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/***************************************************************************
UndoTransactionGuard.h - guard class for undo transactions
-------------------
begin : Sat May 26, 2001
copyright : (C) 2001 by Thomas Eschenbacher
email : Thomas Eschenbacher <thomas.eschenbacher@gmx.de>
***************************************************************************/
/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#ifndef UNDO_TRANSACTION_GUARD_H
#define UNDO_TRANSACTION_GUARD_H
#include "config.h"
#include "libkwave_export.h"
#include <QtGlobal>
class QString;
namespace Kwave {
class SignalManager;
class UndoAction;
class Plugin;
/**
* @class UndoTransactionGuard
* A simple guard class for opening and closing an undo transaction
* operating on a SignalManager. Several nested UndoTransactionGuards
* (or undo transactions) are allowed.
*/
class LIBKWAVE_EXPORT UndoTransactionGuard
{
public:
/**
* Constructor. Also determines the name of the transaction if
* it is the first of several nested transactions.
* @param manager reference to the SignalManager we operate on
* @param name the name of the transaction as a user-readable and
* localized string. [optional]
*/
explicit UndoTransactionGuard(Kwave::SignalManager &manager,
const QString &name = QString());
/**
* Constructor for use from a plugin. Also determines the name of the
* transaction if it is the first of several nested transactions.
* @param plugin reference to the plugin (you should pass
* <code>*this</code>.
* @param name the name of the transaction as a user-readable and
* localized string. [optional] If you pass null or omit this
* parameter, the name of the plugin will be used instead.
*/
explicit UndoTransactionGuard(Kwave::Plugin &plugin,
const QString &name = QString());
/** Destructor. */
virtual ~UndoTransactionGuard();
/**
* Tries to free memory for a new undo action and stores all needed
* data if successful.
* @param action UndoAction to that is to be registered
* @return true if the action is allowed, false if the user has
* chosen to abort the operation if the memory limit of
* the undo buffer would be exceeded. The return value
* will also be false if the action is null.
* @note If undo is currently not enabled, the passed UndoAction
* will be ignored and not freed, the return value will
* be false. So it is safer not to call this function if
* undo is not enabled.
*/
bool registerUndoAction(UndoAction *action);
/**
* Aborts the undo transaction, discards all undo data and restores
* the previous "modified" state of the signal.
*/
void abort();
private:
/** Reference to the responsible SignalManager */
Kwave::SignalManager &m_manager;
/** the initial "modified" state of the signal */
bool m_initial_modified;
};
}
#endif /* UNDO_TRANSACTION_GUARD_H */
//***************************************************************************
//***************************************************************************
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