heif_cxx.h

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/*
 * C++ interface to libheif
 * Copyright (c) 2018 struktur AG, Dirk Farin <farin@struktur.de>
 *
 * This file is part of libheif.
 *
 * heif is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * heif is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with heif.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef LIBHEIF_HEIF_CXX_H
#define LIBHEIF_HEIF_CXX_H
 
#include <memory>
#include <string>
#include <vector>
 
extern "C" {
#include <libheif/heif.h>
}
 
 
namespace heif {
 
  class Error
  {
  public:
    Error() {
      m_code = heif_error_Ok;
      m_subcode = heif_suberror_Unspecified;
      m_message = "Ok";
    }
 
    Error(const heif_error& err) {
      m_code = err.code;
      m_subcode = err.subcode;
      m_message = err.message;
    }
 
    std::string get_message() const { return m_message; }
 
    heif_error_code get_code() const { return m_code; }
 
    heif_suberror_code get_subcode() const { return m_subcode; }
 
    operator bool() const { return m_code != heif_error_Ok; }
 
  private:
    heif_error_code m_code;
    heif_suberror_code m_subcode;
    std::string m_message;
  };
 
 
  class ImageHandle;
  class Image;
 
  class Encoder;
  class EncoderParameter;
  class EncoderDescriptor;
 
 
  class Context
  {
  public:
    Context();
 
    class ReadingOptions { };
 
    // throws Error
    void read_from_file(std::string filename, const ReadingOptions& opts = ReadingOptions());
 
    // DEPRECATED. Use read_from_memory_without_copy() instead.
    // throws Error
    void read_from_memory(const void* mem, size_t size, const ReadingOptions& opts = ReadingOptions());
 
    // throws Error
    void read_from_memory_without_copy(const void* mem, size_t size, const ReadingOptions& opts = ReadingOptions());
 
    class Reader {
    public:
      virtual ~Reader() { }
 
      virtual int64_t get_position() const = 0;
      virtual int read(void* data, size_t size) = 0;
      virtual int seek(int64_t position) = 0;
      virtual heif_reader_grow_status wait_for_file_size(int64_t target_size) = 0;
    };
 
    // throws Error
    void read_from_reader(Reader&, const ReadingOptions& opts = ReadingOptions());
 
    int get_number_of_top_level_images() const noexcept;
 
    bool is_top_level_image_ID(heif_item_id id) const noexcept;
 
    std::vector<heif_item_id> get_list_of_top_level_image_IDs() const noexcept;
 
    // throws Error
    heif_item_id get_primary_image_ID() const;
 
    // throws Error
    ImageHandle get_primary_image_handle() const;
 
    ImageHandle get_image_handle(heif_item_id id) const;
 
 
 
    class EncodingOptions : public heif_encoding_options {
    public:
      EncodingOptions();
    };
 
    // throws Error
    ImageHandle encode_image(const Image& img, Encoder& encoder,
                             const EncodingOptions& options = EncodingOptions());
 
    // throws Error
    void set_primary_image(ImageHandle& new_primary_image_handle);
 
    // throws Error
    ImageHandle encode_thumbnail(const Image& image,
                                 const ImageHandle& master_image,
                                 Encoder& encoder,
                                 const EncodingOptions&,
                                 int bbox_size);
 
    // throws Error
    void assign_thumbnail(const ImageHandle& thumbnail_image,
                          const ImageHandle& master_image);
 
    // throws Error
    void add_exif_metadata(const ImageHandle& master_image,
                           const void* data, int size);
 
    // throws Error
    void add_XMP_metadata(const ImageHandle& master_image,
                          const void* data, int size);
 
    class Writer {
    public:
      virtual ~Writer() { }
 
      virtual heif_error write(const void* data, size_t size) = 0;
    };
 
    // throws Error
    void write(Writer&);
 
    // throws Error
    void write_to_file(std::string filename) const;
 
  private:
    std::shared_ptr<heif_context> m_context;
 
    friend struct ::heif_error heif_writer_trampoline_write(struct heif_context* ctx,
                                                            const void* data,
                                                            size_t size,
                                                            void* userdata);
 
    //static Context wrap_without_releasing(heif_context*); // internal use in friend function only
  };
 
 
 
  class ImageHandle
  {
  public:
    ImageHandle() { }
 
    ImageHandle(heif_image_handle* handle);
 
    bool empty() const noexcept { return !m_image_handle; }
 
    bool is_primary_image() const noexcept;
 
    int get_width() const noexcept;
 
    int get_height() const noexcept;
 
    bool has_alpha_channel() const noexcept;
 
    // ------------------------- depth images -------------------------
 
    // TODO
 
    // ------------------------- thumbnails -------------------------
 
    int get_number_of_thumbnails() const noexcept;
 
    std::vector<heif_item_id> get_list_of_thumbnail_IDs() const noexcept;
 
    // throws Error
    ImageHandle get_thumbnail(heif_item_id id);
 
    // ------------------------- metadata (Exif / XMP) -------------------------
 
    // Can optionally be filtered by type ("Exif" / "XMP")
    std::vector<heif_item_id> get_list_of_metadata_block_IDs(const char* type_filter = nullptr) const noexcept;
 
    std::string get_metadata_type(heif_item_id metadata_id) const noexcept;
 
    std::string get_metadata_content_type(heif_item_id metadata_id) const noexcept;
 
    // throws error
    std::vector<uint8_t> get_metadata(heif_item_id) const;
 
 
    class DecodingOptions { };
 
    // throws Error
    Image decode_image(heif_colorspace colorspace, heif_chroma chroma,
                       const DecodingOptions& options = DecodingOptions());
 
 
    heif_image_handle* get_raw_image_handle() noexcept { return m_image_handle.get(); }
    const heif_image_handle* get_raw_image_handle() const noexcept { return m_image_handle.get(); }
 
  private:
    std::shared_ptr<heif_image_handle> m_image_handle;
  };
 
 
  class Image
  {
  public:
    Image() { }
    Image(heif_image* image);
 
 
    // throws Error
    void create(int width, int height,
                enum heif_colorspace colorspace,
                enum heif_chroma chroma);
 
    // throws Error
    void add_plane(enum heif_channel channel,
                   int width, int height, int bit_depth);
 
    heif_colorspace get_colorspace() const noexcept;
 
    heif_chroma get_chroma_format() const noexcept;
 
    int get_width(enum heif_channel channel) const noexcept;
 
    int get_height(enum heif_channel channel) const noexcept;
 
    int get_bits_per_pixel(enum heif_channel channel) const noexcept;
 
    bool has_channel(enum heif_channel channel) const noexcept;
 
    const uint8_t* get_plane(enum heif_channel channel, int* out_stride) const noexcept;
 
    uint8_t* get_plane(enum heif_channel channel, int* out_stride) noexcept;
 
    class ScalingOptions { };
 
    // throws Error
    Image scale_image(int width, int height,
                      const ScalingOptions& options = ScalingOptions()) const;
 
  private:
    std::shared_ptr<heif_image> m_image;
 
    friend class Context;
  };
 
 
 
  class EncoderDescriptor
  {
  public:
    static std::vector<EncoderDescriptor>
      get_encoder_descriptors(enum heif_compression_format format_filter,
                              const char* name_filter) noexcept;
 
    std::string get_name() const noexcept;
 
    std::string get_id_name() const noexcept;
 
    enum heif_compression_format get_compression_format() const noexcept;
 
    bool supportes_lossy_compression() const noexcept;
 
    bool supportes_lossless_compression() const noexcept;
 
 
    // throws Error
    Encoder get_encoder() const;
 
 
  private:
  EncoderDescriptor(const struct heif_encoder_descriptor* descr) : m_descriptor(descr) { }
 
    const struct heif_encoder_descriptor* m_descriptor = nullptr;
  };
 
 
 
  class EncoderParameter
  {
  public:
    std::string get_name() const noexcept;
 
    enum heif_encoder_parameter_type get_type() const noexcept;
 
    bool is_integer() const noexcept;
    // Returns 'true' if the integer range is limited.
    bool get_valid_integer_range(int& out_minimum, int& out_maximum);
 
    bool is_boolean() const noexcept;
 
    bool is_string() const noexcept;
    std::vector<std::string> get_valid_string_values() const;
 
  private:
    EncoderParameter(const heif_encoder_parameter*);
 
    const struct heif_encoder_parameter* m_parameter;
 
    friend class Encoder;
  };
 
 
  class Encoder
  {
  public:
    // throws Error
    Encoder(enum heif_compression_format format);
 
    // throws Error
    void set_lossy_quality(int quality);
 
    // throws Error
    void set_lossless(bool enable_lossless);
 
    std::vector<EncoderParameter> list_parameters() const noexcept;
 
    void set_integer_parameter(std::string parameter_name, int value);
    int  get_integer_parameter(std::string parameter_name) const;
 
    void set_boolean_parameter(std::string parameter_name, bool value);
    bool get_boolean_parameter(std::string parameter_name) const;
 
    void        set_string_parameter(std::string parameter_name, std::string value);
    std::string get_string_parameter(std::string parameter_name) const;
 
    void        set_parameter(std::string parameter_name, std::string parameter_value);
    std::string get_parameter(std::string parameter_name) const;
 
  private:
    Encoder(struct heif_encoder*) noexcept;
 
    std::shared_ptr<heif_encoder> m_encoder;
 
    friend class EncoderDescriptor;
    friend class Context;
  };
 
 
  // ==========================================================================================
  //                                     IMPLEMENTATION
  // ==========================================================================================
 
  inline Context::Context() {
    heif_context* ctx = heif_context_alloc();
    m_context = std::shared_ptr<heif_context>(ctx,
                                              [] (heif_context* c) { heif_context_free(c); });
  }
 
  inline void Context::read_from_file(std::string filename, const ReadingOptions& /*opts*/) {
    Error err = Error(heif_context_read_from_file(m_context.get(), filename.c_str(), NULL));
    if (err) {
      throw err;
    }
  }
 
  inline void Context::read_from_memory(const void* mem, size_t size, const ReadingOptions& /*opts*/) {
    Error err = Error(heif_context_read_from_memory(m_context.get(), mem, size, NULL));
    if (err) {
      throw err;
    }
  }
 
  inline void Context::read_from_memory_without_copy(const void* mem, size_t size, const ReadingOptions& /*opts*/) {
    Error err = Error(heif_context_read_from_memory_without_copy(m_context.get(), mem, size, NULL));
    if (err) {
      throw err;
    }
  }
 
 
  inline int64_t heif_reader_trampoline_get_position(void* userdata) {
    Context::Reader* reader = (Context::Reader*)userdata;
    return reader->get_position();
  }
 
  inline int heif_reader_trampoline_read(void* data, size_t size, void* userdata) {
    Context::Reader* reader = (Context::Reader*)userdata;
    return reader->read(data,size);
  }
 
  inline int heif_reader_trampoline_seek(int64_t position, void* userdata) {
    Context::Reader* reader = (Context::Reader*)userdata;
    return reader->seek(position);
  }
 
  inline heif_reader_grow_status heif_reader_trampoline_wait_for_file_size(int64_t target_size, void* userdata) {
    Context::Reader* reader = (Context::Reader*)userdata;
    return reader->wait_for_file_size(target_size);
  }
 
 
  static struct heif_reader heif_reader_trampoline =
    {
      1,
      heif_reader_trampoline_get_position,
      heif_reader_trampoline_read,
      heif_reader_trampoline_seek,
      heif_reader_trampoline_wait_for_file_size
    };
 
  inline void Context::read_from_reader(Reader& reader, const ReadingOptions& /*opts*/) {
    Error err = Error(heif_context_read_from_reader(m_context.get(), &heif_reader_trampoline,
                                                    &reader, NULL));
    if (err) {
      throw err;
    }
  }
 
 
  inline int Context::get_number_of_top_level_images() const noexcept {
    return heif_context_get_number_of_top_level_images(m_context.get());
  }
 
  inline bool Context::is_top_level_image_ID(heif_item_id id) const noexcept {
    return heif_context_is_top_level_image_ID(m_context.get(), id);
  }
 
  inline std::vector<heif_item_id> Context::get_list_of_top_level_image_IDs() const noexcept {
    int num = get_number_of_top_level_images();
    std::vector<heif_item_id> IDs(num);
    heif_context_get_list_of_top_level_image_IDs(m_context.get(), IDs.data(), num);
    return IDs;
  }
 
  inline heif_item_id Context::get_primary_image_ID() const {
    heif_item_id id;
    Error err = Error(heif_context_get_primary_image_ID(m_context.get(), &id));
    if (err) {
      throw err;
    }
    return id;
  }
 
  inline ImageHandle Context::get_primary_image_handle() const {
    heif_image_handle* handle;
    Error err = Error(heif_context_get_primary_image_handle(m_context.get(), &handle));
    if (err) {
      throw err;
    }
 
    return ImageHandle(handle);
  }
 
  inline ImageHandle Context::get_image_handle(heif_item_id id) const {
    struct heif_image_handle* handle;
    Error err = Error(heif_context_get_image_handle(m_context.get(), id, &handle));
    if (err) {
      throw err;
    }
    return ImageHandle(handle);
  }
 
#if 0
  inline Context Context::wrap_without_releasing(heif_context* ctx) {
    Context context;
    context.m_context = std::shared_ptr<heif_context>(ctx,
                                                      [] (heif_context*) { /* NOP */ });
    return context;
  }
#endif
 
  inline struct ::heif_error heif_writer_trampoline_write(struct heif_context* ctx,
                                                          const void* data,
                                                          size_t size,
                                                          void* userdata) {
    Context::Writer* writer = (Context::Writer*)userdata;
 
    (void)ctx;
 
    //Context context = Context::wrap_without_releasing(ctx);
    //return writer->write(context, data, size);
    return writer->write(data, size);
  }
 
  static struct heif_writer heif_writer_trampoline =
    {
      1,
      &heif_writer_trampoline_write
    };
 
  inline void Context::write(Writer& writer) {
    Error err = Error(heif_context_write(m_context.get(), &heif_writer_trampoline, &writer));
    if (err) {
      throw err;
    }
  }
 
  inline void Context::write_to_file(std::string filename) const {
    Error err = Error(heif_context_write_to_file(m_context.get(), filename.c_str()));
    if (err) {
      throw err;
    }
  }
 
 
 
  inline ImageHandle::ImageHandle(heif_image_handle* handle) {
    if (handle != nullptr) {
      m_image_handle = std::shared_ptr<heif_image_handle>(handle,
                                                          [] (heif_image_handle* h) { heif_image_handle_release(h); });
    }
  }
 
  inline bool ImageHandle::is_primary_image() const noexcept {
    return heif_image_handle_is_primary_image(m_image_handle.get()) != 0;
  }
 
  inline int ImageHandle::get_width() const noexcept {
    return heif_image_handle_get_width(m_image_handle.get());
  }
 
  inline int ImageHandle::get_height() const noexcept {
    return heif_image_handle_get_height(m_image_handle.get());
  }
 
  inline bool ImageHandle::has_alpha_channel() const noexcept {
    return heif_image_handle_has_alpha_channel(m_image_handle.get()) != 0;
  }
 
  // ------------------------- depth images -------------------------
 
  // TODO
 
  // ------------------------- thumbnails -------------------------
 
  inline int ImageHandle::get_number_of_thumbnails() const noexcept {
    return heif_image_handle_get_number_of_thumbnails(m_image_handle.get());
  }
 
  inline std::vector<heif_item_id> ImageHandle::get_list_of_thumbnail_IDs() const noexcept {
    int num = get_number_of_thumbnails();
    std::vector<heif_item_id> IDs(num);
    heif_image_handle_get_list_of_thumbnail_IDs(m_image_handle.get(), IDs.data(), num);
    return IDs;
  }
 
  inline ImageHandle ImageHandle::get_thumbnail(heif_item_id id) {
    heif_image_handle* handle;
    Error err = Error(heif_image_handle_get_thumbnail(m_image_handle.get(), id, &handle));
    if (err) {
      throw err;
    }
 
    return ImageHandle(handle);
  }
 
  inline Image ImageHandle::decode_image(heif_colorspace colorspace, heif_chroma chroma,
                                         const DecodingOptions& /*options*/) {
    heif_image* out_img;
    Error err = Error(heif_decode_image(m_image_handle.get(),
                                        &out_img,
                                        colorspace,
                                        chroma,
                                        nullptr)); //const struct heif_decoding_options* options);
    if (err) {
      throw err;
    }
 
    return Image(out_img);
  }
 
 
  inline std::vector<heif_item_id> ImageHandle::get_list_of_metadata_block_IDs(const char* type_filter) const noexcept {
    int nBlocks = heif_image_handle_get_number_of_metadata_blocks(m_image_handle.get(),
                                                                  type_filter);
    std::vector<heif_item_id> ids(nBlocks);
    int n = heif_image_handle_get_list_of_metadata_block_IDs(m_image_handle.get(),
                                                             type_filter,
                                                             ids.data(), nBlocks);
    (void)n;
    //assert(n==nBlocks);
    return ids;
  }
 
  inline std::string ImageHandle::get_metadata_type(heif_item_id metadata_id) const noexcept {
    return heif_image_handle_get_metadata_type(m_image_handle.get(), metadata_id);
  }
 
  inline std::string ImageHandle::get_metadata_content_type(heif_item_id metadata_id) const noexcept {
    return heif_image_handle_get_metadata_content_type(m_image_handle.get(), metadata_id);
  }
 
  inline std::vector<uint8_t> ImageHandle::get_metadata(heif_item_id metadata_id) const {
    size_t data_size = heif_image_handle_get_metadata_size(m_image_handle.get(),
                                                           metadata_id);
 
    std::vector<uint8_t> data(data_size);
 
    Error err = Error(heif_image_handle_get_metadata(m_image_handle.get(),
                                                     metadata_id,
                                                     data.data()));
    if (err) {
      throw err;
    }
 
    return data;
  }
 
 
 
  inline Image::Image(heif_image* image) {
    m_image = std::shared_ptr<heif_image>(image,
                                          [] (heif_image* h) { heif_image_release(h); });
  }
 
 
  inline void Image::create(int width, int height,
                            enum heif_colorspace colorspace,
                            enum heif_chroma chroma) {
    heif_image* image;
    Error err = Error(heif_image_create(width, height, colorspace, chroma, &image));
    if (err) {
      m_image.reset();
      throw err;
    }
    else {
      m_image = std::shared_ptr<heif_image>(image,
                                            [] (heif_image* h) { heif_image_release(h); });
    }
  }
 
  inline void Image::add_plane(enum heif_channel channel,
                               int width, int height, int bit_depth) {
    Error err = Error(heif_image_add_plane(m_image.get(), channel, width, height, bit_depth));
    if (err) {
      throw err;
    }
  }
 
  inline heif_colorspace Image::get_colorspace() const noexcept {
    return heif_image_get_colorspace(m_image.get());
  }
 
  inline heif_chroma Image::get_chroma_format() const noexcept {
    return heif_image_get_chroma_format(m_image.get());
  }
 
  inline int Image::get_width(enum heif_channel channel) const noexcept {
    return heif_image_get_width(m_image.get(), channel);
  }
 
  inline int Image::get_height(enum heif_channel channel) const noexcept {
    return heif_image_get_height(m_image.get(), channel);
  }
 
  inline int Image::get_bits_per_pixel(enum heif_channel channel) const noexcept {
    return heif_image_get_bits_per_pixel(m_image.get(), channel);
  }
 
  inline bool Image::has_channel(enum heif_channel channel) const noexcept {
    return heif_image_has_channel(m_image.get(), channel);
  }
 
  inline const uint8_t* Image::get_plane(enum heif_channel channel, int* out_stride) const noexcept {
    return heif_image_get_plane_readonly(m_image.get(), channel, out_stride);
  }
 
  inline uint8_t* Image::get_plane(enum heif_channel channel, int* out_stride) noexcept {
    return heif_image_get_plane(m_image.get(), channel, out_stride);
  }
 
  inline Image Image::scale_image(int width, int height,
                                  const ScalingOptions&) const {
    heif_image* img;
    Error err = Error(heif_image_scale_image(m_image.get(), &img, width,height,
                                             nullptr)); // TODO: scaling options not defined yet
    if (err) {
      throw err;
    }
 
    return Image(img);
  }
 
 
 
  inline std::vector<EncoderDescriptor>
    EncoderDescriptor::get_encoder_descriptors(enum heif_compression_format format_filter,
                                               const char* name_filter) noexcept {
    int maxDescriptors = 10;
    int nDescriptors;
    for (;;) {
      const struct heif_encoder_descriptor** descriptors;
      descriptors = new const heif_encoder_descriptor*[maxDescriptors];
 
      nDescriptors = heif_context_get_encoder_descriptors(nullptr,
                                                          format_filter,
                                                          name_filter,
                                                          descriptors,
                                                          maxDescriptors);
      if (nDescriptors < maxDescriptors) {
        std::vector<EncoderDescriptor> outDescriptors;
        for (int i=0;i<nDescriptors;i++) {
          outDescriptors.push_back(EncoderDescriptor(descriptors[i]));
        }
 
        delete[] descriptors;
 
        return outDescriptors;
      }
      else {
        delete[] descriptors;
        maxDescriptors *= 2;
      }
    }
  }
 
 
  inline std::string EncoderDescriptor::get_name() const noexcept {
    return heif_encoder_descriptor_get_name(m_descriptor);
  }
 
  inline std::string EncoderDescriptor::get_id_name() const noexcept {
    return heif_encoder_descriptor_get_id_name(m_descriptor);
  }
 
  inline enum heif_compression_format EncoderDescriptor::get_compression_format() const noexcept {
    return heif_encoder_descriptor_get_compression_format(m_descriptor);
  }
 
  inline bool EncoderDescriptor::supportes_lossy_compression() const noexcept {
    return heif_encoder_descriptor_supportes_lossy_compression(m_descriptor);
  }
 
  inline bool EncoderDescriptor::supportes_lossless_compression() const noexcept {
    return heif_encoder_descriptor_supportes_lossless_compression(m_descriptor);
  }
 
  inline Encoder EncoderDescriptor::get_encoder() const {
    heif_encoder* encoder;
    Error err = Error(heif_context_get_encoder(nullptr, m_descriptor, &encoder));
    if (err) {
      throw err;
    }
 
    return Encoder(encoder);
  }
 
 
  inline Encoder::Encoder(enum heif_compression_format format) {
    heif_encoder* encoder;
    Error err = Error(heif_context_get_encoder_for_format(nullptr, format, &encoder));
    if (err) {
      throw err;
    }
 
    m_encoder = std::shared_ptr<heif_encoder>(encoder,
                                              [] (heif_encoder* e) { heif_encoder_release(e); });
  }
 
  inline Encoder::Encoder(struct heif_encoder* encoder) noexcept
  {
    m_encoder = std::shared_ptr<heif_encoder>(encoder,
                                              [] (heif_encoder* e) { heif_encoder_release(e); });
  }
 
 
  inline EncoderParameter::EncoderParameter(const heif_encoder_parameter* param)
    : m_parameter(param)
  {
  }
 
  inline std::string EncoderParameter::get_name() const noexcept {
    return heif_encoder_parameter_get_name(m_parameter);
  }
 
  inline enum heif_encoder_parameter_type EncoderParameter::get_type() const noexcept {
    return heif_encoder_parameter_get_type(m_parameter);
  }
 
  inline bool EncoderParameter::is_integer() const noexcept {
    return get_type() == heif_encoder_parameter_type_integer;
  }
 
  inline bool EncoderParameter::get_valid_integer_range(int& out_minimum, int& out_maximum) {
    int have_minimum_maximum;
    Error err = Error(heif_encoder_parameter_get_valid_integer_range(m_parameter,
                                                                     &have_minimum_maximum,
                                                                     &out_minimum, &out_maximum));
    if (err) {
      throw err;
    }
 
    return have_minimum_maximum;
  }
 
  inline bool EncoderParameter::is_boolean() const noexcept {
    return get_type() == heif_encoder_parameter_type_boolean;
  }
 
  inline bool EncoderParameter::is_string() const noexcept {
    return get_type() == heif_encoder_parameter_type_string;
  }
 
  inline std::vector<std::string> EncoderParameter::get_valid_string_values() const {
    const char*const* stringarray;
    Error err = Error(heif_encoder_parameter_get_valid_string_values(m_parameter,
                                                                     &stringarray));
    if (err) {
      throw err;
    }
 
    std::vector<std::string> values;
    for (int i=0; stringarray[i]; i++) {
      values.push_back(stringarray[i]);
    }
 
    return values;
  }
 
  inline std::vector<EncoderParameter> Encoder::list_parameters() const noexcept {
    std::vector<EncoderParameter> parameters;
 
    for (const struct heif_encoder_parameter*const* params = heif_encoder_list_parameters(m_encoder.get());
         *params;
         params++) {
      parameters.push_back(EncoderParameter(*params));
    }
 
    return parameters;
  }
 
 
  inline void Encoder::set_lossy_quality(int quality) {
    Error err = Error(heif_encoder_set_lossy_quality(m_encoder.get(), quality));
    if (err) {
      throw err;
    }
  }
 
  inline void Encoder::set_lossless(bool enable_lossless) {
    Error err = Error(heif_encoder_set_lossless(m_encoder.get(), enable_lossless));
    if (err) {
      throw err;
    }
  }
 
  inline void Encoder::set_integer_parameter(std::string parameter_name, int value) {
    Error err = Error(heif_encoder_set_parameter_integer(m_encoder.get(), parameter_name.c_str(), value));
    if (err) {
      throw err;
    }
  }
 
  inline int  Encoder::get_integer_parameter(std::string parameter_name) const {
    int value;
    Error err = Error(heif_encoder_get_parameter_integer(m_encoder.get(), parameter_name.c_str(), &value));
    if (err) {
      throw err;
    }
    return value;
  }
 
  inline void Encoder::set_boolean_parameter(std::string parameter_name, bool value) {
    Error err = Error(heif_encoder_set_parameter_boolean(m_encoder.get(), parameter_name.c_str(), value));
    if (err) {
      throw err;
    }
  }
 
  inline bool Encoder::get_boolean_parameter(std::string parameter_name) const {
    int value;
    Error err = Error(heif_encoder_get_parameter_boolean(m_encoder.get(), parameter_name.c_str(), &value));
    if (err) {
      throw err;
    }
    return value;
  }
 
  inline void Encoder::set_string_parameter(std::string parameter_name, std::string value) {
    Error err = Error(heif_encoder_set_parameter_string(m_encoder.get(), parameter_name.c_str(), value.c_str()));
    if (err) {
      throw err;
    }
  }
 
  inline std::string Encoder::get_string_parameter(std::string parameter_name) const {
    const int max_size = 250;
    char value[max_size];
    Error err = Error(heif_encoder_get_parameter_string(m_encoder.get(), parameter_name.c_str(),
                                                        value, max_size));
    if (err) {
      throw err;
    }
    return value;
  }
 
  inline void Encoder::set_parameter(std::string parameter_name, std::string parameter_value) {
    Error err = Error(heif_encoder_set_parameter(m_encoder.get(), parameter_name.c_str(),
                                                 parameter_value.c_str()));
    if (err) {
      throw err;
    }
  }
 
  inline std::string Encoder::get_parameter(std::string parameter_name) const {
    const int max_size = 250;
    char value[max_size];
    Error err = Error(heif_encoder_get_parameter(m_encoder.get(), parameter_name.c_str(),
                                                 value, max_size));
    if (err) {
      throw err;
    }
    return value;
  }
 
  inline void Context::set_primary_image(ImageHandle& new_primary_image_handle) {
    Error err = Error(heif_context_set_primary_image(m_context.get(),
                                                     new_primary_image_handle.get_raw_image_handle()));
    if (err) {
      throw err;
    }
  }
 
 
  inline Context::EncodingOptions::EncodingOptions() {
    // TODO: this is a bit hacky. It would be better to have an API function to set
    // the options to default values. But I do not see any reason for that apart from
    // this use-case.
 
    struct heif_encoding_options* default_options = heif_encoding_options_alloc();
    *static_cast<heif_encoding_options*>(this) = *default_options; // copy over all options
    heif_encoding_options_free(default_options);
  }
 
 
  inline ImageHandle Context::encode_image(const Image& img, Encoder& encoder,
                                           const EncodingOptions& options) {
    struct heif_image_handle* image_handle;
 
    Error err = Error(heif_context_encode_image(m_context.get(),
                                                img.m_image.get(),
                                                encoder.m_encoder.get(),
                                                &options,
                                                &image_handle));
    if (err) {
      throw err;
    }
 
    return ImageHandle(image_handle);
  }
 
 
  inline ImageHandle Context::encode_thumbnail(const Image& image,
                                               const ImageHandle& master_image_handle,
                                               Encoder& encoder,
                                               const EncodingOptions& options,
                                               int bbox_size) {
    struct heif_image_handle* thumb_image_handle;
 
    Error err = Error(heif_context_encode_thumbnail(m_context.get(),
                                                    image.m_image.get(),
                                                    master_image_handle.get_raw_image_handle(),
                                                    encoder.m_encoder.get(),
                                                    &options,
                                                    bbox_size,
                                                    &thumb_image_handle));
    if (err) {
      throw err;
    }
 
    return ImageHandle(thumb_image_handle);
  }
 
 
  inline void Context::assign_thumbnail(const ImageHandle& thumbnail_image,
                                        const ImageHandle& master_image) {
    Error err = Error(heif_context_assign_thumbnail(m_context.get(),
                                                    thumbnail_image.get_raw_image_handle(),
                                                    master_image.get_raw_image_handle()));
    if (err) {
      throw err;
    }
  }
 
  inline void Context::add_exif_metadata(const ImageHandle& master_image,
                                         const void* data, int size) {
    Error err = Error(heif_context_add_exif_metadata(m_context.get(),
                                                     master_image.get_raw_image_handle(),
                                                     data, size));
    if (err) {
      throw err;
    }
  }
 
  inline void Context::add_XMP_metadata(const ImageHandle& master_image,
                                        const void* data, int size) {
    Error err = Error(heif_context_add_XMP_metadata(m_context.get(),
                                                    master_image.get_raw_image_handle(),
                                                    data, size));
    if (err) {
      throw err;
    }
  }
}
 
 
#endif