2 Copyright (C) 2006 Paul Davis
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 #ifndef __lib_pbd_memento_command_h__
22 #define __lib_pbd_memento_command_h__
26 #include "pbd/command.h"
27 #include "pbd/stacktrace.h"
28 #include "pbd/xml++.h"
29 #include "pbd/demangle.h"
31 #include <sigc++/slot.h>
34 /** A class that can return a Stateful object which is the subject of a MementoCommand.
36 * The existence of this class means that the undo record can refer to objects which
37 * don't exist in the session file. Currently this is used for
39 * 1. MIDI automation; when MIDI automation is edited, undo records are
40 * written for the AutomationList being changed. However this AutomationList
41 * is a temporary structure, built by a MidiModel, which doesn't get written
42 * to the session file. Hence we need to be able to go from a MidiSource and
43 * Parameter to an AutomationList. This Binder mechanism allows this through
44 * MidiAutomationListBinder; the undo record stores the source and parameter,
45 * and these are bound to an AutomationList by the Binder.
47 * 2. Crossfades; unlike regions, these are completely removed from a session
48 * when they are deleted. This means that the undo record can contain
49 * references to non-existant crossfades. To get around this, CrossfadeBinder
50 * can do `just-in-time' binding from the crossfade ID.
52 template <class obj_T>
53 class MementoCommandBinder : public PBD::Destructible
56 /** @return Stateful object to operate on */
57 virtual obj_T* get () const = 0;
59 /** @return Name of our type */
60 virtual std::string type_name () const {
61 return PBD::demangled_name (*get ());
64 /** Add our own state to an XMLNode */
65 virtual void add_state (XMLNode *) = 0;
68 /** A simple MementoCommandBinder which binds directly to an object */
69 template <class obj_T>
70 class SimpleMementoCommandBinder : public MementoCommandBinder<obj_T>
73 SimpleMementoCommandBinder (obj_T& o)
76 _object.Destroyed.connect_same_thread (_object_death_connection, boost::bind (&SimpleMementoCommandBinder::object_died, this));
83 void add_state (XMLNode* node) {
84 node->add_property ("obj_id", _object.id().to_s());
88 /* The object we are binding died, so drop references to ourselves */
89 this->drop_references ();
94 PBD::ScopedConnection _object_death_connection;
97 /** This command class is initialized with before and after mementos
98 * (from Stateful::get_state()), so undo becomes restoring the before
99 * memento, and redo is restoring the after memento.
101 template <class obj_T>
102 class MementoCommand : public Command
105 MementoCommand (obj_T& a_object, XMLNode* a_before, XMLNode* a_after)
106 : _binder (new SimpleMementoCommandBinder<obj_T> (a_object)), before (a_before), after (a_after)
108 /* The binder's object died, so we must die */
109 _binder->DropReferences.connect_same_thread (_binder_death_connection, boost::bind (&MementoCommand::binder_dying, this));
112 MementoCommand (MementoCommandBinder<obj_T>* b, XMLNode* a_before, XMLNode* a_after)
113 : _binder (b), before (a_before), after (a_after)
115 /* The binder's object died, so we must die */
116 _binder->DropReferences.connect_same_thread (_binder_death_connection, boost::bind (&MementoCommand::binder_dying, this));
126 void binder_dying () {
132 _binder->get()->set_state(*after, Stateful::current_state_version);
138 _binder->get()->set_state(*before, Stateful::current_state_version);
142 virtual XMLNode &get_state() {
144 if (before && after) {
145 name = "MementoCommand";
147 name = "MementoUndoCommand";
149 name = "MementoRedoCommand";
152 XMLNode* node = new XMLNode(name);
153 _binder->add_state (node);
155 node->add_property ("type_name", _binder->type_name ());
158 node->add_child_copy(*before);
162 node->add_child_copy(*after);
169 MementoCommandBinder<obj_T>* _binder;
172 PBD::ScopedConnection _binder_death_connection;
175 #endif // __lib_pbd_memento_h__