oxjstmp/build/js/ox.png.js
2010-01-07 21:21:07 +01:00

58 lines
1.6 KiB
JavaScript

onmessage = function(e) {
if (e.data.message) {
} else {
}
}
function encode() {
str = Ox.encodeUTF8(str);
var c = Ox.canvas(img), len = str.length;
if (len > maxLength(img.width, img.height)) {
throw new RangeError("PNG codec can't encode " + len +
" bytes into " + (img.width * img.height) + " pixels");
}
len = Ox.pad(Ox.encodeBase256(len), 4, Ox.char(0));
Ox.each(Ox.map(len + str, function(byte) {
return Ox.map(new Array(8), function(v, i) {
return byte.charCodeAt(0) >> 7 - i & 1;
}).join("");
}).join(""), function(i, bit) {
var index, byte = c.data[index = parseInt(i * 4/3)];
c.data[index] = bit == xor(byte) ? byte :
byte & 254 | !(byte & 1);
});
c.context.putImageData(c.imageData, 0, 0);
postMessage(c.canvas.toDataURL());
}
function decode() {
var c = Ox.canvas(img), bits = "", str = "", i = 0; len = 4, flag = false;
do {
bits += xor(c.data[parseInt(i * 4/3)]);
if (++i % 8 == 0) {
str += Ox.char(parseInt(bits, 2));
bits = "";
len--;
if (len == 0 && !flag) {
if ((len = Ox.decodeBase256(str)) >
maxLength(img.width, img.height)) {
throwPNGError();
}
str = "";
flag = true;
}
}
} while (len);
try {
return Ox.decodeUTF8(str);
} catch(e) {
throwPNGError();
}
}
function throwError() {
throw new RangeError("PNG codec can't decode image");
}