45 lines
1.2 KiB
JavaScript
45 lines
1.2 KiB
JavaScript
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// http://atlc.sourceforge.net/bmp.html
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// Any better format documentation?
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var fs = require('fs');
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var Pixmap = require('./pixmap').Pixmap;
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var Buffer = require('buffer').Buffer;
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require('../../lib/unpackbuffer').addUnpack(Buffer);
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var reversed = new Buffer(256);
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for (var i=0; i < 256; ++i)
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{
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var res = 0;
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for (b = 0; b < 8; ++b)
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{
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res += ((i & (1 << b) ) >> b) << (7-b);
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}
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reversed[i] = res;
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}
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module.exports.decodeBuffer = function(buffer)
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{
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var h = buffer.unpack('CCLxxxxLLLLSSLLLL');
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var header = {};
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header.filesize = h[2];
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header.data_offset = h[3];
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header.header_size = h[4];
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header.width = h[5];
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header.height = h[6];
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header.num_planes = h[7];
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header.bpp = h[8];
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header.compression = h[9];
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header.data_size = h[10];
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header.hresolution = h[11]; // pixels per METER!
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header.vresolution = h[12];
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// skipped: num colors, num important colors, palette
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var data = buffer.slice(header.data_offset, header.data_offset+header.data_size);
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// TODO: decode compressed bitmap
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//console.log(header);
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// mirror bits & invert
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for (var i=0; i < data.length; ++i)
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data[i] = 255 - reversed[data[i]];
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return new Pixmap(header.bpp, header.width, header.height, data);
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}
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