavaScript programs from the
;;; web and rewrote them using ParenScript. This is a nice slideshow
;;; example from

     http://www.dynamicdrive.com/dynamicindex14/dhtmlslide.htm

;;; The slideshow will be accessible under "/slideshow", and will
;;; slide through the images "photo1.png", "photo2.png" and
;;; "photo3.png". The first ParenScript version will be very similar
;;; to the original JavaScript code. The second version will then show
;;; how to integrate data from the Lisp environment into the
;;; ParenScript code, allowing us to customize the slideshow
;;; application by supplying a list of image names. We first setup the
;;; slideshow path.

(publish :path "/slideshow"
         :content-type "text/html"
         :function #'(lambda (req ent)
                       (with-http-response (req ent)
                         (with-http-body (req ent)
                           (slideshow req ent)))))

(publish :path "/slideshow.js"
         :content-type "text/html"
         :function #'(lambda (req ent)
                       (with-http-response (req ent)
                         (with-http-body (req ent)
                           (js-slideshow req ent)))))

;;; The images are just random images I found on my harddrive. We will
;;; publish them by hand for now.

(publish-file :path "/photo1.png"
              :file "/home/manuel/bknr-sputnik.png")
(publish-file :path "/photo2.png"
              :file "/home/manuel/bknrlogo_red648.png")
(publish-file :path "/photo3.png"
              :file "/home/manuel/bknr-sputnik.png")

;;; The function `SLIDESHOW' generates the HTML code for the main
;;; slideshow page. It also features little bits of ParenScript. These
;;; are the callbacks on the links for the slideshow application. In
;;; this special case, the javascript generates the links itself by
;;; using `document.write' in a "SCRIPT" element. Users that don't
;;; have JavaScript enabled won't see anything at all.
;;;
;;; `SLIDESHOW' also generates a static array called `PHOTOS' which
;;; holds the links to the photos of the slideshow. This array is
;;; handled by the ParenScript code in "slideshow.js". Note how the
;;; HTML code issued by the JavaScript is generated using the `HTML'
;;; construct. In fact, we have two different HTML generators in the
;;; example below, one is the standard Lisp HTML generator, and the
;;; other is the JavaScript HTML generator, which generates a
;;; JavaScript expression.

(defun slideshow (req ent)
  (declare (ignore req ent))
  (html
   (:html
    (:head (:title "ParenScript slideshow")
           ((:script :language "JavaScript"
                     :src "/slideshow.js"))
           (js-script
            (defvar *linkornot* 0)
            (defvar photos (array "photo1.png"
                                  "photo2.png"
                                  "photo3.png"))))
    (:body (:h1 "ParenScript slideshow")
         (:body (:h2 "Hello")
                ((:table :border 0
                         :cellspacing 0
                         :cellpadding 0)
                 (:tr ((:td :width "100%" :colspan 2 :height 22)
           (:center
            (js-script
             (let ((img
                    (html
                     ((:img :src (aref photos 0)
                            :name "photoslider"
                            :style ( + "filter:"
                                       (js (reveal-trans
                                            (setf duration 2)
                                            (setf transition 23))))
                               :border 0)))))
               (document.write
                (if (= *linkornot* 1)
                    (html ((:a :href "#"
                               :onclick (js-inline (transport)))
                           img))
                    img)))))))
                 (:tr ((:td :width "50%" :height "21")
                       ((:p :align "left")
                        ((:a :href "#"
                             :onclick (js-inline (backward)
                                                 (return false)))
                         "Previous Slide")))
                      ((:td :width "50%" :height "21")
                       ((:p :align "right")
                        ((:a :href "#"
                             :onclick (js-inline (forward)
                                                 (return false)))
                         "Next Slide"))))))))))

;;; `SLIDESHOW' generates the following HTML code (long lines have
;;; been broken down):

<html><head><title>ParenScript slideshow</title>
<script language="JavaScript" src="/slideshow.js"></script>
<script type="text/javascript">
// <![CDATA[
var LINKORNOT = 0;
var photos = [ "photo1.png", "photo2.png", "photo3.png" ];
// ]]>
</script>
</head>
<body><h1>ParenScript slideshow</h1>
<body><h2>Hello</h2>
<table border="0" cellspacing="0" cellpadding="0">
<tr><td width="100%" colspan="2" height="22">
<center><script type="text/javascript">
// <![CDATA[
var img =
    "<img src=\"" + photos[0]
    + "\" name=\"photoslider\"
      style=\"filter:revealTrans(duration=2,transition=23)\"
      border=\"0\"></img>";
document.write(LINKORNOT == 1 ?
                   "<a href=\"#\"
                       onclick=\"javascript:transport()\">"
                   + img + "</a>"
                   : img);
// ]]>
</script>
</center>
</td>
</tr>
<tr><td width="50%" height="21"><p align="left">
<a href="#"
   onclick="javascript:backward(); return false;">Previous Slide</a>

</p>
</td>
<td width="50%" height="21"><p align="right">
<a href="#"
   onclick="javascript:forward(); return false;">Next Slide</a>
</p>
</td>
</tr>
</table>
</body>
</body>
</html>

;;; The actual slideshow application is generated by the function
;;; `JS-SLIDESHOW', which generates a ParenScript file. The code is
;;; pretty straightforward for a lisp savy person. Symbols are
;;; converted to JavaScript variables, but the dot "." is left as
;;; is. This enables us to access object "slots" without using the
;;; `SLOT-VALUE' function all the time. However, when the object we
;;; are referring to is not a variable, but for example an element of
;;; an array, we have to revert to `SLOT-VALUE'.

(defun js-slideshow (req ent)
  (declare (ignore req ent))
  (js-file
   (defvar *preloaded-images* (make-array))
   (defun preload-images (photos)
     (dotimes (i photos.length)
       (setf (aref *preloaded-images* i) (new *Image)
             (slot-value (aref *preloaded-images* i) 'src)
             (aref photos i))))

   (defun apply-effect ()
     (when (and document.all photoslider.filters)
       (let ((trans photoslider.filters.reveal-trans))
         (setf (slot-value trans '*Transition)
               (floor (* (random) 23)))
         (trans.stop)
         (trans.apply))))

   (defun play-effect ()
     (when (and document.all photoslider.filters)
       (photoslider.filters.reveal-trans.play)))

   (defvar *which* 0)

   (defun keep-track ()
     (setf window.status
           (+ "Image " (1+ *which*) " of " photos.length)))

   (defun backward ()
     (when (> *which* 0)
       (decf *which*)
       (apply-effect)
       (setf document.images.photoslider.src
             (aref photos *which*))
       (play-effect)
       (keep-track)))

   (defun forward ()
     (when (< *which* (1- photos.length))
       (incf *which*)
       (apply-effect)
       (setf document.images.photoslider.src
             (aref photos *which*))
       (play-effect)
       (keep-track)))

   (defun transport ()
     (setf window.location (aref photoslink *which*)))))

;;; `JS-SLIDESHOW' generates the following JavaScript code:

var PRELOADEDIMAGES = new Array();
function preloadImages(photos) {
  for (var i = 0; i != photos.length; i = i++) {
    PRELOADEDIMAGES[i] = new Image;
    PRELOADEDIMAGES[i].src = photos[i];
  }
}
function applyEffect() {
  if (document.all && photoslider.filters) {
    var trans = photoslider.filters.revealTrans;
    trans.Transition = Math.floor(Math.random() * 23);
    trans.stop();
    trans.apply();
  }
}
function playEffect() {
  if (document.all && photoslider.filters) {
    photoslider.filters.revealTrans.play();
  }
}
var WHICH = 0;
function keepTrack() {
  window.status = "Image " + (WHICH + 1) + " of " +
                  photos.length;
}
function backward() {
  if (WHICH > 0) {
    --WHICH;
    applyEffect();
    document.images.photoslider.src = photos[WHICH];
    playEffect();
    keepTrack();
  }
}
function forward() {
  if (WHICH < photos.length - 1) {
    ++WHICH;
    applyEffect();
    document.images.photoslider.src = photos[WHICH];
    playEffect();
    keepTrack();
  }
}
function transport() {
  window.location = photoslink[WHICH];
}

;;;# Customizing the slideshow

;;; For now, the slideshow has the path to all the slideshow images
;;; hardcoded in the HTML code, as well as in the publish
;;; statements. We now want to customize this by publishing a
;;; slideshow under a certain path, and giving it a list of image urls
;;; and pathnames where those images can be found. For this, we will
;;; create a function `PUBLISH-SLIDESHOW' which takes a prefix as
;;; argument, as well as a list of image pathnames to be published.

(defun publish-slideshow (prefix images)
  (let* ((js-url (format nil "~Aslideshow.js" prefix))
         (html-url (format nil "~Aslideshow" prefix))
         (image-urls
          (mapcar #'(lambda (image)
                      (format nil "~A~A.~A" prefix
                              (pathname-name image)
                              (pathname-type image)))
                  images)))
    (publish :path html-url
             :content-type "text/html"
             :function #'(lambda (req ent)
                           (with-http-response (req ent)
                             (with-http-body (req ent)
                               (slideshow2 req ent image-urls)))))
    (publish :path js-url
             :content-type "text/html"
             :function #'(lambda (req ent)
                           (with-http-response (req ent)
                             (with-http-body (req ent)
                               (js-slideshow req ent)))))
    (map nil #'(lambda (image url)
                 (publish-file :path url
                               :file image))
         images image-urls)))

(defun slideshow2 (req ent image-urls)
  (declare (ignore req ent))
  (html
   (:html
    (:head (:title "ParenScript slideshow")
           ((:script :language "JavaScript"
                     :src "/slideshow.js"))
           ((:script :type "text/javascript")
            (:princ (format nil "~%// <![CDATA[~%"))
            (:princ (js (defvar *linkornot* 0)))
            (:princ (js-to-string `(defvar photos
                                    (array ,@image-urls))))
            (:princ (format nil "~%// ]]>~%"))))
    (:body (:h1 "ParenScript slideshow")
         (:body (:h2 "Hello")
                ((:table :border 0
                         :cellspacing 0
                         :cellpadding 0)
                 (:tr ((:td :width "100%" :colspan 2 :height 22)
         (:center
          (js-script
           (let ((img
                  (html
                   ((:img :src (aref photos 0)
                          :name "photoslider"
                          :style ( + "filter:"
                                     (js (reveal-trans
                                          (setf duration 2)
                                          (setf transition 23))))
                          :border 0)))))
                (document.write
                 (if (= *linkornot* 1)
                     (html ((:a :href "#"
                                :onclick (js-inline (transport)))
                            img))
                     img)))))))
                 (:tr ((:td :width "50%" :height "21")
                       ((:p :align "left")
                        ((:a :href "#"
                             :onclick (js-inline (backward)
                                                 (return false)))
                         "Previous Slide")))
                      ((:td :width "50%" :height "21")
                       ((:p :align "right")
                        ((:a :href "#"
                             :onclick (js-inline (forward)
                                                 (return false)))
                         "Next Slide"))))))))))

;;; We can now publish the same slideshow as before, under the
;;; "/bknr/" prefix:

(publish-slideshow "/bknr/"
  `("/home/manuel/bknr-sputnik.png"
    "/home/manuel/bknrlogo_red648.png"
    "/home/manuel/screenshots/screenshot-14.03.2005-11.54.33.png"))

;;; That's it, we can now access our customized slideshow under

   http://localhost:8000/bknr/slideshow
Commit	Line	Data
8e198a08 MB	1	;;;# ParenScript Tutorial
	2
	3	;;; This chapter is a short introductory tutorial to ParenScript. It
	4	;;; hopefully will give you an idea how ParenScript can be used in a
	5	;;; Lisp web application.
	6
	7	;;;# Setting up the ParenScript environment
	8
	9	;;; In this tutorial, we will use the Portable Allegroserve webserver
	10	;;; to serve the tutorial web application. We use the ASDF system to
	11	;;; load both Allegroserve and ParenScript. I assume you have
	12	;;; installed and downloaded Allegroserve and Parenscript, and know
	13	;;; how to setup the central registry for ASDF.
	14
	15	(asdf:oos 'asdf:load-op :aserve)
	16
	17	; ... lots of compiler output ...
	18
	19	(asdf:oos 'asdf:load-op :parenscript)
	20
	21	; ... lots of compiler output ...
	22
	23	;;; The tutorial will be placed in its own package, which we first
	24	;;; have to define.
	25
	26	(defpackage :js-tutorial
d5ede101	27	(:use :common-lisp :net.aserve :net.html.generator :parenscript))
8e198a08 MB	28
	29	(in-package :js-tutorial)
	30
	31	;;; The next command starts the webserver on the port 8000.
	32
	33	(start :port 8000)
	34
	35	;;; We are now ready to generate the first JavaScript-enabled webpages
	36	;;; using ParenScript.
	37
	38	;;;# A simple embedded example
	39
	40	;;; The first document we will generate is a simple HTML document,
	41	;;; which features a single hyperlink. When clicking the hyperlink, a
	42	;;; JavaScript handler opens a popup alert window with the string
	43	;;; "Hello world". To facilitate the development, we will factor out
	44	;;; the HTML generation to a separate function, and setup a handler
	45	;;; for the url "/tutorial1", which will generate HTTP headers and
	46	;;; call the function `TUTORIAL1'. At first, our function does nothing.
	47
	48	(defun tutorial1 (req ent)
	49	(declare (ignore req ent))
	50	nil)
	51
	52	(publish :path "/tutorial1"
	53	:content-type "text/html; charset=ISO-8859-1"
	54	:function #'(lambda (req ent)
	55	(with-http-response (req ent)
	56	(with-http-body (req ent)
	57	(tutorial1 req ent)))))
	58
	59	;;; Browsing "http://localhost:8000/tutorial1" should return an empty
	60	;;; HTML page. It's now time to fill this rather page with
	61	;;; content. ParenScript features a macro that generates a string that
94a05cdf	62	;;; can be used as an attribute value of HTML nodes.
8e198a08 MB	63
	64	(defun tutorial1 (req ent)
	65	(declare (ignore req ent))
	66	(html
	67	(:html
	68	(:head (:title "ParenScript tutorial: 1st example"))
	69	(:body (:h1 "ParenScript tutorial: 1st example")
	70	(:p "Please click the link below." :br
	71	((:a :href "#" :onclick (js-inline
	72	(alert "Hello World")))
	73	"Hello World"))))))
	74
	75	;;; Browsing "http://localhost:8000/tutorial1" should return the
	76	;;; following HTML:
	77
8e198a08 MB	78	<html><head><title>ParenScript tutorial: 1st example</title>
	79	</head>
	80	<body><h1>ParenScript tutorial: 1st example</h1>
	81	<p>Please click the link below.<br/>
	82	<a href="#"
	83	onclick="javascript:alert("Hello World");">Hello World</a>
	84	</p>
	85	</body>
	86	</html>
	87
	88	;;;# Adding an inline ParenScript
	89
	90	;;; Suppose we now want to have a general greeting function. One way
	91	;;; to do this is to add the javascript in a `SCRIPT' element at the
	92	;;; top of the HTML page. This is done using the `JS-SCRIPT' macro
	93	;;; which will generate the necessary XML and comment tricks to
	94	;;; cleanly embed JavaScript. We will redefine our `TUTORIAL1'
	95	;;; function and add a few links:
	96
	97	(defun tutorial1 (req ent)
	98	(declare (ignore req ent))
	99	(html
	100	(:html
	101	(:head
	102	(:title "ParenScript tutorial: 2nd example")
	103	(js-script
	104	(defun greeting-callback ()
	105	(alert "Hello World"))))
	106	(:body
	107	(:h1 "ParenScript tutorial: 2nd example")
	108	(:p "Please click the link below." :br
	109	((:a :href "#" :onclick (js-inline (greeting-callback)))
	110	"Hello World")
	111	:br "And maybe this link too." :br
	112	((:a :href "#" :onclick (js-inline (greeting-callback)))
	113	"Knock knock")
	114	:br "And finally a third link." :br
	115	((:a :href "#" :onclick (js-inline (greeting-callback)))
	116	"Hello there"))))))
	117
	118	;;; This will generate the following HTML page, with the embedded
	119	;;; JavaScript nicely sitting on top. Take note how
	120	;;; `GREETING-CALLBACK' was converted to camelcase, and how the lispy
	121	;;; `DEFUN' was converted to a JavaScript function declaration.
	122
8e198a08 MB	123	<html><head><title>ParenScript tutorial: 2nd example</title>
	124	<script type="text/javascript">
	125	// <![CDATA[
	126	function greetingCallback() {
	127	alert("Hello World");
	128	}
	129	// ]]>
	130	</script>
	131	</head>
	132	<body><h1>ParenScript tutorial: 2nd example</h1>
	133	<p>Please click the link below.<br/>
	134	<a href="#"
	135	onclick="javascript:greetingCallback();">Hello World</a>
	136	<br/>
	137	And maybe this link too.<br/>
	138	<a href="#"
	139	onclick="javascript:greetingCallback();">Knock knock</a>
	140	<br/>
	141
	142	And finally a third link.<br/>
	143	<a href="#"
	144	onclick="javascript:greetingCallback();">Hello there</a>
	145	</p>
	146	</body>
	147	</html>
	148
	149	;;;# Generating a JavaScript file
	150
	151	;;; The best way to integrate ParenScript into a Lisp application is
	152	;;; to generate a JavaScript file from ParenScript code. This file can
	153	;;; be cached by intermediate proxies, and webbrowsers won't have to
	154	;;; reload the javascript code on each pageview. A standalone
	155	;;; JavaScript can be generated using the macro `JS-FILE'. We will
	156	;;; publish the tutorial JavaScript under "/tutorial.js".
	157
	158	(defun tutorial1-file (req ent)
	159	(declare (ignore req ent))
	160	(js-file
	161	(defun greeting-callback ()
	162	(alert "Hello World"))))
	163
	164	(publish :path "/tutorial1.js"
	165	:content-type "text/javascript; charset=ISO-8859-1"
	166	:function #'(lambda (req ent)
	167	(with-http-response (req ent)
	168	(with-http-body (req ent)
	169	(tutorial1-file req ent)))))
	170
	171	(defun tutorial1 (req ent)
	172	(declare (ignore req ent))
	173	(html
	174	(:html
	175	(:head
	176	(:title "ParenScript tutorial: 3rd example")
	177	((:script :language "JavaScript" :src "/tutorial1.js")))
	178	(:body
	179	(:h1 "ParenScript tutorial: 3rd example")
	180	(:p "Please click the link below." :br
	181	((:a :href "#" :onclick (js-inline (greeting-callback)))
	182	"Hello World")
	183	:br "And maybe this link too." :br
	184	((:a :href "#" :onclick (js-inline (greeting-callback)))
	185	"Knock knock")
	186	:br "And finally a third link." :br
187	((:a :href "#" :onclick (js-inline (greeting-callback)))
188	"Hello there"))))))
189
190	;;; This will generate the following JavaScript code under
191	;;; "/tutorial1.js":
192
193	function greetingCallback() {
194	alert("Hello World");
195	}
196
197	;;; and the following HTML code:
198
199	<html><head><title>ParenScript tutorial: 3rd example</title>
200	<script language="JavaScript" src="/tutorial1.js"></script>
201	</head>
202	<body><h1>ParenScript tutorial: 3rd example</h1>
203	<p>Please click the link below.<br/>
204	<a href="#" onclick="javascript:greetingCallback();">Hello World</a>
205	<br/>
206	And maybe this link too.<br/>
207	<a href="#" onclick="javascript:greetingCallback();">Knock knock</a>
208	<br/>
209
210	And finally a third link.<br/>
211	<a href="#" onclick="javascript:greetingCallback();">Hello there</a>
212	</p>
213	</body>
214	</html>
215
216	;;;# A ParenScript slideshow
217
218	;;; While developing ParenScript, I used JavaScript programs from the
219	;;; web and rewrote them using ParenScript. This is a nice slideshow
220	;;; example from
221
222	http://www.dynamicdrive.com/dynamicindex14/dhtmlslide.htm
223
224	;;; The slideshow will be accessible under "/slideshow", and will
225	;;; slide through the images "photo1.png", "photo2.png" and
226	;;; "photo3.png". The first ParenScript version will be very similar
227	;;; to the original JavaScript code. The second version will then show
228	;;; how to integrate data from the Lisp environment into the
229	;;; ParenScript code, allowing us to customize the slideshow
230	;;; application by supplying a list of image names. We first setup the
231	;;; slideshow path.
232
233	(publish :path "/slideshow"
234	:content-type "text/html"
235	:function #'(lambda (req ent)
236	(with-http-response (req ent)
237	(with-http-body (req ent)
238	(slideshow req ent)))))
239
240	(publish :path "/slideshow.js"
241	:content-type "text/html"
242	:function #'(lambda (req ent)
243	(with-http-response (req ent)
244	(with-http-body (req ent)
245	(js-slideshow req ent)))))
246
247	;;; The images are just random images I found on my harddrive. We will
248	;;; publish them by hand for now.
249
250	(publish-file :path "/photo1.png"
251	:file "/home/manuel/bknr-sputnik.png")
252	(publish-file :path "/photo2.png"
253	:file "/home/manuel/bknrlogo_red648.png")
254	(publish-file :path "/photo3.png"
255	:file "/home/manuel/bknr-sputnik.png")
256
257	;;; The function `SLIDESHOW' generates the HTML code for the main
258	;;; slideshow page. It also features little bits of ParenScript. These
259	;;; are the callbacks on the links for the slideshow application. In
260	;;; this special case, the javascript generates the links itself by
261	;;; using `document.write' in a "SCRIPT" element. Users that don't
262	;;; have JavaScript enabled won't see anything at all.
263	;;;
264	;;; `SLIDESHOW' also generates a static array called `PHOTOS' which
265	;;; holds the links to the photos of the slideshow. This array is
266	;;; handled by the ParenScript code in "slideshow.js". Note how the
267	;;; HTML code issued by the JavaScript is generated using the `HTML'
268	;;; construct. In fact, we have two different HTML generators in the
269	;;; example below, one is the standard Lisp HTML generator, and the
270	;;; other is the JavaScript HTML generator, which generates a
271	;;; JavaScript expression.
272
273	(defun slideshow (req ent)
274	(declare (ignore req ent))
275	(html
276	(:html
277	(:head (:title "ParenScript slideshow")
278	((:script :language "JavaScript"
279	:src "/slideshow.js"))
280	(js-script
281	(defvar linkornot 0)
282	(defvar photos (array "photo1.png"
283	"photo2.png"
284	"photo3.png"))))
285	(:body (:h1 "ParenScript slideshow")
286	(:body (:h2 "Hello")
287	((:table :border 0
288	:cellspacing 0
289	:cellpadding 0)
290	(:tr ((:td :width "100%" :colspan 2 :height 22)
291	(:center
292	(js-script
293	(let ((img
294	(html
295	((:img :src (aref photos 0)
296	:name "photoslider"
297	:style ( + "filter:"
298	(js (reveal-trans
299	(setf duration 2)
300	(setf transition 23))))
301	:border 0)))))
302	(document.write
303	(if (= linkornot 1)
304	(html ((:a :href "#"
305	:onclick (js-inline (transport)))
306	img))
307	img)))))))
308	(:tr ((:td :width "50%" :height "21")
309	((:p :align "left")
310	((:a :href "#"
311	:onclick (js-inline (backward)
312	(return false)))
313	"Previous Slide")))
314	((:td :width "50%" :height "21")
315	((:p :align "right")
316	((:a :href "#"
317	:onclick (js-inline (forward)
318	(return false)))
319	"Next Slide"))))))))))
320
321	;;; `SLIDESHOW' generates the following HTML code (long lines have
322	;;; been broken down):
323
324	<html><head><title>ParenScript slideshow</title>
325	<script language="JavaScript" src="/slideshow.js"></script>
326	<script type="text/javascript">
327	// <![CDATA[
328	var LINKORNOT = 0;
329	var photos = [ "photo1.png", "photo2.png", "photo3.png" ];
330	// ]]>
331	</script>
332	</head>
333	<body><h1>ParenScript slideshow</h1>
334	<body><h2>Hello</h2>
335	<table border="0" cellspacing="0" cellpadding="0">
336	<tr><td width="100%" colspan="2" height="22">
337	<center><script type="text/javascript">
338	// <![CDATA[
339	var img =
340	"<img src=\"" + photos[0]
341	+ "\" name=\"photoslider\"
342	style=\"filter:revealTrans(duration=2,transition=23)\"
343	border=\"0\"></img>";
344	document.write(LINKORNOT == 1 ?
345	"<a href=\"#\"
346	onclick=\"javascript:transport()\">"
347	+ img + "</a>"
348	: img);
349	// ]]>
350	</script>
351	</center>
352	</td>
353	</tr>
354	<tr><td width="50%" height="21"><p align="left">
355	<a href="#"
356	onclick="javascript:backward(); return false;">Previous Slide</a>
357
358	</p>
359	</td>
360	<td width="50%" height="21"><p align="right">
361	<a href="#"
362	onclick="javascript:forward(); return false;">Next Slide</a>
363	</p>
364	</td>
365	</tr>
366	</table>
367	</body>
368	</body>
369	</html>
370
8e198a08 MB	371	;;; The actual slideshow application is generated by the function
	372	;;; `JS-SLIDESHOW', which generates a ParenScript file. The code is
	373	;;; pretty straightforward for a lisp savy person. Symbols are
	374	;;; converted to JavaScript variables, but the dot "." is left as
	375	;;; is. This enables us to access object "slots" without using the
	376	;;; `SLOT-VALUE' function all the time. However, when the object we
	377	;;; are referring to is not a variable, but for example an element of
	378	;;; an array, we have to revert to `SLOT-VALUE'.
	379
	380	(defun js-slideshow (req ent)
	381	(declare (ignore req ent))
	382	(js-file
	383	(defvar preloaded-images (make-array))
	384	(defun preload-images (photos)
	385	(dotimes (i photos.length)
	386	(setf (aref preloaded-images i) (new *Image)
	387	(slot-value (aref preloaded-images i) 'src)
	388	(aref photos i))))
551080b7	389
8e198a08 MB	390	(defun apply-effect ()
	391	(when (and document.all photoslider.filters)
	392	(let ((trans photoslider.filters.reveal-trans))
	393	(setf (slot-value trans '*Transition)
	394	(floor (* (random) 23)))
	395	(trans.stop)
	396	(trans.apply))))
551080b7	397
8e198a08 MB	398	(defun play-effect ()
	399	(when (and document.all photoslider.filters)
	400	(photoslider.filters.reveal-trans.play)))
	401
	402	(defvar which 0)
551080b7	403
8e198a08 MB	404	(defun keep-track ()
	405	(setf window.status
	406	(+ "Image " (1+ which) " of " photos.length)))
551080b7	407
8e198a08 MB	408	(defun backward ()
	409	(when (> which 0)
	410	(decf which)
	411	(apply-effect)
	412	(setf document.images.photoslider.src
	413	(aref photos which))
	414	(play-effect)
	415	(keep-track)))
551080b7	416
8e198a08 MB	417	(defun forward ()
	418	(when (< which (1- photos.length))
	419	(incf which)
	420	(apply-effect)
	421	(setf document.images.photoslider.src
	422	(aref photos which))
	423	(play-effect)
	424	(keep-track)))
551080b7	425
8e198a08 MB	426	(defun transport ()
	427	(setf window.location (aref photoslink which)))))
	428
	429	;;; `JS-SLIDESHOW' generates the following JavaScript code:
	430
	431	var PRELOADEDIMAGES = new Array();
	432	function preloadImages(photos) {
	433	for (var i = 0; i != photos.length; i = i++) {
	434	PRELOADEDIMAGES[i] = new Image;
	435	PRELOADEDIMAGES[i].src = photos[i];
	436	}
	437	}
	438	function applyEffect() {
	439	if (document.all && photoslider.filters) {
	440	var trans = photoslider.filters.revealTrans;
	441	trans.Transition = Math.floor(Math.random() * 23);
	442	trans.stop();
	443	trans.apply();
	444	}
	445	}
	446	function playEffect() {
	447	if (document.all && photoslider.filters) {
	448	photoslider.filters.revealTrans.play();
	449	}
	450	}
	451	var WHICH = 0;
	452	function keepTrack() {
	453	window.status = "Image " + (WHICH + 1) + " of " +
	454	photos.length;
	455	}
	456	function backward() {
	457	if (WHICH > 0) {
	458	--WHICH;
	459	applyEffect();
	460	document.images.photoslider.src = photos[WHICH];
	461	playEffect();
	462	keepTrack();
	463	}
	464	}
	465	function forward() {
	466	if (WHICH < photos.length - 1) {
	467	++WHICH;
	468	applyEffect();
	469	document.images.photoslider.src = photos[WHICH];
	470	playEffect();
	471	keepTrack();
	472	}
	473	}
	474	function transport() {
	475	window.location = photoslink[WHICH];
	476	}
	477
	478	;;;# Customizing the slideshow
	479
	480	;;; For now, the slideshow has the path to all the slideshow images
	481	;;; hardcoded in the HTML code, as well as in the publish
	482	;;; statements. We now want to customize this by publishing a
	483	;;; slideshow under a certain path, and giving it a list of image urls
	484	;;; and pathnames where those images can be found. For this, we will
	485	;;; create a function `PUBLISH-SLIDESHOW' which takes a prefix as
	486	;;; argument, as well as a list of image pathnames to be published.
	487
	488	(defun publish-slideshow (prefix images)
	489	(let* ((js-url (format nil "~Aslideshow.js" prefix))
490	(html-url (format nil "~Aslideshow" prefix))
491	(image-urls
492	(mapcar #'(lambda (image)
493	(format nil "~A~A.~A" prefix
494	(pathname-name image)
495	(pathname-type image)))
496	images)))
497	(publish :path html-url
498	:content-type "text/html"
499	:function #'(lambda (req ent)
500	(with-http-response (req ent)
501	(with-http-body (req ent)
502	(slideshow2 req ent image-urls)))))
503	(publish :path js-url
504	:content-type "text/html"
505	:function #'(lambda (req ent)
506	(with-http-response (req ent)
507	(with-http-body (req ent)
508	(js-slideshow req ent)))))
509	(map nil #'(lambda (image url)
510	(publish-file :path url
511	:file image))
512	images image-urls)))
513
514	(defun slideshow2 (req ent image-urls)
515	(declare (ignore req ent))
516	(html
517	(:html
518	(:head (:title "ParenScript slideshow")
519	((:script :language "JavaScript"
520	:src "/slideshow.js"))
521	((:script :type "text/javascript")
522	(:princ (format nil "~%// <![CDATA[~%"))
523	(:princ (js (defvar linkornot 0)))
524	(:princ (js-to-string `(defvar photos
525	(array ,@image-urls))))
526	(:princ (format nil "~%// ]]>~%"))))
527	(:body (:h1 "ParenScript slideshow")
528	(:body (:h2 "Hello")
529	((:table :border 0
530	:cellspacing 0
531	:cellpadding 0)
532	(:tr ((:td :width "100%" :colspan 2 :height 22)
533	(:center
534	(js-script
535	(let ((img
536	(html
537	((:img :src (aref photos 0)
538	:name "photoslider"
539	:style ( + "filter:"
540	(js (reveal-trans
541	(setf duration 2)
542	(setf transition 23))))
543	:border 0)))))
544	(document.write
545	(if (= linkornot 1)
546	(html ((:a :href "#"
547	:onclick (js-inline (transport)))
548	img))
549	img)))))))
550	(:tr ((:td :width "50%" :height "21")
551	((:p :align "left")
552	((:a :href "#"
553	:onclick (js-inline (backward)
554	(return false)))
555	"Previous Slide")))
556	((:td :width "50%" :height "21")
557	((:p :align "right")
558	((:a :href "#"
559	:onclick (js-inline (forward)
560	(return false)))
561	"Next Slide"))))))))))
562
563	;;; We can now publish the same slideshow as before, under the
564	;;; "/bknr/" prefix:
565
94a05cdf	566	(publish-slideshow "/bknr/"
8e198a08 MB	567	`("/home/manuel/bknr-sputnik.png"
	568	"/home/manuel/bknrlogo_red648.png"
	569	"/home/manuel/screenshots/screenshot-14.03.2005-11.54.33.png"))
	570
	571	;;; That's it, we can now access our customized slideshow under
	572
	573	http://localhost:8000/bknr/slideshow
	574