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92 lines
2.5 KiB
C++
92 lines
2.5 KiB
C++
/*
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LodePNG Examples
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Copyright (c) 2005-2012 Lode Vandevenne
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source
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distribution.
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*/
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#include "lodepng.h"
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#include <iostream>
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#include <stdlib.h>
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/*
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Encodes given file as a gzip file.
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See also the gzip specification, RFC 1952: http://www.gzip.org/zlib/rfc-gzip.html
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*/
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//g++ lodepng.cpp example_gzip.cpp -ansi -pedantic -Wall -Wextra -O3
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//saves image to filename given as argument. Warning, this overwrites the file without warning!
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int main(int argc, char *argv[]) {
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if(argc < 2) {
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std::cout << "Please provide input filename (output is input with .gz)" << std::endl;
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return 0;
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}
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//NOTE: this sample will overwrite the output file without warning!
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std::string infilename = argv[1];
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std::string outfilename = infilename + ".gz";
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std::vector<unsigned char> in;
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lodepng::load_file(in, infilename);
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size_t outsize = 10;
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unsigned char* out = (unsigned char*)malloc(outsize);
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out[0] = 31; //ID1
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out[1] = 139; //ID2
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out[2] = 8; //CM
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out[3] = 0; //FLG
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//MTIME
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out[4] = 0;
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out[5] = 0;
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out[6] = 0;
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out[7] = 0;
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out[8] = 2; //2 = slow, 4 = fast compression
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out[9] = 255; //OS unknown
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lodepng_deflate(&out, &outsize, &in[0], in.size(), &lodepng_default_compress_settings);
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unsigned crc = lodepng_crc32(&in[0], in.size());
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size_t footer = outsize;
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outsize += 8;
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out = (unsigned char*)realloc(out, outsize);
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//CRC
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out[footer + 0] = crc % 256;
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out[footer + 1] = (crc >> 8) % 256;
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out[footer + 2] = (crc >> 16) % 256;
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out[footer + 3] = (crc >> 24) % 256;
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//ISIZE
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out[footer + 4] = in.size() % 256;
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out[footer + 5] = (in.size() >> 8) % 256;
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out[footer + 6] = (in.size() >> 16) % 256;
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out[footer + 7] = (in.size() >> 24) % 256;
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lodepng_save_file(out, outsize, outfilename.c_str());
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free(out);
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}
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