92 lines
2.5 KiB
C++
92 lines
2.5 KiB
C++
#include <exception>
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#include "grey.hpp"
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#include <arpa/inet.h>
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#define STB_IMAGE_IMPLEMENTATION
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#include "stb_image.h"
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#define STB_IMAGE_WRITE_IMPLEMENTATION
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#include "stb_image_write.h"
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static void push_in_network_order(std::uint32_t input, std::vector<std::uint8_t>& output)
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{
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input = htonl(input);
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auto pointer_range = reinterpret_cast<std::uint8_t *>(&input);
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std::copy(pointer_range, pointer_range + 4, std::back_inserter(output));
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}
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static std::uint32_t pop_in_native_order(std::string::const_iterator& input)
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{
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std::uint32_t in_native = ntohl(*reinterpret_cast<const std::uint32_t *>(&*input));
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input += 4;
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return in_native;
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}
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std::vector<std::uint8_t> to_rle(const std::filesystem::path& input)
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{
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int x, y, n;
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unsigned char *data = stbi_load(input.native().data(), &x, &y, &n, 1);
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if (data == nullptr)
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{
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throw std::runtime_error(stbi_failure_reason());
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}
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unsigned char *original_data = data;
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std::uint8_t current_color = 255;
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std::uint32_t current_count = 0;
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std::vector<std::uint8_t> rle_stream;
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push_in_network_order(x, rle_stream);
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push_in_network_order(y, rle_stream);
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push_in_network_order(1, rle_stream);
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for (std::size_t i = 0; i < x; ++i)
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{
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for (std::size_t j = 0; j < y; ++j)
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{
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if (current_color == *data)
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{
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++current_count;
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}
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else
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{
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current_color = current_color == 255 ? 0 : 255;
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push_in_network_order(current_count, rle_stream);
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current_count = 1;
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}
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++data;
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}
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}
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stbi_image_free(original_data);
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if (current_count != 0)
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{
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push_in_network_order(current_count, rle_stream);
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}
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return rle_stream;
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}
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void from_rle(const std::string& input, const std::filesystem::path& output)
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{
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std::vector<std::uint8_t> buffer;
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auto input_position = std::cbegin(input);
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int x = pop_in_native_order(input_position);
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int y = pop_in_native_order(input_position);
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int comp = pop_in_native_order(input_position);
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std::uint8_t current_color = 255;
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std::uint32_t current_count = 0;
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while (input_position != std::cend(input))
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{
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auto in_native = pop_in_native_order(input_position);
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for (; in_native > 0; --in_native)
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{
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buffer.push_back(current_color);
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}
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current_color = current_color == 255 ? 0 : 255;
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}
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stbi_write_jpg(output.native().data(), x, y, comp, buffer.data(), 100);
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}
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