psemek/libs/gfx/source/netpbm.cpp

#include <psemek/gfx/pixmap.hpp>
#include <psemek/util/exception.hpp>

#include <iostream>
#include <sstream>
#include <vector>

namespace psemek::gfx
{

	pixmap_monochrome read_pbm(std::istream & is)
	{
		auto fail = [](std::string str)
		{
			throw util::exception("Error loading PBM image: " + str);
		};

		std::string line;
		std::getline(is, line);

		bool binary = true;

		if (line == "P1")
		{
			binary = false;
		}
		else if (line == "P4")
		{
			binary = true;
		}
		else
			fail("unknown format " + line);

		if (!binary)
			fail("P1 format is not supported");

		std::getline(is, line);
		if (!is)
			fail("stream error");
		std::istringstream sline(line);

		std::size_t width, height;
		pixmap_monochrome pixmap;

		sline >> width >> height;
		if (!sline)
			fail("stream error");

		pixmap.resize({width, height});

		std::size_t bytes = width * height;
		if ((bytes % 8) == 0)
			bytes = bytes / 8;
		else
			bytes = (bytes + 7) / 8;
		std::vector<std::uint8_t> data(bytes);
		is.read(reinterpret_cast<char *>(data.data()), bytes);

		for (std::size_t i = 0; i < width * height; ++i)
		{
			std::size_t b = i / 8;
			std::size_t o = 7 - (i % 8);
			bool const white = (data[b] & (1 << o)) == 0;
			pixmap.data()[i] = white ? 255 : 0;
		}

		if (!is)
			fail("stream error");

		return pixmap;
	}

	pixmap_monochrome read_pgm(std::istream & is)
	{
		auto fail = [](std::string str)
		{
			throw util::exception("Error loading PGM image: " + str);
		};

		std::string line;
		std::getline(is, line);

		bool binary = true;

		if (line == "P2")
		{
			binary = false;
		}
		else if (line == "P5")
		{
			binary = true;
		}
		else
			fail("unknown format " + line);

		std::getline(is, line);
		if (!is)
			fail("stream error");
		std::istringstream sline(line);

		std::size_t width, height;
		std::size_t max;
		pixmap_monochrome pixmap;

		sline >> width >> height;
		if (!sline)
			fail("stream error");

		std::getline(is, line);
		if (!is)
			fail("stream error");
		sline.clear();
		sline.str(line);
		sline >> max;
		if (!sline)
			fail("stream error");

		if (max != 255)
			fail("max value " + std::to_string(max) + " is not supported");

		pixmap.resize({width, height});

		if (binary)
			is.read(reinterpret_cast<char *>(pixmap.data()), width * height * sizeof(pixmap.data()[0]));
		else
			fail("P2 format is not supported");

		if (!is)
			fail("stream error");

		return pixmap;
	}

	pixmap_rgb read_ppm(std::istream & is)
	{
		auto fail = [](std::string str)
		{
			throw util::exception("Error loading PPM image: " + str);
		};

		std::string line;
		std::getline(is, line);

		bool binary = true;

		if (line == "P3")
		{
			binary = false;
		}
		else if (line == "P6")
		{
			binary = true;
		}
		else
			fail("unknown format " + line);

		std::getline(is, line);
		if (!is)
			fail("stream error");
		std::istringstream sline(line);

		std::size_t width, height;
		std::size_t max;
		pixmap_rgb pixmap;

		sline >> width >> height;

		if (!sline)
			fail("stream error");

		std::getline(is, line);
		if (!is)
			fail("stream error");
		sline.clear();
		sline.str(line);
		sline >> max;
		if (!sline)
			fail("stream error");

		if (max != 255)
			fail("max value " + std::to_string(max) + " is not supported");

		pixmap.resize({width, height});

		if (binary)
			is.read(reinterpret_cast<char *>(pixmap.data()), width * height * sizeof(pixmap.data()[0]));
		else
			fail("P3 format is not supported");

		if (!is)
			fail("stream error");

		return pixmap;
	}

	void write_pgm(pixmap_monochrome const & p, std::ostream & os)
	{
		os << "P5\n" << p.width() << " " << p.height() << "\n255\n";
		os.write(reinterpret_cast<char const *>(p.data()), p.width() * p.height() * sizeof(p.data()[0]));
	}

	void write_ppm(pixmap_rgb const & p, std::ostream & os)
	{
		os << "P6\n" << p.width() << " " << p.height() << "\n255\n";
		os.write(reinterpret_cast<char const *>(p.data()), p.width() * p.height() * sizeof(p.data()[0]));
	}

}