Proposed fix managing shared playlists (see #7150)

Actually, when duplicating a track with "share playlist", the current
playlist is owned by the new created track(orig-track-id). The sharing
mecanism is made by diskstreams pointing on the same(shared) playlist.
Since playlist now owned by the new track, selecting another playlist in
the original track "forgets" the playlist for this track.You can't
select the shared playlist anymore from the original track.

This commit adds a way to keep trace of shared playlist between tracks.

libs/ardour/ardour/playlist.h

@@ -117,6 +117,13 @@ public:
 
 	bool hidden() const { return _hidden; }
 	bool empty() const;
+
+	bool shared () const { return !_shared_with_ids.empty(); }
+	void share_with (const PBD::ID&);
+	void unshare_with (const PBD::ID&);
+	bool shared_with (const PBD::ID&) const;
+	void reset_shares ();
+
 	uint32_t n_regions() const;
 	bool all_regions_empty() const;
 	std::pair<framepos_t, framepos_t> get_extent () const;
@@ -311,6 +318,7 @@ public:
 	uint32_t         subcnt;
 	PBD::ID         _orig_track_id;
 	uint32_t        _combine_ops;
+	std::list<PBD::ID> _shared_with_ids;
 
 	void init (bool hide);
 

libs/ardour/audio_diskstream.cc

@@ -316,6 +316,7 @@ AudioDiskstream::use_copy_playlist ()
 	newname = Playlist::bump_name (_playlist->name(), _session);
 
 	if ((playlist = boost::dynamic_pointer_cast<AudioPlaylist>(PlaylistFactory::create (audio_playlist(), newname))) != 0) {
+		playlist->reset_shares();
 		return use_playlist (playlist);
 	} else {
 		return -1;

libs/ardour/playlist.cc

@@ -26,6 +26,7 @@
 
 #include "pbd/convert.h"
 #include "pbd/stateful_diff_command.h"
+#include "pbd/strsplit.h"
 #include "pbd/xml++.h"
 
 #include "ardour/debug.h"
@@ -157,6 +158,7 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, string namestr, boo
 	, regions (*this)
 	, _type(other->_type)
 	, _orig_track_id (other->_orig_track_id)
+	, _shared_with_ids (other->_shared_with_ids)
 {
 	init (hide);
 
@@ -189,6 +191,7 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, framepos_t start, f
 	, regions (*this)
 	, _type(other->_type)
 	, _orig_track_id (other->_orig_track_id)
+	, _shared_with_ids (other->_shared_with_ids)
 {
 	RegionReadLock rlock2 (const_cast<Playlist*> (other.get()));
 
@@ -2234,6 +2237,16 @@ Playlist::find_next_region (framepos_t frame, RegionPoint point, int dir)
 			 _frozen = string_is_affirmative (prop->value());
 		 } else if (prop->name() == X_("combine-ops")) {
 			 _combine_ops = atoi (prop->value());
+		 } else if (prop->name() == X_("shared-with-ids")) {
+			 string shared_ids = prop->value ();
+			 if (!shared_ids.empty()) {
+				vector<string> result;
+				::split (shared_ids, result, ',');
+				vector<string>::iterator it = result.begin();
+				for (; it != result.end(); ++it) {
+					_shared_with_ids.push_back (PBD::ID(*it));
+				}
+			 }
 		 }
 	 }
 
@@ -2321,6 +2334,17 @@ Playlist::state (bool full_state)
 
 	_orig_track_id.print (buf, sizeof (buf));
 	node->add_property (X_("orig-track-id"), buf);
+
+	string shared_ids;
+	list<PBD::ID>::const_iterator it = _shared_with_ids.begin();
+	for (; it != _shared_with_ids.end(); ++it) {
+		shared_ids += "," + (*it).to_s();
+	}
+	if (!shared_ids.empty()) {
+		shared_ids.erase(0,1);
+	}
+
+	node->add_property (X_("shared-with-ids"), shared_ids);
 	node->add_property (X_("frozen"), _frozen ? "yes" : "no");
 
 	if (full_state) {
@@ -3317,9 +3341,56 @@ Playlist::max_source_level () const
 void
 Playlist::set_orig_track_id (const PBD::ID& id)
 {
+	if (shared_with(id)) {
+		// Swap 'shared_id' / origin_track_id
+		unshare_with (id);
+		share_with (_orig_track_id);
+	}
 	_orig_track_id = id;
 }
 
+void
+Playlist::share_with (const PBD::ID& id)
+{
+	if (!shared_with(id)) {
+		_shared_with_ids.push_back (id);
+	}
+}
+
+void
+Playlist::unshare_with (const PBD::ID& id)
+{
+	list<PBD::ID>::iterator it = _shared_with_ids.begin ();
+	while (it != _shared_with_ids.end()) {
+		if (*it == id) {
+			_shared_with_ids.erase (it);
+			break;
+		}
+		++it;
+	}
+}
+
+bool
+Playlist::shared_with (const PBD::ID& id) const
+{
+	bool shared = false;
+	list<PBD::ID>::const_iterator it = _shared_with_ids.begin ();
+	while (it != _shared_with_ids.end() && !shared) {
+		if (*it == id) {
+			shared = true;
+		}
+		++it;
+	}
+
+	return shared;
+}
+
+void
+Playlist::reset_shares ()
+{
+	_shared_with_ids.clear();
+}
+
 /** Take a list of ranges, coalesce any that can be coalesced, then call
  *  check_crossfades for each one.
  */

libs/ardour/session.cc

@@ -3255,7 +3255,15 @@ Session::new_route_from_template (uint32_t how_many, PresentationInfo::order_t i
 					boost::shared_ptr<Playlist> playlist = playlists->by_name (playlist_name);
 					// Use same name as Route::set_name_in_state so playlist copy
 					// is picked up when creating the Route in XMLRouteFactory below
-					PlaylistFactory::create (playlist, string_compose ("%1.1", name));
+					playlist = PlaylistFactory::create (playlist, string_compose ("%1.1", name));
+					playlist->reset_shares ();
+				}
+			} else if (pd == SharePlaylist) {
+				XMLNode* ds_node = find_named_node (node_copy, "Diskstream");
+				if (ds_node) {
+					const std::string playlist_name = ds_node->property (X_("playlist"))->value ();
+					boost::shared_ptr<Playlist> playlist = playlists->by_name (playlist_name);
+					playlist->share_with ((node_copy.property (X_("id")))->value());
 				}
 			}
 

libs/ardour/session_playlists.cc

@@ -527,7 +527,10 @@ SessionPlaylists::playlists_for_track (boost::shared_ptr<Track> tr) const
 	vector<boost::shared_ptr<Playlist> > pl_tr;
 
 	for (vector<boost::shared_ptr<Playlist> >::iterator i = pl.begin(); i != pl.end(); ++i) {
-		if (((*i)->get_orig_track_id() == tr->id()) || (tr->playlist()->id() == (*i)->id())) {
+		if ( ((*i)->get_orig_track_id() == tr->id()) ||
+			(tr->playlist()->id() == (*i)->id())    ||
+			((*i)->shared_with (tr->id())) )
+		{
 			pl_tr.push_back (*i);
 		}
 	}