ardour/ardour/region.h

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/*
 * Copyright (C) 2000-2017 Paul Davis <paul@linuxaudiosystems.com>
 * Copyright (C) 2006-2014 David Robillard <d@drobilla.net>
 * Copyright (C) 2007-2012 Carl Hetherington <carl@carlh.net>
 * Copyright (C) 2013-2019 Robin Gareus <robin@gareus.org>
 * Copyright (C) 2015-2017 Nick Mainsbridge <mainsbridge@gmail.com>
 * Copyright (C) 2018 Ben Loftis <ben@harrisonconsoles.com>
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#pragma once
 
#include <memory>
#include <optional>
#include <vector>
 
#include "temporal/domain_swap.h"
#include "temporal/timeline.h"
#include "temporal/range.h"
#include "temporal/tempo.h"
 
#include "pbd/undo.h"
#include "pbd/signals.h"
#include "ardour/ardour.h"
#include "ardour/data_type.h"
#include "ardour/automatable.h"
#include "ardour/movable.h"
#include "ardour/readable.h"
#include "ardour/session_object.h"
#include "ardour/trimmable.h"
#include "ardour/types_convert.h"
 
class XMLNode;
 
namespace PBD {
        class Progress;
}
 
namespace ARDOUR {
 
namespace Properties {
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              muted;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              opaque;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              locked;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              video_locked;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              automatic;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              whole_file;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              import;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              external;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              sync_marked;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              left_of_split;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              right_of_split;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              hidden;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              position_locked;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              valid_transients; // used for signal only
        LIBARDOUR_API extern PBD::PropertyDescriptor<timepos_t>         start;
        LIBARDOUR_API extern PBD::PropertyDescriptor<timecnt_t>         length;
        LIBARDOUR_API extern PBD::PropertyDescriptor<timepos_t>         sync_position;
        LIBARDOUR_API extern PBD::PropertyDescriptor<layer_t>           layer;
        LIBARDOUR_API extern PBD::PropertyDescriptor<timepos_t>         ancestral_start;
        LIBARDOUR_API extern PBD::PropertyDescriptor<timecnt_t>         ancestral_length;
        LIBARDOUR_API extern PBD::PropertyDescriptor<float>             stretch;
        LIBARDOUR_API extern PBD::PropertyDescriptor<float>             shift;
        LIBARDOUR_API extern PBD::PropertyDescriptor<uint64_t>          layering_index;
        LIBARDOUR_API extern PBD::PropertyDescriptor<std::string>       tags;
        LIBARDOUR_API extern PBD::PropertyDescriptor<uint64_t>          reg_group;
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              contents; // type doesn't matter here, used for signal only
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              region_fx; // type doesn't matter here, used for signal only
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              region_fx_changed; // type doesn't matter here, used for signal only
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              region_tempo; // type doesn't matter here, used for signal only
        LIBARDOUR_API extern PBD::PropertyDescriptor<bool>              region_meter; // type doesn't matter here, used for signal only
};
 
class Playlist;
class Filter;
class ExportSpecification;
class Plugin;
class RegionFxPlugin;
 
enum LIBARDOUR_API RegionEditState {
        EditChangesNothing = 0,
        EditChangesName    = 1,
        EditChangesID      = 2
};
 
enum LIBARDOUR_API RegionOperationFlag {
        LeftOfSplit    = 0,
        InnerSplit     = 1, // when splitting a Range, there's left/center/right parts of the split
        RightOfSplit   = 2,
        Paste          = 4
};
 
class LIBARDOUR_API Region
        : public SessionObject
        , public std::enable_shared_from_this<Region>
        , public Trimmable
        , public Movable
        , public Temporal::TimeDomainSwapper
{
public:
        typedef std::vector<std::shared_ptr<Source> > SourceList;
        typedef std::list<std::shared_ptr<RegionFxPlugin>> RegionFxList;
 
        static void make_property_quarks ();
 
        static PBD::Signal<void(std::shared_ptr<RegionList>, const PBD::PropertyChange&)> RegionsPropertyChanged;
 
        typedef std::map <PBD::PropertyChange, RegionList> ChangeMap;
 
        virtual ~Region();
 
        bool set_name (const std::string& str);
 
        PBD::PropertyList derive_properties (bool with_times = true, bool with_envelope = false) const;
 
        const DataType& data_type () const { return _type; }
        Temporal::TimeDomain time_domain() const;
        void start_domain_bounce (Temporal::DomainBounceInfo&);
        void finish_domain_bounce (Temporal::DomainBounceInfo&);
 
        timepos_t position ()  const { return _length.val().position(); }
        timepos_t start ()     const { return _start.val(); }
        timecnt_t length ()    const { return _length.val(); }
        timepos_t end()        const;
        timepos_t nt_last()    const { return end().decrement(); }
 
        virtual timecnt_t tail () const { return timecnt_t (0); }
 
        timepos_t source_position () const;
        timecnt_t source_relative_position (Temporal::timepos_t const &) const;
        timecnt_t region_relative_position (Temporal::timepos_t const &) const;
 
        samplepos_t position_sample ()  const { return position().samples(); }
        samplecnt_t start_sample ()     const { return _start.val().samples(); }
        samplecnt_t length_samples ()   const { return _length.val().samples(); }
 
        layer_t    layer ()     const { return _layer; }
 
        void set_selected_for_solo(bool yn);
 
        timepos_t source_length (uint32_t n) const;
        uint32_t   max_source_level () const;
 
        /* these two are valid ONLY during a StateChanged signal handler */
 
        timepos_t last_position () const { return _last_length.position(); }
        timecnt_t last_length ()   const { return _last_length; }
 
        samplecnt_t ancestral_start_sample ()  const { return _ancestral_start.val().samples(); }
        samplecnt_t ancestral_length_samples () const { return _ancestral_length.val().samples(); }
        timepos_t ancestral_start ()  const { return _ancestral_start.val(); }
        timecnt_t ancestral_length () const { return _ancestral_length.val(); }
 
        struct RegionGroupRetainer {
                RegionGroupRetainer ()
                {
                        Glib::Threads::Mutex::Lock lm (_operation_rgroup_mutex);
                        if (_retained_group_id == 0) {
                                _retained_take_cnt = 0;
                                ++_next_group_id;
                                _operation_rgroup_map.clear ();              // this is used for split & paste operations that honor the region's prior grouping
                                _retained_group_id    = _next_group_id << 4; // this is used for newly created regions via recording or importing
                                _clear_on_destruction = true;
                        } else {
                                _clear_on_destruction = false;
                        }
                }
                ~RegionGroupRetainer ()
                {
                        if (_clear_on_destruction) {
                                Glib::Threads::Mutex::Lock lm (_operation_rgroup_mutex);
                                _retained_group_id = 0;
                                _next_group_id += _retained_take_cnt;
                                _operation_rgroup_map.clear();
                        }
                }
                bool _clear_on_destruction;
        };
 
        static uint64_t next_group_id () { return _next_group_id; }
        static void set_next_group_id (uint64_t ngid) { _next_group_id = ngid; }
 
        /* access the retained group-id for actions like Recording, Import.
         *
         * Note When a single take creates multiple layered regions (e.g. loop recording)
         * then the group id need to be bumped for each take
         */
        static uint64_t get_retained_group_id (uint64_t take = 0) {
                _retained_take_cnt = std::max (_retained_take_cnt, take);
                return _retained_group_id + (take << 4);
        }
 
        /* access the group-id for an operation on a region, honoring the existing region's group status */
        static uint64_t get_region_operation_group_id (uint64_t old_region_group, RegionOperationFlag flags);
 
        uint64_t region_group () const { return _reg_group; }
        void set_region_group (uint64_t rg, bool explicitly = false) { _reg_group = rg | (explicitly ? Explicit : NoGroup); }
        void unset_region_group (bool explicitly = false) { _reg_group = (explicitly ? Explicit : NoGroup); }
 
        bool is_explicitly_grouped()   { return (_reg_group & Explicit) == Explicit; }
        bool is_implicitly_ungrouped() { return (_reg_group == NoGroup); }
        bool is_explicitly_ungrouped() { return (_reg_group == Explicit); }
 
        float stretch () const { return _stretch; }
        float shift ()   const { return _shift; }
 
        void set_ancestral_data (timepos_t const & start, timecnt_t const & length, float stretch, float shift);
 
        timecnt_t sync_offset (int& dir) const;
        timepos_t sync_position () const;
 
        timepos_t adjust_to_sync (timepos_t const &) const;
 
        /* first_sample() is an alias; last_sample() just hides some math */
 
        samplepos_t first_sample () const { return position().samples(); }
        samplepos_t last_sample ()  const { return first_sample() + length_samples() - 1; }
 
        timepos_t earliest_possible_position () const;
        samplepos_t latest_possible_sample () const;
 
        Temporal::TimeRange last_range () const {
                return Temporal::TimeRange (last_position(), last_position() + _last_length);
        }
 
        Temporal::TimeRange range_samples () const {
                return Temporal::TimeRange (timepos_t (first_sample()), timepos_t (first_sample() + length_samples()));
        }
 
        Temporal::TimeRange range () const {
                return Temporal::TimeRange (position(), position() + length());
        }
 
        bool hidden ()           const { return _hidden; }
        bool muted ()            const { return _muted; }
        bool opaque ()           const { return _opaque; }
        bool locked ()           const { return _locked; }
        bool position_locked ()  const { return _position_locked; }
        bool video_locked ()     const { return _video_locked; }
        bool automatic ()        const { return _automatic; }
        bool whole_file ()       const { return _whole_file; }
        bool captured ()         const { return !(_import || _external); }
        bool can_move ()         const { return !_position_locked && !_locked; }
        bool sync_marked ()      const { return _sync_marked; }
        bool external ()         const { return _external; }
        bool import ()           const { return _import; }
 
        Trimmable::CanTrim can_trim () const;
 
        Temporal::TimeDomain position_time_domain () const;
        void set_position_time_domain (Temporal::TimeDomain ps);
        void recompute_position_from_time_domain ();
 
        void suspend_property_changes ();
 
        bool covers (samplepos_t sample) const {
                return first_sample() <= sample && sample <= last_sample();
        }
 
        bool covers (timepos_t const & pos) const {
                return position() <= pos && pos <= nt_last();
        }
 
        Temporal::OverlapType coverage (timepos_t const & start, timepos_t const & end, bool with_tail = false) const {
                return Temporal::coverage_exclusive_ends (position(), with_tail ? nt_last() + tail() : nt_last(), start, end);
        }
 
        bool exact_equivalent (std::shared_ptr<const Region>) const;
        bool size_equivalent (std::shared_ptr<const Region>) const;
        bool overlap_equivalent (std::shared_ptr<const Region>) const;
        bool enclosed_equivalent (std::shared_ptr<const Region>) const;
        bool layer_and_time_equivalent (std::shared_ptr<const Region>) const;
        bool source_equivalent (std::shared_ptr<const Region>) const;
        bool any_source_equivalent (std::shared_ptr<const Region>) const;
        bool uses_source (std::shared_ptr<const Source>, bool shallow = false) const;
        void deep_sources (std::set<std::shared_ptr<Source> >&) const;
 
        std::string source_string () const;
 
 
        /* EDITING OPERATIONS */
 
        void set_length (timecnt_t const &);
        void set_start (timepos_t const &);
        void set_position (timepos_t const &);
        void set_initial_position (timepos_t const &);
        void special_set_position (timepos_t const &);
        virtual void update_after_tempo_map_change (bool send_change = true);
        void nudge_position (timecnt_t const &);
 
        bool at_natural_position () const;
        void move_to_natural_position ();
 
        void move_start (timecnt_t const & distance);
        void trim_front (timepos_t const & new_position);
        void trim_end (timepos_t const & new_position);
        void trim_to (timepos_t const & pos,  timecnt_t const & length);
 
        /* fades are inherently audio in nature and we specify them in samples */
        virtual void fade_range (samplepos_t, samplepos_t) {}
 
        void cut_front (timepos_t const & new_position);
        void cut_end (timepos_t const & new_position);
 
        void raise ();
        void lower ();
        void raise_to_top ();
        void lower_to_bottom ();
 
        void set_sync_position (timepos_t const & n);
        void clear_sync_position ();
        void set_hidden (bool yn);
        void set_muted (bool yn);
        void set_whole_file (bool yn);
        void set_automatic (bool yn);
        void set_opaque (bool yn);
        void set_locked (bool yn);
        void set_video_locked (bool yn);
        void set_position_locked (bool yn);
 
        /* ONLY Playlist can call this */
        void set_layer (layer_t l);
        void set_length_unchecked (timecnt_t const &);
        void set_position_unchecked (timepos_t const &);
        void modify_front_unchecked (timepos_t const & new_position, bool reset_fade);
        void modify_end_unchecked (timepos_t const & new_position, bool reset_fade);
 
        Temporal::timepos_t region_beats_to_absolute_time(Temporal::Beats beats) const;
        Temporal::timepos_t region_beats_to_region_time (Temporal::Beats beats) const {
                return timepos_t (position().distance (region_beats_to_absolute_time (beats)));
        }
        Temporal::Beats region_beats_to_source_beats (Temporal::Beats beats) const {
                return position().distance (region_beats_to_absolute_time (beats)).beats ();
        }
        Temporal::Beats region_distance_to_region_beats (Temporal::timecnt_t const &) const;
 
        Temporal::Beats source_beats_to_absolute_beats(Temporal::Beats beats) const;
 
        Temporal::timepos_t source_beats_to_absolute_time(Temporal::Beats beats) const;
 
        Temporal::timepos_t source_beats_to_region_time(Temporal::Beats beats) const {
                return timepos_t (position().distance (source_beats_to_absolute_time (beats)));
        }
        Temporal::Beats absolute_time_to_source_beats(Temporal::timepos_t const &) const;
 
        Temporal::Beats absolute_time_to_soucre_beats (Temporal::timepos_t const &) const;
 
        Temporal::timepos_t absolute_time_to_region_time (Temporal::timepos_t const &) const;
 
        int apply (Filter &, PBD::Progress* progress = 0);
 
        std::shared_ptr<ARDOUR::Playlist> playlist () const { return _playlist.lock(); }
        virtual void set_playlist (std::weak_ptr<ARDOUR::Playlist>);
 
        void source_deleted (std::weak_ptr<Source>);
 
        bool is_compound () const;
 
        std::shared_ptr<Source> source (uint32_t n=0) const { return _sources[ (n < _sources.size()) ? n : 0 ]; }
 
        SourceList& sources_for_edit ()           { return _sources; }
        const SourceList& sources ()        const { return _sources; }
        const SourceList& master_sources () const { return _master_sources; }
 
        std::vector<std::string> master_source_names();
        void set_master_sources (const SourceList&);
 
        /* automation */
 
        virtual std::shared_ptr<Evoral::Control>
                control (const Evoral::Parameter& id, bool create=false) = 0;
 
        virtual std::shared_ptr<const Evoral::Control>
        control (const Evoral::Parameter& id) const = 0;
 
        /* tags */
 
        std::string tags()    const { return _tags; }
        virtual bool set_tags (const std::string& str) {
                if (_tags != str) {
                        _tags = str;
                        PropertyChanged (PBD::PropertyChange (Properties::tags));
                }
                return true;
        }
 
        /* serialization */
 
        XMLNode&         get_state () const;
        virtual int      set_state (const XMLNode&, int version);
 
        virtual bool do_export (std::string const&) const = 0;
 
        virtual std::shared_ptr<Region> get_parent() const;
 
        uint64_t layering_index () const { return _layering_index; }
        void set_layering_index (uint64_t when) { _layering_index = when; }
 
        virtual bool is_dependent() const { return false; }
        virtual bool depends_on (std::shared_ptr<Region> /*other*/) const { return false; }
 
        virtual void add_transient (samplepos_t) {
                // no transients, but its OK
        }
 
        virtual void clear_transients () {
                // no transients, but its OK
        }
 
        virtual void update_transient (samplepos_t /* old_position */, samplepos_t /* new_position */) {
                // no transients, but its OK
        }
 
        virtual void remove_transient (samplepos_t /* where */) {
                // no transients, but its OK
        }
 
        virtual void set_onsets (AnalysisFeatureList&) {
                // no transients, but its OK
        }
 
        void transients (AnalysisFeatureList&);
 
        void captured_xruns (XrunPositions&, bool abs = false) const;
 
        virtual void get_transients (AnalysisFeatureList&) {
                // no transients, but its OK
        }
 
        /* wrapper to the above for easy access throug Lua */
        AnalysisFeatureList transients () {
                AnalysisFeatureList rv;
                get_transients (rv);
                return rv;
        }
 
        bool has_transients () const;
 
        virtual int separate_by_channel (std::vector< std::shared_ptr<Region> >&) const {
                return -1;
        }
 
        void maybe_invalidate_transients ();
 
        void drop_sources ();
 
        /* Allow to collect RegionsPropertyChanged signal emissions */
        void set_changemap (ChangeMap* changemap) {
                _changemap = changemap;
        }
 
        void get_cue_markers (CueMarkers&, bool abs = false) const;
        void move_cue_marker (CueMarker const &, timepos_t const & region_relative_position);
        void rename_cue_marker (CueMarker&, std::string const &);
 
        /* Region Fx */
        bool load_plugin (ARDOUR::PluginType type, std::string const& name);
        bool add_plugin (std::shared_ptr<RegionFxPlugin>, std::shared_ptr<RegionFxPlugin> pos = std::shared_ptr<RegionFxPlugin> ());
        virtual bool remove_plugin (std::shared_ptr<RegionFxPlugin>) { return false; }
        virtual void reorder_plugins (RegionFxList const&);
 
        bool has_region_fx () const {
                Glib::Threads::RWLock::ReaderLock lm (_fx_lock);
                return !_plugins.empty ();
        }
 
        size_t n_region_fx () const {
                Glib::Threads::RWLock::ReaderLock lm (_fx_lock);
                return _plugins.size ();
        }
 
        std::shared_ptr<RegionFxPlugin> nth_plugin (uint32_t n) const {
                Glib::Threads::RWLock::ReaderLock lm (_fx_lock);
                for (auto const& i : _plugins) {
                        if (0 == n--) {
                                return i;
                        }
                }
                return std::shared_ptr<RegionFxPlugin> ();
        }
 
        void foreach_plugin (std::function<void(std::weak_ptr<RegionFxPlugin>)> method) const {
                Glib::Threads::RWLock::ReaderLock lm (_fx_lock);
                for (auto const& i : _plugins) {
                        method (std::weak_ptr<RegionFxPlugin> (i));
                }
        }
 
        std::optional<Temporal::Tempo> tempo() const;
        void set_tempo (Temporal::Tempo const &);
        std::optional<Temporal::Meter> meter() const;
        void set_meter (Temporal::Meter const &);
 
        std::shared_ptr<Temporal::TempoMap> tempo_map() const;
 
protected:
        virtual XMLNode& state () const;
 
        friend class RegionFactory;
 
        Region (const SourceList& srcs);
 
        Region (std::shared_ptr<const Region>);
 
        Region (std::shared_ptr<const Region>, timecnt_t const & start_offset);
 
        Region (std::shared_ptr<const Region>, const SourceList&);
 
        Region (Session& s, timepos_t const & start, timecnt_t const & length, const std::string& name, DataType);
 
        virtual bool can_trim_start_before_source_start () const {
                return false;
        }
 
protected:
        virtual bool _add_plugin (std::shared_ptr<RegionFxPlugin>, std::shared_ptr<RegionFxPlugin>, bool) { return false; }
        virtual void fx_latency_changed (bool no_emit);
        virtual void fx_tail_changed (bool no_emit);
 
        virtual void send_change (const PBD::PropertyChange&);
        virtual int _set_state (const XMLNode&, int version, PBD::PropertyChange& what_changed, bool send_signal);
        virtual void set_position_internal (timepos_t const & pos);
        void set_length_internal (timecnt_t const &);
        virtual void set_start_internal (timepos_t const &);
        bool verify_start_and_length (timepos_t const &, timecnt_t&);
        void first_edit ();
        virtual void ensure_length_sanity () {}
 
        void override_opaqueness (bool yn) {
                _opaque = yn;
        }
 
        /* This is always using AudioTime. convenient for evenlopes in AudioRegion */
        timepos_t len_as_tpos () const { return timepos_t((samplepos_t)_length.val().samples()); }
 
        DataType _type;
 
        mutable Glib::Threads::RWLock _fx_lock;
        uint32_t                      _fx_latency;
        uint32_t                      _fx_tail;
        RegionFxList                  _plugins;
 
        PBD::Property<bool>      _sync_marked;
        PBD::Property<bool>      _left_of_split;
        PBD::Property<bool>      _right_of_split;
        PBD::Property<bool>      _valid_transients;
        PBD::Property<timepos_t> _start;
        PBD::Property<timecnt_t> _length;
        PBD::Property<timepos_t> _sync_position;
 
        SourceList              _sources;
        SourceList              _master_sources;
 
        std::weak_ptr<ARDOUR::Playlist> _playlist;
 
        void merge_features (AnalysisFeatureList&, const AnalysisFeatureList&, const sampleoffset_t) const;
 
        AnalysisFeatureList     _onsets; // used by the Ferret (Aubio OnsetDetector)
 
        // _transient_user_start is covered by  _valid_transients
        AnalysisFeatureList     _user_transients; // user added
        samplepos_t             _transient_user_start; // region's _start relative to user_transients
 
        // these are used by Playlist::find_next_transient() in absence of onsets
        AnalysisFeatureList     _transients; // Source Analysis (QM Transient), user read-only
        samplepos_t             _transient_analysis_start;
        samplepos_t             _transient_analysis_end;
 
        bool                    _soloSelected;
 
private:
        void mid_thaw (const PBD::PropertyChange&);
 
        void trim_to_internal (timepos_t const & position, timecnt_t const & length);
 
        void maybe_uncopy ();
        void subscribe_to_source_drop ();
 
        bool verify_start (timepos_t const &);
        bool verify_length (timecnt_t&);
 
        virtual void recompute_at_start () = 0;
        virtual void recompute_at_end () = 0;
 
        PBD::Property<bool>        _muted;
        PBD::Property<bool>        _opaque;
        PBD::Property<bool>        _locked;
        PBD::Property<bool>        _video_locked;
        PBD::Property<bool>        _automatic;
        PBD::Property<bool>        _whole_file;
        PBD::Property<bool>        _import;
        PBD::Property<bool>        _external;
        PBD::Property<bool>        _hidden;
        PBD::Property<bool>        _position_locked;
        PBD::Property<timepos_t>   _ancestral_start;
        PBD::Property<timecnt_t>   _ancestral_length;
        PBD::Property<float>       _stretch;
        PBD::Property<float>       _shift;
        PBD::Property<uint64_t>    _layering_index;
        PBD::Property<std::string> _tags;
        PBD::Property<uint64_t>    _reg_group;
        PBD::Property<bool>        _contents; // type is irrelevant
 
        timecnt_t             _last_length;
        mutable RegionEditState _first_edit;
        layer_t                 _layer;
 
        ChangeMap* _changemap;
 
        void register_properties ();
 
        void use_sources (SourceList const &);
 
        enum RegionGroupFlags : uint64_t {
                NoGroup   = 0x0, // no flag: implicitly grouped if the id is nonzero; or implicitly 'un-grouped' if the group-id is zero
                Explicit  = 0x1, // the user has explicitly grouped or ungrouped this region. explicitly grouped regions can cross track-group boundaries
        };
        static uint64_t _retained_group_id;
        static uint64_t _retained_take_cnt;
        static uint64_t _next_group_id;
 
        static Glib::Threads::Mutex         _operation_rgroup_mutex;
        static std::map<uint64_t, uint64_t> _operation_rgroup_map;
 
        std::atomic<int>          _source_deleted;
        Glib::Threads::Mutex      _source_list_lock;
        PBD::ScopedConnectionList _source_deleted_connections;
};
 
} /* namespace ARDOUR */