Спринт 15. Археологические раскопки: подключаем LibJPEG. Задание 1.

*** PACKAGE ImgConverter ***

-----------------------------------------------------------------------
CMakeLists.txt
-----------------------------------------------------------------------
cmake_minimum_required(VERSION 3.11)

project(Negate CXX)
set(CMAKE_CXX_STANDARD 17)

add_subdirectory(../ImgLib ImgLibBuildDir)

if (CMAKE_SYSTEM_NAME MATCHES "^MINGW")
    set(SYSTEM_LIBS -lstdc++)
else()
    set(SYSTEM_LIBS)
endif()

add_executable(imgconv main.cpp)

target_include_directories(imgconv PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/../ImgLib")

target_link_libraries(imgconv ImgLib ${SYSTEM_LIBS})
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main.cpp
-----------------------------------------------------------------------
#include <img_lib.h>
#include <jpeg_image.h>
#include <ppm_image.h>

#include <filesystem>
#include <string_view>
#include <iostream>

using namespace std;

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

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

    img_lib::Path in_path = argv[1];
    img_lib::Path out_path = argv[2];

    img_lib::Image image = img_lib::LoadPPM(in_path);

    if (!image) {
        cerr << "Loading failed"sv << endl;
        return 4;
    }

    if (!img_lib::SaveJPEG(out_path, image)) {
        cerr << "Saving failed"sv << endl;
        return 5;
    }

    cout << "Successfully converted"sv << endl;
}

*** PACKAGE ImgConverter END ***

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

*** PACKAGE ImgLib ***

-----------------------------------------------------------------------
CMakeLists.txt
-----------------------------------------------------------------------
cmake_minimum_required(VERSION 3.11)

project(ImgLib CXX)
set(CMAKE_CXX_STANDARD 17)

set(LIBJPEG_DIR CACHE STRING "LibJPEG static library directory")

if(NOT LIBJPEG_DIR)
    message(FATAL_ERROR "Please, specify LibJPEG directory via -DLIBJPEG_DIR=<dir>")
endif()
    message(STATUS "LibJPEG dir is ${LIBJPEG_DIR}, change via -DLIBJPEG_DIR=<dir>")

set(IMGLIB_MAIN_FILES img_lib.h img_lib.cpp)

set(IMGLIB_FORMAT_FILES ppm_image.h ppm_image.cpp
                        jpeg_image.h jpeg_image.cpp)

add_library(ImgLib STATIC ${IMGLIB_MAIN_FILES}
                          ${IMGLIB_FORMAT_FILES})

target_include_directories(ImgLib PUBLIC "${LIBJPEG_DIR}/include")

target_link_directories(ImgLib INTERFACE "${LIBJPEG_DIR}/lib/$<IF:$<CONFIG:Debug>,Debug,Release>")

target_link_libraries(ImgLib INTERFACE jpeg)
-----------------------------------------------------------------------
jpeg_image.h
-----------------------------------------------------------------------
#pragma once
#include "img_lib.h"

#include <filesystem>

namespace img_lib {

using Path = std::filesystem::path;

bool SaveJPEG(const Path& file, const Image& image);
Image LoadJPEG(const Path& file);

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

#include <array>
#include <fstream>
#include <stdio.h>
#include <setjmp.h>
#include <vector>

#include <jpeglib.h>

using namespace std;

namespace img_lib {

struct my_error_mgr {
    struct jpeg_error_mgr pub;
    jmp_buf setjmp_buffer;
};

typedef struct my_error_mgr* my_error_ptr;

METHODDEF(void)
my_error_exit (j_common_ptr cinfo) {
    my_error_ptr myerr = (my_error_ptr) cinfo->err;
    (*cinfo->err->output_message) (cinfo);
    longjmp(myerr->setjmp_buffer, 1);
}

bool SaveJPEG(const Path& file, const Image& image) {

    jpeg_compress_struct cinfo;
    jpeg_error_mgr jerr;

    FILE* outfile;
    JSAMPROW row_pointer[1];
    int row_stride;

    cinfo.err = jpeg_std_error(&jerr);
    jpeg_create_compress(&cinfo);

#ifdef _MSC_VER
    if ((outfile = _wfopen(file.wstring().c_str(), "wb")) == NULL) {
#else
    if ((outfile = fopen(file.string().c_str(), "wb")) == NULL) {
#endif
    return false;}

    jpeg_stdio_dest(&cinfo, outfile);

    cinfo.image_width = image.GetWidth();
    cinfo.image_height = image.GetHeight();
    cinfo.input_components = 3;
    cinfo.in_color_space = JCS_RGB;

    jpeg_set_defaults(&cinfo);
    jpeg_start_compress(&cinfo, TRUE);
    row_stride = image.GetWidth() * 3;

    while (cinfo.next_scanline < cinfo.image_height) {
        std::vector<JSAMPLE> jsample(row_stride);

        for (int i = 0; i < image.GetWidth(); ++i) {

            jsample[3 * i] = JSAMPLE(image.GetLine(cinfo.next_scanline)[i].r);
            jsample[1 + 3 * i] = JSAMPLE(image.GetLine(cinfo.next_scanline)[i].g);
            jsample[2 + 3 * i] = JSAMPLE(image.GetLine(cinfo.next_scanline)[i].b);
        }

        row_pointer[0] = &jsample[0];
        (void)jpeg_write_scanlines(&cinfo, row_pointer, 1);
    }

    jpeg_finish_compress(&cinfo);
    fclose(outfile);

    jpeg_destroy_compress(&cinfo);

    return true;
}

void SaveScanlineToImage(const JSAMPLE* row, int y, Image& out_image) {

    Color* line = out_image.GetLine(y);

    for (int x = 0; x < out_image.GetWidth(); ++x) {

        const JSAMPLE* pixel = row + x * 3;
        line[x] = Color{byte{pixel[0]}, byte{pixel[1]}, byte{pixel[2]}, byte{255}};
    }
}

Image LoadJPEG(const Path& file) {
    jpeg_decompress_struct cinfo;
    my_error_mgr jerr;

    FILE* infile;
    JSAMPARRAY buffer;
    int row_stride;

#ifdef _MSC_VER
    if ((infile = _wfopen(file.wstring().c_str(), "rb")) == NULL) {
#else
    if ((infile = fopen(file.string().c_str(), "rb")) == NULL) {
#endif
        return {};
    }

    cinfo.err = jpeg_std_error(&jerr.pub);
    jerr.pub.error_exit = my_error_exit;

    if (setjmp(jerr.setjmp_buffer)) {
        jpeg_destroy_decompress(&cinfo);
        fclose(infile);
        return {};
    }

    jpeg_create_decompress(&cinfo);
    jpeg_stdio_src(&cinfo, infile);
    (void) jpeg_read_header(&cinfo, TRUE);
    cinfo.out_color_space = JCS_RGB;
    cinfo.output_components = 3;
    (void) jpeg_start_decompress(&cinfo);

    row_stride = cinfo.output_width * cinfo.output_components;
    buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);

    Image result(cinfo.output_width, cinfo.output_height, Color::Black());

    while (cinfo.output_scanline < cinfo.output_height) {
        int y = cinfo.output_scanline;
        (void) jpeg_read_scanlines(&cinfo, buffer, 1);

        SaveScanlineToImage(buffer[0], y, result);
    }

    (void) jpeg_finish_decompress(&cinfo);

    jpeg_destroy_decompress(&cinfo);
    fclose(infile);

    return result;
}

}//end namespace img_lib
-----------------------------------------------------------------------
img_lib.h
-----------------------------------------------------------------------
#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
-----------------------------------------------------------------------
#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
-----------------------------------------------------------------------
#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
-----------------------------------------------------------------------
ppm_image.cpp
-----------------------------------------------------------------------
#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 out(file, ios::binary);

    out << PPM_SIG << '\n' << image.GetWidth() << ' ' << image.GetHeight() << '\n' << PPM_MAX << '\n';

    const int w = image.GetWidth();
    const int h = image.GetHeight();
    std::vector<char> buff(w * 3);

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

        const Color* line = image.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);
        }

        out.write(buff.data(), w * 3);
    }

    return out.good();
}

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

*** PACKAGE ImgLib END ***