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diff --git a/src/gui/editors/segment/segmentcanvas/SegmentItemPreview.h b/src/gui/editors/segment/segmentcanvas/SegmentItemPreview.h
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+
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
+
+/*
+    Rosegarden
+    A MIDI and audio sequencer and musical notation editor.
+
+    This program is Copyright 2000-2008
+        Guillaume Laurent   <[email protected]>,
+        Chris Cannam        <[email protected]>,
+        Richard Bown        <[email protected]>
+
+    The moral rights of Guillaume Laurent, Chris Cannam, and Richard
+    Bown to claim authorship of this work have been asserted.
+
+    Other copyrights also apply to some parts of this work.  Please
+    see the AUTHORS file and individual file headers for details.
+
+    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.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#ifndef _RG_SEGMENTITEMPREVIEW_H_
+#define _RG_SEGMENTITEMPREVIEW_H_
+
+#include <qrect.h>
+
+
+class QWMatrix;
+class QPainter;
+
+
+namespace Rosegarden
+{
+
+class Segment;
+class RulerScale;
+
+
+//////////////////////////////////////////////////////////////////////
+class SegmentItemPreview 
+{
+public:
+    SegmentItemPreview(Segment& parent,
+                       RulerScale* scale);
+    virtual ~SegmentItemPreview();
+
+    enum PreviewState {
+        PreviewChanged,
+        PreviewCalculating,
+        PreviewCurrent
+    };
+
+    virtual void drawShape(QPainter&) = 0;
+
+    PreviewState getPreviewState() const { return m_previewState; }
+
+    /**
+     * Sets whether the preview shape shown in the segment needs
+     * to be refreshed
+     */
+    void setPreviewCurrent(bool c)
+    { m_previewState = (c ? PreviewCurrent : PreviewChanged); }
+
+    /**
+     * Clears out the preview entirely so that it will be regenerated
+     * next time
+     */
+    virtual void clearPreview() = 0;
+
+    QRect rect();
+    
+protected:
+    virtual void updatePreview(const QWMatrix &matrix) = 0;
+
+    //--------------- Data members ---------------------------------
+
+    Segment *m_segment;
+    RulerScale *m_rulerScale;
+
+    PreviewState m_previewState;
+};
+
+
+
+}
+
+#endif