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undo-stack-observer.h
/**
 * Undo stack observer interface
 *
 * Observes undo, redo, and undo log commit events.
 *
 * Authors:
 * David Yip <yipdw@rose-hulman.edu>
 *
 * Copyright (c) 2005 Authors
 *
 * Released under GNU GPL, read the file 'COPYING' for more information
 */

#ifndef __UNDO_COMMIT_OBSERVER_H__
#define __UNDO_COMMIT_OBSERVER_H__

#include "gc-managed.h"

namespace Inkscape {

class Event;

/**
 * Observes changes made to the undo and redo stacks.
 *
 * More specifically, an UndoStackObserver is a class that receives notifications when
 * any of the following events occur:
 * <ul>
 *    <li>A change is committed to the undo stack.</li>
 *    <li>An undo action is made.</li>
 *    <li>A redo action is made.</li>
 * </ul>
 *
 * UndoStackObservers should not be used on their own.  Instead, they should be registered
 * with a CompositeUndoStackObserver.
 */
00037 class UndoStackObserver : public GC::Managed<> {
public:
      UndoStackObserver() { }
      virtual ~UndoStackObserver() { }

      /**
       * Triggered when the user issues an undo command.
       *
       * \param log Pointer to an Event describing the undone event.
       */
      virtual void notifyUndoEvent(Event* log) = 0;

      /**
       * Triggered when the user issues a redo command.
       *
       * \param log Pointer to an Event describing the redone event.
       */
      virtual void notifyRedoEvent(Event* log) = 0;

      /**
       * Triggered when a set of transactions is committed to the undo log.
       *
       * \param log Pointer to an Event describing the committed events.
       */
      virtual void notifyUndoCommitEvent(Event* log) = 0;

      /**
       * Triggered when the undo log is cleared.
       */
      virtual void notifyClearUndoEvent() = 0;

      /**
       * Triggered when the redo log is cleared.
       */
      virtual void notifyClearRedoEvent() = 0;

};

}

#endif

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