new Lollipop canvas item

libs/canvas/canvas/lollipop.h

@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2012 Carl Hetherington <carl@carlh.net>
+ * Copyright (C) 2013-2014 Paul Davis <paul@linuxaudiosystems.com>
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef __CANVAS_LOLLIPOP_H__
+#define __CANVAS_LOLLIPOP_H__
+
+#include "canvas/item.h"
+#include "canvas/outline.h"
+#include "canvas/poly_line.h"
+#include "canvas/visibility.h"
+
+namespace ArdourCanvas {
+
+/* A line with a circle of radius _radius drawn at (x, max (y0,y1))
+ */
+
+class LIBCANVAS_API Lollipop : public Item
+{
+public:
+	Lollipop (Canvas*);
+	Lollipop (Item*);
+
+	void render (Rect const & area, Cairo::RefPtr<Cairo::Context>) const;
+	void compute_bounding_box () const;
+	bool covers (Duple const &) const;
+
+	void set_radius (Coord);
+	Coord radius() const { return _radius; }
+
+	void set_length (Coord);
+	void set_x (Coord);
+
+	/* Set origin, length, radius in one pass */
+	void set (Duple, Coord, Coord);
+
+	Coord x0 () const {
+		return _points[0].x;
+	}
+	Coord y0 () const {
+		return _points[0].y;
+	}
+	Coord x1 () const {
+		return _points[1].x;
+	}
+	Coord y1 () const {
+		return _points[1].y;
+	}
+
+  private:
+	Duple _points[2];
+	Coord _radius;
+};
+
+}
+
+#endif

libs/canvas/lollipop.cc

@@ -0,0 +1,171 @@
+/*
+ * Copyright (C) 2012 Carl Hetherington <carl@carlh.net>
+ * Copyright (C) 2013-2014 Paul Davis <paul@linuxaudiosystems.com>
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <algorithm>
+#include <cairomm/context.h>
+#include "pbd/compose.h"
+#include "canvas/lollipop.h"
+#include "canvas/types.h"
+#include "canvas/debug.h"
+#include "canvas/utils.h"
+#include "canvas/canvas.h"
+
+using namespace std;
+using namespace ArdourCanvas;
+
+Lollipop::Lollipop (Canvas* c)
+	: Item (c)
+{
+}
+
+Lollipop::Lollipop (Item* parent)
+	: Item (parent)
+{
+}
+
+void
+Lollipop::compute_bounding_box () const
+{
+	Rect bbox;
+
+	bbox.x0 = min (_points[0].x, _points[1].x);
+	bbox.y0 = min (_points[0].y, _points[1].y);
+	bbox.x1 = max (_points[0].x, _points[1].x) + _radius;
+	bbox.y1 = max (_points[0].y, _points[1].y) + _radius;
+
+	bbox = bbox.expand (0.5 + (_outline_width / 2));
+
+	_bounding_box = bbox;
+	set_bbox_clean ();
+}
+
+void
+Lollipop::render (Rect const & /*area*/, Cairo::RefPtr<Cairo::Context> context) const
+{
+	setup_outline_context (context);
+
+	Duple p0 = item_to_window (Duple (_points[0].x, _points[0].y));
+	Duple p1 = item_to_window (Duple (_points[1].x, _points[1].y));
+
+	if (_outline_width <= 1.0) {
+		/* See Cairo FAQ on single pixel lines to understand why we add 0.5
+		 */
+
+		const Duple half_a_pixel (0.5, 0.5);
+		p0 = p0.translate (half_a_pixel);
+		p1 = p1.translate (half_a_pixel);
+	}
+
+	context->move_to (p0.x, p0.y);
+	context->line_to (p1.x, p1.y);
+	context->stroke ();
+
+	/* the circle */
+
+	context->arc (p1.x, p1.y, _radius, 0.0 * (M_PI/180.0), 360.0 * (M_PI/180.0));
+
+	if (fill()) {
+		setup_fill_context (context);
+		if (outline()) {
+			context->fill_preserve ();
+		} else {
+			context->fill ();
+		}
+	}
+
+	if (outline()) {
+		setup_outline_context (context);
+		context->stroke ();
+	}
+}
+
+void
+Lollipop::set_radius (Coord r)
+{
+	if (_radius != r) {
+		begin_change ();
+		_radius = r;
+		set_bbox_dirty ();
+		end_change ();
+	}
+}
+
+void
+Lollipop::set_x (Coord x)
+{
+	if (x != _points[0].x) {
+		begin_change ();
+
+		_points[0].x = x;
+		_points[1].x = x;
+
+		set_bbox_dirty ();
+		end_change ();
+	}
+}
+
+bool
+Lollipop::covers (Duple const & point) const
+{
+	const Duple p = window_to_item (point);
+	static const Distance threshold = 2.0;
+
+	/* this quick check works for vertical and horizontal lines, which are
+	 * common.
+	 */
+
+	if (_points[0].x == _points[1].x) {
+		/* line is vertical, just check x coordinate */
+		return fabs (_points[0].x - p.x) <= threshold;
+	}
+
+	if (_points[0].y == _points[1].y) {
+		/* line is horizontal, just check y coordinate */
+		return fabs (_points[0].y - p.y) <= threshold;
+	}
+
+	Duple at;
+	double t;
+	Duple a (_points[0]);
+	Duple b (_points[1]);
+	const Rect visible (window_to_item (_canvas->visible_area()));
+
+	/*
+	   Clamp the line endpoints to the visible area of the canvas. If we do
+	   not do this, we have a line segment extending to COORD_MAX and our
+	   math goes wrong.
+	*/
+
+	a.x = min (a.x, visible.x1);
+	a.y = min (a.y, visible.y1);
+	b.x = min (b.x, visible.x1);
+	b.y = min (b.y, visible.y1);
+
+	double d = distance_to_segment_squared (p, a, b, t, at);
+
+	if (t < 0.0 || t > 1.0) {
+		return false;
+	}
+
+	if (d < threshold) {
+		return true;
+	}
+
+	return false;
+}