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