add Canvas::Arc and derive Canvas::Circle from it

libs/canvas/arc.cc

@@ -0,0 +1,120 @@
+/*
+    Copyright (C) 2013 Paul Davis
+
+    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.
+*/
+
+#include <algorithm>
+#include <cairomm/context.h>
+#include "pbd/compose.h"
+#include "canvas/circle.h"
+#include "canvas/types.h"
+#include "canvas/debug.h"
+#include "canvas/utils.h"
+#include "canvas/canvas.h"
+
+using namespace std;
+using namespace ArdourCanvas;
+
+Arc::Arc (Group* parent)
+	: Item (parent)
+	, Outline (parent)
+	, Fill (parent)
+	, _radius (0.0)
+	, _arc_degrees (0.0)
+	, _start_degrees (0.0)
+{
+
+}
+
+void
+Arc::compute_bounding_box () const
+{
+	Rect bbox;
+
+	/* this could be smaller in the case of small _arc values
+	   but I can't be bothered to optimize it.
+	*/
+	
+	bbox.x0 = _center.x - _radius;
+	bbox.y0 = _center.y - _radius;
+	bbox.x1 = _center.x + _radius;
+	bbox.y1 = _center.y + _radius;
+
+	bbox = bbox.expand (0.5 + (_outline_width / 2));
+
+	_bounding_box = bbox;
+	_bounding_box_dirty = false;
+}
+
+void
+Arc::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context) const
+{
+	if (_radius <= 0.0 || _arc_degrees <= 0.0) {
+		return;
+	}
+	context->arc (_center.x, _center.y, _radius, _start_degrees * (M_PI/180.0), _arc_degrees * (M_PI/180.0));
+	setup_fill_context (context);
+	context->fill_preserve ();
+	setup_outline_context (context);
+	context->stroke ();
+}
+
+void
+Arc::set_center (Duple const & c)
+{
+	begin_change ();
+
+	_center = c;
+
+	_bounding_box_dirty = true;
+	end_change ();
+}
+
+void
+Arc::set_radius (Coord r)
+{
+	begin_change ();
+	
+	_radius = r;
+
+	_bounding_box_dirty = true;
+	end_change ();
+}	
+
+
+void
+Arc::set_arc (double deg)
+{
+	begin_change ();
+	
+	_arc_degrees = deg;
+
+	_bounding_box_dirty = true;
+	end_change ();
+}	
+
+
+void
+Arc::set_start (double deg)
+{
+	begin_change ();
+	
+	_start_degrees = deg;
+	
+	_bounding_box_dirty = true;
+	end_change ();
+}	
+

libs/canvas/canvas/arc.h

@@ -0,0 +1,63 @@
+/*
+    Copyright (C) 2013 Paul Davis
+
+    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.
+*/
+
+#ifndef __CANVAS_ARC_H__
+#define __CANVAS_ARC_H__
+
+#include "canvas/item.h"
+#include "canvas/outline.h"
+#include "canvas/fill.h"
+
+namespace ArdourCanvas {
+
+class Arc : virtual public Item, public Outline, public Fill
+{
+public:
+	Arc (Group *);
+
+	void render (Rect const & area, Cairo::RefPtr<Cairo::Context>) const;
+	void compute_bounding_box () const;
+
+        void set_center (Duple const &);
+	void set_radius (Coord);
+	void set_arc (double degrees);
+	void set_start (double degrees);
+
+        Duple center() const { 
+		return _center;
+	}
+	Coord radius () const {
+		return _radius;
+	}
+	double arc_degrees () const {
+		return _arc_degrees;
+	}
+        double start_degrees () const {
+		return _start_degrees;
+	}
+
+private:
+        Duple  _center;
+        Coord  _radius;
+        double _arc_degrees;
+        double _start_degrees;
+};
+	
+}
+
+#endif