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diff --git a/src/gvcore/busylevelmanager.h b/src/gvcore/busylevelmanager.h
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+// vim: set tabstop=4 shiftwidth=4 noexpandtab
+/*
+Gwenview - A simple image viewer for KDE
+Copyright 2000-2004 Aurélien Gâteau
+ 
+ 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+*/
+#ifndef BUSYLEVELMANAGER_H
+#define BUSYLEVELMANAGER_H
+
+// Qt
+#include <qtimer.h>
+namespace Gwenview {
+
+// KDE
+#include "libgwenview_export.h"
+
+/*
+ Busy level of the application.
+ Sorted by increasing priority.
+*/
+enum BusyLevel {
+	BUSY_NONE,
+	BUSY_THUMBNAILS,
+	BUSY_PRELOADING,
+	BUSY_LOADING,
+	BUSY_SMOOTHING,
+	BUSY_PAINTING,
+	BUSY_CHECKING_NEW_IMAGE
+};
+
+class LIBGWENVIEW_EXPORT BusyLevelManager : public QObject {
+Q_OBJECT
+public:
+	static BusyLevelManager* instance();
+
+	/**
+	 * Announces that the given object is busy.
+	 */
+	void setBusyLevel( QObject* obj, BusyLevel level );
+
+	/**
+	 * Returns the busy level of the whole application (i.e. maximum).
+	 */
+	BusyLevel busyLevel() const;
+
+signals:
+	/**
+	 * When emitted, operations that are less important than current level
+	 * should be suspended until the level decreases to their level.
+	 * E.g. when loading a picture thumbnail generation should get suspended.
+	 */
+	void busyLevelChanged( BusyLevel level );
+
+private slots:
+	void delayedBusyLevelChanged();
+	void objectDestroyed( QObject* obj );
+
+private:
+	BusyLevelManager();
+	QMap< QObject*, BusyLevel > mBusyLevels;
+	BusyLevel mCurrentBusyLevel;
+	QTimer mDelayedBusyLevelTimer;
+};
+
+
+/**
+  Helper class. Constructor sets its busy level to the given level,
+  destructor resets the busy level to none.
+ */
+class BusyLevelHelper : public QObject {
+Q_OBJECT
+public:
+	BusyLevelHelper( BusyLevel level );
+	~BusyLevelHelper();
+	void reset();
+};
+
+inline
+BusyLevelHelper::BusyLevelHelper( BusyLevel level )
+{
+	BusyLevelManager::instance()->setBusyLevel( this, level );
+}
+
+inline
+void BusyLevelHelper::reset()
+{
+	BusyLevelManager::instance()->setBusyLevel( this, BUSY_NONE );
+}
+
+inline
+BusyLevelHelper::~BusyLevelHelper()
+{
+	reset();
+}
+
+
+} // namespace
+#endif
+