98 lines
2.7 KiB
C++
98 lines
2.7 KiB
C++
#include "png.hpp"
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#include <fstream>
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#include <iostream>
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#include <cstdint>
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#include <boost/iostreams/categories.hpp>
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#include <boost/iostreams/copy.hpp>
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#include <boost/iostreams/stream.hpp>
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#include <boost/iostreams/stream_buffer.hpp>
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#include <boost/iostreams/filter/symmetric.hpp>
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#include <boost/iostreams/filter/zlib.hpp>
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#include <boost/iostreams/filtering_stream.hpp>
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#include <boost/iostreams/device/back_inserter.hpp>
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#include <zlib.h>
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namespace
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{
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void encode32(char* _buf, uint32_t val) throw()
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{
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unsigned char* buf = reinterpret_cast<unsigned char*>(_buf);
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buf[0] = ((val >> 24) & 0xFF);
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buf[1] = ((val >> 16) & 0xFF);
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buf[2] = ((val >> 8) & 0xFF);
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buf[3] = (val & 0xFF);
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}
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class png_hunk_output
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{
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public:
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typedef char char_type;
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struct category : boost::iostreams::closable_tag, boost::iostreams::sink_tag {};
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png_hunk_output(std::ostream& _os, uint32_t _type)
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: os(_os), type(_type)
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{
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}
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void close()
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{
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uint32_t crc = crc32(0, NULL, 0);
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char fixed[12];
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encode32(fixed, stream.size());
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encode32(fixed + 4, type);
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crc = crc32(crc, reinterpret_cast<Bytef*>(fixed + 4), 4);
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if(stream.size() > 0)
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crc = crc32(crc, reinterpret_cast<Bytef*>(&stream[0]), stream.size());
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encode32(fixed + 8, crc);
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os.write(fixed, 8);
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os.write(&stream[0], stream.size());
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os.write(fixed + 8, 4);
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}
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std::streamsize write(const char* s, std::streamsize n)
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{
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size_t oldsize = stream.size();
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stream.resize(oldsize + n);
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memcpy(&stream[oldsize], s, n);
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return n;
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}
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protected:
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std::vector<char> stream;
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std::ostream& os;
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uint32_t type;
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};
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}
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void save_png_data(const std::string& file, uint8_t* data24, uint32_t width, uint32_t height) throw(std::bad_alloc,
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std::runtime_error)
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{
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char* data = reinterpret_cast<char*>(data24);
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std::ofstream filp(file.c_str());
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if(!filp)
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throw std::runtime_error("Can't open target PNG file");
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char png_magic[] = {-119, 80, 78, 71, 13, 10, 26, 10};
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filp.write(png_magic, sizeof(png_magic));
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char ihdr[] = {25, 25, 25, 25, 25, 25, 25, 25, 8, 2, 0, 0, 0};
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boost::iostreams::stream<png_hunk_output> ihdr_h(filp, 0x49484452);
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encode32(ihdr, width);
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encode32(ihdr + 4, height);
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ihdr_h.write(ihdr, sizeof(ihdr));
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ihdr_h.close();
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boost::iostreams::filtering_ostream idat_h;
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boost::iostreams::zlib_params params;
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params.noheader = false;
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idat_h.push(boost::iostreams::zlib_compressor(params));
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idat_h.push(png_hunk_output(filp, 0x49444154));
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for(uint32_t i = 0; i < height; i++) {
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char identity_filter = 0;
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idat_h.write(&identity_filter, 1);
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idat_h.write(data + i * 3 * width, 3 * width);
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}
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idat_h.pop();
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idat_h.pop();
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boost::iostreams::stream<png_hunk_output> iend_h(filp, 0x49454E44);
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iend_h.close();
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if(!filp)
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throw std::runtime_error("Can't write target PNG file");
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}
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