45 lines
857 B
Plaintext
45 lines
857 B
Plaintext
'use strict';
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var ParserStream = require('../common').ParserStream;
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var str2arr = require('../common').str2arr;
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var sliceEq = require('../common').sliceEq;
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var SIG_PNG = str2arr('\x89PNG\r\n\x1a\n');
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var SIG_IHDR = str2arr('IHDR');
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module.exports = function () {
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var parser = new ParserStream();
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parser._bytes(24, function (data) {
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parser._skipBytes(Infinity);
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// check PNG signature
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if (!sliceEq(data, 0, SIG_PNG)) {
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parser.push(null);
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return;
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}
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// check that first chunk is IHDR
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if (!sliceEq(data, 12, SIG_IHDR)) {
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parser.push(null);
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return;
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}
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parser.push({
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width: data.readUInt32BE(16),
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height: data.readUInt32BE(20),
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type: 'png',
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mime: 'image/png',
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wUnits: 'px',
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hUnits: 'px'
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});
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parser.push(null);
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});
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return parser;
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};
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