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diff --git a/src/base/LayoutEngine.h b/src/base/LayoutEngine.h
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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 _LAYOUT_ENGINE_H_
+#define _LAYOUT_ENGINE_H_
+
+#include "RulerScale.h"
+
+namespace Rosegarden {
+
+class Staff;
+class TimeSignature;
+
+
+/**
+ * Base classes for layout engines.  The intention is that
+ * different sorts of renderers (piano-roll, score etc) can be
+ * implemented by simply plugging different implementations
+ * of Staff and LayoutEngine into a single view class.
+ */
+class LayoutEngine
+{
+public: 
+    LayoutEngine();
+    virtual ~LayoutEngine();
+
+    /**
+     * Resets internal data stores for all staffs
+     */
+    virtual void reset() = 0;
+
+    /**
+     * Resets internal data stores for a specific staff.
+     * 
+     * If startTime == endTime, act on the whole staff; otherwise only
+     * the given section.
+     */
+    virtual void resetStaff(Staff &staff,
+                            timeT startTime = 0,
+                            timeT endTime = 0) = 0;
+
+    /**
+     * Precomputes layout data for a single staff, updating any
+     * internal data stores associated with that staff and updating
+     * any layout-related properties in the events on the staff's
+     * segment.
+     * 
+     * If startTime == endTime, act on the whole staff; otherwise only
+     * the given section.
+     */
+    virtual void scanStaff(Staff &staff,
+                           timeT startTime = 0,
+                           timeT endTime = 0) = 0;
+
+    /**
+     * Computes any layout data that may depend on the results of
+     * scanning more than one staff.  This may mean doing most of
+     * the layout (likely for horizontal layout) or nothing at all
+     * (likely for vertical layout).
+     * 
+     * If startTime == endTime, act on the whole staff; otherwise only
+     * the given section.
+     */
+    virtual void finishLayout(timeT startTime = 0,
+                              timeT endTime = 0) = 0;
+
+    unsigned int getStatus() const { return m_status; }
+
+protected:
+    unsigned int m_status;
+};
+
+
+class HorizontalLayoutEngine : public LayoutEngine,
+                               public RulerScale
+{
+public:
+    HorizontalLayoutEngine(Composition *c);
+    virtual ~HorizontalLayoutEngine();
+
+    /**
+     * Sets a page width for the layout.
+     *
+     * A layout implementation does not have to use this.  Some might
+     * use it (for example) to ensure that bar lines fall precisely at
+     * the right-hand margin of each page.  The computed x-coordinates
+     * will still require to be wrapped into lines by the staff or
+     * view implementation, however.
+     *
+     * A width of zero indicates no requirement for division into
+     * pages.
+     */
+    virtual void setPageWidth(double) { /* default: ignore it */ }
+
+    /**
+     * Returns the number of the first visible bar line on the given
+     * staff
+     */
+    virtual int getFirstVisibleBarOnStaff(Staff &) {
+        return  getFirstVisibleBar();
+    }
+
+    /**
+     * Returns the number of the last visible bar line on the given
+     * staff
+     */
+    virtual int getLastVisibleBarOnStaff(Staff &) {
+        return  getLastVisibleBar();
+    }
+
+    /**
+     * Returns true if the specified bar has the correct length
+     */
+    virtual bool isBarCorrectOnStaff(Staff &, int/* barNo */) {
+        return true;
+    }
+
+    /**
+     * Returns true if there is a new time signature in the given bar,
+     * setting timeSignature appropriately and setting timeSigX to its
+     * x-coord
+     */
+    virtual bool getTimeSignaturePosition
+    (Staff &, int /* barNo */, TimeSignature &, double &/* timeSigX */) {
+        return 0;
+    }
+};
+
+
+
+class VerticalLayoutEngine : public LayoutEngine
+{
+public:
+    VerticalLayoutEngine();
+    virtual ~VerticalLayoutEngine();
+
+    // I don't think we need to add anything here for now
+};
+
+}
+
+
+#endif