rs_frame.hpp

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// License: Apache 2.0. See LICENSE file in root directory.
// Copyright(c) 2017 RealSense, Inc. All Rights Reserved.

#ifndef LIBREALSENSE_RS2_FRAME_HPP
#define LIBREALSENSE_RS2_FRAME_HPP

#include "rs_types.hpp"

namespace rs2
{
    class frame_source;
    class frame_queue;
    class syncer;
    class processing_block;
    class pointcloud;
    class sensor;
    class frame;
    class pipeline_profile;
    class points;
    class video_stream_profile;

    class stream_profile
    {
    public:
        stream_profile() : _profile(nullptr) {}

        int stream_index() const { return _index; }
        rs2_stream stream_type() const { return _type; }
        rs2_format format() const { return _format; }
        int fps() const { return _framerate; }
        int unique_id() const { return _uid; }

        stream_profile clone(rs2_stream type, int index, rs2_format format) const
        {
            rs2_error* e = nullptr;
            auto ref = rs2_clone_stream_profile(_profile, type, index, format, &e);
            error::handle(e);
            stream_profile res(ref);
            res._clone = std::shared_ptr<rs2_stream_profile>(ref, [](rs2_stream_profile* r) { rs2_delete_stream_profile(r); });

            return res;
        }

        bool operator==(const stream_profile& rhs)
        {
            return  stream_index() == rhs.stream_index() &&
                stream_type() == rhs.stream_type() &&
                format() == rhs.format() &&
                fps() == rhs.fps();
        }

        template<class T>
        bool is() const
        {
            T extension(*this);
            return extension;
        }

        template<class T>
        T as() const
        {
            T extension(*this);
            return extension;
        }

        std::string stream_name() const
        {
            rs2_error * e = nullptr;
            std::string name = rs2_get_stream_profile_name( _profile, &e );

            if( name.empty() )
            {
                std::stringstream ss;
                ss << rs2_stream_to_string( stream_type() );
                if( stream_index() != 0 )
                    ss << " " << stream_index();
                name = ss.str();
            }

            return name;
        }

        bool is_default() const { return _default; }

        operator bool() const { return _profile != nullptr; }

        const rs2_stream_profile* get() const { return _profile; }

        rs2_extrinsics get_extrinsics_to(const stream_profile& to) const
        {
            rs2_error* e = nullptr;
            rs2_extrinsics res;
            rs2_get_extrinsics(get(), to.get(), &res, &e);
            error::handle(e);
            return res;
        }
        void register_extrinsics_to(const stream_profile& to, rs2_extrinsics extrinsics)
        {
            rs2_error* e = nullptr;
            rs2_register_extrinsics(get(), to.get(), extrinsics, &e);
            error::handle(e);
        }

        bool is_cloned() { return bool(_clone); }
        explicit stream_profile(const rs2_stream_profile* profile) : _profile(profile)
        {
            rs2_error* e = nullptr;
            rs2_get_stream_profile_data(_profile, &_type, &_format, &_index, &_uid, &_framerate, &e);
            error::handle(e);

            _default = !!(rs2_is_stream_profile_default(_profile, &e));
            error::handle(e);

        }
        operator const rs2_stream_profile*() { return _profile; }
        explicit operator std::shared_ptr<rs2_stream_profile>() { return _clone; }

    protected:
        friend class rs2::sensor;
        friend class rs2::frame;
        friend class rs2::pipeline_profile;
        friend class rs2::video_stream_profile;

        const rs2_stream_profile* _profile;
        std::shared_ptr<rs2_stream_profile> _clone;

        int _index = 0;
        int _uid = 0;
        int _framerate = 0;
        rs2_format _format = RS2_FORMAT_ANY;
        rs2_stream _type = RS2_STREAM_ANY;

        bool _default = false;
    };

    class video_stream_profile : public stream_profile
    {
    public:
        video_stream_profile() : stream_profile() {}

        explicit video_stream_profile(const stream_profile& sp)
            : stream_profile(sp)
        {
            rs2_error* e = nullptr;
            if (!sp || (rs2_stream_profile_is(sp.get(), RS2_EXTENSION_VIDEO_PROFILE, &e) == 0 && !e))
            {
                _profile = nullptr;
            }
            error::handle(e);

            if (_profile)
            {
                rs2_get_video_stream_resolution(_profile, &_width, &_height, &e);
                error::handle(e);
            }
        }

        int width() const
        {
            return _width;
        }

        int height() const
        {
            return _height;
        }
        rs2_intrinsics get_intrinsics() const
        {
            rs2_error* e = nullptr;
            rs2_intrinsics intr;
            rs2_get_video_stream_intrinsics(_profile, &intr, &e);
            error::handle(e);
            return intr;
        }

        bool operator==(const video_stream_profile& other) const
        {
            return (((stream_profile&)*this)==other && 
                    width() == other.width() &&
                    height() == other.height());
        }

        using stream_profile::clone;

        stream_profile clone(rs2_stream type, int index, rs2_format format, int width, int height, const rs2_intrinsics& intr) const
        {
            rs2_error* e = nullptr;
            auto ref = rs2_clone_video_stream_profile(_profile, type, index, format, width, height, &intr, &e);
            error::handle(e);
            stream_profile res(ref);
            res._clone = std::shared_ptr<rs2_stream_profile>(ref, [](rs2_stream_profile* r) { rs2_delete_stream_profile(r); });

            return res;
        }
    private:
        int _width = 0;
        int _height = 0;
    };


    class motion_stream_profile : public stream_profile
    {
    public:
        explicit motion_stream_profile(const stream_profile& sp)
            : stream_profile(sp)
        {
            rs2_error* e = nullptr;
            if (!sp || (rs2_stream_profile_is(sp.get(), RS2_EXTENSION_MOTION_PROFILE, &e) == 0 && !e))
            {
                _profile = nullptr;
            }
            error::handle(e);
        }

        rs2_motion_device_intrinsic get_motion_intrinsics() const
        {
            rs2_error* e = nullptr;
            rs2_motion_device_intrinsic intrin;
            rs2_get_motion_intrinsics(_profile, &intrin, &e);
            error::handle(e);
            return intrin;
        }
    };

    class pose_stream_profile : public stream_profile
    {
    public:
        explicit pose_stream_profile(const stream_profile& sp)
            : stream_profile(sp)
        {
            rs2_error* e = nullptr;
            if (!sp || (rs2_stream_profile_is(sp.get(), RS2_EXTENSION_POSE_PROFILE, &e) == 0 && !e))
            {
                _profile = nullptr;
            }
            error::handle(e);
        }
    };

    class perception_stream_profile : public stream_profile
    {
    public:
        explicit perception_stream_profile(const stream_profile& sp)
            : stream_profile(sp)
        {
            rs2_error* e = nullptr;
            if (!sp || (rs2_stream_profile_is(sp.get(), RS2_EXTENSION_PERCEPTION_PROFILE, &e) == 0 && !e))
            {
                _profile = nullptr;
            }
            error::handle(e);
        }
    };

    class filter_interface
    {
    public:
        virtual rs2::frame process(rs2::frame frame) const = 0;
        virtual ~filter_interface() = default;
    };

    class frame
    {
    public:
        frame() : frame_ref(nullptr) {}
        frame(rs2_frame* ref) : frame_ref(ref)
        {
#ifdef _DEBUG
            if (ref)
            {
                rs2_error* e = nullptr;
                auto r = rs2_get_frame_number(ref, &e);
                if (!e)
                    frame_number = r;
                auto s = rs2_get_frame_stream_profile(ref, &e);
                if (!e)
                    profile = stream_profile(s);
            }
            else
            {
                frame_number = 0;
                profile = stream_profile();
            }
#endif
        }
        frame(frame&& other) noexcept : frame_ref(other.frame_ref)
        {
            other.frame_ref = nullptr;
#ifdef _DEBUG
            frame_number = other.frame_number;
            profile = other.profile;
#endif
        }
        frame& operator=(frame other)
        {
            swap(other);
            return *this;
        }

        frame(const frame& other)
            : frame_ref(other.frame_ref)
        {
            if (frame_ref) add_ref();
#ifdef _DEBUG
            frame_number = other.frame_number;
            profile = other.profile;
#endif
        }
        void swap(frame& other)
        {
            std::swap(frame_ref, other.frame_ref);

#ifdef _DEBUG
            std::swap(frame_number, other.frame_number);
            std::swap(profile, other.profile);
#endif
        }

        ~frame()
        {
            if (frame_ref)
            {
                rs2_release_frame(frame_ref);
            }
        }

        void keep() { rs2_keep_frame(frame_ref); }

        operator bool() const { return frame_ref != nullptr; }

        rs2_sensor* get_sensor()
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_sensor(frame_ref, &e);
            error::handle(e);
            return r;
        }

        double get_timestamp() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_timestamp(frame_ref, &e);
            error::handle(e);
            return r;
        }

        rs2_timestamp_domain get_frame_timestamp_domain() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_timestamp_domain(frame_ref, &e);
            error::handle(e);
            return r;
        }

        rs2_metadata_type get_frame_metadata(rs2_frame_metadata_value frame_metadata) const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_metadata(frame_ref, frame_metadata, &e);
            error::handle(e);
            return r;
        }

        bool supports_frame_metadata(rs2_frame_metadata_value frame_metadata) const
        {
            rs2_error* e = nullptr;
            auto r = rs2_supports_frame_metadata(frame_ref, frame_metadata, &e);
            error::handle(e);
            return r != 0;
        }

        unsigned long long get_frame_number() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_number(frame_ref, &e);
            error::handle(e);
            return r;
        }

        const int get_data_size() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_data_size(frame_ref, &e);
            error::handle(e);
            return r;
        }

        const void* get_data() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_data(frame_ref, &e);
            error::handle(e);
            return r;
        }

        const void* get_gpu_data_or_upload( bool* copied = nullptr ) const
        {
            rs2_error* e = nullptr;
            int c = 0;
            auto r = rs2_get_frame_gpu_data_or_upload(frame_ref, &c, &e);
            error::handle(e);
            if( copied ) *copied = ( c != 0 );
            return r;
        }

        stream_profile get_profile() const
        {
            rs2_error* e = nullptr;
            auto s = rs2_get_frame_stream_profile(frame_ref, &e);
            error::handle(e);
            return stream_profile(s);
        }

        template<class T>
        bool is() const
        {
            T extension(*this);
            return extension;
        }
        template<class T>
        T as() const
        {
            T extension(*this);
            return extension;
        }

        rs2_frame* get() const { return frame_ref; }
        explicit operator rs2_frame*() { return frame_ref; }

        frame apply_filter(filter_interface& filter)
        {
            return filter.process(*this);
        }

    protected:
        void add_ref() const
        {
            rs2_error* e = nullptr;
            rs2_frame_add_ref(frame_ref, &e);
            error::handle(e);
        }

        void reset()
        {
            if (frame_ref)
            {
                rs2_release_frame(frame_ref);
            }
            frame_ref = nullptr;
        }

    private:
        friend class rs2::frame_source;
        friend class rs2::frame_queue;
        friend class rs2::syncer;
        friend class rs2::processing_block;
        friend class rs2::pointcloud;
        friend class rs2::points;

        rs2_frame* frame_ref;

#ifdef _DEBUG
        stream_profile profile;
        unsigned long long frame_number = 0;
#endif
    };

    class video_frame : public frame
    {
    public:
        video_frame(const frame& f)
            : frame(f)
        {
            rs2_error* e = nullptr;
            if (!f || (rs2_is_frame_extendable_to(f.get(), RS2_EXTENSION_VIDEO_FRAME, &e) == 0 && !e))
            {
                reset();
            }
            error::handle(e);
        }


        int get_width() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_width(get(), &e);
            error::handle(e);
            return r;
        }

        int get_height() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_height(get(), &e);
            error::handle(e);
            return r;
        }

        int get_stride_in_bytes() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_stride_in_bytes(get(), &e);
            error::handle(e);
            return r;
        }

        int get_bits_per_pixel() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_bits_per_pixel(get(), &e);
            error::handle(e);
            return r;
        }

        int get_bytes_per_pixel() const { return get_bits_per_pixel() / 8; }

        bool extract_target_dimensions(rs2_calib_target_type calib_type, float* target_dims, unsigned int target_dims_size) const
        {
            rs2_error* e = nullptr;
            rs2_extract_target_dimensions(get(), calib_type, target_dims, target_dims_size, &e);
            error::handle(e);
            return (e == nullptr);
        }
    };

    struct vertex {
        float x, y, z;
        operator const float*() const { return &x; }
    };
    struct texture_coordinate {
        float u, v;
        operator const float*() const { return &u; }
    };
 
    class points : public frame
    {
    public:
        points() : frame(), _size(0) {}

        points(const frame& f)
            : frame(f), _size(0)
        {
            rs2_error* e = nullptr;
            if (!f || (rs2_is_frame_extendable_to(f.get(), RS2_EXTENSION_POINTS, &e) == 0 && !e))
            {
                reset();
            }
            error::handle(e);

            if (get())
            {
                _size = rs2_get_frame_points_count(get(), &e);
                error::handle(e);
            }
        }
        const vertex* get_vertices() const
        {
            rs2_error* e = nullptr;
            auto res = rs2_get_frame_vertices(get(), &e);
            error::handle(e);
            return (const vertex*)res;
        }

        void export_to_ply(const std::string& fname, video_frame texture)
        {
            rs2_frame* ptr = nullptr;
            std::swap(texture.frame_ref, ptr);
            rs2_error* e = nullptr;
            rs2_export_to_ply(get(), fname.c_str(), ptr, &e);
            error::handle(e);
        }
        const texture_coordinate* get_texture_coordinates() const
        {
            rs2_error* e = nullptr;
            auto res = rs2_get_frame_texture_coordinates(get(), &e);
            error::handle(e);
            return (const texture_coordinate*)res;
        }

        size_t size() const
        {
            return _size;
        }

    private:
        size_t _size;
    };


    class labeled_points : public frame
    {
    public:
        labeled_points() : frame(), _size(0) {}

        labeled_points(const frame& f)
            : frame(f), _size(0)
        {
            rs2_error* e = nullptr;
            if (!f || (rs2_is_frame_extendable_to(f.get(), RS2_EXTENSION_LABELED_POINTS, &e) == 0 && !e))
            {
                reset();
            }
            error::handle(e);

            if (get())
            {
                _size = rs2_get_frame_labeled_points_count(get(), &e);
                error::handle(e);
            }
        }

        const vertex* get_vertices() const
        {
            rs2_error* e = nullptr;
            auto res = rs2_get_frame_labeled_vertices(get(), &e);
            error::handle(e);
            return (const vertex*)res;
        }

        const uint8_t* get_labels() const
        {
            rs2_error* e = nullptr;
            auto res = rs2_get_frame_labels(get(), &e);
            error::handle(e);
            return (uint8_t * )res;
        }

        // Returns the vertices counts
        size_t size() const
        {
            return _size;
        }

        unsigned int get_width() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_labeled_points_width(get(), &e);
            error::handle(e);
            return r;
        }

        unsigned int get_height() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_labeled_points_height(get(), &e);
            error::handle(e);
            return r;
        }

        unsigned int get_bits_per_pixel() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_labeled_points_bits_per_pixel(get(), &e);
            error::handle(e);
            return r;
        }

    private:
        size_t _size;
    };

    class depth_frame : public video_frame
    {
    public:
        depth_frame(const frame& f)
            : video_frame(f)
        {
            rs2_error* e = nullptr;
            if (!f || (rs2_is_frame_extendable_to(f.get(), RS2_EXTENSION_DEPTH_FRAME, &e) == 0 && !e))
            {
                reset();
            }
            error::handle(e);
        }

        float get_distance(int x, int y) const
        {
            rs2_error * e = nullptr;
            auto r = rs2_depth_frame_get_distance(get(), x, y, &e);
            error::handle(e);
            return r;
        }

        float get_units() const
        {
            rs2_error * e = nullptr;
            auto r = rs2_depth_frame_get_units( get(), &e );
            error::handle( e );
            return r;
        }
    };

    class disparity_frame : public depth_frame
    {
    public:
        disparity_frame(const frame& f)
            : depth_frame(f)
        {
            rs2_error* e = nullptr;
            if (!f || (rs2_is_frame_extendable_to(f.get(), RS2_EXTENSION_DISPARITY_FRAME, &e) == 0 && !e))
            {
                reset();
            }
            error::handle(e);
        }
        float get_baseline(void) const
        {
            rs2_error * e = nullptr;
            auto r = rs2_depth_stereo_frame_get_baseline(get(), &e);
            error::handle(e);
            return r;
        }
    };

    class gpu_frame : public frame
    {
    public:
        gpu_frame(const frame& f)
            : frame(f)
        {
            rs2_error* e = nullptr;
            if (!f || (rs2_is_frame_extendable_to(f.get(), RS2_EXTENSION_GPU_FRAME, &e) == 0 && !e))
            {
                reset();
            }
            error::handle(e);
        }

        const void* get_gpu_data() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_gpu_data(get(), &e);
            error::handle(e);
            return r;
        }
    };

    class motion_frame : public frame
    {
    public:
        motion_frame(const frame& f)
            : frame(f)
        {
            rs2_error* e = nullptr;
            if (!f || (rs2_is_frame_extendable_to(f.get(), RS2_EXTENSION_MOTION_FRAME, &e) == 0 && !e))
            {
                reset();
            }
            error::handle(e);
        }
        rs2_vector get_motion_data() const
        {
            auto data = reinterpret_cast<const float*>(get_data());
            return rs2_vector{ data[0], data[1], data[2] };
        }
        rs2_combined_motion get_combined_motion_data() const
        {
            return *reinterpret_cast< rs2_combined_motion const * >( get_data() );
        }
    };

    class pose_frame : public frame
    {
    public:
        pose_frame(const frame& f)
            : frame(f)
        {
            rs2_error* e = nullptr;
            if (!f || (rs2_is_frame_extendable_to(f.get(), RS2_EXTENSION_POSE_FRAME, &e) == 0 && !e))
            {
                reset();
            }
            error::handle(e);
        }
        rs2_pose get_pose_data() const
        {
            rs2_pose pose_data;
            rs2_error* e = nullptr;
            rs2_pose_frame_get_pose_data(get(), &pose_data, &e);
            error::handle(e);
            return pose_data;
        }
    };

    class perception_frame : public frame
    {
    public:
        perception_frame() : frame()
        {
        }

        perception_frame( const frame & f ) : frame( f )
        {
            rs2_error * e = nullptr;
            if( ! f || ( rs2_is_frame_extendable_to( f.get(), RS2_EXTENSION_PERCEPTION_FRAME, &e ) == 0 && ! e ) )
            {
                reset();
            }
            error::handle( e );
        }
    };

    class object_detection_frame : public perception_frame
    {
    public:
        object_detection_frame() : perception_frame() {}

        object_detection_frame(const frame& f)
            : perception_frame(f)
        {
            rs2_error* e = nullptr;
            if (!f || (rs2_is_frame_extendable_to(f.get(), RS2_EXTENSION_OBJECT_DETECTION_FRAME, &e) == 0 && !e))
            {
                reset();
            }
            error::handle(e);
        }

        unsigned int get_detection_count() const
        {
            rs2_error* e = nullptr;
            auto r = rs2_get_frame_object_detection_count(get(), &e);
            error::handle(e);
            return r;
        }

        rs2_object_detection get_detection(unsigned int index) const
        {
            rs2_object_detection detection;
            rs2_error* e = nullptr;
            rs2_get_frame_object_detection(get(), index, &detection, &e);
            error::handle(e);
            return detection;
        }
    };

    class frameset : public frame
    {
    public:
        frameset() :_size(0) {};
        frameset(const frame& f)
            : frame(f), _size(0)
        {
            rs2_error* e = nullptr;
            if (!f || (rs2_is_frame_extendable_to(f.get(), RS2_EXTENSION_COMPOSITE_FRAME, &e) == 0 && !e))
            {
                reset();
                // TODO - consider explicit constructor to move resultion to compile time
            }
            error::handle(e);

            if (get())
            {
                _size = rs2_embedded_frames_count(get(), &e);
                error::handle(e);
            }
        }

        frame first_or_default(rs2_stream s, rs2_format f = RS2_FORMAT_ANY) const
        {
            frame result;
            foreach_rs([&result, s, f](frame frm) {
                if (!result && frm.get_profile().stream_type() == s && (f == RS2_FORMAT_ANY || f == frm.get_profile().format()))
                {
                    result = std::move(frm);
                }
            });
            return result;
        }
        frame first(rs2_stream s, rs2_format f = RS2_FORMAT_ANY) const
        {
            auto frm = first_or_default(s, f);
            if (!frm) throw error("Frame of requested stream type was not found!");
            return frm;
        }

        depth_frame get_depth_frame() const
        {
            auto f = first_or_default(RS2_STREAM_DEPTH, RS2_FORMAT_Z16);
            return f.as<depth_frame>();
        }
        video_frame get_color_frame( const size_t index = 0 ) const
        {
            frame f;

            foreach_rs( [&f, index]( const frame & frm ) {
                if( !f && frm.get_profile().stream_type() == RS2_STREAM_COLOR &&
                          frm.get_profile().stream_index() == index )
                    f = frm;
            } );

            if( ! f )
            {
                // Color frame can also come from infrared sensor
                foreach_rs( [&f, index]( const frame & frm ) {
                    if( !f && frm.get_profile().stream_type() == RS2_STREAM_INFRARED &&
                              frm.get_profile().stream_index() == index &&
                              frm.get_profile().format() == RS2_FORMAT_RGB8 )
                        f = frm;
                } );
            }

            return f;
        }

        labeled_points get_labeled_point_cloud_frame() const
        {
            auto f = first_or_default(RS2_STREAM_LABELED_POINT_CLOUD);

            return f.as<labeled_points>();
        }
        video_frame get_infrared_frame(const size_t index = 0) const
        {
            frame f;
            if (!index)
            {
                f = first_or_default(RS2_STREAM_INFRARED);
            }
            else
            {
                foreach_rs([&f, index](const frame& frm) {
                    if( !f && frm.get_profile().stream_type() == RS2_STREAM_INFRARED &&
                              frm.get_profile().stream_index() == index )
                        f = frm;
                });
            }
            return f;
        }

        video_frame get_fisheye_frame(const size_t index = 0) const
        {
            frame f;
            if (!index)
            {
                f = first_or_default(RS2_STREAM_FISHEYE);
            }
            else
            {
                foreach_rs([&f, index](const frame& frm) {
                    if (frm.get_profile().stream_type() == RS2_STREAM_FISHEYE &&
                        frm.get_profile().stream_index() == index) f = frm;
                });
            }
            return f;
        }

        pose_frame get_pose_frame(const size_t index = 0) const
        {
            frame f;
            if (!index)
            {
                f = first_or_default(RS2_STREAM_POSE);
            }
            else
            {
                foreach_rs([&f, index](const frame& frm) {
                    if (frm.get_profile().stream_type() == RS2_STREAM_POSE &&
                        frm.get_profile().stream_index() == index) f = frm;
                });
            }
            return f.as<pose_frame>();
        }

        object_detection_frame get_object_detection_frame(const size_t index = 0) const
        {
            frame f;
            if (!index)
            {
                f = first_or_default(RS2_STREAM_OBJECT_DETECTION);
            }
            else
            {
                foreach_rs([&f, index](const frame& frm) {
                    if (frm.get_profile().stream_type() == RS2_STREAM_OBJECT_DETECTION &&
                        frm.get_profile().stream_index() == index) f = frm;
                });
            }
            return f.as<object_detection_frame>();
        }

        size_t size() const
        {
            return _size;
        }

        template<class T>
        void foreach_rs(T action) const
        {
            rs2_error* e = nullptr;
            auto count = size();
            for (size_t i = 0; i < count; i++)
            {
                auto fref = rs2_extract_frame(get(), (int)i, &e);
                error::handle(e);

                action(frame(fref));
            }
        }
        frame operator[](size_t index) const
        {
            rs2_error* e = nullptr;
            if (index < size())
            {
                auto fref = rs2_extract_frame(get(), (int)index, &e);
                error::handle(e);
                return frame(fref);
            }

            throw error("Requested index is out of range!");
        }

        class iterator
        {
        public:
            // inheriting from std::iterator template is deprecated in C++17, this is the new way to define an iterator
            // go to https://www.fluentcpp.com/2018/05/08/std-iterator-deprecated/ for more info
            using iterator_category = std::forward_iterator_tag;
            using value_type = frame;
            using difference_type = std::ptrdiff_t;
            using pointer = frame*;
            using reference = frame&;

            iterator(const frameset* owner, size_t index = 0) : _index(index), _owner(owner) {}
            iterator& operator++() { ++_index; return *this; }
            bool operator==(const iterator& other) const { return _index == other._index; }
            bool operator!=(const iterator& other) const { return !(*this == other); }

            frame operator*() { return (*_owner)[_index]; }
        private:
            size_t _index = 0;
            const frameset* _owner;
        };

        iterator begin() const { return iterator(this); }
        iterator end() const { return iterator(this, size()); }
    private:
        size_t _size;
    };

    template<class T>
    class frame_callback : public rs2_frame_callback
    {
        T on_frame_function;
    public:
        explicit frame_callback(T on_frame) : on_frame_function(on_frame) {}

        void on_frame(rs2_frame* fref) override
        {
            on_frame_function(frame{ fref });
        }

        void release() override { delete this; }
    };
}
#endif // LIBREALSENSE_RS2_FRAME_HPP