src/library/png.cpp

   1 #include "png.hpp"
   2
   3 #include <fstream>
   4 #include <iostream>
   5 #include <cstdint>
   6 #include <zlib.h>
   7 #include <boost/iostreams/categories.hpp>
   8 #include <boost/iostreams/copy.hpp>
   9 #include <boost/iostreams/stream.hpp>
  10 #include <boost/iostreams/stream_buffer.hpp>
  11 #include <boost/iostreams/filter/symmetric.hpp>
  12 #include <boost/iostreams/filter/zlib.hpp>
  13 #include <boost/iostreams/filtering_stream.hpp>
  14 #include <boost/iostreams/device/back_inserter.hpp>
  15
  16 namespace
  17 {
  18         void encode32(char* _buf, uint32_t val) throw()
  19         {
  20                 unsigned char* buf = reinterpret_cast<unsigned char*>(_buf);
  21                 buf[0] = ((val >> 24) & 0xFF);
  22                 buf[1] = ((val >> 16) & 0xFF);
  23                 buf[2] = ((val >> 8) & 0xFF);
  24                 buf[3] = (val & 0xFF);
  25         }
  26
  27         class png_hunk_output
  28         {
  29         public:
  30                 typedef char char_type;
  31                 struct category : boost::iostreams::closable_tag, boost::iostreams::sink_tag {};
  32                 png_hunk_output(std::ostream& _os, uint32_t _type)
  33                         : os(_os), type(_type)
  34                 {
  35                 }
  36
  37                 void close()
  38                 {
  39                         uint32_t crc = crc32(0, NULL, 0);
  40                         char fixed[12];
  41                         encode32(fixed, stream.size());
  42                         encode32(fixed + 4, type);
  43                         crc = crc32(crc, reinterpret_cast<Bytef*>(fixed + 4), 4);
  44                         if(stream.size() > 0)
  45                                 crc = crc32(crc, reinterpret_cast<Bytef*>(&stream[0]), stream.size());
  46                         encode32(fixed + 8, crc);
  47                         os.write(fixed, 8);
  48                         os.write(&stream[0], stream.size());
  49                         os.write(fixed + 8, 4);
  50                 }
  51
  52                 std::streamsize write(const char* s, std::streamsize n)
  53                 {
  54                         size_t oldsize = stream.size();
  55                         stream.resize(oldsize + n);
  56                         memcpy(&stream[oldsize], s, n);
  57                         return n;
  58                 }
  59         protected:
  60                 std::vector<char> stream;
  61                 std::ostream& os;
  62                 uint32_t type;
  63         };
  64 }
  65
  66 void save_png_data(const std::string& file, uint8_t* data24, uint32_t width, uint32_t height) throw(std::bad_alloc,
  67         std::runtime_error)
  68 {
  69         char* data = reinterpret_cast<char*>(data24);
  70         std::ofstream filp(file.c_str());
  71         if(!filp)
  72                 throw std::runtime_error("Can't open target PNG file");
  73         char png_magic[] = {-119, 80, 78, 71, 13, 10, 26, 10};
  74         filp.write(png_magic, sizeof(png_magic));
  75         char ihdr[] = {25, 25, 25, 25, 25, 25, 25, 25, 8, 2, 0, 0, 0};
  76         boost::iostreams::stream<png_hunk_output> ihdr_h(filp, 0x49484452);
  77         encode32(ihdr, width);
  78         encode32(ihdr + 4, height);
  79         ihdr_h.write(ihdr, sizeof(ihdr));
  80         ihdr_h.close();
  81
  82         boost::iostreams::filtering_ostream idat_h;
  83         boost::iostreams::zlib_params params;
  84         params.noheader = false;
  85         idat_h.push(boost::iostreams::zlib_compressor(params));
  86         idat_h.push(png_hunk_output(filp, 0x49444154));
  87         for(uint32_t i = 0; i < height; i++) {
  88                 char identity_filter = 0;
  89                 idat_h.write(&identity_filter, 1);
  90                 idat_h.write(data + i * 3 * width, 3 * width);
  91         }
  92         idat_h.pop();
  93         idat_h.pop();
  94
  95         boost::iostreams::stream<png_hunk_output> iend_h(filp, 0x49454E44);
  96         iend_h.close();
  97         if(!filp)
  98                 throw std::runtime_error("Can't write target PNG file");
  99 }