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koffice/krita/sdk/kis_canvas_observer.h

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/*
* Copyright (c) 2003 Patrick Julien <freak@codepimps.org>
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef KIS_CANVAS_OBSERVER_H_
#define KIS_CANVAS_OBSERVER_H_
class KisCanvasSubject;
/**
* This is the base interface plugins use to implement the Observer
* design pattern. Observer can register themselves with an implementation
* of KisCanvasSubject. The KisCanvasSubject will then call update()
* on all registered observers whenever something interesting has happened.
*
* (This is something my predecessor should have done with signals and slots,
* I think...)
*/
class KisCanvasObserver {
public:
KisCanvasObserver() {};
virtual ~KisCanvasObserver() {};
public:
/**
* Implement this function to query the KisCanvasSubject implementation
* about state that may be interesting, such as current paint color and
* so on.
*
* @param subject the KisCanvasSubject that may know something that's
* interesting for us.
*/
virtual void update(KisCanvasSubject *subject) = 0;
private:
KisCanvasObserver(const KisCanvasObserver&);
KisCanvasObserver& operator=(const KisCanvasObserver&);
};
#endif // KIS_CANVAS_OBSERVER_H_