mirror of
https://github.com/scratchfoundation/scratchx.git
synced 2024-12-11 00:31:01 -05:00
47 lines
1.7 KiB
JavaScript
47 lines
1.7 KiB
JavaScript
// Convert ArrayBuffers to/from Base64
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(function() {
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var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
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window.ab_to_b64 = function (arraybuffer) {
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var bytes = new Uint8Array(arraybuffer), i, len = bytes.length, base64 = '';
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for (i = 0; i < len; i += 3) {
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base64 += chars[bytes[i] >> 2];
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base64 += chars[((bytes[i] & 3) << 4) | (bytes[i + 1] >> 4)];
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base64 += chars[((bytes[i + 1] & 15) << 2) | (bytes[i + 2] >> 6)];
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base64 += chars[bytes[i + 2] & 63];
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}
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if ((len % 3) === 2) {
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base64 = base64.substring(0, base64.length - 1) + '=';
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} else if (len % 3 === 1) {
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base64 = base64.substring(0, base64.length - 2) + '==';
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}
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return base64;
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}
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window.b64_to_ab = function (base64) {
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var bufferLength = base64.length * 0.75, len = base64.length, i, p = 0, encoded1, encoded2, encoded3, encoded4;
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if (base64[base64.length - 1] === '=') {
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--bufferLength;
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if (base64[base64.length - 2] === '=') {
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--bufferLength;
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}
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}
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var arraybuffer = new ArrayBuffer(bufferLength), bytes = new Uint8Array(arraybuffer);
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for (i = 0; i < len; i += 4) {
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encoded1 = chars.indexOf(base64[i]);
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encoded2 = chars.indexOf(base64[i + 1]);
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encoded3 = chars.indexOf(base64[i + 2]);
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encoded4 = chars.indexOf(base64[i + 3]);
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bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
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bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
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bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
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}
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return arraybuffer;
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}
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})();
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