Revert internals of the last layering-related commit, and go back a slightly-cleaned...
[ardour.git] / libs / ardour / playlist.cc
index 851cf8596ede7e518861cf14c8b062cc1ecf2a3e..7ef59645d136202f4ffd898df8af43411a398391 100644 (file)
@@ -17,9 +17,7 @@
 
 */
 
-#define __STDC_LIMIT_MACROS
 #include <stdint.h>
-
 #include <set>
 #include <fstream>
 #include <algorithm>
@@ -30,6 +28,7 @@
 
 #include <boost/lexical_cast.hpp>
 
+#include "pbd/convert.h"
 #include "pbd/failed_constructor.h"
 #include "pbd/stateful_diff_command.h"
 #include "pbd/xml++.h"
 #include "ardour/session.h"
 #include "ardour/region.h"
 #include "ardour/region_factory.h"
+#include "ardour/region_sorters.h"
 #include "ardour/playlist_factory.h"
+#include "ardour/playlist_source.h"
 #include "ardour/transient_detector.h"
 #include "ardour/session_playlists.h"
+#include "ardour/source_factory.h"
 
 #include "i18n.h"
 
@@ -64,88 +66,84 @@ struct ShowMeTheList {
     string name;
 };
 
-struct RegionSortByLayer {
-    bool operator() (boost::shared_ptr<Region> a, boost::shared_ptr<Region> b) {
-           return a->layer() < b->layer();
-    }
-};
 
-struct RegionSortByLayerWithPending {
-       bool operator () (boost::shared_ptr<Region> a, boost::shared_ptr<Region> b) {
 
-               double p = a->layer ();
-               if (a->pending_explicit_relayer()) {
-                       p += 0.5;
-               }
+void
+Playlist::make_property_quarks ()
+{
+       Properties::regions.property_id = g_quark_from_static_string (X_("regions"));
+       DEBUG_TRACE (DEBUG::Properties, string_compose ("quark for regions = %1\n",
+                                                       Properties::regions.property_id));
+}
 
-               double q = b->layer ();
-               if (b->pending_explicit_relayer()) {
-                       q += 0.5;
-               }
+RegionListProperty::RegionListProperty (Playlist& pl)
+       : SequenceProperty<std::list<boost::shared_ptr<Region> > > (Properties::regions.property_id, boost::bind (&Playlist::update, &pl, _1))
+       , _playlist (pl)
+{
 
-               return p < q;
-       }
-};
+}
 
-struct RegionSortByPosition {
-    bool operator() (boost::shared_ptr<Region> a, boost::shared_ptr<Region> b) {
-           return a->position() < b->position();
-    }
-};
+RegionListProperty::RegionListProperty (RegionListProperty const & p)
+       : PBD::SequenceProperty<std::list<boost::shared_ptr<Region> > > (p)
+       , _playlist (p._playlist)
+{
 
-struct RegionSortByLastLayerOp {
-    bool operator() (boost::shared_ptr<Region> a, boost::shared_ptr<Region> b) {
-           return a->last_layer_op() < b->last_layer_op();
-    }
-};
+}
 
-void
-Playlist::make_property_quarks ()
+RegionListProperty *
+RegionListProperty::clone () const
 {
-        Properties::regions.property_id = g_quark_from_static_string (X_("regions"));
-        DEBUG_TRACE (DEBUG::Properties, string_compose ("quark for regions = %1\n",         Properties::regions.property_id));
+       return new RegionListProperty (*this);
 }
 
-RegionListProperty::RegionListProperty (Playlist& pl)
-        : SequenceProperty<std::list<boost::shared_ptr<Region> > > (Properties::regions.property_id, boost::bind (&Playlist::update, &pl, _1))
-        , _playlist (pl)
+RegionListProperty *
+RegionListProperty::create () const
 {
+       return new RegionListProperty (_playlist);
 }
 
-boost::shared_ptr<Region>
-RegionListProperty::lookup_id (const ID& id)
+void
+RegionListProperty::get_content_as_xml (boost::shared_ptr<Region> region, XMLNode & node) const
 {
-        boost::shared_ptr<Region> ret =  _playlist.region_by_id (id);
-        
-        if (!ret) {
-                ret = RegionFactory::region_by_id (id);
-        }
+       /* All regions (even those which are deleted) have their state saved by other
+          code, so we can just store ID here.
+       */
 
-        return ret;
+       node.add_property ("id", region->id().to_s ());
 }
 
-SequenceProperty<std::list<boost::shared_ptr<Region> > >* RegionListProperty::create () const
+boost::shared_ptr<Region>
+RegionListProperty::get_content_from_xml (XMLNode const & node) const
 {
-       return new RegionListProperty (_playlist);
+       XMLProperty const * prop = node.property ("id");
+       assert (prop);
+
+       PBD::ID id (prop->value ());
+
+       boost::shared_ptr<Region> ret = _playlist.region_by_id (id);
+
+       if (!ret) {
+               ret = RegionFactory::region_by_id (id);
+       }
+
+       return ret;
 }
 
 Playlist::Playlist (Session& sess, string nom, DataType type, bool hide)
        : SessionObject(sess, nom)
-        , regions (*this)
+       , regions (*this)
        , _type(type)
 {
        init (hide);
        first_set_state = false;
        _name = nom;
-        _set_sort_id ();
-
+       _set_sort_id ();
 }
 
 Playlist::Playlist (Session& sess, const XMLNode& node, DataType type, bool hide)
        : SessionObject(sess, "unnamed playlist")
-        , regions (*this)      
-        , _type(type)
-
+       , regions (*this)
+       , _type(type)
 {
 #ifndef NDEBUG
        const XMLProperty* prop = node.property("type");
@@ -154,16 +152,16 @@ Playlist::Playlist (Session& sess, const XMLNode& node, DataType type, bool hide
 
        init (hide);
        _name = "unnamed"; /* reset by set_state */
-        _set_sort_id ();
+       _set_sort_id ();
 
        /* set state called by derived class */
 }
 
 Playlist::Playlist (boost::shared_ptr<const Playlist> other, string namestr, bool hide)
        : SessionObject(other->_session, namestr)
-        , regions (*this)
+       , regions (*this)
        , _type(other->_type)
-       , _orig_diskstream_id (other->_orig_diskstream_id)
+       , _orig_track_id (other->_orig_track_id)
 {
        init (hide);
 
@@ -187,18 +185,14 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, string namestr, boo
        in_flush = false;
        in_partition = false;
        subcnt = 0;
-       _read_data_count = 0;
        _frozen = other->_frozen;
-
-       layer_op_counter = other->layer_op_counter;
-       freeze_length = other->freeze_length;
 }
 
 Playlist::Playlist (boost::shared_ptr<const Playlist> other, framepos_t start, framecnt_t cnt, string str, bool hide)
        : SessionObject(other->_session, str)
-        , regions (*this)
+       , regions (*this)
        , _type(other->_type)
-       , _orig_diskstream_id (other->_orig_diskstream_id)
+       , _orig_track_id (other->_orig_track_id)
 {
        RegionLock rlock2 (const_cast<Playlist*> (other.get()));
 
@@ -253,12 +247,13 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, framepos_t start, f
 
                RegionFactory::region_name (new_name, region->name(), false);
 
-               PropertyList plist; 
+               PropertyList plist;
 
                plist.add (Properties::start, region->start() + offset);
                plist.add (Properties::length, len);
                plist.add (Properties::name, new_name);
                plist.add (Properties::layer, region->layer());
+               plist.add (Properties::layering_index, region->layering_index());
 
                new_region = RegionFactory::RegionFactory::create (region, plist);
 
@@ -267,8 +262,6 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, framepos_t start, f
 
        in_set_state--;
        first_set_state = false;
-
-       /* this constructor does NOT notify others (session) */
 }
 
 void
@@ -296,20 +289,19 @@ Playlist::copy_regions (RegionList& newlist) const
        RegionLock rlock (const_cast<Playlist *> (this));
 
        for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
-               newlist.push_back (RegionFactory::RegionFactory::create (*i));
+               newlist.push_back (RegionFactory::RegionFactory::create (*i, true));
        }
 }
 
 void
 Playlist::init (bool hide)
 {
-        add_property (regions);
-        _xml_node_name = X_("Playlist");
+       add_property (regions);
+       _xml_node_name = X_("Playlist");
 
        g_atomic_int_set (&block_notifications, 0);
        g_atomic_int_set (&ignore_state_changes, 0);
        pending_contents_change = false;
-       pending_length = false;
        pending_layering = false;
        first_set_state = true;
        _refcnt = 0;
@@ -318,20 +310,17 @@ Playlist::init (bool hide)
        _shuffling = false;
        _nudging = false;
        in_set_state = 0;
-        in_update = false;
+       in_update = false;
        _edit_mode = Config->get_edit_mode();
        in_flush = false;
        in_partition = false;
        subcnt = 0;
-       _read_data_count = 0;
        _frozen = false;
-       layer_op_counter = 0;
-       freeze_length = 0;
-       _explicit_relayering = false;
+       _combine_ops = 0;
 
        _session.history().BeginUndoRedo.connect_same_thread (*this, boost::bind (&Playlist::begin_undo, this));
        _session.history().EndUndoRedo.connect_same_thread (*this, boost::bind (&Playlist::end_undo, this));
-       
+
        ContentsChanged.connect_same_thread (*this, boost::bind (&Playlist::mark_session_dirty, this));
 }
 
@@ -353,27 +342,27 @@ Playlist::~Playlist ()
 void
 Playlist::_set_sort_id ()
 {
-        /*
-          Playlists are given names like <track name>.<id>
-          or <track name>.<edit group name>.<id> where id
-          is an integer. We extract the id and sort by that.
-        */
-        
-        size_t dot_position = _name.val().find_last_of(".");
+       /*
+         Playlists are given names like <track name>.<id>
+         or <track name>.<edit group name>.<id> where id
+         is an integer. We extract the id and sort by that.
+       */
+
+       size_t dot_position = _name.val().find_last_of(".");
 
-        if (dot_position == string::npos) {
-                _sort_id = 0;
-        } else {
-                string t = _name.val().substr(dot_position + 1);
+       if (dot_position == string::npos) {
+               _sort_id = 0;
+       } else {
+               string t = _name.val().substr(dot_position + 1);
 
-                try {
-                        _sort_id = boost::lexical_cast<int>(t);
-                }
+               try {
+                       _sort_id = boost::lexical_cast<int>(t);
+               }
 
-                catch (boost::bad_lexical_cast e) {
-                        _sort_id = 0;
-                }
-        }
+               catch (boost::bad_lexical_cast e) {
+                       _sort_id = 0;
+               }
+       }
 }
 
 bool
@@ -387,13 +376,13 @@ Playlist::set_name (const string& str)
 
        if (_refcnt > 2) {
                return false;
-       } 
+       }
 
-        bool ret =  SessionObject::set_name(str);
-        if (ret) {
-                _set_sort_id ();
-        }
-        return ret;
+       bool ret =  SessionObject::set_name(str);
+       if (ret) {
+               _set_sort_id ();
+       }
+       return ret;
 }
 
 /***********************************************************************
@@ -407,7 +396,7 @@ Playlist::set_name (const string& str)
 void
 Playlist::begin_undo ()
 {
-        in_update = true;
+       in_update = true;
        freeze ();
 }
 
@@ -415,7 +404,7 @@ void
 Playlist::end_undo ()
 {
        thaw (true);
-        in_update = false;
+       in_update = false;
 }
 
 void
@@ -438,7 +427,6 @@ void
 Playlist::delay_notifications ()
 {
        g_atomic_int_inc (&block_notifications);
-       freeze_length = _get_extent().second;
 }
 
 /** @param from_undo true if this release is triggered by the end of an undo on this playlist */
@@ -447,8 +435,7 @@ Playlist::release_notifications (bool from_undo)
 {
        if (g_atomic_int_dec_and_test (&block_notifications)) {
                flush_notifications (from_undo);
-        }
-
+       }
 }
 
 void
@@ -479,13 +466,10 @@ Playlist::notify_region_removed (boost::shared_ptr<Region> r)
        if (holding_state ()) {
                pending_removes.insert (r);
                pending_contents_change = true;
-               pending_length = true;
        } else {
                /* this might not be true, but we have to act
                   as though it could be.
                */
-               pending_length = false;
-               LengthChanged (); /* EMIT SIGNAL */
                pending_contents_change = false;
                RegionRemoved (boost::weak_ptr<Region> (r)); /* EMIT SIGNAL */
                ContentsChanged (); /* EMIT SIGNAL */
@@ -510,40 +494,69 @@ Playlist::notify_region_moved (boost::shared_ptr<Region> r)
 
 }
 
+void
+Playlist::notify_region_start_trimmed (boost::shared_ptr<Region> r)
+{
+       if (r->position() >= r->last_position()) {
+               /* trimmed shorter */
+               return;
+       }
+
+       Evoral::Range<framepos_t> const extra (r->position(), r->last_position());
+
+       if (holding_state ()) {
+
+               pending_region_extensions.push_back (extra);
+
+       } else {
+
+               list<Evoral::Range<framepos_t> > r;
+               r.push_back (extra);
+               RegionsExtended (r);
+
+       }
+}
+
+void
+Playlist::notify_region_end_trimmed (boost::shared_ptr<Region> r)
+{
+       if (r->length() < r->last_length()) {
+               /* trimmed shorter */
+       }
+
+       Evoral::Range<framepos_t> const extra (r->position() + r->last_length(), r->position() + r->length());
+
+       if (holding_state ()) {
+
+               pending_region_extensions.push_back (extra);
+
+       } else {
+
+               list<Evoral::Range<framepos_t> > r;
+               r.push_back (extra);
+               RegionsExtended (r);
+       }
+}
+
+
 void
 Playlist::notify_region_added (boost::shared_ptr<Region> r)
 {
        /* the length change might not be true, but we have to act
           as though it could be.
        */
-        
+
        if (holding_state()) {
                pending_adds.insert (r);
                pending_contents_change = true;
-               pending_length = true;
        } else {
-                r->clear_history ();
-               pending_length = false;
-               LengthChanged (); /* EMIT SIGNAL */
+               r->clear_changes ();
                pending_contents_change = false;
                RegionAdded (boost::weak_ptr<Region> (r)); /* EMIT SIGNAL */
                ContentsChanged (); /* EMIT SIGNAL */
        }
 }
 
-void
-Playlist::notify_length_changed ()
-{
-       if (holding_state ()) {
-               pending_length = true;
-       } else {
-               pending_length = false;
-               LengthChanged(); /* EMIT SIGNAL */
-               pending_contents_change = false;
-               ContentsChanged (); /* EMIT SIGNAL */
-       }
-}
-
 /** @param from_undo true if this flush is triggered by the end of an undo on this playlist */
 void
 Playlist::flush_notifications (bool from_undo)
@@ -551,8 +564,6 @@ Playlist::flush_notifications (bool from_undo)
        set<boost::shared_ptr<Region> > dependent_checks_needed;
        set<boost::shared_ptr<Region> >::iterator s;
        uint32_t regions_changed = false;
-       bool check_length = false;
-       framecnt_t old_length = 0;
 
        if (in_flush) {
                return;
@@ -562,10 +573,6 @@ Playlist::flush_notifications (bool from_undo)
 
        if (!pending_bounds.empty() || !pending_removes.empty() || !pending_adds.empty()) {
                regions_changed = true;
-               if (!pending_length) {
-                       old_length = _get_extent ().second;
-                       check_length = true;
-               }
        }
 
        /* we have no idea what order the regions ended up in pending
@@ -578,9 +585,6 @@ Playlist::flush_notifications (bool from_undo)
        // pending_bounds.sort (cmp);
 
        for (RegionList::iterator r = pending_bounds.begin(); r != pending_bounds.end(); ++r) {
-               if (_session.config.get_layer_model() == MoveAddHigher) {
-                       timestamp_layer_op (*r);
-               }
                dependent_checks_needed.insert (*r);
        }
 
@@ -591,1668 +595,1622 @@ Playlist::flush_notifications (bool from_undo)
        }
 
        for (s = pending_adds.begin(); s != pending_adds.end(); ++s) {
-               // cerr << _name << " sends RegionAdded\n";
-                /* don't emit RegionAdded signal until relayering is done,
-                   so that the region is fully setup by the time
-                   anyone hear's that its been added
-                */
-               dependent_checks_needed.insert (*s);
-       }
-
-       if (check_length) {
-               if (old_length != _get_extent().second) {
-                       pending_length = true;
-                       // cerr << _name << " length has changed\n";
-               }
-       }
+                // cerr << _name << " sends RegionAdded\n";
+                /* don't emit RegionAdded signal until relayering is done,
+                   so that the region is fully setup by the time
+                   anyone hear's that its been added
+                */
+                dependent_checks_needed.insert (*s);
+        }
+
+        if (regions_changed || pending_contents_change) {
+                if (!in_set_state) {
+                        relayer ();
+                }
+                pending_contents_change = false;
+                // cerr << _name << " sends 5 contents change @ " << get_microseconds() << endl;
+                ContentsChanged (); /* EMIT SIGNAL */
+                // cerr << _name << "done contents change @ " << get_microseconds() << endl;
+        }
+
+        for (s = pending_adds.begin(); s != pending_adds.end(); ++s) {
+                (*s)->clear_changes ();
+                RegionAdded (boost::weak_ptr<Region> (*s)); /* EMIT SIGNAL */
+        }
+
+        for (s = dependent_checks_needed.begin(); s != dependent_checks_needed.end(); ++s) {
+                check_dependents (*s, false);
+        }
+
+        if (!pending_range_moves.empty ()) {
+                RangesMoved (pending_range_moves, from_undo);
+        }
+
+        if (!pending_region_extensions.empty ()) {
+                RegionsExtended (pending_region_extensions);
+        }
+
+        clear_pending ();
+
+        in_flush = false;
+ }
+
+ void
+ Playlist::clear_pending ()
+ {
+        pending_adds.clear ();
+        pending_removes.clear ();
+        pending_bounds.clear ();
+        pending_range_moves.clear ();
+        pending_region_extensions.clear ();
+        pending_contents_change = false;
+ }
+
+ /*************************************************************
+   PLAYLIST OPERATIONS
+  *************************************************************/
+
+ void
+ Playlist::add_region (boost::shared_ptr<Region> region, framepos_t position, float times, bool auto_partition)
+ {
+        RegionLock rlock (this);
+        times = fabs (times);
+
+        int itimes = (int) floor (times);
+
+        framepos_t pos = position;
+
+        if (times == 1 && auto_partition){
+                partition(pos - 1, (pos + region->length()), true);
+        }
+
+        if (itimes >= 1) {
+                region->set_pending_layer (DBL_MAX);
+                add_region_internal (region, pos);
+                pos += region->length();
+                --itimes;
+        }
+
+
+        /* note that itimes can be zero if we being asked to just
+           insert a single fraction of the region.
+        */
 
-       if (pending_length || (freeze_length != _get_extent().second)) {
-               pending_length = false;
-               // cerr << _name << " sends LengthChanged\n";
-               LengthChanged(); /* EMIT SIGNAL */
-       }
+        for (int i = 0; i < itimes; ++i) {
+                boost::shared_ptr<Region> copy = RegionFactory::create (region, true);
+                copy->set_pending_layer (DBL_MAX);
+                add_region_internal (copy, pos);
+                pos += region->length();
+        }
 
-       if (regions_changed || pending_contents_change) {
-               if (!in_set_state) {
-                       relayer ();
-               }
-               pending_contents_change = false;
-               // cerr << _name << " sends 5 contents change @ " << get_microseconds() << endl;
-               ContentsChanged (); /* EMIT SIGNAL */
-               // cerr << _name << "done contents change @ " << get_microseconds() << endl;
-       }
+        framecnt_t length = 0;
 
-       for (s = pending_adds.begin(); s != pending_adds.end(); ++s) {
-                (*s)->clear_history ();
-               RegionAdded (boost::weak_ptr<Region> (*s)); /* EMIT SIGNAL */
-        }
+        if (floor (times) != times) {
+                length = (framecnt_t) floor (region->length() * (times - floor (times)));
+                string name;
+                RegionFactory::region_name (name, region->name(), false);
 
-       for (s = dependent_checks_needed.begin(); s != dependent_checks_needed.end(); ++s) {
-               check_dependents (*s, false);
-       }
+                {
+                        PropertyList plist;
 
-       if (!pending_range_moves.empty ()) {
-               RangesMoved (pending_range_moves, from_undo);
-       }
-       
-       clear_pending ();
+                        plist.add (Properties::start, region->start());
+                        plist.add (Properties::length, length);
+                        plist.add (Properties::name, name);
+                        plist.add (Properties::layer, region->layer());
 
-       in_flush = false;
-}
+                        boost::shared_ptr<Region> sub = RegionFactory::create (region, plist);
+                        sub->set_pending_layer (DBL_MAX);
+                        add_region_internal (sub, pos);
+                }
+        }
 
-void
-Playlist::clear_pending ()
-{
-       pending_adds.clear ();
-       pending_removes.clear ();
-       pending_bounds.clear ();
-       pending_range_moves.clear ();
-       pending_contents_change = false;
-       pending_length = false;
-}
+        possibly_splice_unlocked (position, (pos + length) - position, boost::shared_ptr<Region>());
+ }
 
-/*************************************************************
-  PLAYLIST OPERATIONS
- *************************************************************/
+ void
+ Playlist::set_region_ownership ()
+ {
+        RegionLock rl (this);
+        RegionList::iterator i;
+        boost::weak_ptr<Playlist> pl (shared_from_this());
 
-void
-Playlist::add_region (boost::shared_ptr<Region> region, framepos_t position, float times, bool auto_partition)
-{
-       RegionLock rlock (this);
-       times = fabs (times);
+        for (i = regions.begin(); i != regions.end(); ++i) {
+                (*i)->set_playlist (pl);
+        }
+ }
 
-       int itimes = (int) floor (times);
+ bool
+ Playlist::add_region_internal (boost::shared_ptr<Region> region, framepos_t position)
+ {
+        if (region->data_type() != _type) {
+                return false;
+        }
 
-       framepos_t pos = position;
+        RegionSortByPosition cmp;
 
-       if (times == 1 && auto_partition){
-               partition(pos - 1, (pos + region->length()), true);
-       }
+        if (!first_set_state) {
+                boost::shared_ptr<Playlist> foo (shared_from_this());
+                region->set_playlist (boost::weak_ptr<Playlist>(foo));
+        }
+
+        region->set_position (position);
+
+        regions.insert (upper_bound (regions.begin(), regions.end(), region, cmp), region);
+        all_regions.insert (region);
+
+        possibly_splice_unlocked (position, region->length(), region);
+
+        if (!holding_state ()) {
+                /* layers get assigned from XML state, and are not reset during undo/redo */
+                relayer ();
+        }
+
+        /* we need to notify the existence of new region before checking dependents. Ick. */
+
+        notify_region_added (region);
+
+        if (!holding_state ()) {
+                check_dependents (region, false);
+        }
+
+        region->PropertyChanged.connect_same_thread (region_state_changed_connections, boost::bind (&Playlist::region_changed_proxy, this, _1, boost::weak_ptr<Region> (region)));
+
+        return true;
+ }
+
+ void
+ Playlist::replace_region (boost::shared_ptr<Region> old, boost::shared_ptr<Region> newr, framepos_t pos)
+ {
+        RegionLock rlock (this);
+
+        bool old_sp = _splicing;
+        _splicing = true;
+
+        remove_region_internal (old);
+        newr->set_pending_layer (newr->layer ());
+        add_region_internal (newr, pos);
+
+        _splicing = old_sp;
+
+        possibly_splice_unlocked (pos, old->length() - newr->length());
+ }
+
+ void
+ Playlist::remove_region (boost::shared_ptr<Region> region)
+ {
+        RegionLock rlock (this);
+        remove_region_internal (region);
+ }
+
+ int
+ Playlist::remove_region_internal (boost::shared_ptr<Region> region)
+ {
+        RegionList::iterator i;
+
+        if (!in_set_state) {
+                /* unset playlist */
+                region->set_playlist (boost::weak_ptr<Playlist>());
+        }
+
+        /* XXX should probably freeze here .... */
+
+        for (i = regions.begin(); i != regions.end(); ++i) {
+                if (*i == region) {
+
+                        framepos_t pos = (*i)->position();
+                        framecnt_t distance = (*i)->length();
+
+                        regions.erase (i);
+
+                        possibly_splice_unlocked (pos, -distance);
+
+                        if (!holding_state ()) {
+                                relayer ();
+                                remove_dependents (region);
+                        }
+
+                        notify_region_removed (region);
+                        break;
+                }
+        }
+
+        return -1;
+ }
+
+ void
+ Playlist::get_equivalent_regions (boost::shared_ptr<Region> other, vector<boost::shared_ptr<Region> >& results)
+ {
+        if (Config->get_use_overlap_equivalency()) {
+                for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                        if ((*i)->overlap_equivalent (other)) {
+                                results.push_back ((*i));
+                        }
+                }
+        } else {
+                for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                        if ((*i)->equivalent (other)) {
+                                results.push_back ((*i));
+                        }
+                }
+        }
+ }
 
-       if (itimes >= 1) {
-               add_region_internal (region, pos);
-               pos += region->length();
-               --itimes;
-       }
+ void
+ Playlist::get_region_list_equivalent_regions (boost::shared_ptr<Region> other, vector<boost::shared_ptr<Region> >& results)
+ {
+        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+
+                if ((*i) && (*i)->region_list_equivalent (other)) {
+                        results.push_back (*i);
+                }
+        }
+ }
+
+ void
+ Playlist::partition (framepos_t start, framepos_t end, bool cut)
+ {
+        RegionList thawlist;
+
+        partition_internal (start, end, cut, thawlist);
+
+        for (RegionList::iterator i = thawlist.begin(); i != thawlist.end(); ++i) {
+                (*i)->resume_property_changes ();
+        }
+ }
+
+/** Go through each region on the playlist and cut them at start and end, removing the section between
+ *  start and end if cutting == true.  Regions that lie entirely within start and end are always
+ *  removed.
+ */
 
+ void
+ Playlist::partition_internal (framepos_t start, framepos_t end, bool cutting, RegionList& thawlist)
+ {
+        RegionList new_regions;
 
-       /* note that itimes can be zero if we being asked to just
-          insert a single fraction of the region.
-       */
+        {
+                RegionLock rlock (this);
 
-       for (int i = 0; i < itimes; ++i) {
-               boost::shared_ptr<Region> copy = RegionFactory::create (region);
-               add_region_internal (copy, pos);
-               pos += region->length();
-       }
+                boost::shared_ptr<Region> region;
+                boost::shared_ptr<Region> current;
+                string new_name;
+                RegionList::iterator tmp;
+                OverlapType overlap;
+                framepos_t pos1, pos2, pos3, pos4;
 
-       framecnt_t length = 0;
+                in_partition = true;
 
-       if (floor (times) != times) {
-               length = (framecnt_t) floor (region->length() * (times - floor (times)));
-               string name;
-               RegionFactory::region_name (name, region->name(), false);
+                /* need to work from a copy, because otherwise the regions we add during the process
+                   get operated on as well.
+                */
 
-               {
-                       PropertyList plist;
-                       
-                       plist.add (Properties::start, region->start());
-                       plist.add (Properties::length, length);
-                       plist.add (Properties::name, name);
-                       plist.add (Properties::layer, region->layer());
+                RegionList copy = regions.rlist();
 
-                       boost::shared_ptr<Region> sub = RegionFactory::create (region, plist);
-                       add_region_internal (sub, pos);
-               }
-       }
+                for (RegionList::iterator i = copy.begin(); i != copy.end(); i = tmp) {
 
-       possibly_splice_unlocked (position, (pos + length) - position, boost::shared_ptr<Region>());
-}
+                        tmp = i;
+                        ++tmp;
 
-void
-Playlist::set_region_ownership ()
-{
-       RegionLock rl (this);
-       RegionList::iterator i;
-       boost::weak_ptr<Playlist> pl (shared_from_this());
+                        current = *i;
 
-       for (i = regions.begin(); i != regions.end(); ++i) {
-               (*i)->set_playlist (pl);
-       }
-}
+                        if (current->first_frame() >= start && current->last_frame() < end) {
 
-bool
-Playlist::add_region_internal (boost::shared_ptr<Region> region, framepos_t position)
-{
-       if (region->data_type() != _type){
-               return false;
-       }
+                                if (cutting) {
+                                        remove_region_internal (current);
+                                }
 
-       RegionSortByPosition cmp;
+                                continue;
+                        }
 
-       framecnt_t old_length = 0;
+                        /* coverage will return OverlapStart if the start coincides
+                           with the end point. we do not partition such a region,
+                           so catch this special case.
+                        */
 
-       if (!holding_state()) {
-                old_length = _get_extent().second;
-       }
+                        if (current->first_frame() >= end) {
+                                continue;
+                        }
 
-       if (!first_set_state) {
-               boost::shared_ptr<Playlist> foo (shared_from_this());
-               region->set_playlist (boost::weak_ptr<Playlist>(foo));
-       }
+                        if ((overlap = current->coverage (start, end)) == OverlapNone) {
+                                continue;
+                        }
 
-       region->set_position (position, this);
+                        pos1 = current->position();
+                        pos2 = start;
+                        pos3 = end;
+                        pos4 = current->last_frame();
 
-       timestamp_layer_op (region);
+                        if (overlap == OverlapInternal) {
+                                /* split: we need 3 new regions, the front, middle and end.
+                                   cut:   we need 2 regions, the front and end.
+                                */
 
-       regions.insert (upper_bound (regions.begin(), regions.end(), region, cmp), region);
-       all_regions.insert (region);
+                                /*
+                                         start                 end
+                          ---------------*************************------------
+                                         P1  P2              P3  P4
+                          SPLIT:
+                          ---------------*****++++++++++++++++====------------
+                          CUT
+                          ---------------*****----------------====------------
 
-       possibly_splice_unlocked (position, region->length(), region);
+                                */
 
-       if (!holding_state ()) {
-               /* layers get assigned from XML state, and are not reset during undo/redo */
-               relayer ();
-       }
+                                if (!cutting) {
+                                        /* "middle" ++++++ */
 
-       /* we need to notify the existence of new region before checking dependents. Ick. */
+                                        RegionFactory::region_name (new_name, current->name(), false);
 
-       notify_region_added (region);
+                                        PropertyList plist;
 
-       if (!holding_state ()) {
+                                        plist.add (Properties::start, current->start() + (pos2 - pos1));
+                                        plist.add (Properties::length, pos3 - pos2);
+                                        plist.add (Properties::name, new_name);
+                                        plist.add (Properties::layer, current->layer ());
+                                        plist.add (Properties::layering_index, current->layering_index ());
+                                        plist.add (Properties::automatic, true);
+                                        plist.add (Properties::left_of_split, true);
+                                        plist.add (Properties::right_of_split, true);
 
-               check_dependents (region, false);
+                                        region = RegionFactory::create (current, plist);
+                                        add_region_internal (region, start);
+                                        new_regions.push_back (region);
+                                }
 
-               if (old_length != _get_extent().second) {
-                       notify_length_changed ();
-               }
-       }
+                                /* "end" ====== */
 
-       region->PropertyChanged.connect_same_thread (region_state_changed_connections, boost::bind (&Playlist::region_changed_proxy, this, _1, boost::weak_ptr<Region> (region)));
+                                RegionFactory::region_name (new_name, current->name(), false);
 
-       return true;
-}
+                                PropertyList plist;
 
-void
-Playlist::replace_region (boost::shared_ptr<Region> old, boost::shared_ptr<Region> newr, framepos_t pos)
-{
-       RegionLock rlock (this);
+                                plist.add (Properties::start, current->start() + (pos3 - pos1));
+                                plist.add (Properties::length, pos4 - pos3);
+                                plist.add (Properties::name, new_name);
+                                plist.add (Properties::layer, current->layer ());
+                                plist.add (Properties::layering_index, current->layering_index ());
+                                plist.add (Properties::automatic, true);
+                                plist.add (Properties::right_of_split, true);
 
-       bool old_sp = _splicing;
-       _splicing = true;
+                                region = RegionFactory::create (current, plist);
 
-       remove_region_internal (old);
-       add_region_internal (newr, pos);
+                                add_region_internal (region, end);
+                                new_regions.push_back (region);
 
-       _splicing = old_sp;
+                                /* "front" ***** */
 
-       possibly_splice_unlocked (pos, old->length() - newr->length());
-}
+                                current->suspend_property_changes ();
+                                thawlist.push_back (current);
+                                current->cut_end (pos2 - 1);
 
-void
-Playlist::remove_region (boost::shared_ptr<Region> region)
-{
-       RegionLock rlock (this);
-       remove_region_internal (region);
-}
+                        } else if (overlap == OverlapEnd) {
 
-int
-Playlist::remove_region_internal (boost::shared_ptr<Region> region)
-{
-       RegionList::iterator i;
-       framecnt_t old_length = 0;
-       int ret = -1;
+                                /*
+                                                              start           end
+                                    ---------------*************************------------
+                                                   P1           P2         P4   P3
+                                    SPLIT:
+                                    ---------------**************+++++++++++------------
+                                    CUT:
+                                    ---------------**************-----------------------
+                                */
 
-       if (!holding_state()) {
-               old_length = _get_extent().second;
-       }
+                                if (!cutting) {
 
-       if (!in_set_state) {
-               /* unset playlist */
-               region->set_playlist (boost::weak_ptr<Playlist>());
-       }
+                                        /* end +++++ */
 
-       /* XXX should probably freeze here .... */
+                                        RegionFactory::region_name (new_name, current->name(), false);
 
-       for (i = regions.begin(); i != regions.end(); ++i) {
-               if (*i == region) {
+                                        PropertyList plist;
 
-                       framepos_t pos = (*i)->position();
-                       framecnt_t distance = (*i)->length();
+                                        plist.add (Properties::start, current->start() + (pos2 - pos1));
+                                        plist.add (Properties::length, pos4 - pos2);
+                                        plist.add (Properties::name, new_name);
+                                        plist.add (Properties::layer, current->layer ());
+                                        plist.add (Properties::layering_index, current->layering_index ());
+                                        plist.add (Properties::automatic, true);
+                                        plist.add (Properties::left_of_split, true);
 
-                       regions.erase (i);
+                                        region = RegionFactory::create (current, plist);
 
-                       possibly_splice_unlocked (pos, -distance);
+                                        add_region_internal (region, start);
+                                        new_regions.push_back (region);
+                                }
 
-                       if (!holding_state ()) {
-                                relayer ();
-                               remove_dependents (region);
+                                /* front ****** */
 
-                               if (old_length != _get_extent().second) {
-                                       notify_length_changed ();
-                               }
-                       }
+                                current->suspend_property_changes ();
+                                thawlist.push_back (current);
+                                current->cut_end (pos2 - 1);
 
-                       notify_region_removed (region);
-                       ret = 0;
-                       break;
-               }
-       }
+                        } else if (overlap == OverlapStart) {
 
-       return -1;
-}
+                                /* split: we need 2 regions: the front and the end.
+                                   cut: just trim current to skip the cut area
+                                */
 
-void
-Playlist::get_equivalent_regions (boost::shared_ptr<Region> other, vector<boost::shared_ptr<Region> >& results)
-{
-       if (Config->get_use_overlap_equivalency()) {
-               for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-                       if ((*i)->overlap_equivalent (other)) {
-                               results.push_back ((*i));
-                       }
-               }
-       } else {
-               for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-                       if ((*i)->equivalent (other)) {
-                               results.push_back ((*i));
-                       }
-               }
-       }
-}
+                                /*
+                                                        start           end
+                                    ---------------*************************------------
+                                       P2          P1 P3                   P4
 
-void
-Playlist::get_region_list_equivalent_regions (boost::shared_ptr<Region> other, vector<boost::shared_ptr<Region> >& results)
-{
-       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                                    SPLIT:
+                                    ---------------****+++++++++++++++++++++------------
+                                    CUT:
+                                    -------------------*********************------------
 
-               if ((*i) && (*i)->region_list_equivalent (other)) {
-                       results.push_back (*i);
-               }
-       }
-}
+                                */
 
-void
-Playlist::partition (framepos_t start, framepos_t end, bool cut)
-{
-       RegionList thawlist;
+                                if (!cutting) {
+                                        /* front **** */
+                                        RegionFactory::region_name (new_name, current->name(), false);
 
-       partition_internal (start, end, cut, thawlist);
+                                        PropertyList plist;
 
-       for (RegionList::iterator i = thawlist.begin(); i != thawlist.end(); ++i) {
-               (*i)->resume_property_changes ();
-       }
-}
+                                        plist.add (Properties::start, current->start());
+                                        plist.add (Properties::length, pos3 - pos1);
+                                        plist.add (Properties::name, new_name);
+                                        plist.add (Properties::layer, current->layer ());
+                                        plist.add (Properties::layering_index, current->layering_index ());
+                                        plist.add (Properties::automatic, true);
+                                        plist.add (Properties::right_of_split, true);
 
-void
-Playlist::partition_internal (framepos_t start, framepos_t end, bool cutting, RegionList& thawlist)
-{
-       RegionList new_regions;
+                                        region = RegionFactory::create (current, plist);
 
-       {
-               RegionLock rlock (this);
+                                        add_region_internal (region, pos1);
+                                        new_regions.push_back (region);
+                                }
 
-               boost::shared_ptr<Region> region;
-               boost::shared_ptr<Region> current;
-               string new_name;
-               RegionList::iterator tmp;
-               OverlapType overlap;
-               framepos_t pos1, pos2, pos3, pos4;
+                                /* end */
 
-               in_partition = true;
+                                current->suspend_property_changes ();
+                                thawlist.push_back (current);
+                                current->trim_front (pos3);
+                        } else if (overlap == OverlapExternal) {
 
-               /* need to work from a copy, because otherwise the regions we add during the process
-                  get operated on as well.
-               */
+                                /* split: no split required.
+                                   cut: remove the region.
+                                */
 
-               RegionList copy = regions.rlist();
+                                /*
+                                       start                                      end
+                                    ---------------*************************------------
+                                       P2          P1 P3                   P4
 
-               for (RegionList::iterator i = copy.begin(); i != copy.end(); i = tmp) {
+                                    SPLIT:
+                                    ---------------*************************------------
+                                    CUT:
+                                    ----------------------------------------------------
 
-                       tmp = i;
-                       ++tmp;
+                                */
 
-                       current = *i;
+                                if (cutting) {
+                                        remove_region_internal (current);
+                                }
 
-                       if (current->first_frame() >= start && current->last_frame() < end) {
+                                new_regions.push_back (current);
+                        }
+                }
 
-                               if (cutting) {
-                                       remove_region_internal (current);
-                               }
+                in_partition = false;
+        }
 
-                               continue;
-                       }
+        for (RegionList::iterator i = new_regions.begin(); i != new_regions.end(); ++i) {
+                check_dependents (*i, false);
+        }
+ }
 
-                       /* coverage will return OverlapStart if the start coincides
-                          with the end point. we do not partition such a region,
-                          so catch this special case.
-                       */
+ boost::shared_ptr<Playlist>
+ Playlist::cut_copy (boost::shared_ptr<Playlist> (Playlist::*pmf)(framepos_t, framecnt_t,bool), list<AudioRange>& ranges, bool result_is_hidden)
+ {
+        boost::shared_ptr<Playlist> ret;
+        boost::shared_ptr<Playlist> pl;
+        framepos_t start;
+
+        if (ranges.empty()) {
+                return boost::shared_ptr<Playlist>();
+        }
 
-                       if (current->first_frame() >= end) {
-                               continue;
-                       }
+        start = ranges.front().start;
+
+        for (list<AudioRange>::iterator i = ranges.begin(); i != ranges.end(); ++i) {
+
+                pl = (this->*pmf)((*i).start, (*i).length(), result_is_hidden);
+
+                if (i == ranges.begin()) {
+                        ret = pl;
+                } else {
+
+                        /* paste the next section into the nascent playlist,
+                           offset to reflect the start of the first range we
+                           chopped.
+                        */
+
+                        ret->paste (pl, (*i).start - start, 1.0f);
+                }
+        }
+
+        return ret;
+ }
+
+ boost::shared_ptr<Playlist>
+ Playlist::cut (list<AudioRange>& ranges, bool result_is_hidden)
+ {
+        boost::shared_ptr<Playlist> (Playlist::*pmf)(framepos_t,framecnt_t,bool) = &Playlist::cut;
+        return cut_copy (pmf, ranges, result_is_hidden);
+ }
+
+ boost::shared_ptr<Playlist>
+ Playlist::copy (list<AudioRange>& ranges, bool result_is_hidden)
+ {
+        boost::shared_ptr<Playlist> (Playlist::*pmf)(framepos_t,framecnt_t,bool) = &Playlist::copy;
+        return cut_copy (pmf, ranges, result_is_hidden);
+ }
+
+ boost::shared_ptr<Playlist>
+ Playlist::cut (framepos_t start, framecnt_t cnt, bool result_is_hidden)
+ {
+        boost::shared_ptr<Playlist> the_copy;
+        RegionList thawlist;
+        char buf[32];
+
+        snprintf (buf, sizeof (buf), "%" PRIu32, ++subcnt);
+        string new_name = _name;
+        new_name += '.';
+        new_name += buf;
+
+        if ((the_copy = PlaylistFactory::create (shared_from_this(), start, cnt, new_name, result_is_hidden)) == 0) {
+                return boost::shared_ptr<Playlist>();
+        }
+
+        partition_internal (start, start+cnt-1, true, thawlist);
+
+        for (RegionList::iterator i = thawlist.begin(); i != thawlist.end(); ++i) {
+                (*i)->resume_property_changes();
+        }
+
+        return the_copy;
+ }
+
+ boost::shared_ptr<Playlist>
+ Playlist::copy (framepos_t start, framecnt_t cnt, bool result_is_hidden)
+ {
+        char buf[32];
+
+        snprintf (buf, sizeof (buf), "%" PRIu32, ++subcnt);
+        string new_name = _name;
+        new_name += '.';
+        new_name += buf;
+
+        cnt = min (_get_extent().second - start, cnt);
+        return PlaylistFactory::create (shared_from_this(), start, cnt, new_name, result_is_hidden);
+ }
+
+ int
+ Playlist::paste (boost::shared_ptr<Playlist> other, framepos_t position, float times)
+ {
+        times = fabs (times);
+
+        {
+                RegionLock rl1 (this);
+                RegionLock rl2 (other.get());
+
+                int itimes = (int) floor (times);
+                framepos_t pos = position;
+                framecnt_t const shift = other->_get_extent().second;
+                layer_t top = top_layer ();
+
+                while (itimes--) {
+                        for (RegionList::iterator i = other->regions.begin(); i != other->regions.end(); ++i) {
+                                boost::shared_ptr<Region> copy_of_region = RegionFactory::create (*i, true);
+
+                                /* put these new regions on top of all existing ones, but preserve
+                                   the ordering they had in the original playlist.
+                                */
+
+                                copy_of_region->set_pending_layer (copy_of_region->layer() + top);
+                                add_region_internal (copy_of_region, (*i)->position() + pos);
+                        }
+                        pos += shift;
+                }
+        }
+
+        return 0;
+ }
+
+
+ void
+ Playlist::duplicate (boost::shared_ptr<Region> region, framepos_t position, float times)
+ {
+        times = fabs (times);
+
+        RegionLock rl (this);
+        int itimes = (int) floor (times);
+        framepos_t pos = position + 1;
+
+        while (itimes--) {
+                boost::shared_ptr<Region> copy = RegionFactory::create (region, true);
+                copy->set_pending_layer (DBL_MAX);
+                add_region_internal (copy, pos);
+                pos += region->length();
+        }
+
+        if (floor (times) != times) {
+                framecnt_t length = (framecnt_t) floor (region->length() * (times - floor (times)));
+                string name;
+                RegionFactory::region_name (name, region->name(), false);
+
+                {
+                        PropertyList plist;
+
+                        plist.add (Properties::start, region->start());
+                        plist.add (Properties::length, length);
+                        plist.add (Properties::name, name);
+
+                        boost::shared_ptr<Region> sub = RegionFactory::create (region, plist);
+                        sub->set_pending_layer (DBL_MAX);
+                        add_region_internal (sub, pos);
+                }
+        }
+ }
+
+ void
+ Playlist::shift (framepos_t at, frameoffset_t distance, bool move_intersected, bool ignore_music_glue)
+ {
+        RegionLock rlock (this);
+        RegionList copy (regions.rlist());
+        RegionList fixup;
+
+        for (RegionList::iterator r = copy.begin(); r != copy.end(); ++r) {
+
+                if ((*r)->last_frame() < at) {
+                        /* too early */
+                        continue;
+                }
+
+                if (at > (*r)->first_frame() && at < (*r)->last_frame()) {
+                        /* intersected region */
+                        if (!move_intersected) {
+                                continue;
+                        }
+                }
+
+                /* do not move regions glued to music time - that
+                   has to be done separately.
+                */
+
+                if (!ignore_music_glue && (*r)->position_lock_style() != AudioTime) {
+                        fixup.push_back (*r);
+                        continue;
+                }
+
+                (*r)->set_position ((*r)->position() + distance);
+        }
+
+        /* XXX: may not be necessary; Region::post_set should do this, I think */
+        for (RegionList::iterator r = fixup.begin(); r != fixup.end(); ++r) {
+                (*r)->recompute_position_from_lock_style ();
+        }
+ }
+
+ void
+ Playlist::split (framepos_t at)
+ {
+        RegionLock rlock (this);
+        RegionList copy (regions.rlist());
+
+        /* use a copy since this operation can modify the region list
+         */
+
+        for (RegionList::iterator r = copy.begin(); r != copy.end(); ++r) {
+                _split_region (*r, at);
+        }
+ }
+
+ void
+ Playlist::split_region (boost::shared_ptr<Region> region, framepos_t playlist_position)
+ {
+        RegionLock rl (this);
+        _split_region (region, playlist_position);
+ }
+
+ void
+ Playlist::_split_region (boost::shared_ptr<Region> region, framepos_t playlist_position)
+ {
+        if (!region->covers (playlist_position)) {
+                return;
+        }
+
+        if (region->position() == playlist_position ||
+            region->last_frame() == playlist_position) {
+                return;
+        }
+
+        boost::shared_ptr<Region> left;
+        boost::shared_ptr<Region> right;
+        frameoffset_t before;
+        frameoffset_t after;
+        string before_name;
+        string after_name;
+
+        /* split doesn't change anything about length, so don't try to splice */
+
+        bool old_sp = _splicing;
+        _splicing = true;
+
+        before = playlist_position - region->position();
+        after = region->length() - before;
+
+        RegionFactory::region_name (before_name, region->name(), false);
+
+        {
+                PropertyList plist;
+
+                plist.add (Properties::position, region->position ());
+                plist.add (Properties::length, before);
+                plist.add (Properties::name, before_name);
+                plist.add (Properties::left_of_split, true);
+                plist.add (Properties::layering_index, region->layering_index ());
+                plist.add (Properties::layer, region->layer ());
+
+                /* note: we must use the version of ::create with an offset here,
+                   since it supplies that offset to the Region constructor, which
+                   is necessary to get audio region gain envelopes right.
+                */
+                left = RegionFactory::create (region, 0, plist);
+        }
+
+        RegionFactory::region_name (after_name, region->name(), false);
+
+        {
+                PropertyList plist;
+
+                plist.add (Properties::position, region->position() + before);
+                plist.add (Properties::length, after);
+                plist.add (Properties::name, after_name);
+                plist.add (Properties::right_of_split, true);
+                plist.add (Properties::layering_index, region->layering_index ());
+                plist.add (Properties::layer, region->layer ());
+
+                /* same note as above */
+                right = RegionFactory::create (region, before, plist);
+        }
+
+        add_region_internal (left, region->position());
+        add_region_internal (right, region->position() + before);
+
+        finalize_split_region (region, left, right);
+
+        remove_region_internal (region);
+
+        _splicing = old_sp;
+ }
+
+ void
+ Playlist::possibly_splice (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
+ {
+        if (_splicing || in_set_state) {
+                /* don't respond to splicing moves or state setting */
+                return;
+        }
+
+        if (_edit_mode == Splice) {
+                splice_locked (at, distance, exclude);
+        }
+ }
+
+ void
+ Playlist::possibly_splice_unlocked (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
+ {
+        if (_splicing || in_set_state) {
+                /* don't respond to splicing moves or state setting */
+                return;
+        }
+
+        if (_edit_mode == Splice) {
+                splice_unlocked (at, distance, exclude);
+        }
+ }
+
+ void
+ Playlist::splice_locked (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
+ {
+        {
+                RegionLock rl (this);
+                core_splice (at, distance, exclude);
+        }
+ }
+
+ void
+ Playlist::splice_unlocked (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
+ {
+        core_splice (at, distance, exclude);
+ }
+
+ void
+ Playlist::core_splice (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
+ {
+        _splicing = true;
+
+        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+
+                if (exclude && (*i) == exclude) {
+                        continue;
+                }
+
+                if ((*i)->position() >= at) {
+                        framepos_t new_pos = (*i)->position() + distance;
+                        if (new_pos < 0) {
+                                new_pos = 0;
+                        } else if (new_pos >= max_framepos - (*i)->length()) {
+                                new_pos = max_framepos - (*i)->length();
+                        }
+
+                        (*i)->set_position (new_pos);
+                }
+        }
+
+        _splicing = false;
+
+        notify_contents_changed ();
+ }
+
+ void
+ Playlist::region_bounds_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
+ {
+        if (in_set_state || _splicing || _nudging || _shuffling) {
+                return;
+        }
+
+        if (what_changed.contains (Properties::position)) {
+
+                /* remove it from the list then add it back in
+                   the right place again.
+                */
+
+                RegionSortByPosition cmp;
+
+                RegionList::iterator i = find (regions.begin(), regions.end(), region);
+
+                if (i == regions.end()) {
+                        /* the region bounds are being modified but its not currently
+                           in the region list. we will use its bounds correctly when/if
+                           it is added
+                        */
+                        return;
+                }
+
+                regions.erase (i);
+                regions.insert (upper_bound (regions.begin(), regions.end(), region, cmp), region);
+        }
+
+        if (what_changed.contains (Properties::position) || what_changed.contains (Properties::length)) {
+
+                frameoffset_t delta = 0;
+
+                if (what_changed.contains (Properties::position)) {
+                        delta = region->position() - region->last_position();
+                }
+
+                if (what_changed.contains (Properties::length)) {
+                        delta += region->length() - region->last_length();
+                }
+
+                if (delta) {
+                        possibly_splice (region->last_position() + region->last_length(), delta, region);
+                }
+
+                if (holding_state ()) {
+                        pending_bounds.push_back (region);
+                } else {
+                        notify_contents_changed ();
+                        relayer ();
+                        check_dependents (region, false);
+                }
+        }
+ }
+
+ void
+ Playlist::region_changed_proxy (const PropertyChange& what_changed, boost::weak_ptr<Region> weak_region)
+ {
+        boost::shared_ptr<Region> region (weak_region.lock());
+
+        if (!region) {
+                return;
+        }
+
+        /* this makes a virtual call to the right kind of playlist ... */
+
+        region_changed (what_changed, region);
+ }
+
+ bool
+ Playlist::region_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
+ {
+        PropertyChange our_interests;
+        PropertyChange bounds;
+        PropertyChange pos_and_length;
+        bool save = false;
+
+        if (in_set_state || in_flush) {
+                return false;
+        }
+
+        our_interests.add (Properties::muted);
+        our_interests.add (Properties::layer);
+        our_interests.add (Properties::opaque);
+
+        bounds.add (Properties::start);
+        bounds.add (Properties::position);
+        bounds.add (Properties::length);
+
+        pos_and_length.add (Properties::position);
+        pos_and_length.add (Properties::length);
+
+        if (what_changed.contains (bounds)) {
+                region_bounds_changed (what_changed, region);
+                save = !(_splicing || _nudging);
+        }
+
+        if (what_changed.contains (our_interests) && !what_changed.contains (pos_and_length)) {
+                check_dependents (region, false);
+        }
+
+        if (what_changed.contains (Properties::position) && !what_changed.contains (Properties::length)) {
+                notify_region_moved (region);
+        } else if (!what_changed.contains (Properties::position) && what_changed.contains (Properties::length)) {
+                notify_region_end_trimmed (region);
+        } else if (what_changed.contains (Properties::position) && what_changed.contains (Properties::length)) {
+                notify_region_start_trimmed (region);
+        }
+
+        /* don't notify about layer changes, since we are the only object that can initiate
+           them, and we notify in ::relayer()
+        */
 
-                       if ((overlap = current->coverage (start, end)) == OverlapNone) {
-                               continue;
-                       }
+        if (what_changed.contains (our_interests)) {
+                save = true;
+        }
 
-                       pos1 = current->position();
-                       pos2 = start;
-                       pos3 = end;
-                       pos4 = current->last_frame();
-
-                       if (overlap == OverlapInternal) {
-                               /* split: we need 3 new regions, the front, middle and end.
-                                  cut:   we need 2 regions, the front and end.
-                               */
-
-                               /*
-                                        start                 end
-                         ---------------*************************------------
-                                        P1  P2              P3  P4
-                         SPLIT:
-                         ---------------*****++++++++++++++++====------------
-                         CUT
-                         ---------------*****----------------====------------
-
-                               */
-
-                               if (!cutting) {
-                                       /* "middle" ++++++ */
-
-                                       RegionFactory::region_name (new_name, current->name(), false);
-
-                                       PropertyList plist;
-                                       
-                                       plist.add (Properties::start, current->start() + (pos2 - pos1));
-                                       plist.add (Properties::length, pos3 - pos2);
-                                       plist.add (Properties::name, new_name);
-                                       plist.add (Properties::layer, regions.size());
-                                       plist.add (Properties::automatic, true);
-                                       plist.add (Properties::left_of_split, true);
-                                       plist.add (Properties::right_of_split, true);
-
-                                       region = RegionFactory::create (current, plist);
-                                       add_region_internal (region, start);
-                                       new_regions.push_back (region);
-                               }
+        return save;
+ }
 
-                               /* "end" ====== */
-
-                               RegionFactory::region_name (new_name, current->name(), false);
-
-                               PropertyList plist;
-                               
-                               plist.add (Properties::start, current->start() + (pos3 - pos1));
-                               plist.add (Properties::length, pos4 - pos3);
-                               plist.add (Properties::name, new_name);
-                               plist.add (Properties::layer, regions.size());
-                               plist.add (Properties::automatic, true);
-                               plist.add (Properties::right_of_split, true);
-                               
-                               region = RegionFactory::create (current, plist);
-
-                               add_region_internal (region, end);
-                               new_regions.push_back (region);
-
-                               /* "front" ***** */
-
-                               current->suspend_property_changes ();
-                               thawlist.push_back (current);
-                               current->cut_end (pos2 - 1, this);
-
-                       } else if (overlap == OverlapEnd) {
-
-                               /*
-                                                             start           end
-                                   ---------------*************************------------
-                                                  P1           P2         P4   P3
-                                    SPLIT:
-                                   ---------------**************+++++++++++------------
-                                    CUT:
-                                   ---------------**************-----------------------
-                               */
-
-                               if (!cutting) {
-
-                                       /* end +++++ */
-
-                                       RegionFactory::region_name (new_name, current->name(), false);
-                                       
-                                       PropertyList plist;
-                                       
-                                       plist.add (Properties::start, current->start() + (pos2 - pos1));
-                                       plist.add (Properties::length, pos4 - pos2);
-                                       plist.add (Properties::name, new_name);
-                                       plist.add (Properties::layer, regions.size());
-                                       plist.add (Properties::automatic, true);
-                                       plist.add (Properties::left_of_split, true);
-
-                                       region = RegionFactory::create (current, plist);
-
-                                       add_region_internal (region, start);
-                                       new_regions.push_back (region);
-                               }
+ void
+ Playlist::drop_regions ()
+ {
+        RegionLock rl (this);
+        regions.clear ();
+        all_regions.clear ();
+ }
 
-                               /* front ****** */
+ void
+ Playlist::sync_all_regions_with_regions ()
+ {
+        RegionLock rl (this);
 
-                               current->suspend_property_changes ();
-                               thawlist.push_back (current);
-                               current->cut_end (pos2 - 1, this);
+        all_regions.clear ();
 
-                       } else if (overlap == OverlapStart) {
+        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                all_regions.insert (*i);
+        }
+ }
 
-                               /* split: we need 2 regions: the front and the end.
-                                  cut: just trim current to skip the cut area
-                               */
+ void
+ Playlist::clear (bool with_signals)
+ {
+        {
+                RegionLock rl (this);
 
-                               /*
-                                                       start           end
-                                   ---------------*************************------------
-                                      P2          P1 P3                   P4
+                region_state_changed_connections.drop_connections ();
 
-                                   SPLIT:
-                                   ---------------****+++++++++++++++++++++------------
-                                   CUT:
-                                   -------------------*********************------------
+                for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                        pending_removes.insert (*i);
+                }
 
-                               */
+                regions.clear ();
 
-                               if (!cutting) {
-                                       /* front **** */
-                                       RegionFactory::region_name (new_name, current->name(), false);
+                for (set<boost::shared_ptr<Region> >::iterator s = pending_removes.begin(); s != pending_removes.end(); ++s) {
+                        remove_dependents (*s);
+                }
+        }
 
-                                       PropertyList plist;
-                                       
-                                       plist.add (Properties::start, current->start());
-                                       plist.add (Properties::length, pos3 - pos1);
-                                       plist.add (Properties::name, new_name);
-                                       plist.add (Properties::layer, regions.size());
-                                       plist.add (Properties::automatic, true);
-                                       plist.add (Properties::right_of_split, true);
+        if (with_signals) {
 
-                                       region = RegionFactory::create (current, plist);
+                for (set<boost::shared_ptr<Region> >::iterator s = pending_removes.begin(); s != pending_removes.end(); ++s) {
+                        RegionRemoved (boost::weak_ptr<Region> (*s)); /* EMIT SIGNAL */
+                }
 
-                                       add_region_internal (region, pos1);
-                                       new_regions.push_back (region);
-                               }
+                pending_removes.clear ();
+                pending_contents_change = false;
+                ContentsChanged ();
+        }
 
-                               /* end */
+ }
 
-                               current->suspend_property_changes ();
-                               thawlist.push_back (current);
-                               current->trim_front (pos3, this);
-                       } else if (overlap == OverlapExternal) {
+ /***********************************************************************
+  FINDING THINGS
+  **********************************************************************/
 
-                               /* split: no split required.
-                                  cut: remove the region.
-                               */
+ Playlist::RegionList *
+ Playlist::regions_at (framepos_t frame)
 
-                               /*
-                                      start                                      end
-                                   ---------------*************************------------
-                                      P2          P1 P3                   P4
+ {
+        RegionLock rlock (this);
+        return find_regions_at (frame);
+ }
 
-                                   SPLIT:
-                                   ---------------*************************------------
-                                   CUT:
-                                   ----------------------------------------------------
+ uint32_t
+ Playlist::count_regions_at (framepos_t frame) const
+ {
+        RegionLock rlock (const_cast<Playlist*>(this));
+        uint32_t cnt = 0;
 
-                               */
+        for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
+                if ((*i)->covers (frame)) {
+                        cnt++;
+                }
+        }
+
+        return cnt;
+ }
+
+ boost::shared_ptr<Region>
+ Playlist::top_region_at (framepos_t frame)
+
+ {
+        RegionLock rlock (this);
+        RegionList *rlist = find_regions_at (frame);
+        boost::shared_ptr<Region> region;
+
+        if (rlist->size()) {
+                RegionSortByLayer cmp;
+                rlist->sort (cmp);
+                region = rlist->back();
+        }
+
+        delete rlist;
+        return region;
+ }
+
+ boost::shared_ptr<Region>
+ Playlist::top_unmuted_region_at (framepos_t frame)
+
+ {
+        RegionLock rlock (this);
+        RegionList *rlist = find_regions_at (frame);
+
+        for (RegionList::iterator i = rlist->begin(); i != rlist->end(); ) {
 
-                               if (cutting) {
-                                       remove_region_internal (current);
-                               }
+                RegionList::iterator tmp = i;
+                ++tmp;
 
-                               new_regions.push_back (current);
-                       }
-               }
+                if ((*i)->muted()) {
+                        rlist->erase (i);
+                }
 
-               in_partition = false;
-       }
+                i = tmp;
+        }
 
-       for (RegionList::iterator i = new_regions.begin(); i != new_regions.end(); ++i) {
-               check_dependents (*i, false);
-       }
-}
+        boost::shared_ptr<Region> region;
 
-boost::shared_ptr<Playlist>
-Playlist::cut_copy (boost::shared_ptr<Playlist> (Playlist::*pmf)(framepos_t, framecnt_t,bool), list<AudioRange>& ranges, bool result_is_hidden)
-{
-       boost::shared_ptr<Playlist> ret;
-       boost::shared_ptr<Playlist> pl;
-       framepos_t start;
+        if (rlist->size()) {
+                RegionSortByLayer cmp;
+                rlist->sort (cmp);
+                region = rlist->back();
+        }
 
-       if (ranges.empty()) {
-               return boost::shared_ptr<Playlist>();
      }
+        delete rlist;
+        return region;
+ }
 
-       start = ranges.front().start;
+ Playlist::RegionList*
+ Playlist::regions_to_read (framepos_t start, framepos_t end)
+ {
+        /* Caller must hold lock */
 
-       for (list<AudioRange>::iterator i = ranges.begin(); i != ranges.end(); ++i) {
+        RegionList covering;
+        set<framepos_t> to_check;
+        set<boost::shared_ptr<Region> > unique;
 
-               pl = (this->*pmf)((*i).start, (*i).length(), result_is_hidden);
+        to_check.insert (start);
+        to_check.insert (end);
 
-               if (i == ranges.begin()) {
-                       ret = pl;
-               } else {
+        DEBUG_TRACE (DEBUG::AudioPlayback, ">>>>> REGIONS TO READ\n");
 
-                       /* paste the next section into the nascent playlist,
-                          offset to reflect the start of the first range we
-                          chopped.
-                       */
+        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
 
-                       ret->paste (pl, (*i).start - start, 1.0f);
-               }
-       }
+                /* find all/any regions that span start+end */
 
-       return ret;
-}
+                switch ((*i)->coverage (start, end)) {
+                case OverlapNone:
+                        break;
 
-boost::shared_ptr<Playlist>
-Playlist::cut (list<AudioRange>& ranges, bool result_is_hidden)
-{
-       boost::shared_ptr<Playlist> (Playlist::*pmf)(framepos_t,framecnt_t,bool) = &Playlist::cut;
-       return cut_copy (pmf, ranges, result_is_hidden);
-}
+                case OverlapInternal:
+                        covering.push_back (*i);
+                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will cover %1 (OInternal)\n", (*i)->name()));
+                        break;
 
-boost::shared_ptr<Playlist>
-Playlist::copy (list<AudioRange>& ranges, bool result_is_hidden)
-{
-       boost::shared_ptr<Playlist> (Playlist::*pmf)(framepos_t,framecnt_t,bool) = &Playlist::copy;
-       return cut_copy (pmf, ranges, result_is_hidden);
-}
+                case OverlapStart:
+                        to_check.insert ((*i)->position());
+                        if ((*i)->position() != 0) {
+                                to_check.insert ((*i)->position()-1);
+                        }
+                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will check %1 for %2\n", (*i)->position(), (*i)->name()));
+                        covering.push_back (*i);
+                        break;
 
-boost::shared_ptr<Playlist>
-Playlist::cut (framepos_t start, framecnt_t cnt, bool result_is_hidden)
-{
-       boost::shared_ptr<Playlist> the_copy;
-       RegionList thawlist;
-       char buf[32];
+                case OverlapEnd:
+                        to_check.insert ((*i)->last_frame());
+                        to_check.insert ((*i)->last_frame()+1);
+                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will cover %1 (OEnd)\n", (*i)->name()));
+                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->last_frame(), (*i)->name()));
+                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->last_frame(), (*i)->name()));
+                        covering.push_back (*i);
+                        break;
 
-       snprintf (buf, sizeof (buf), "%" PRIu32, ++subcnt);
-       string new_name = _name;
-       new_name += '.';
-       new_name += buf;
+                case OverlapExternal:
+                        covering.push_back (*i);
+                        to_check.insert ((*i)->position());
+                        if ((*i)->position() != 0) {
+                                to_check.insert ((*i)->position()-1);
+                        }
+                        to_check.insert ((*i)->last_frame());
+                        to_check.insert ((*i)->last_frame()+1);
+                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will cover %1 (OExt)\n", (*i)->name()));
+                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->position(), (*i)->name()));
+                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->last_frame(), (*i)->name()));
+                        break;
+                }
 
-       if ((the_copy = PlaylistFactory::create (shared_from_this(), start, cnt, new_name, result_is_hidden)) == 0) {
-               return boost::shared_ptr<Playlist>();
-       }
+                /* don't go too far */
 
-       partition_internal (start, start+cnt-1, true, thawlist);
+                if ((*i)->position() > end) {
+                        break;
+                }
+        }
 
-       for (RegionList::iterator i = thawlist.begin(); i != thawlist.end(); ++i) {
-               (*i)->resume_property_changes();
-       }
+        RegionList* rlist = new RegionList;
 
-       return the_copy;
-}
+        /* find all the regions that cover each position .... */
 
-boost::shared_ptr<Playlist>
-Playlist::copy (framepos_t start, framecnt_t cnt, bool result_is_hidden)
-{
-       char buf[32];
+        if (covering.size() == 1) {
 
-       snprintf (buf, sizeof (buf), "%" PRIu32, ++subcnt);
-       string new_name = _name;
-       new_name += '.';
-       new_name += buf;
+                rlist->push_back (covering.front());
+                DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("Just one covering region (%1)\n", covering.front()->name()));
 
-       cnt = min (_get_extent().second - start, cnt);
-       return PlaylistFactory::create (shared_from_this(), start, cnt, new_name, result_is_hidden);
-}
+        } else {
 
-int
-Playlist::paste (boost::shared_ptr<Playlist> other, framepos_t position, float times)
-{
-       times = fabs (times);
+                RegionList here;
+                for (set<framepos_t>::iterator t = to_check.begin(); t != to_check.end(); ++t) {
+
+                        here.clear ();
+
+                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("++++ Considering %1\n", *t));
+
+                        for (RegionList::iterator x = covering.begin(); x != covering.end(); ++x) {
+
+                                if ((*x)->covers (*t)) {
+                                        here.push_back (*x);
+                                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("region %1 covers %2\n",
+                                                                                           (*x)->name(),
+                                                                                           (*t)));
+                                } else {
+                                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("region %1 does NOT covers %2\n",
+                                                                                           (*x)->name(),
+                                                                                           (*t)));
+                                }
+
+                        }
 
-       {
-               RegionLock rl1 (this);
-               RegionLock rl2 (other.get());
+                        RegionSortByLayer cmp;
+                        here.sort (cmp);
 
-               framecnt_t const old_length = _get_extent().second;
+                        /* ... and get the top/transparent regions at "here" */
 
-               int itimes = (int) floor (times);
-               framepos_t pos = position;
-               framecnt_t const shift = other->_get_extent().second;
-               layer_t top_layer = regions.size();
+                        for (RegionList::reverse_iterator c = here.rbegin(); c != here.rend(); ++c) {
+
+                                unique.insert (*c);
 
-               while (itimes--) {
-                       for (RegionList::iterator i = other->regions.begin(); i != other->regions.end(); ++i) {
-                               boost::shared_ptr<Region> copy_of_region = RegionFactory::create (*i);
+                                if ((*c)->opaque()) {
+
+                                        /* the other regions at this position are hidden by this one */
+                                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("%1 is opaque, ignore all others\n",
+                                                                                           (*c)->name()));
+                                        break;
+                                }
+                        }
+                }
+
+                for (set<boost::shared_ptr<Region> >::iterator s = unique.begin(); s != unique.end(); ++s) {
+                        rlist->push_back (*s);
+                }
+
+                if (rlist->size() > 1) {
+                        /* now sort by time order */
+
+                        RegionSortByPosition cmp;
+                        rlist->sort (cmp);
+                }
+        }
+
+        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("<<<<< REGIONS TO READ returns %1\n", rlist->size()));
+
+        return rlist;
+ }
+
+ Playlist::RegionList *
+ Playlist::find_regions_at (framepos_t frame)
+ {
+        /* Caller must hold lock */
+
+        RegionList *rlist = new RegionList;
+
+        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                if ((*i)->covers (frame)) {
+                        rlist->push_back (*i);
+                }
+        }
+
+        return rlist;
+ }
+
+ Playlist::RegionList *
+ Playlist::regions_touched (framepos_t start, framepos_t end)
+ {
+        RegionLock rlock (this);
+        RegionList *rlist = new RegionList;
 
-                               /* put these new regions on top of all existing ones, but preserve
-                                  the ordering they had in the original playlist.
-                               */
+        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                if ((*i)->coverage (start, end) != OverlapNone) {
+                        rlist->push_back (*i);
+                }
+        }
+
+        return rlist;
+ }
 
-                               copy_of_region->set_layer (copy_of_region->layer() + top_layer);
-                               add_region_internal (copy_of_region, copy_of_region->position() + pos);
-                       }
-                       pos += shift;
-               }
+ framepos_t
+ Playlist::find_next_transient (framepos_t from, int dir)
+ {
+        RegionLock rlock (this);
+        AnalysisFeatureList points;
+        AnalysisFeatureList these_points;
+
+        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                if (dir > 0) {
+                        if ((*i)->last_frame() < from) {
+                                continue;
+                        }
+                } else {
+                        if ((*i)->first_frame() > from) {
+                                continue;
+                        }
+                }
+
+                (*i)->get_transients (these_points);
+
+                /* add first frame, just, err, because */
+
+                these_points.push_back ((*i)->first_frame());
+
+                points.insert (points.end(), these_points.begin(), these_points.end());
+                these_points.clear ();
+        }
+
+        if (points.empty()) {
+                return -1;
+        }
+
+        TransientDetector::cleanup_transients (points, _session.frame_rate(), 3.0);
+        bool reached = false;
+
+        if (dir > 0) {
+                for (AnalysisFeatureList::iterator x = points.begin(); x != points.end(); ++x) {
+                        if ((*x) >= from) {
+                                reached = true;
+                        }
+
+                        if (reached && (*x) > from) {
+                                return *x;
+                        }
+                }
+        } else {
+                for (AnalysisFeatureList::reverse_iterator x = points.rbegin(); x != points.rend(); ++x) {
+                        if ((*x) <= from) {
+                                reached = true;
+                        }
+
+                        if (reached && (*x) < from) {
+                                return *x;
+                        }
+                }
+        }
+
+        return -1;
+ }
+
+ boost::shared_ptr<Region>
+ Playlist::find_next_region (framepos_t frame, RegionPoint point, int dir)
+ {
+        RegionLock rlock (this);
+        boost::shared_ptr<Region> ret;
+        framepos_t closest = max_framepos;
+
+        bool end_iter = false;
+
+        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+
+                if(end_iter) break;
+
+                frameoffset_t distance;
+                boost::shared_ptr<Region> r = (*i);
+                framepos_t pos = 0;
+
+                switch (point) {
+                case Start:
+                        pos = r->first_frame ();
+                        break;
+                case End:
+                        pos = r->last_frame ();
+                        break;
+                case SyncPoint:
+                        pos = r->sync_position ();
+                        break;
+                }
+
+                switch (dir) {
+                case 1: /* forwards */
 
+                        if (pos > frame) {
+                                if ((distance = pos - frame) < closest) {
+                                        closest = distance;
+                                        ret = r;
+                                        end_iter = true;
+                                }
+                        }
 
-               /* XXX shall we handle fractional cases at some point? */
+                        break;
 
-               if (old_length != _get_extent().second) {
-                       notify_length_changed ();
-               }
+                default: /* backwards */
 
+                        if (pos < frame) {
+                                if ((distance = frame - pos) < closest) {
+                                        closest = distance;
+                                        ret = r;
+                                }
+                        }
+                        else {
+                                end_iter = true;
+                        }
 
-       }
+                        break;
+                }
+        }
 
-       return 0;
-}
+        return ret;
+ }
 
+ framepos_t
+ Playlist::find_next_region_boundary (framepos_t frame, int dir)
+ {
+        RegionLock rlock (this);
 
-void
-Playlist::duplicate (boost::shared_ptr<Region> region, framepos_t position, float times)
-{
-       times = fabs (times);
+        framepos_t closest = max_framepos;
+        framepos_t ret = -1;
+
+        if (dir > 0) {
+
+                for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+
+                        boost::shared_ptr<Region> r = (*i);
+                        frameoffset_t distance;
+
+                        if (r->first_frame() > frame) {
+
+                                distance = r->first_frame() - frame;
+
+                                if (distance < closest) {
+                                        ret = r->first_frame();
+                                        closest = distance;
+                                }
+                        }
+
+                        if (r->last_frame () > frame) {
+
+                                distance = r->last_frame () - frame;
+
+                                if (distance < closest) {
+                                        ret = r->last_frame ();
+                                        closest = distance;
+                                }
+                        }
+                }
 
-       RegionLock rl (this);
-       int itimes = (int) floor (times);
-       framepos_t pos = position + 1;
+        } else {
 
-       while (itimes--) {
-               boost::shared_ptr<Region> copy = RegionFactory::create (region);
-               add_region_internal (copy, pos);
-               pos += region->length();
-       }
+                for (RegionList::reverse_iterator i = regions.rbegin(); i != regions.rend(); ++i) {
 
-       if (floor (times) != times) {
-               framecnt_t length = (framecnt_t) floor (region->length() * (times - floor (times)));
-               string name;
-               RegionFactory::region_name (name, region->name(), false);
-               
-               {
-                       PropertyList plist;
-                       
-                       plist.add (Properties::start, region->start());
-                       plist.add (Properties::length, length);
-                       plist.add (Properties::name, name);
-                       
-                       boost::shared_ptr<Region> sub = RegionFactory::create (region, plist);
-                       add_region_internal (sub, pos);
-               }
-       }
-}
+                        boost::shared_ptr<Region> r = (*i);
+                        frameoffset_t distance;
 
-void
-Playlist::shift (framepos_t at, frameoffset_t distance, bool move_intersected, bool ignore_music_glue)
-{
-       RegionLock rlock (this);
-       RegionList copy (regions.rlist());
-       RegionList fixup;
+                        if (r->last_frame() < frame) {
 
-       for (RegionList::iterator r = copy.begin(); r != copy.end(); ++r) {
+                                distance = frame - r->last_frame();
 
-               if ((*r)->last_frame() < at) {
-                       /* too early */
-                       continue;
-               }
+                                if (distance < closest) {
+                                        ret = r->last_frame();
+                                        closest = distance;
+                                }
+                        }
+
+                        if (r->first_frame() < frame) {
+
+                                distance = frame - r->first_frame();
+
+                                if (distance < closest) {
+                                        ret = r->first_frame();
+                                        closest = distance;
+                                }
+                        }
+                }
+        }
 
-               if (at > (*r)->first_frame() && at < (*r)->last_frame()) {
-                       /* intersected region */
-                       if (!move_intersected) {
-                               continue;
-                       }
-               }
+        return ret;
+ }
 
-               /* do not move regions glued to music time - that
-                  has to be done separately.
-               */
 
-               if (!ignore_music_glue && (*r)->position_lock_style() != AudioTime) {
-                       fixup.push_back (*r);
-                       continue;
-               }
+ /***********************************************************************/
 
-               (*r)->set_position ((*r)->position() + distance, this);
-       }
 
-       for (RegionList::iterator r = fixup.begin(); r != fixup.end(); ++r) {
-               (*r)->recompute_position_from_lock_style ();
-       }
-}
 
-void
-Playlist::split (framepos_t at)
-{
-       RegionLock rlock (this);
-       RegionList copy (regions.rlist());
 
-       /* use a copy since this operation can modify the region list
-        */
+ void
+ Playlist::mark_session_dirty ()
+ {
+        if (!in_set_state && !holding_state ()) {
+                _session.set_dirty();
+        }
+ }
 
-       for (RegionList::iterator r = copy.begin(); r != copy.end(); ++r) {
-               _split_region (*r, at);
-       }
-}
+ void
+ Playlist::rdiff (vector<Command*>& cmds) const
+ {
+        RegionLock rlock (const_cast<Playlist *> (this));
+        Stateful::rdiff (cmds);
+ }
 
-void
-Playlist::split_region (boost::shared_ptr<Region> region, framepos_t playlist_position)
-{
-       RegionLock rl (this);
-       _split_region (region, playlist_position);
-}
+ void
+ Playlist::clear_owned_changes ()
+ {
+        RegionLock rlock (this);
+        Stateful::clear_owned_changes ();
+ }
 
-void
-Playlist::_split_region (boost::shared_ptr<Region> region, framepos_t playlist_position)
-{
-       if (!region->covers (playlist_position)) {
-               return;
-       }
-
-       if (region->position() == playlist_position ||
-           region->last_frame() == playlist_position) {
-               return;
-       }
-
-       boost::shared_ptr<Region> left;
-       boost::shared_ptr<Region> right;
-       frameoffset_t before;
-       frameoffset_t after;
-       string before_name;
-       string after_name;
-
-       /* split doesn't change anything about length, so don't try to splice */
-
-       bool old_sp = _splicing;
-       _splicing = true;
-
-       before = playlist_position - region->position();
-       after = region->length() - before;
-
-       RegionFactory::region_name (before_name, region->name(), false);
-
-       {
-               PropertyList plist;
-               
-               plist.add (Properties::length, before);
-               plist.add (Properties::name, before_name);
-               plist.add (Properties::left_of_split, true);
-
-               /* note: we must use the version of ::create with an offset here,
-                  since it supplies that offset to the Region constructor, which
-                  is necessary to get audio region gain envelopes right.
-               */
-               left = RegionFactory::create (region, 0, plist);
-       }
-
-       RegionFactory::region_name (after_name, region->name(), false);
-
-       {
-               PropertyList plist;
-               
-               plist.add (Properties::length, after);
-               plist.add (Properties::name, after_name);
-               plist.add (Properties::right_of_split, true);
-
-               /* same note as above */
-               right = RegionFactory::create (region, before, plist);
-       }
-
-       add_region_internal (left, region->position());
-       add_region_internal (right, region->position() + before);
-
-       uint64_t orig_layer_op = region->last_layer_op();
-       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-               if ((*i)->last_layer_op() > orig_layer_op) {
-                       (*i)->set_last_layer_op( (*i)->last_layer_op() + 1 );
-               }
-       }
-
-       left->set_last_layer_op ( orig_layer_op );
-       right->set_last_layer_op ( orig_layer_op + 1);
-
-       layer_op_counter++;
-
-       finalize_split_region (region, left, right);
-
-       remove_region_internal (region);
-
-       _splicing = old_sp;
-}
-
-void
-Playlist::possibly_splice (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
-{
-       if (_splicing || in_set_state) {
-               /* don't respond to splicing moves or state setting */
-               return;
-       }
-
-       if (_edit_mode == Splice) {
-               splice_locked (at, distance, exclude);
-       }
-}
-
-void
-Playlist::possibly_splice_unlocked (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
-{
-       if (_splicing || in_set_state) {
-               /* don't respond to splicing moves or state setting */
-               return;
-       }
-
-       if (_edit_mode == Splice) {
-               splice_unlocked (at, distance, exclude);
-       }
-}
-
-void
-Playlist::splice_locked (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
-{
-       {
-               RegionLock rl (this);
-               core_splice (at, distance, exclude);
-       }
-}
-
-void
-Playlist::splice_unlocked (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
-{
-       core_splice (at, distance, exclude);
-}
-
-void
-Playlist::core_splice (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
-{
-       _splicing = true;
-
-       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-
-               if (exclude && (*i) == exclude) {
-                       continue;
-               }
-
-               if ((*i)->position() >= at) {
-                       framepos_t new_pos = (*i)->position() + distance;
-                       if (new_pos < 0) {
-                               new_pos = 0;
-                       } else if (new_pos >= max_frames - (*i)->length()) {
-                               new_pos = max_frames - (*i)->length();
-                       }
-
-                       (*i)->set_position (new_pos, this);
-               }
-       }
-
-       _splicing = false;
-
-       notify_length_changed ();
-}
-
-void
-Playlist::region_bounds_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
-{
-       if (in_set_state || _splicing || _nudging || _shuffling) {
-               return;
-       }
-
-       if (what_changed.contains (Properties::position)) {
-
-               /* remove it from the list then add it back in
-                  the right place again.
-               */
-
-               RegionSortByPosition cmp;
-
-               RegionList::iterator i = find (regions.begin(), regions.end(), region);
-
-               if (i == regions.end()) {
-                        /* the region bounds are being modified but its not currently
-                           in the region list. we will use its bounds correctly when/if
-                           it is added
-                        */
-                       return;
-               }
-
-               regions.erase (i);
-               regions.insert (upper_bound (regions.begin(), regions.end(), region, cmp), region);
-       }
-
-       if (what_changed.contains (Properties::position) || what_changed.contains (Properties::length)) {
-
-               frameoffset_t delta = 0;
-
-               if (what_changed.contains (Properties::position)) {
-                       delta = region->position() - region->last_position();
-               }
-
-               if (what_changed.contains (Properties::length)) {
-                       delta += region->length() - region->last_length();
-               }
-
-               if (delta) {
-                       possibly_splice (region->last_position() + region->last_length(), delta, region);
-               }
-
-               if (holding_state ()) {
-                       pending_bounds.push_back (region);
-               } else {
-                       if (_session.config.get_layer_model() == MoveAddHigher) {
-                               /* it moved or changed length, so change the timestamp */
-                               timestamp_layer_op (region);
-                       }
-
-                       notify_length_changed ();
-                       relayer ();
-                       check_dependents (region, false);
-               }
-       }
-}
-
-void
-Playlist::region_changed_proxy (const PropertyChange& what_changed, boost::weak_ptr<Region> weak_region)
-{
-       boost::shared_ptr<Region> region (weak_region.lock());
-
-       if (!region) {
-               return;
-       }
-
-       /* this makes a virtual call to the right kind of playlist ... */
-
-       region_changed (what_changed, region);
-}
-
-bool
-Playlist::region_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
-{
-       PropertyChange our_interests;
-       PropertyChange bounds;
-       PropertyChange pos_and_length;
-       bool save = false;
-
-       if (in_set_state || in_flush) {
-               return false;
-       }
-
-       our_interests.add (Properties::muted);
-       our_interests.add (Properties::layer);
-       our_interests.add (Properties::opaque);
-
-       bounds.add (Properties::start);
-       bounds.add (Properties::position);
-       bounds.add (Properties::length);
-
-       pos_and_length.add (Properties::position);
-       pos_and_length.add (Properties::length);
-
-       if (what_changed.contains (bounds)) {
-               region_bounds_changed (what_changed, region);
-               save = !(_splicing || _nudging);
-       }
-
-       if (what_changed.contains (our_interests) && !what_changed.contains (pos_and_length)) {
-               check_dependents (region, false);
-       }
-
-       if (what_changed.contains (Properties::position) && !what_changed.contains (Properties::length)) {
-               notify_region_moved (region);
-       }
-
-
-       /* don't notify about layer changes, since we are the only object that can initiate
-          them, and we notify in ::relayer()
-       */
-
-       if (what_changed.contains (our_interests)) {
-               save = true;
-       }
-
-       return save;
-}
-
-void
-Playlist::drop_regions ()
-{
-       RegionLock rl (this);
-       regions.clear ();
-       all_regions.clear ();
-}
-
-void
-Playlist::clear (bool with_signals)
-{
-       {
-               RegionLock rl (this);
-
-               region_state_changed_connections.drop_connections ();
-
-               for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-                       pending_removes.insert (*i);
-               }
-
-               regions.clear ();
-
-                for (set<boost::shared_ptr<Region> >::iterator s = pending_removes.begin(); s != pending_removes.end(); ++s) {
-                        remove_dependents (*s);
-                }
-       }
-
-       if (with_signals) {
-
-                for (set<boost::shared_ptr<Region> >::iterator s = pending_removes.begin(); s != pending_removes.end(); ++s) {
-                        RegionRemoved (boost::weak_ptr<Region> (*s)); /* EMIT SIGNAL */
-                }
-
-                pending_removes.clear ();
-               pending_length = false;
-               LengthChanged ();
-               pending_contents_change = false;
-               ContentsChanged ();
-       }
-
-}
-
-/***********************************************************************
- FINDING THINGS
- **********************************************************************/
-
-Playlist::RegionList *
-Playlist::regions_at (framepos_t frame)
-
-{
-       RegionLock rlock (this);
-       return find_regions_at (frame);
-}
-
-boost::shared_ptr<Region>
-Playlist::top_region_at (framepos_t frame)
-
-{
-       RegionLock rlock (this);
-       RegionList *rlist = find_regions_at (frame);
-       boost::shared_ptr<Region> region;
-
-       if (rlist->size()) {
-               RegionSortByLayer cmp;
-               rlist->sort (cmp);
-               region = rlist->back();
-       }
-
-       delete rlist;
-       return region;
-}
-
-boost::shared_ptr<Region>
-Playlist::top_unmuted_region_at (framepos_t frame)
-
-{
-       RegionLock rlock (this);
-       RegionList *rlist = find_regions_at (frame);
-
-       for (RegionList::iterator i = rlist->begin(); i != rlist->end(); ) {
-
-               RegionList::iterator tmp = i;
-               ++tmp;
-
-               if ((*i)->muted()) {
-                       rlist->erase (i);
-               }
-
-               i = tmp;
-       }
-
-       boost::shared_ptr<Region> region;
-
-       if (rlist->size()) {
-               RegionSortByLayer cmp;
-               rlist->sort (cmp);
-               region = rlist->back();
-       }
-
-       delete rlist;
-       return region;
-}
-
-Playlist::RegionList*
-Playlist::regions_to_read (framepos_t start, framepos_t end)
-{
-       /* Caller must hold lock */
-
-       RegionList covering;
-       set<framepos_t> to_check;
-       set<boost::shared_ptr<Region> > unique;
-
-       to_check.insert (start);
-       to_check.insert (end);
-
-        DEBUG_TRACE (DEBUG::AudioPlayback, ">>>>> REGIONS TO READ\n");
-
-       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-
-               /* find all/any regions that span start+end */
-
-               switch ((*i)->coverage (start, end)) {
-               case OverlapNone:
-                       break;
-
-               case OverlapInternal:
-                       covering.push_back (*i);
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will cover %1 (OInternal)\n", (*i)->name()));
-                       break;
-
-               case OverlapStart:
-                       to_check.insert ((*i)->position());
-                        if ((*i)->position() != 0) {
-                                to_check.insert ((*i)->position()-1);
-                        }
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will check %1 for %2\n", (*i)->position(), (*i)->name()));
-                       covering.push_back (*i);
-                       break;
-
-               case OverlapEnd:
-                       to_check.insert ((*i)->last_frame());
-                       to_check.insert ((*i)->last_frame()+1);
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will cover %1 (OEnd)\n", (*i)->name()));
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->last_frame(), (*i)->name()));
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->last_frame(), (*i)->name()));
-                       covering.push_back (*i);
-                       break;
-
-               case OverlapExternal:
-                       covering.push_back (*i);
-                       to_check.insert ((*i)->position());
-                        if ((*i)->position() != 0) {
-                                to_check.insert ((*i)->position()-1);
-                        }
-                       to_check.insert ((*i)->last_frame());
-                       to_check.insert ((*i)->last_frame()+1);
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("toread: will cover %1 (OExt)\n", (*i)->name()));
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->position(), (*i)->name()));
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("\ttoread: will check %1 for %2\n", (*i)->last_frame(), (*i)->name()));
-                       break;
-               }
-
-               /* don't go too far */
-
-               if ((*i)->position() > end) {
-                       break;
-               }
-       }
-
-       RegionList* rlist = new RegionList;
-
-       /* find all the regions that cover each position .... */
-
-       if (covering.size() == 1) {
-
-               rlist->push_back (covering.front());
-                DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("Just one covering region (%1)\n", covering.front()->name()));
-
-       } else {
-
-               RegionList here;
-               for (set<framepos_t>::iterator t = to_check.begin(); t != to_check.end(); ++t) {
-
-                       here.clear ();
-
-                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("++++ Considering %1\n", *t));
-
-                       for (RegionList::iterator x = covering.begin(); x != covering.end(); ++x) {
-
-                               if ((*x)->covers (*t)) {
-                                       here.push_back (*x);
-                                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("region %1 covers %2\n",
-                                                                                           (*x)->name(),
-                                                                                           (*t)));
-                               } else {
-                                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("region %1 does NOT covers %2\n",
-                                                                                           (*x)->name(),
-                                                                                           (*t)));
-                                }
-                                        
-                       }
-
-                       RegionSortByLayer cmp;
-                       here.sort (cmp);
-
-                       /* ... and get the top/transparent regions at "here" */
-
-                       for (RegionList::reverse_iterator c = here.rbegin(); c != here.rend(); ++c) {
-
-                               unique.insert (*c);
-
-                               if ((*c)->opaque()) {
-
-                                       /* the other regions at this position are hidden by this one */
-                                        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("%1 is opaque, ignore all others\n",
-                                                                                           (*c)->name()));
-                                       break;
-                               }
-                       }
-               }
-
-               for (set<boost::shared_ptr<Region> >::iterator s = unique.begin(); s != unique.end(); ++s) {
-                       rlist->push_back (*s);
-               }
-
-               if (rlist->size() > 1) {
-                       /* now sort by time order */
-
-                       RegionSortByPosition cmp;
-                       rlist->sort (cmp);
-               }
-       }
-
-        DEBUG_TRACE (DEBUG::AudioPlayback, string_compose ("<<<<< REGIONS TO READ returns %1\n", rlist->size()));
-
-       return rlist;
-}
-
-Playlist::RegionList *
-Playlist::find_regions_at (framepos_t frame)
-{
-       /* Caller must hold lock */
-
-       RegionList *rlist = new RegionList;
-
-       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-               if ((*i)->covers (frame)) {
-                       rlist->push_back (*i);
-               }
-       }
-
-       return rlist;
-}
-
-Playlist::RegionList *
-Playlist::regions_touched (framepos_t start, framepos_t end)
-{
-       RegionLock rlock (this);
-       RegionList *rlist = new RegionList;
-
-       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-               if ((*i)->coverage (start, end) != OverlapNone) {
-                       rlist->push_back (*i);
-               }
-       }
-
-       return rlist;
-}
-
-framepos_t
-Playlist::find_next_transient (framepos_t from, int dir)
-{
-       RegionLock rlock (this);
-       AnalysisFeatureList points;
-       AnalysisFeatureList these_points;
-
-       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-               if (dir > 0) {
-                       if ((*i)->last_frame() < from) {
-                               continue;
-                       }
-               } else {
-                       if ((*i)->first_frame() > from) {
-                               continue;
-                       }
-               }
-
-               (*i)->get_transients (these_points);
+ void
+ Playlist::update (const RegionListProperty::ChangeRecord& change)
+ {
+        DEBUG_TRACE (DEBUG::Properties, string_compose ("Playlist %1 updates from a change record with %2 adds %3 removes\n",
+                                                        name(), change.added.size(), change.removed.size()));
 
-               /* add first frame, just, err, because */
+        freeze ();
+        /* add the added regions */
+        for (RegionListProperty::ChangeContainer::iterator i = change.added.begin(); i != change.added.end(); ++i) {
+                add_region ((*i), (*i)->position());
+        }
+        /* remove the removed regions */
+        for (RegionListProperty::ChangeContainer::iterator i = change.removed.begin(); i != change.removed.end(); ++i) {
+                remove_region (*i);
+        }
 
-               these_points.push_back ((*i)->first_frame());
-
-               points.insert (points.end(), these_points.begin(), these_points.end());
-               these_points.clear ();
-       }
+        thaw ();
+ }
 
-       if (points.empty()) {
-               return -1;
-       }
+ int
+ Playlist::set_state (const XMLNode& node, int version)
+ {
+        XMLNode *child;
+        XMLNodeList nlist;
+        XMLNodeConstIterator niter;
+        XMLPropertyList plist;
+        XMLPropertyConstIterator piter;
+        XMLProperty *prop;
+        boost::shared_ptr<Region> region;
+        string region_name;
+        bool seen_region_nodes = false;
+        int ret = 0;
 
-       TransientDetector::cleanup_transients (points, _session.frame_rate(), 3.0);
-       bool reached = false;
+        in_set_state++;
 
-       if (dir > 0) {
-               for (AnalysisFeatureList::iterator x = points.begin(); x != points.end(); ++x) {
-                       if ((*x) >= from) {
-                               reached = true;
-                       }
+        if (node.name() != "Playlist") {
+                in_set_state--;
+                return -1;
+        }
 
-                       if (reached && (*x) > from) {
-                               return *x;
-                       }
-               }
-       } else {
-               for (AnalysisFeatureList::reverse_iterator x = points.rbegin(); x != points.rend(); ++x) {
-                       if ((*x) <= from) {
-                               reached = true;
-                       }
+        freeze ();
 
-                       if (reached && (*x) < from) {
-                               return *x;
-                       }
-               }
-       }
+        plist = node.properties();
 
-       return -1;
-}
+        set_id (node);
 
-boost::shared_ptr<Region>
-Playlist::find_next_region (framepos_t frame, RegionPoint point, int dir)
-{
-       RegionLock rlock (this);
-       boost::shared_ptr<Region> ret;
-       framepos_t closest = max_frames;
+        for (piter = plist.begin(); piter != plist.end(); ++piter) {
 
-       bool end_iter = false;
+                prop = *piter;
 
-       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                if (prop->name() == X_("name")) {
+                        _name = prop->value();
+                        _set_sort_id ();
+                } else if (prop->name() == X_("orig-diskstream-id")) {
+                        /* XXX legacy session: fix up later */
+                        _orig_track_id = prop->value ();
+                } else if (prop->name() == X_("orig-track-id")) {
+                        _orig_track_id = prop->value ();
+                } else if (prop->name() == X_("frozen")) {
+                        _frozen = string_is_affirmative (prop->value());
+                } else if (prop->name() == X_("combine-ops")) {
+                        _combine_ops = atoi (prop->value());
+                }
+        }
 
-               if(end_iter) break;
+        clear (true);
 
-               frameoffset_t distance;
-               boost::shared_ptr<Region> r = (*i);
-               framepos_t pos = 0;
+        nlist = node.children();
 
-               switch (point) {
-               case Start:
-                       pos = r->first_frame ();
-                       break;
-               case End:
-                       pos = r->last_frame ();
-                       break;
-               case SyncPoint:
-                       pos = r->sync_position ();
-                       // r->adjust_to_sync (r->first_frame());
-                       break;
-               }
+        for (niter = nlist.begin(); niter != nlist.end(); ++niter) {
 
-               switch (dir) {
-               case 1: /* forwards */
+                child = *niter;
 
-                       if (pos > frame) {
-                               if ((distance = pos - frame) < closest) {
-                                       closest = distance;
-                                       ret = r;
-                                       end_iter = true;
-                               }
+                if (child->name() == "Region") {
+
+                        seen_region_nodes = true;
+
+                        if ((prop = child->property ("id")) == 0) {
+                                error << _("region state node has no ID, ignored") << endmsg;
+                                continue;
+                        }
+
+                        ID id = prop->value ();
+
+                        if ((region = region_by_id (id))) {
+
+                                region->suspend_property_changes ();
+
+                                if (region->set_state (*child, version)) {
+                                        region->resume_property_changes ();
+                                        continue;
+                                }
+
+                        } else if ((region = RegionFactory::create (_session, *child, true)) != 0) {
+                                region->suspend_property_changes ();
+                        } else {
+                                error << _("Playlist: cannot create region from XML") << endmsg;
+                               return -1;
                        }
 
-                       break;
-
-               default: /* backwards */
-
-                       if (pos < frame) {
-                               if ((distance = frame - pos) < closest) {
-                                       closest = distance;
-                                       ret = r;
-                               }
-                       }
-                       else {
-                               end_iter = true;
-                       }
+                       add_region (region, region->position(), 1.0);
+                       
+                       region->resume_property_changes ();
 
-                       break;
                }
        }
 
-       return ret;
-}
-
-framepos_t
-Playlist::find_next_region_boundary (framepos_t frame, int dir)
-{
-       RegionLock rlock (this);
-
-       framepos_t closest = max_frames;
-       framepos_t ret = -1;
-
-       if (dir > 0) {
-
-               for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-
-                       boost::shared_ptr<Region> r = (*i);
-                       frameoffset_t distance;
-
-                       if (r->first_frame() > frame) {
-
-                               distance = r->first_frame() - frame;
-
-                               if (distance < closest) {
-                                       ret = r->first_frame();
-                                       closest = distance;
-                               }
-                       }
-
-                       if (r->last_frame () > frame) {
-
-                               distance = r->last_frame () - frame;
-
-                               if (distance < closest) {
-                                       ret = r->last_frame ();
-                                       closest = distance;
-                               }
-                       }
-               }
-
+       if (seen_region_nodes && regions.empty()) {
+               ret = -1;
        } else {
 
-               for (RegionList::reverse_iterator i = regions.rbegin(); i != regions.rend(); ++i) {
-
-                       boost::shared_ptr<Region> r = (*i);
-                       frameoffset_t distance;
-
-                       if (r->last_frame() < frame) {
-
-                               distance = frame - r->last_frame();
-
-                               if (distance < closest) {
-                                       ret = r->last_frame();
-                                       closest = distance;
-                               }
-                       }
-
-                       if (r->first_frame() < frame) {
-
-                               distance = frame - r->first_frame();
-
-                               if (distance < closest) {
-                                       ret = r->first_frame();
-                                       closest = distance;
-                               }
-                       }
-               }
-       }
-
-       return ret;
-}
-
-
-/***********************************************************************/
-
-
-
-
-void
-Playlist::mark_session_dirty ()
-{
-       if (!in_set_state && !holding_state ()) {
-               _session.set_dirty();
-       }
-}
-
-bool
-Playlist::set_property (const PropertyBase& prop)
-{
-        if (prop == Properties::regions.property_id) {
-                const RegionListProperty::ChangeRecord& change (dynamic_cast<const RegionListProperty*>(&prop)->change());
-                regions.update (change);
-                return (!change.added.empty() && !change.removed.empty());
-        }
-        return false;
-}
-
-void
-Playlist::rdiff (vector<StatefulDiffCommand*>& cmds) const
-{
-       RegionLock rlock (const_cast<Playlist *> (this));
-
-       for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
-               if ((*i)->changed ()) {
-                        StatefulDiffCommand* sdc = new StatefulDiffCommand (*i);
-                        cmds.push_back (sdc);
-                }
-       }
-}
-
-void
-Playlist::clear_owned_history ()
-{
-       RegionLock rlock (this);
-
-       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-                (*i)->clear_history ();
-        }
-}
-
-void
-Playlist::update (const RegionListProperty::ChangeRecord& change)
-{
-        DEBUG_TRACE (DEBUG::Properties, string_compose ("Playlist %1 updates from a change record with %2 adds %3 removes\n", 
-                                                        name(), change.added.size(), change.removed.size()));
-        
-        freeze ();
-        /* add the added regions */
-        for (RegionListProperty::ChangeContainer::iterator i = change.added.begin(); i != change.added.end(); ++i) {
-                add_region ((*i), (*i)->position());
-        }
-        /* remove the removed regions */
-        for (RegionListProperty::ChangeContainer::iterator i = change.removed.begin(); i != change.removed.end(); ++i) {
-                remove_region (*i);
-        }
-
-        thaw ();
-}
-
-PropertyList*
-Playlist::property_factory (const XMLNode& history_node) const
-{
-        const XMLNodeList& children (history_node.children());
-        PropertyList* prop_list = 0;
-
-        for (XMLNodeList::const_iterator i = children.begin(); i != children.end(); ++i) {
-
-                if ((*i)->name() == capitalize (regions.property_name())) {
-                        
-                        RegionListProperty* rlp = new RegionListProperty (*const_cast<Playlist*> (this));
-
-                        if (rlp->load_history_state (**i)) {
-                                if (!prop_list) {
-                                        prop_list = new PropertyList();
-                                }
-                                prop_list->add (rlp);
-                        } else {
-                                delete rlp;
-                        }
-                }
-        }
-
-        return prop_list;
-}
-
-int
-Playlist::set_state (const XMLNode& node, int version)
-{
-       XMLNode *child;
-       XMLNodeList nlist;
-       XMLNodeConstIterator niter;
-       XMLPropertyList plist;
-       XMLPropertyConstIterator piter;
-       XMLProperty *prop;
-       boost::shared_ptr<Region> region;
-       string region_name;
-
-       in_set_state++;
-
-       if (node.name() != "Playlist") {
-               in_set_state--;
-               return -1;
-       }
-
-       freeze ();
-
-       plist = node.properties();
-
-       for (piter = plist.begin(); piter != plist.end(); ++piter) {
-
-               prop = *piter;
-
-               if (prop->name() == X_("name")) {
-                       _name = prop->value();
-                        _set_sort_id ();
-               } else if (prop->name() == X_("id")) {
-                        _id = prop->value();
-               } else if (prop->name() == X_("orig_diskstream_id")) {
-                       _orig_diskstream_id = prop->value ();
-               } else if (prop->name() == X_("frozen")) {
-                       _frozen = string_is_affirmative (prop->value());
-               }
-       }
-
-       clear (true);
-
-       nlist = node.children();
-
-       for (niter = nlist.begin(); niter != nlist.end(); ++niter) {
-
-               child = *niter;
-
-               if (child->name() == "Region") {
-
-                       if ((prop = child->property ("id")) == 0) {
-                               error << _("region state node has no ID, ignored") << endmsg;
-                               continue;
-                       }
-                       
-                       ID id = prop->value ();
-
-                       if ((region = region_by_id (id))) {
-
-                               region->suspend_property_changes ();
-
-                               if (region->set_state (*child, version)) {
-                                       region->resume_property_changes ();
-                                       continue;
-                               }
-                               
-                       } else if ((region = RegionFactory::create (_session, *child, true)) != 0) {
-                               region->suspend_property_changes ();
-                       } else {
-                               error << _("Playlist: cannot create region from XML") << endmsg;
-                               continue;
-                       }
-
-
-                       add_region (region, region->position(), 1.0);
-
-                       // So that layer_op ordering doesn't get screwed up
-                       region->set_last_layer_op( region->layer());
-                       region->resume_property_changes ();
+               /* update dependents, which was not done during add_region_internal
+                  due to in_set_state being true
+               */
+               
+               for (RegionList::iterator r = regions.begin(); r != regions.end(); ++r) {
+                       check_dependents (*r, false);
                }
        }
-
-       /* update dependents, which was not done during add_region_internal
-          due to in_set_state being true
-       */
-
-       for (RegionList::iterator r = regions.begin(); r != regions.end(); ++r) {
-               check_dependents (*r, false);
-       }
-
+               
        thaw ();
        notify_contents_changed ();
 
        in_set_state--;
        first_set_state = false;
-       return 0;
+       return ret;
 }
 
 XMLNode&
@@ -2273,19 +2231,22 @@ XMLNode&
 Playlist::state (bool full_state)
 {
        XMLNode *node = new XMLNode (X_("Playlist"));
-       char buf[64] = "";
+       char buf[64];
 
        node->add_property (X_("id"), id().to_s());
        node->add_property (X_("name"), _name);
        node->add_property (X_("type"), _type.to_string());
 
-       _orig_diskstream_id.print (buf, sizeof (buf));
-       node->add_property (X_("orig_diskstream_id"), buf);
+       _orig_track_id.print (buf, sizeof (buf));
+       node->add_property (X_("orig-track-id"), buf);
        node->add_property (X_("frozen"), _frozen ? "yes" : "no");
 
        if (full_state) {
                RegionLock rlock (this, false);
 
+               snprintf (buf, sizeof (buf), "%u", _combine_ops);
+               node->add_property ("combine-ops", buf);
+
                for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
                        node->add_child_nocopy ((*i)->get_state());
                }
@@ -2312,20 +2273,25 @@ Playlist::n_regions() const
        return regions.size();
 }
 
-pair<framecnt_t, framecnt_t>
+pair<framepos_t, framepos_t>
 Playlist::get_extent () const
 {
        RegionLock rlock (const_cast<Playlist *>(this), false);
        return _get_extent ();
 }
 
-pair<framecnt_t, framecnt_t>
+pair<framepos_t, framepos_t>
 Playlist::_get_extent () const
 {
-       pair<framecnt_t, framecnt_t> ext (max_frames, 0);
+       pair<framepos_t, framepos_t> ext (max_framepos, 0);
+
+       if (regions.empty()) {
+               ext.first = 0;
+               return ext;
+       }
 
        for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
-               pair<framecnt_t, framecnt_t> const e ((*i)->position(), (*i)->position() + (*i)->length());
+               pair<framepos_t, framepos_t> const e ((*i)->position(), (*i)->position() + (*i)->length());
                if (e.first < ext.first) {
                        ext.first = e.first;
                }
@@ -2368,18 +2334,20 @@ Playlist::set_edit_mode (EditMode mode)
        _edit_mode = mode;
 }
 
-/********************
- * Region Layering
- ********************/
+struct RelayerSort {
+       bool operator () (boost::shared_ptr<Region> a, boost::shared_ptr<Region> b) {
+               return a->layering_index() < b->layering_index();
+       }
+};
 
 void
 Playlist::relayer ()
 {
-        /* never compute layers when changing state for undo/redo or setting from XML */
+       /* never compute layers when changing state for undo/redo or setting from XML */
 
-        if (in_update || in_set_state) {
-                return;
-        }
+       if (in_update || in_set_state) {
+               return;
+       }
 
        bool changed = false;
 
@@ -2405,29 +2373,46 @@ Playlist::relayer ()
        vector<vector<RegionList> > layers;
        layers.push_back (vector<RegionList> (divisions));
 
-       /* we want to go through regions from desired lowest to desired highest layer,
-          which depends on the layer model
-       */
-
        RegionList copy = regions.rlist();
+       RegionList pending;
 
-       /* sort according to the model and the layering mode that we're in */
-
-       if (_explicit_relayering) {
+       /* Remove regions with pending relayers */
+       for (RegionList::iterator i = copy.begin(); i != copy.end(); ) {
 
-               copy.sort (RegionSortByLayerWithPending ());
+               RegionList::iterator j = i;
+               ++j;
+               
+               if ((*i)->pending_layer()) {
+                       pending.push_back (*i);
+                       copy.erase (i);
+               }
 
-       } else if (_session.config.get_layer_model() == MoveAddHigher || _session.config.get_layer_model() == AddHigher) {
+               i = j;
+       }
 
-               copy.sort (RegionSortByLastLayerOp ());
+       /* Sort the remainder */
+       copy.sort (RelayerSort ());
 
+       /* Re-insert the pending layers in the right places */
+       for (RegionList::iterator i = pending.begin(); i != pending.end(); ++i) {
+               RegionList::iterator j = copy.begin();
+               while (j != copy.end ()) {
+                       if ((*j)->pending_layer().get_value_or ((*j)->layer ()) > (*i)->pending_layer().get ()) {
+                               break;
+                       }
+                       ++j;
+               }
+               copy.insert (j, *i);
        }
 
+       bool had_pending = false;
 
        for (RegionList::iterator i = copy.begin(); i != copy.end(); ++i) {
 
-               /* reset the pending explicit relayer flag for every region, now that we're relayering */
-               (*i)->set_pending_explicit_relayer (false);
+               /* reset the pending layer for every region now that we're relayering */
+               if ((*i)->reset_pending_layer ()) {
+                       had_pending = true;
+               }
 
                /* find the time divisions that this region covers; if there are no regions on the list,
                   division_size will equal 0 and in this case we'll just say that
@@ -2470,184 +2455,68 @@ Playlist::relayer ()
                        }
 
                        if (overlap) {
-                               /* overlap, so we must use layer j */
-                               break;
-                       }
-
-                       --j;
-               }
-
-               if (j == layers.size()) {
-                       /* we need a new layer for this region */
-                       layers.push_back (vector<RegionList> (divisions));
-               }
-
-               /* put a reference to this region in each of the divisions that it exists in */
-               for (int k = start_division; k <= end_division; ++k) {
-                       layers[j][k].push_back (*i);
-               }
-               
-               if ((*i)->layer() != j) {
-                       changed = true;
-               }
-
-               (*i)->set_layer (j);
-       }
-
-       if (changed) {
-               notify_layering_changed ();
-       }
-}
-
-/* XXX these layer functions are all deprecated */
-
-void
-Playlist::raise_region (boost::shared_ptr<Region> region)
-{
-       uint32_t rsz = regions.size();
-       layer_t target = region->layer() + 1U;
-
-       if (target >= rsz) {
-               /* its already at the effective top */
-               return;
-       }
-
-       move_region_to_layer (target, region, 1);
-}
-
-void
-Playlist::lower_region (boost::shared_ptr<Region> region)
-{
-       if (region->layer() == 0) {
-               /* its already at the bottom */
-               return;
-       }
-
-       layer_t target = region->layer() - 1U;
-
-       move_region_to_layer (target, region, -1);
-}
-
-void
-Playlist::raise_region_to_top (boost::shared_ptr<Region> region)
-{
-       /* does nothing useful if layering mode is later=higher */
-       switch (_session.config.get_layer_model()) {
-       case LaterHigher:
-               return;
-       default:
-               break;
-       }
-
-       layer_t top = regions.size() - 1;
-
-       if (region->layer() >= top) {
-               /* already on the top */
-               return;
-       }
-
-       move_region_to_layer (top, region, 1);
-       /* mark the region's last_layer_op as now, so that it remains on top when
-          doing future relayers (until something else takes over)
-        */
-       timestamp_layer_op (region);
-}
-
-void
-Playlist::lower_region_to_bottom (boost::shared_ptr<Region> region)
-{
-       /* does nothing useful if layering mode is later=higher */
-       switch (_session.config.get_layer_model()) {
-       case LaterHigher:
-               return;
-       default:
-               break;
-       }
-
-       if (region->layer() == 0) {
-               /* already on the bottom */
-               return;
-       }
-
-       move_region_to_layer (0, region, -1);
-       /* force region's last layer op to zero so that it stays at the bottom
-          when doing future relayers
-       */
-       region->set_last_layer_op (0);
-}
-
-int
-Playlist::move_region_to_layer (layer_t target_layer, boost::shared_ptr<Region> region, int dir)
-{
-       RegionList::iterator i;
-       typedef pair<boost::shared_ptr<Region>,layer_t> LayerInfo;
-       list<LayerInfo> layerinfo;
-
-       {
-               RegionLock rlock (const_cast<Playlist *> (this));
-
-               for (i = regions.begin(); i != regions.end(); ++i) {
-
-                       if (region == *i) {
-                               continue;
-                       }
-
-                       layer_t dest;
-
-                       if (dir > 0) {
-
-                               /* region is moving up, move all regions on intermediate layers
-                                  down 1
-                               */
-
-                               if ((*i)->layer() > region->layer() && (*i)->layer() <= target_layer) {
-                                       dest = (*i)->layer() - 1;
-                               } else {
-                                       /* not affected */
-                                       continue;
-                               }
-                       } else {
-
-                               /* region is moving down, move all regions on intermediate layers
-                                  up 1
-                               */
-
-                               if ((*i)->layer() < region->layer() && (*i)->layer() >= target_layer) {
-                                       dest = (*i)->layer() + 1;
-                               } else {
-                                       /* not affected */
-                                       continue;
-                               }
+                               /* overlap, so we must use layer j */
+                               break;
                        }
 
-                       LayerInfo newpair;
+                       --j;
+               }
 
-                       newpair.first = *i;
-                       newpair.second = dest;
+               if (j == layers.size()) {
+                       /* we need a new layer for this region */
+                       layers.push_back (vector<RegionList> (divisions));
+               }
 
-                       layerinfo.push_back (newpair);
+               /* put a reference to this region in each of the divisions that it exists in */
+               for (int k = start_division; k <= end_division; ++k) {
+                       layers[j][k].push_back (*i);
                }
-       }
 
-       /* now reset the layers without holding the region lock */
+               if ((*i)->layer() != j) {
+                       changed = true;
+               }
 
-       for (list<LayerInfo>::iterator x = layerinfo.begin(); x != layerinfo.end(); ++x) {
-               x->first->set_layer (x->second);
+               (*i)->set_layer (j);
        }
 
-       region->set_layer (target_layer);
-
-#if 0
-       /* now check all dependents */
+       if (changed) {
+               notify_layering_changed ();
+       }
 
-       for (list<LayerInfo>::iterator x = layerinfo.begin(); x != layerinfo.end(); ++x) {
-               check_dependents (x->first, false);
+       if (had_pending) {
+               uint64_t i = 0;
+               for (RegionList::iterator j = copy.begin(); j != copy.end(); ++j) {
+                       (*j)->set_layering_index (i++);
+               }
        }
+}
 
-       check_dependents (region, false);
-#endif
+void
+Playlist::raise_region (boost::shared_ptr<Region> region)
+{
+       region->set_pending_layer (region->layer() + 1.5);
+       relayer ();
+}
+
+void
+Playlist::lower_region (boost::shared_ptr<Region> region)
+{
+       region->set_pending_layer (region->layer() - 1.5);
+       relayer ();
+}
 
-       return 0;
+void
+Playlist::raise_region_to_top (boost::shared_ptr<Region> region)
+{
+       region->set_pending_layer (DBL_MAX);
+       relayer ();
+}
+
+void
+Playlist::lower_region_to_bottom (boost::shared_ptr<Region> region)
+{
+       region->set_pending_layer (-0.5);
+       relayer ();
 }
 
 void
@@ -2669,8 +2538,8 @@ Playlist::nudge_after (framepos_t start, framecnt_t distance, bool forwards)
 
                                if (forwards) {
 
-                                       if ((*i)->last_frame() > max_frames - distance) {
-                                               new_pos = max_frames - (*i)->length();
+                                       if ((*i)->last_frame() > max_framepos - distance) {
+                                               new_pos = max_framepos - (*i)->length();
                                        } else {
                                                new_pos = (*i)->position() + distance;
                                        }
@@ -2684,7 +2553,7 @@ Playlist::nudge_after (framepos_t start, framecnt_t distance, bool forwards)
                                        }
                                }
 
-                               (*i)->set_position (new_pos, this);
+                               (*i)->set_position (new_pos);
                                moved = true;
                        }
                }
@@ -2692,9 +2561,23 @@ Playlist::nudge_after (framepos_t start, framecnt_t distance, bool forwards)
 
        if (moved) {
                _nudging = false;
-               notify_length_changed ();
+               notify_contents_changed ();
+       }
+
+}
+
+bool
+Playlist::uses_source (boost::shared_ptr<const Source> src) const
+{
+       RegionLock rlock (const_cast<Playlist*> (this));
+
+       for (set<boost::shared_ptr<Region> >::iterator r = all_regions.begin(); r != all_regions.end(); ++r) {
+               if ((*r)->uses_source (src)) {
+                       return true;
+               }
        }
 
+       return false;
 }
 
 boost::shared_ptr<Region>
@@ -2713,8 +2596,23 @@ Playlist::find_region (const ID& id) const
        return boost::shared_ptr<Region> ();
 }
 
+uint32_t
+Playlist::region_use_count (boost::shared_ptr<Region> r) const
+{
+       RegionLock rlock (const_cast<Playlist*> (this));
+       uint32_t cnt = 0;
+
+       for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
+               if ((*i) == r) {
+                       cnt++;
+               }
+       }
+
+       return cnt;
+}
+
 boost::shared_ptr<Region>
-Playlist::region_by_id (const ID& id)
+Playlist::region_by_id (const ID& id) const
 {
        /* searches all regions ever added to this playlist */
 
@@ -2753,13 +2651,6 @@ Playlist::set_frozen (bool yn)
        _frozen = yn;
 }
 
-void
-Playlist::timestamp_layer_op (boost::shared_ptr<Region> region)
-{
-       region->set_last_layer_op (++layer_op_counter);
-}
-
-
 void
 Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
 {
@@ -2806,8 +2697,8 @@ Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
                                                        new_pos = region->position() + (*next)->length();
                                                }
 
-                                               (*next)->set_position (region->position(), this);
-                                               region->set_position (new_pos, this);
+                                               (*next)->set_position (region->position());
+                                               region->set_position (new_pos);
 
                                                /* avoid a full sort */
 
@@ -2847,8 +2738,8 @@ Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
                                                        new_pos = (*prev)->position() + region->length();
                                                }
 
-                                               region->set_position ((*prev)->position(), this);
-                                               (*prev)->set_position (new_pos, this);
+                                               region->set_position ((*prev)->position());
+                                               (*prev)->set_position (new_pos);
 
                                                /* avoid a full sort */
 
@@ -2897,7 +2788,7 @@ Playlist::update_after_tempo_map_change ()
        freeze ();
 
        for (RegionList::iterator i = copy.begin(); i != copy.end(); ++i) {
-               (*i)->update_position_after_tempo_map_change ();
+               (*i)->update_after_tempo_map_change ();
        }
 
        thaw ();
@@ -2912,34 +2803,11 @@ Playlist::foreach_region (boost::function<void(boost::shared_ptr<Region>)> s)
        }
 }
 
-void
-Playlist::set_explicit_relayering (bool e)
-{
-       if (e == false && _explicit_relayering == true) {
-
-               /* We are changing from explicit to implicit relayering; layering may have been changed whilst
-                  we were in explicit mode, and we don't want that to be undone next time an implicit relayer
-                  occurs.  Hence now we'll set up region last_layer_op values so that an implicit relayer
-                  at this point would keep regions on the same layers.
-
-                  From then on in, it's just you and your towel.
-               */
-
-               RegionLock rl (this);
-               for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
-                       (*i)->set_last_layer_op ((*i)->layer ());
-               }
-       }
-
-       _explicit_relayering = e;
-}
-
-
 bool
 Playlist::has_region_at (framepos_t const p) const
 {
        RegionLock (const_cast<Playlist *> (this));
-       
+
        RegionList::const_iterator i = regions.begin ();
        while (i != regions.end() && !(*i)->covers (p)) {
                ++i;
@@ -2953,12 +2821,12 @@ void
 Playlist::remove_region_by_source (boost::shared_ptr<Source> s)
 {
        RegionLock rl (this);
-       
+
        RegionList::iterator i = regions.begin();
        while (i != regions.end()) {
                RegionList::iterator j = i;
                ++j;
-               
+
                if ((*i)->uses_source (s)) {
                        remove_region_internal (*i);
                }
@@ -2966,3 +2834,365 @@ Playlist::remove_region_by_source (boost::shared_ptr<Source> s)
                i = j;
        }
 }
+
+/** Look from a session frame time and find the start time of the next region
+ *  which is on the top layer of this playlist.
+ *  @param t Time to look from.
+ *  @return Position of next top-layered region, or max_framepos if there isn't one.
+ */
+framepos_t
+Playlist::find_next_top_layer_position (framepos_t t) const
+{
+       RegionLock rlock (const_cast<Playlist *> (this));
+
+       layer_t const top = top_layer ();
+
+       RegionList copy = regions.rlist ();
+       copy.sort (RegionSortByPosition ());
+
+       for (RegionList::const_iterator i = copy.begin(); i != copy.end(); ++i) {
+               if ((*i)->position() >= t && (*i)->layer() == top) {
+                       return (*i)->position();
+               }
+       }
+
+       return max_framepos;
+}
+
+boost::shared_ptr<Region>
+Playlist::combine (const RegionList& r)
+{
+       PropertyList plist;
+       uint32_t channels = 0;
+       uint32_t layer = 0;
+       framepos_t earliest_position = max_framepos;
+       vector<TwoRegions> old_and_new_regions;
+       vector<boost::shared_ptr<Region> > originals;
+       vector<boost::shared_ptr<Region> > copies;
+       string parent_name;
+       string child_name;
+       uint32_t max_level = 0;
+
+       /* find the maximum depth of all the regions we're combining */
+
+       for (RegionList::const_iterator i = r.begin(); i != r.end(); ++i) {
+               max_level = max (max_level, (*i)->max_source_level());
+       }
+
+       parent_name = RegionFactory::compound_region_name (name(), combine_ops(), max_level, true);
+       child_name = RegionFactory::compound_region_name (name(), combine_ops(), max_level, false);
+
+       boost::shared_ptr<Playlist> pl = PlaylistFactory::create (_type, _session, parent_name, true);
+
+       for (RegionList::const_iterator i = r.begin(); i != r.end(); ++i) {
+               earliest_position = min (earliest_position, (*i)->position());
+       }
+
+       /* enable this so that we do not try to create xfades etc. as we add
+        * regions
+        */
+
+       pl->in_partition = true;
+
+       for (RegionList::const_iterator i = r.begin(); i != r.end(); ++i) {
+
+               /* copy the region */
+
+               boost::shared_ptr<Region> original_region = (*i);
+               boost::shared_ptr<Region> copied_region = RegionFactory::create (original_region, false);
+
+               old_and_new_regions.push_back (TwoRegions (original_region,copied_region));
+               originals.push_back (original_region);
+               copies.push_back (copied_region);
+
+               RegionFactory::add_compound_association (original_region, copied_region);
+
+               /* make position relative to zero */
+
+               pl->add_region (copied_region, original_region->position() - earliest_position);
+
+               /* use the maximum number of channels for any region */
+
+               channels = max (channels, original_region->n_channels());
+
+               /* it will go above the layer of the highest existing region */
+
+               layer = max (layer, original_region->layer());
+       }
+
+       pl->in_partition = false;
+
+       pre_combine (copies);
+
+       /* add any dependent regions to the new playlist */
+
+       copy_dependents (old_and_new_regions, pl.get());
+
+       /* now create a new PlaylistSource for each channel in the new playlist */
+
+       SourceList sources;
+       pair<framepos_t,framepos_t> extent = pl->get_extent();
+
+       for (uint32_t chn = 0; chn < channels; ++chn) {
+               sources.push_back (SourceFactory::createFromPlaylist (_type, _session, pl, id(), parent_name, chn, 0, extent.second, false, false));
+
+       }
+
+       /* now a new whole-file region using the list of sources */
+
+       plist.add (Properties::start, 0);
+       plist.add (Properties::length, extent.second);
+       plist.add (Properties::name, parent_name);
+       plist.add (Properties::whole_file, true);
+
+       boost::shared_ptr<Region> parent_region = RegionFactory::create (sources, plist, true);
+
+       /* now the non-whole-file region that we will actually use in the
+        * playlist
+        */
+
+       plist.clear ();
+       plist.add (Properties::start, 0);
+       plist.add (Properties::length, extent.second);
+       plist.add (Properties::name, child_name);
+       plist.add (Properties::layer, layer+1);
+
+       boost::shared_ptr<Region> compound_region = RegionFactory::create (parent_region, plist, true);
+
+       /* remove all the selected regions from the current playlist
+        */
+
+       freeze ();
+
+       for (RegionList::const_iterator i = r.begin(); i != r.end(); ++i) {
+               remove_region (*i);
+       }
+
+       /* do type-specific stuff with the originals and the new compound
+          region
+       */
+
+       post_combine (originals, compound_region);
+
+       /* add the new region at the right location */
+
+       add_region (compound_region, earliest_position);
+
+       _combine_ops++;
+
+       thaw ();
+
+       return compound_region;
+}
+
+void
+Playlist::uncombine (boost::shared_ptr<Region> target)
+{
+       boost::shared_ptr<PlaylistSource> pls;
+       boost::shared_ptr<const Playlist> pl;
+       vector<boost::shared_ptr<Region> > originals;
+       vector<TwoRegions> old_and_new_regions;
+
+       // (1) check that its really a compound region
+
+       if ((pls = boost::dynamic_pointer_cast<PlaylistSource>(target->source (0))) == 0) {
+               return;
+       }
+
+       pl = pls->playlist();
+
+       framepos_t adjusted_start = 0; // gcc isn't smart enough
+       framepos_t adjusted_end = 0;   // gcc isn't smart enough
+
+       /* the leftmost (earliest) edge of the compound region
+          starts at zero in its source, or larger if it
+          has been trimmed or content-scrolled.
+
+          the rightmost (latest) edge of the compound region
+          relative to its source is the starting point plus
+          the length of the region.
+       */
+
+       // (2) get all the original regions
+
+       const RegionList& rl (pl->region_list().rlist());
+       RegionFactory::CompoundAssociations& cassocs (RegionFactory::compound_associations());
+       frameoffset_t move_offset = 0;
+
+       /* there are two possibilities here:
+          1) the playlist that the playlist source was based on
+          is us, so just add the originals (which belonged to
+          us anyway) back in the right place.
+
+          2) the playlist that the playlist source was based on
+          is NOT us, so we need to make copies of each of
+          the original regions that we find, and add them
+          instead.
+       */
+       bool same_playlist = (pls->original() == id());
+
+       for (RegionList::const_iterator i = rl.begin(); i != rl.end(); ++i) {
+
+               boost::shared_ptr<Region> current (*i);
+
+               RegionFactory::CompoundAssociations::iterator ca = cassocs.find (*i);
+
+               if (ca == cassocs.end()) {
+                       continue;
+               }
+
+               boost::shared_ptr<Region> original (ca->second);
+               bool modified_region;
+
+               if (i == rl.begin()) {
+                       move_offset = (target->position() - original->position()) - target->start();
+                       adjusted_start = original->position() + target->start();
+                       adjusted_end = adjusted_start + target->length();
+               }
+
+               if (!same_playlist) {
+                       framepos_t pos = original->position();
+                       /* make a copy, but don't announce it */
+                       original = RegionFactory::create (original, false);
+                       /* the pure copy constructor resets position() to zero,
+                          so fix that up.
+                       */
+                       original->set_position (pos);
+               }
+
+               /* check to see how the original region (in the
+                * playlist before compounding occured) overlaps
+                * with the new state of the compound region.
+                */
+
+               original->clear_changes ();
+               modified_region = false;
+
+               switch (original->coverage (adjusted_start, adjusted_end)) {
+               case OverlapNone:
+                       /* original region does not cover any part
+                          of the current state of the compound region
+                       */
+                       continue;
+
+               case OverlapInternal:
+                       /* overlap is just a small piece inside the
+                        * original so trim both ends
+                        */
+                       original->trim_to (adjusted_start, adjusted_end - adjusted_start);
+                       modified_region = true;
+                       break;
+
+               case OverlapExternal:
+                       /* overlap fully covers original, so leave it
+                          as is
+                       */
+                       break;
+
+               case OverlapEnd:
+                       /* overlap starts within but covers end,
+                          so trim the front of the region
+                       */
+                       original->trim_front (adjusted_start);
+                       modified_region = true;
+                       break;
+
+               case OverlapStart:
+                       /* overlap covers start but ends within, so
+                        * trim the end of the region.
+                        */
+                       original->trim_end (adjusted_end);
+                       modified_region = true;
+                       break;
+               }
+
+               if (move_offset) {
+                       /* fix the position to match any movement of the compound region.
+                        */
+                       original->set_position (original->position() + move_offset);
+                       modified_region = true;
+               }
+
+               if (modified_region) {
+                       _session.add_command (new StatefulDiffCommand (original));
+               }
+
+               /* and add to the list of regions waiting to be
+                * re-inserted
+                */
+
+               originals.push_back (original);
+               old_and_new_regions.push_back (TwoRegions (*i, original));
+       }
+
+       pre_uncombine (originals, target);
+
+       in_partition = true;
+       freeze ();
+
+       // (3) remove the compound region
+
+       remove_region (target);
+
+       // (4) add the constituent regions
+
+       for (vector<boost::shared_ptr<Region> >::iterator i = originals.begin(); i != originals.end(); ++i) {
+               add_region ((*i), (*i)->position());
+       }
+
+       /* now move dependent regions back from the compound to this playlist */
+
+       pl->copy_dependents (old_and_new_regions, this);
+
+       in_partition = false;
+       thaw ();
+}
+
+uint32_t
+Playlist::max_source_level () const
+{
+       RegionLock rlock (const_cast<Playlist *> (this));
+       uint32_t lvl = 0;
+
+       for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
+               lvl = max (lvl, (*i)->max_source_level());
+       }
+
+       return lvl;
+}
+
+
+uint32_t
+Playlist::count_joined_regions () const
+{
+       RegionLock rlock (const_cast<Playlist *> (this));
+       uint32_t cnt = 0;
+
+       for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
+               if ((*i)->max_source_level() > 0) {
+                       cnt++;
+               }
+       }
+
+       return cnt;
+}
+
+void
+Playlist::set_orig_track_id (const PBD::ID& id)
+{
+       _orig_track_id = id;
+}
+
+uint64_t
+Playlist::highest_layering_index () const
+{
+       RegionLock rlock (const_cast<Playlist *> (this));
+
+       uint64_t h = 0;
+       for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
+               h = max (h, (*i)->layering_index ());
+       }
+
+       return h;
+}
+