C++ library for streaming images (png/jpg/bmp)
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//
// png.hpp
// ImageStreams
//
// Created by Joshua Moerman on 9/7/12.
// Copyright (c) 2012 Vadovas. All rights reserved.
//
#ifndef ImageStreams_png_hpp
#define ImageStreams_png_hpp
#include <stdio.h>
#include <stdexcept>
#include <vector>
#include <png.h>
#include "basics.hpp"
namespace png{
template <typename P>
int color_type(){
int num_colors = pixel_formats::traits<P>::num_colors;
switch (num_colors) {
case 1: return PNG_COLOR_TYPE_GRAY;
case 2: return PNG_COLOR_TYPE_GRAY_ALPHA;
case 3: return PNG_COLOR_TYPE_RGB;
case 4: return PNG_COLOR_TYPE_RGB_ALPHA;
default: return PNG_COLOR_TYPE_RGB;
}
}
template <typename P = pixel_formats::rgb>
struct ostream{
typedef P pixel;
ostream() = delete;
ostream(ostream const &) = delete;
ostream & operator=(ostream const &) = delete;
ostream(uint32_t width, uint32_t height, std::string filename)
: fp(0)
, png_ptr(0)
, info_ptr(0)
, row(width)
, x(0)
{
fp = fopen(filename.c_str(), "wb");
if(!fp) throw std::runtime_error("Could not open file");
png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
if(!png_ptr) throw std::runtime_error("PNG structure could not be allocated");
info_ptr = png_create_info_struct(png_ptr);
if(!info_ptr) throw std::runtime_error("PNG information structure could not be allocated");
png_init_io(png_ptr, fp);
png_set_IHDR(png_ptr, info_ptr, width, height, pixel_formats::traits<pixel>::bits_per_color, color_type<pixel>(), PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
png_set_compression_level(png_ptr, 9);
png_write_info(png_ptr, info_ptr);
}
~ostream(){
// NOTE: the pnglib already checks for us whether all pixels are written
png_write_end(png_ptr, info_ptr);
png_destroy_info_struct(png_ptr, &info_ptr);
fclose(fp);
}
ostream& operator<<(pixel const & p){
row[x] = p;
++x;
if(x >= row.size()){
png_write_row(png_ptr, reinterpret_cast<unsigned char const*>(row.data()));
x = 0;
}
return *this;
}
private:
FILE* fp;
png_structp png_ptr;
png_infop info_ptr;
std::vector<pixel> row;
uint32_t x;
};
typedef ostream<> colored_ostream;
typedef ostream<pixel_formats::gray> gray_ostream;
}
#endif