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+// -*- c-basic-offset: 4 -*-
+
+/*
+    Rosegarden
+    A 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 right of the authors to claim authorship of this work
+    has been asserted.
+
+    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 _STAFF_H_
+#define _STAFF_H_
+
+#include "ViewElement.h"
+#include "Segment.h"
+
+#include <iostream>
+#include <cassert>
+
+namespace Rosegarden 
+{
+
+class StaffObserver;
+
+/**
+ * Staff is the base class for classes which represent a Segment as an
+ * on-screen graphic.  It manages the relationship between Segment/Event
+ * and specific implementations of ViewElement.
+ *
+ * The template argument T must be a subclass of ViewElement.
+ *
+ * Staff was formerly known as ViewElementsManager.
+ */
+class Staff : public SegmentObserver
+{
+public: 
+    virtual ~Staff();
+
+    /**
+     * Create a new ViewElementList wrapping all Events in the
+     * segment, or return the previously created one
+     */
+    ViewElementList *getViewElementList();
+
+    /**
+     * Create a new ViewElementList wrapping Events in the
+     * [from, to[ interval, or return the previously created one
+     * (even if passed new arguments)
+     */
+    ViewElementList *getViewElementList(Segment::iterator from,
+                                           Segment::iterator to);
+
+    /**
+     * Return the Segment wrapped by this object 
+     */
+    Segment &getSegment() { return m_segment; }
+
+    /**
+     * Return the Segment wrapped by this object 
+     */
+    const Segment &getSegment() const { return m_segment; }
+
+    /**
+     * Return the location of the given event in this Staff
+     */
+    ViewElementList::iterator findEvent(Event *);
+
+    /**
+     * SegmentObserver method - called after the event has been added to
+     * the segment
+     */
+    virtual void eventAdded(const Segment *, Event *);
+
+    /**
+     * SegmentObserver method - called after the event has been removed
+     * from the segment, and just before it is deleted
+     */
+    virtual void eventRemoved(const Segment *, Event *);
+
+    /** 
+     * SegmentObserver method - called after the segment's end marker
+     * time has been changed
+     */
+    virtual void endMarkerTimeChanged(const Segment *, bool shorten);
+
+    /**
+     * SegmentObserver method - called from Segment dtor
+     */
+    virtual void segmentDeleted(const Segment *);
+
+    void addObserver   (StaffObserver *obs) { m_observers.push_back(obs); }
+    void removeObserver(StaffObserver *obs) { m_observers.remove(obs); }
+
+protected:
+    Staff(Segment &);
+    virtual ViewElement* makeViewElement(Event*) = 0;
+    
+    /**
+     * Return true if the event should be wrapped
+     * Useful for piano roll where we only want to wrap notes
+     * (always true by default)
+     */
+    virtual bool wrapEvent(Event *);
+
+    void notifyAdd(ViewElement *) const;
+    void notifyRemove(ViewElement *) const;
+    void notifySourceDeletion() const;
+
+    //--------------- Data members ---------------------------------
+
+    Segment &m_segment;
+    ViewElementList *m_viewElementList;
+
+    typedef std::list<StaffObserver*> ObserverSet;
+    ObserverSet m_observers;
+
+private: // not provided
+    Staff(const Staff &);
+    Staff &operator=(const Staff &);
+};
+
+class StaffObserver
+{
+public:
+    virtual ~StaffObserver() {}
+    virtual void elementAdded(const Staff *, ViewElement *) = 0;
+    virtual void elementRemoved(const Staff *, ViewElement *) = 0;
+
+    /// called when the observed object is being deleted
+    virtual void staffDeleted(const Staff *) = 0;
+};
+
+
+
+}
+
+#endif
+