path: root/src/image.cc

#include "common.hh"

#include "buffer.hh"
#include "image.hh"
#include "mime_types.hh"

#include <algorithm>
#include <limits>

#if HAVE_JPEG
#include <jpeglib.h>
#include <setjmp.h>
#endif

#if HAVE_EXIF
#include <libexif/exif-data.h>
#include <libexif/exif-entry.h>
#include <libexif/exif-format.h>
#include <libexif/exif-ifd.h>
#include <libexif/exif-loader.h>
#endif

namespace {

bool is_jpeg(const unsigned char* data, size_t size);

class ThumbnailImpl : public Image::Thumbnail {
public:
  ThumbnailImpl(std::string mime_type, uint64_t size)
    : mime_type_(std::move(mime_type)), size_(size) {}

  std::string_view mime_type() const override {
    return mime_type_;
  }

  uint64_t size() const override {
    return size_;
  }

private:
  std::string mime_type_;
  uint64_t size_;
};

class ImageImpl : public Image {
public:
  ImageImpl(uint64_t width, uint64_t height)
    : width_(width), height_(height) {}

  uint64_t width() const override {
    return width_;
  }

  uint64_t height() const override {
    return height_;
  }

  Location location() const override {
    return location_;
  }

  Rotation rotation() const override {
    return rotation_;
  }

  Date date() const override {
    return date_;
  }

  Thumbnail* thumbnail() const override {
    return thumbnail_.get();
  }

  void set_location(Location location) {
    location_ = location;
  }

  void set_rotation(Rotation rotation) {
    rotation_ = rotation;
  }

  void set_date(Date date) {
    date_ = date;
  }

  void set_thumbnail(std::string mime_type, uint64_t size) {
    thumbnail_ = std::make_unique<ThumbnailImpl>(std::move(mime_type), size);
  }

private:
  uint64_t width_;
  uint64_t height_;
  Location location_;
  Rotation rotation_{Rotation::UNKNOWN};
  Date date_;
  std::unique_ptr<ThumbnailImpl> thumbnail_;
};

#if HAVE_EXIF
double make_double(ExifRational rat) {
  return static_cast<double>(rat.numerator) / rat.denominator;
}

void load_exif(std::filesystem::path const& path, ImageImpl* img) {
  ExifData *data = exif_data_new_from_file(path.c_str());
  if (!data)
    return;

  auto byte_order = exif_data_get_byte_order(data);

  auto* entry = exif_content_get_entry(data->ifd[EXIF_IFD_0],
                                       EXIF_TAG_ORIENTATION);
  if (entry && entry->format == EXIF_FORMAT_SHORT && entry->components == 1) {
    auto orientation = exif_get_short(entry->data, byte_order);
    switch (orientation) {
    case 1:
      img->set_rotation(Rotation::NONE);
      break;
    case 2:
      img->set_rotation(Rotation::MIRRORED);
      break;
    case 3:
      img->set_rotation(Rotation::ROTATED_180);
      break;
    case 4:
      img->set_rotation(Rotation::ROTATED_180_MIRRORED);
      break;
    case 5:
      img->set_rotation(Rotation::ROTATED_90);
      break;
    case 6:
      img->set_rotation(Rotation::ROTATED_90_MIRRORED);
      break;
    case 7:
      img->set_rotation(Rotation::ROTATED_270);
      break;
    case 8:
      img->set_rotation(Rotation::ROTATED_270_MIRRORED);
      break;
    default:
      break;
    }
  }
  entry = exif_content_get_entry(data->ifd[EXIF_IFD_EXIF],
                                 EXIF_TAG_DATE_TIME_ORIGINAL);
  if (!entry) {
    entry = exif_content_get_entry(data->ifd[EXIF_IFD_EXIF],
                                   EXIF_TAG_DATE_TIME_DIGITIZED);
    if (!entry) {
      entry = exif_content_get_entry(data->ifd[EXIF_IFD_0], EXIF_TAG_DATE_TIME);
    }
  }
  if (entry && entry->format == EXIF_FORMAT_ASCII) {
    auto date = Date::from_format("%Y:%m:%d %H:%M:%S",
                                  reinterpret_cast<char const*>(entry->data));
    if (!date.empty())
      img->set_date(date);
  }
  auto* lat = exif_content_get_entry(
      data->ifd[EXIF_IFD_GPS],
      static_cast<ExifTag>(EXIF_TAG_GPS_LATITUDE));
  auto* lat_ref = exif_content_get_entry(
      data->ifd[EXIF_IFD_GPS],
      static_cast<ExifTag>(EXIF_TAG_GPS_LATITUDE_REF));
  auto* lng = exif_content_get_entry(
      data->ifd[EXIF_IFD_GPS],
      static_cast<ExifTag>(EXIF_TAG_GPS_LONGITUDE));
  auto* lng_ref = exif_content_get_entry(
      data->ifd[EXIF_IFD_GPS],
      static_cast<ExifTag>(EXIF_TAG_GPS_LONGITUDE_REF));
  if (lat && lat->format == EXIF_FORMAT_RATIONAL && lat->components == 3 &&
      lat_ref && lat_ref->format == EXIF_FORMAT_ASCII &&
      lng && lng->format == EXIF_FORMAT_RATIONAL && lng->components == 3 &&
      lng_ref && lng_ref->format == EXIF_FORMAT_ASCII) {
    auto step = exif_format_get_size(EXIF_FORMAT_RATIONAL);
    auto lat_double =
      make_double(exif_get_rational(lat->data + step * 0, byte_order)) +
      make_double(exif_get_rational(lat->data + step * 1,
                                    byte_order)) / 60.0 +
      make_double(exif_get_rational(lat->data + step * 2,
                                    byte_order)) / 3600.0;
    if (lat_ref->data[0] != 'N')
      lat_double = -lat_double;
    auto lng_double =
      make_double(exif_get_rational(lng->data + step * 0, byte_order)) +
      make_double(exif_get_rational(lng->data + step * 1,
                                    byte_order)) / 60.0 +
      make_double(exif_get_rational(lng->data + step * 2,
                                    byte_order)) / 3600.0;
    if (lng_ref->data[0] != 'E')
      lng_double = -lng_double;

    img->set_location(Location(lat_double, lng_double));
  }

  if (data->data) {
    if (is_jpeg(data->data, data->size)) {
      img->set_thumbnail("image/jpeg", data->size);
    }
  }

  exif_data_free(data);
}

class ExifThumbnailReader : public ThumbnailReader {
public:
  ExifThumbnailReader()
    : loader_(exif_loader_new()), data_(nullptr) {}

  ~ExifThumbnailReader() {
    if (loader_)
      exif_loader_unref(loader_);
    if (data_)
      exif_data_free(data_);
  }

  Return drain(RoBuffer* buf, size_t* bytes) override {
    if (bytes) *bytes = 0;
    if (loader_) {
      while (true) {
        size_t avail;
        auto* ptr = buf->rbuf(1, avail);
        if (avail == 0)
          return Return::NEED_MORE;
        avail = std::min(
            avail,
            static_cast<size_t>(std::numeric_limits<unsigned int>::max()));
        if (exif_loader_write(loader_, reinterpret_cast<unsigned char*>(
                                  const_cast<char*>(ptr)), avail)) {
          buf->rcommit(avail);
          if (bytes) *bytes += avail;
          // Loop to see if there is any more data avail.
        } else {
          // No data read or no hope there will be any.
          break;
        }
      }
      data_ = exif_loader_get_data(loader_);
      exif_loader_unref(loader_);
      loader_ = nullptr;
    }
    if (data_ && data_->data)
      return Return::DONE;
    return Return::ERR;
  }

  std::string_view data() const override {
    return data_ && data_->data
      ? std::string_view(reinterpret_cast<char const*>(data_->data),
                         data_->size)
      : std::string_view();
  }

private:
  ExifLoader* loader_;
  ExifData* data_;
};
#else  // HAVE_EXIF
class FailingThumbnailReader : public ThumbnailReader {
public:
  FailingThumbnailReader() = default;

  Return drain(RoBuffer*, size_t* bytes) override {
    if (bytes) *bytes = 0;
    return Return::ERR;
  }

  std::string_view data() const override {
    return std::string_view();
  }
};
#endif  // HAVE_EXIT

#if HAVE_JPEG
struct my_jpeg_error {
  struct jpeg_error_mgr base;
  jmp_buf jmp_buffer;
};

void jpeg_error_exit(j_common_ptr cinfo) {
  auto myerr = reinterpret_cast<my_jpeg_error*>(cinfo->err);
  longjmp(myerr->jmp_buffer, 1);
}

bool is_jpeg(const unsigned char* data, size_t size) {
  struct jpeg_decompress_struct info;
  struct my_jpeg_error err;
  info.err = jpeg_std_error(&err.base);
  err.base.error_exit = jpeg_error_exit;
  if (setjmp(err.jmp_buffer)) {
    jpeg_destroy_decompress(&info);
    return false;
  }
  jpeg_create_decompress(&info);
  jpeg_mem_src(&info, data, size);
  jpeg_read_header(&info, TRUE);
  jpeg_destroy_decompress(&info);
  return true;
}

std::unique_ptr<Image> load_jpeg(std::filesystem::path const& path) {
  struct jpeg_decompress_struct info;
  struct my_jpeg_error err;
  FILE* fh = fopen(path.c_str(), "rb");
  if (!fh)
    return nullptr;
  info.err = jpeg_std_error(&err.base);
  err.base.error_exit = jpeg_error_exit;
  if (setjmp(err.jmp_buffer)) {
    jpeg_destroy_decompress(&info);
    fclose(fh);
    return nullptr;
  }
  jpeg_create_decompress(&info);
  jpeg_stdio_src(&info, fh);
  jpeg_read_header(&info, TRUE);

  auto img = std::make_unique<ImageImpl>(info.image_width, info.image_height);

  jpeg_destroy_decompress(&info);
  fclose(fh);

#if HAVE_EXIF
  load_exif(path, img.get());
#endif

  return img;
}
#endif   // HAVE_JPEG

}  // namespace

std::unique_ptr<Image> Image::load(std::filesystem::path const& path) {
  if (!path.has_extension())
    return nullptr;
  auto mime_type = mime_types::from_extension(
      std::string(path.extension()).substr(1));
#if HAVE_JPEG
  if (mime_type == "image/jpeg") {
    return load_jpeg(path);
  }
#endif   // HAVE_JPEG
  return nullptr;
}

std::unique_ptr<ThumbnailReader> ThumbnailReader::create() {
#if HAVE_EXIF
  return std::make_unique<ExifThumbnailReader>();
#else
  return std::make_unique<FailingThumbnailReader>();
#endif
}