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diff --git a/libs/canvas/canvas/arrow.h b/libs/canvas/canvas/arrow.h
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+/*
+    Copyright (C) 2011 Paul Davis
+    Author: Carl Hetherington <cth@carlh.net>
+
+    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., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+/** @file  canvas/arrow.h
+ *  @brief Declaration of the Arrow canvas object.
+ */
+
+#ifndef __CANVAS_ARROW_H__
+#define __CANVAS_ARROW_H__
+
+#include "canvas/visibility.h"
+
+#include "canvas/group.h"
+
+namespace ArdourCanvas {
+
+class Line;
+class Polygon;
+
+/** A composite item which draws a line with arrow heads
+ *  at either or both ends.
+ *
+ *  The arrow heads are identified by the indices 0 and 1;
+ *  head 0 is at the (x0, y0) end of the line, and head 1
+ *  at the (x1, y1) end.
+ *
+ *  @todo Draws vertical lines only; could be generalised
+ *  to draw lines at any angle.
+ */
+	
+class LIBCANVAS_API Arrow : public Group
+{
+public:
+	Arrow (Group *);
+
+	void set_show_head (int, bool);
+	void set_head_outward (int, bool);
+	void set_head_height (int, Distance);
+	void set_head_width (int, Distance);
+	void set_outline_width (Distance);
+	void set_color (Color);
+
+	Coord x () const;
+	Coord y1 () const;
+
+	void set_x (Coord);
+	void set_y0 (Coord);
+	void set_y1 (Coord);
+	
+        bool covers (Duple const &) const;
+
+private:
+	void setup_polygon (int);
+
+	/** Representation of a single arrow head */
+	struct Head {
+		Polygon* polygon; ///< the polygon which represents its shape
+		bool show;        ///< true if this head should be visible
+		bool outward;     ///< true if this head points out from the line
+		Distance height;  ///< the height of the head
+		Distance width;   ///< the maximum width of the head
+	};
+
+	/** our arrow heads; _heads[0] is at the (x0, y0) end of the line,
+	 *  and _heads[1] at the (x1, y1) end.
+	 */
+	Head _heads[2];
+
+	/** our line */
+	Line* _line;
+};
+
+}
+
+#endif