Спринт 15. Системы сборки и зачем они нужны.

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img_lib.h
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#pragma once

#include <array>
#include <cassert>
#include <cstddef>
#include <vector>

namespace img_lib {

struct Size {
    int width;
    int height;
};

struct Color {
    static Color Black() {return {std::byte{0}, std::byte{0}, std::byte{0}, std::byte{255}};}

    std::byte r, g, b, a;
};

class Image {
public:

    Image() = default;

    Image(int w, int h, Color fill);

    Color GetPixel(int x, int y) const {
        return const_cast<Image*>(this)->GetPixel(x, y);
    }
    Color& GetPixel(int x, int y) {
        assert(x < GetWidth() && y < GetHeight() && x >= 0 && y >= 0);
        return GetLine(y)[x];
    }

    Color* GetLine(int y);
    const Color* GetLine(int y) const;

    int GetWidth() const;
    int GetHeight() const;

    int GetStep() const;

    explicit operator bool() const {return GetWidth() > 0 && GetHeight() > 0;}
    bool operator!() const {return !operator bool();}

private:
    int width_ = 0;
    int height_ = 0;
    int step_;

    std::vector<Color> pixels_;
};

}//end namespace img_lib
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img_lib.cpp
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#include "img_lib.h"

namespace img_lib {

Image::Image(int w, int h, Color fill) : width_(w)
                                       , height_(h)
                                       , step_(w)
                                       , pixels_(step_ * height_, fill) {}

Color* Image::GetLine(int y) {
    assert(y >= 0 && y < height_);
    return pixels_.data() + step_ * y;
}

const Color* Image::GetLine(int y) const {return const_cast<Image*>(this)->GetLine(y);}
int Image::GetWidth() const {return width_;}
int Image::GetHeight() const {return height_;}
int Image::GetStep() const {return step_;}

}//end namespace img_lib
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ppm_image.h
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#pragma once
#include "img_lib.h"

#include <filesystem>

namespace img_lib {
using Path = std::filesystem::path;

bool SavePPM(const Path& file, const Image& image);
Image LoadPPM(const Path& file);

}//end namespace img_lib
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ppm_image.cpp
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#include "ppm_image.h"

#include <array>
#include <fstream>
#include <string_view>

using namespace std;

namespace img_lib {

static const string_view PPM_SIG = "P6"sv;
static const int PPM_MAX = 255;

bool SavePPM(const Path& file, const Image& image) {
    ofstream ofs(file, ios::out | ios::binary);
    int w{image.GetWidth()};
    int h{image.GetHeight()};
    int color_max{PPM_MAX};

    ofs << PPM_SIG << '\n' << w << ' ' << h << '\n' << color_max << '\n';

    Image result{image};
    std::vector<char> buff(w * 3);

    for (int y = 0; y < h; ++y) {

        Color* line = result.GetLine(y);
        for (int x = 0; x < w; ++x) {
            buff[x * 3 + 0] = static_cast<char>(line[x].r);
            buff[x * 3 + 1] = static_cast<char>(line[x].g);
            buff[x * 3 + 2] = static_cast<char>(line[x].b);
        }

        ofs.write(buff.data(), w * 3);

        if (ofs.fail()) {
            return false;
        }
    }

    return true;
}

Image LoadPPM(const Path& file) {
    ifstream ifs(file, ios::binary);
    std::string sign;
    int w, h, color_max;

    ifs >> sign >> w >> h >> color_max;

    if (sign != PPM_SIG || color_max != PPM_MAX) {return {};}

    const char next = ifs.get();
    if (next != '\n') {return {};}

    Image result(w, h, Color::Black());
    std::vector<char> buff(w * 3);

    for (int y = 0; y < h; ++y) {

        Color* line = result.GetLine(y);
        ifs.read(buff.data(), w * 3);

        for (int x = 0; x < w; ++x) {
            line[x].r = static_cast<byte>(buff[x * 3 + 0]);
            line[x].g = static_cast<byte>(buff[x * 3 + 1]);
            line[x].b = static_cast<byte>(buff[x * 3 + 2]);
        }
    }

    return result;
}

}//end namespace img_lib
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main.cpp
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#include "ppm_image.h"

#include <iostream>
#include <string_view>

using namespace std;

int main(int argc, const char** argv) {

    if (argc != 3) {
        cerr << "Usage: "sv << argv[0] << " <input image> <output image>"sv << endl;
        return 1;
    }

    const auto image = img_lib::LoadPPM(argv[1]);
    if (!image) {
        cerr << "Error loading image"sv << endl;
        return 2;
    }

    if (!img_lib::SavePPM(argv[2], image)) {
        cerr << "Error saving image"sv << endl;
        return 3;
    }

    cout << "Image saved successfully!"sv << endl;
}