sanj/oxjs
1
0
Fork 0
forked from 0x2620/oxjs
Code Pull requests Activity

move examples

Browse source
This commit is contained in:
rolux 2012-06-21 23:14:38 +02:00
commit c3047a1586
47 changed files with 52 additions and 39 deletions
Download patch file Download diff file Expand all files Collapse all files

16
examples/images/steganography/css/example.css Normal file
View file

@ -0,0 +1,16 @@
body {
margin: 0;
}
table {
border-spacing: 8px;
}
td {
padding: 0;
border-collapse: collapse;
font-family: Lucida Grande, Segoe UI, DejaVu Sans, Lucida Sans Unicode, Helvetica, Arial, sans-serif;
font-size: 12px;
vertical-align: top;
}
td:first-child {
width: 320px;
}

13
examples/images/steganography/index.html Normal file
View file

@ -0,0 +1,13 @@
<!DOCTYPE html>
<html>
<head>
<title>Steganograpy</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<link rel="shortcut icon" type="image/png" href="../../../source/Ox.UI/themes/classic/png/icon16.png"/>
<link rel="stylesheet" type="text/css" href="css/example.css"/>
<script type="text/javascript" src="../../../dev/Ox.js"></script>
<script type="text/javascript" src="js/example.js"></script>
<script>window.addEventListener('message', function(e) { e.origin == window.location.origin && eval(e.data); });</script>
</head>
<body></body>
</html>

126
examples/images/steganography/js/example.js Normal file
View file

@ -0,0 +1,126 @@
/*
Ox.Image provides a pair of methods, <code>encode</code> and
<code>decode</code>, which can be used for
<a href="http://en.wikipedia.org/wiki/Steganography">steganography</a>, i.e. to
add a hidden message to an image.<br><br>
The signature of the <code>encode</code> function is
<code>image.encode(message, deflate, mode, callback)</code>.
<code>deflate</code> turns deflate-compression on or off, and <code>mode</code>
determines which bits of the image the message will be written to &mdash; but
for most purposes, the default values (<code>true</code> and <code>0</code>)
are fine, so <code>deflate</code> and <code>mode</code> can be omitted.<br>
<br>
In this example, we demonstrate a valid use case for <code>deflate</code> and
<code>mode</code>: To encode an decoy message (a line of text), which will be
relatively easy to detect, and then the the actual message, (another image,
itself containing another line of text), which will be harder to detect.
*/
'use strict';
Ox.load('Image', function() {
var $table = Ox.$('<table>').appendTo(Ox.$('body')),
$tr,
text = {
iceland: 'The first image he told me about '
+ 'was of three children on a road in Iceland in 1965.',
vietnam: 'He said for him it was the image of happiness, '
+ 'and that he had often tried to link it to other images, '
+ 'but it had never worked.'
};
encode(decode);
/*
So we first encode two lines text into two images, by writing them bit by
bit (without compression, <code>deflate = false</code>), into the least
significant bit of each 8-bit RGB value (<code>mode = 1</code>). Then we
encode one image into the other: We take the (deflate-compressed,
<code>deflate = true</code>) data URL of the source image and flip, if
needed, the second least significant bit of each RGB value of the target
image, so that the number of bits set to 1, modulo 2 (for example: 10101010
-&gt; 0), is the bit we're encoding (<code>mode = -1</code>). As the least
significant bit remains untouched, this will preserve the encoded text.
*/
function encode(callback) {
status('Load iceland.png');
Ox.Image('png/iceland.png', function(iceland) {
result(Ox.$('<img>').attr({src: iceland.src()}));
status(
'Encode the text <i>"' + text.iceland + '"</i> into '
+ 'the least significant bits of iceland.png'
);
iceland.encode(text.iceland, false, 1, function(iceland) {
result(Ox.$('<img>').attr({src: iceland.src()}));
status('Load vietnam.png');
Ox.Image('png/vietnam.png', function(vietnam) {
result(Ox.$('<img>').attr({src: vietnam.src()}));
status(
'Encode the text <i>"' + text.vietnam + '"</i> into'
+ ' the least significant bits of vietnam.png'
);
vietnam.encode(text.vietnam, false, 1, function(vietnam) {
result(Ox.$('<img>').attr({src: vietnam.src()}));
status(
'Encode vietnam.png into iceland.png '
+ 'by flipping the second least significant bits'
);
iceland.encode(vietnam.src(), -1, function(iceland) {
result(Ox.$('<img>').attr({src: iceland.src()}));
callback(iceland);
});
});
});
});
});
}
/*
Finally, we decode all the data again.
*/
function decode(iceland) {
status('Decode the least signigicant bits of iceland.png');
iceland.decode(false, 1, function(str) {
result(str);
status('Decode all bits of iceland.png');
iceland.decode(-1, function(src) {
result(
src.slice(0, 32) + '<i> ... ['
+ Ox.formatNumber(src.length - 64)
+ ' more bytes] ... </i>' + src.slice(-32)
);
status('Load as vietnam.png');
Ox.Image(src, function(image) {
result(Ox.$('<img>').attr({src: src}));
status('Decode the least significant bits of vietnam.png');
image.decode(false, 1, function(str) {
result(str);
});
});
});
});
}
function status(value) {
var $td = Ox.$('<td>');
if (Ox.isString(value)) {
$td.html(
value.replace(/(\w+\.png)/g, '<b>$1</b>')
);
} else {
$td.append(value);
}
$tr = Ox.$('<tr>').append($td).appendTo($table);
}
function result(value) {
var $td = Ox.$('<td>');
if (Ox.isString(value)) {
$td.html(value);
} else {
$td.append(value);
}
$tr.append($td);
}
});

BIN
examples/images/steganography/png/iceland.png Normal file
View file

Binary file not shown.
Side by side

After

Width:  |  Height:  |  Size: 250 KiB

BIN
examples/images/steganography/png/vietnam.png Normal file
View file

Binary file not shown.
Side by side

After

Width:  |  Height:  |  Size: 24 KiB