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zopflib/src/zopflipng/lodepng/lodepng_util.cpp  view on Meta::CPAN

    next = lodepng_chunk_next_const(chunk);
    if (next <= chunk) return 1; // integer overflow

    if(name == "PLTE")
    {
      if(l0 == 0) l0 = chunk - begin + 8;
    }
    else if(name == "IDAT")
    {
      if(l0 == 0) l0 = chunk - begin + 8;
      if(l1 == 0) l1 = chunk - begin + 8;
    }
    else if(name == "IEND")
    {
      if(l2 == 0) l2 = chunk - begin + 8;
    }

    chunk = next;
  }

  std::vector<unsigned char> result;
  result.insert(result.end(), png.begin(), png.begin() + l0);
  for(size_t i = 0; i < chunks[0].size(); i++) result.insert(result.end(), chunks[0][i].begin(), chunks[0][i].end());
  result.insert(result.end(), png.begin() + l0, png.begin() + l1);
  for(size_t i = 0; i < chunks[1].size(); i++) result.insert(result.end(), chunks[1][i].begin(), chunks[1][i].end());
  result.insert(result.end(), png.begin() + l1, png.begin() + l2);
  for(size_t i = 0; i < chunks[2].size(); i++) result.insert(result.end(), chunks[2][i].begin(), chunks[2][i].end());
  result.insert(result.end(), png.begin() + l2, png.end());

  png = result;
  return 0;
}

unsigned getFilterTypesInterlaced(std::vector<std::vector<unsigned char> >& filterTypes,
                                  const std::vector<unsigned char>& png)
{
  //Get color type and interlace type
  lodepng::State state;
  unsigned w, h;
  unsigned error;
  error = lodepng_inspect(&w, &h, &state, &png[0], png.size());

  if(error) return 1;

  //Read literal data from all IDAT chunks
  const unsigned char *chunk, *begin, *end, *next;
  end = &png.back() + 1;
  begin = chunk = &png.front() + 8;

  std::vector<unsigned char> zdata;

  while(chunk + 8 < end && chunk >= begin)
  {
    char type[5];
    lodepng_chunk_type(type, chunk);
    if(std::string(type).size() != 4) return 1; //Probably not a PNG file

    if(std::string(type) == "IDAT")
    {
      const unsigned char* cdata = lodepng_chunk_data_const(chunk);
      unsigned clength = lodepng_chunk_length(chunk);
      if(chunk + clength + 12 > end || clength > png.size() || chunk + clength + 12 < begin) {
        // corrupt chunk length
        return 1;
      }

      for(unsigned i = 0; i < clength; i++)
      {
        zdata.push_back(cdata[i]);
      }
    }

    next = lodepng_chunk_next_const(chunk);
    if (next <= chunk) return 1; // integer overflow
    chunk = next;
  }

  //Decompress all IDAT data
  std::vector<unsigned char> data;
  error = lodepng::decompress(data, &zdata[0], zdata.size());

  if(error) return 1;

  if(state.info_png.interlace_method == 0)
  {
    filterTypes.resize(1);

    //A line is 1 filter byte + all pixels
    size_t linebytes = 1 + lodepng_get_raw_size(w, 1, &state.info_png.color);

    for(size_t i = 0; i < data.size(); i += linebytes)
    {
      filterTypes[0].push_back(data[i]);
    }
  }
  else
  {
    //Interlaced
    filterTypes.resize(7);
    static const unsigned ADAM7_IX[7] = { 0, 4, 0, 2, 0, 1, 0 }; /*x start values*/
    static const unsigned ADAM7_IY[7] = { 0, 0, 4, 0, 2, 0, 1 }; /*y start values*/
    static const unsigned ADAM7_DX[7] = { 8, 8, 4, 4, 2, 2, 1 }; /*x delta values*/
    static const unsigned ADAM7_DY[7] = { 8, 8, 8, 4, 4, 2, 2 }; /*y delta values*/
    size_t pos = 0;
    for(size_t j = 0; j < 7; j++)
    {
      unsigned w2 = (w - ADAM7_IX[j] + ADAM7_DX[j] - 1) / ADAM7_DX[j];
      unsigned h2 = (h - ADAM7_IY[j] + ADAM7_DY[j] - 1) / ADAM7_DY[j];
      if(ADAM7_IX[j] >= w) w2 = 0;
      if(ADAM7_IY[j] >= h) h2 = 0;
      size_t linebytes = 1 + lodepng_get_raw_size(w2, 1, &state.info_png.color);
      for(size_t i = 0; i < h2; i++)
      {
        filterTypes[j].push_back(data[pos]);
        pos += linebytes;
      }
    }
  }
  return 0; /* OK */
}


unsigned getFilterTypes(std::vector<unsigned char>& filterTypes, const std::vector<unsigned char>& png)
{
  std::vector<std::vector<unsigned char> > passes;
  unsigned error = getFilterTypesInterlaced(passes, png);
  if(error) return error;

  if(passes.size() == 1)