fix Canvas::LineSet implementation to support horizontal and vertical linesets

libs/canvas/canvas/fwd.h

@@ -24,6 +24,7 @@
 namespace ArdourCanvas {
 	class WaveView;
 	class Line;
+        class LineSet;
 	class Rectangle;
 	class Polygon;
 	class PolyLine;

libs/canvas/canvas/line_set.h

@@ -17,6 +17,11 @@
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
 
+#ifndef __CANVAS_LINESET_H__
+#define __CANVAS_LINESET_H__
+
+#include <vector>
+
 #include "canvas/visibility.h"
 #include "canvas/item.h"
 
@@ -30,29 +35,33 @@ public:
 		Horizontal
 	};
 
-	LineSet (Group *);
+	LineSet (Group *, Orientation o = Vertical);
 
 	void compute_bounding_box () const;
 	void render (Rect const & area, Cairo::RefPtr<Cairo::Context>) const;
 
         bool covers (Duple const &) const;
 
-	void set_height (Distance);
+	void set_extent (Distance);
+	Distance extent() const { return _extent; }
 
 	void add (Coord, Distance, Color);
 	void clear ();
 
 	struct Line {
-		Line (Coord y_, Distance width_, Color color_) : y (y_), width (width_), color (color_) {}
+		Line (Coord p, Distance width_, Color color_) : pos (p), width (width_), color (color_) {}
 		
-		Coord y;
+		Coord pos;
 		Distance width;
 		Color color;
 	};
 
 private:
-	std::list<Line> _lines;
-	Distance _height;
+	std::vector<Line> _lines;
+	Distance          _extent;
+	Orientation       _orientation;
 };
 
 }
+
+#endif /* __CANVAS_LINESET_H__ */

libs/canvas/line_set.cc

@@ -23,42 +23,57 @@
 using namespace std;
 using namespace ArdourCanvas;
 
-/* XXX: hard-wired to horizontal only */
-
 class LineSorter {
 public:
-	bool operator() (LineSet::Line& a, LineSet::Line& b) {
-		return a.y < b.y;
+	bool operator() (LineSet::Line const & a, LineSet::Line const & b) {
+		return a.pos < b.pos;
 	}
 };
 
-LineSet::LineSet (Group* parent)
+LineSet::LineSet (Group* parent, Orientation o)
 	: Item (parent)
-	, _height (0)
+	, _extent (0)
+	, _orientation (o)
 {
 
 }
 
-
 void
 LineSet::compute_bounding_box () const
 {
 	if (_lines.empty ()) {
 		_bounding_box = boost::optional<Rect> ();
 	} else {
-		_bounding_box = Rect (0, _lines.front().y - (_lines.front().width/2.0), COORD_MAX, min (_height, _lines.back().y - (_lines.back().width/2.0)));
+
+		if (_orientation == Horizontal) {
+			
+			_bounding_box = Rect (0, /* x0 */
+					      _lines.front().pos - (_lines.front().width/2.0), /* y0 */
+					      _extent, /* x1 */
+					      _lines.back().pos - (_lines.back().width/2.0) /* y1 */
+				);
+
+		} else {
+			
+			_bounding_box = Rect (_lines.front().pos - _lines.front().width/2.0, /* x0 */
+					      0, /* y0 */
+					      _lines.back().pos + _lines.back().width/2.0, /* x1 */
+					      _extent /* y1 */
+				);
+		}
 	}
+
 	_bounding_box_dirty = false;
 }
 
 void
-LineSet::set_height (Distance height)
+LineSet::set_extent (Distance e)
 {
 	begin_change ();
 
-	_height = height;
-
+	_extent = e;
 	_bounding_box_dirty = true;
+
 	end_change ();
 }
 
@@ -67,19 +82,42 @@ LineSet::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 {
 	/* area is in window coordinates */
 
-	for (list<Line>::const_iterator i = _lines.begin(); i != _lines.end(); ++i) {
+	for (vector<Line>::const_iterator i = _lines.begin(); i != _lines.end(); ++i) {
 
-		Rect self = item_to_window (Rect (0, i->y - (i->width/2.0), COORD_MAX, i->y + (i->width/2.0)));
-		boost::optional<Rect> intersect = self.intersection (area);
+		Rect self;
+
+		if (_orientation == Horizontal) {
+			self = item_to_window (Rect (0, i->pos - (i->width/2.0), _extent, i->pos + (i->width/2.0)));
+		} else {
+			self = item_to_window (Rect (i->pos - (i->width/2.0), 0, i->pos + (i->width/2.0), _extent));
+		}
+
+		boost::optional<Rect> isect = self.intersection (area);
 			
-		if (!intersect) {
+		if (!isect) {
 			continue;	
 		}
 
+		Rect intersection (isect.get());
+
 		set_source_rgba (context, i->color);
 		context->set_line_width (i->width);
-		context->move_to (intersect->x0, self.y0 + ((self.y1 - self.y0)/2.0));
-		context->line_to (intersect->x1, self.y0 + ((self.y1 - self.y0)/2.0));
+
+		/* Not 100% sure that the computation of the invariant
+		 * positions (y and x) below work correctly if the line width
+		 * is not 1.0, but visual inspection suggests it is OK.
+		 */
+
+		if (_orientation == Horizontal) {
+			double y = self.y0 + ((self.y1 - self.y0)/2.0);
+			context->move_to (intersection.x0, y);
+			context->line_to (intersection.x1, y);
+		} else {
+			double x = self.x0 + ((self.x1 - self.x0)/2.0);
+			context->move_to (x, intersection.y0);
+			context->line_to (x, intersection.y1);
+		}
+
 		context->stroke ();
 	}
 }
@@ -90,7 +128,7 @@ LineSet::add (Coord y, Distance width, Color color)
 	begin_change ();
 	
 	_lines.push_back (Line (y, width, color));
-	_lines.sort (LineSorter ());
+	sort (_lines.begin(), _lines.end(), LineSorter());
 
 	_bounding_box_dirty = true;
 	end_change ();
@@ -108,5 +146,11 @@ LineSet::clear ()
 bool
 LineSet::covers (Duple const & /*point*/) const
 {
+	/* lines are ordered by position along primary axis, so binary search
+	 * to find the place to start looking.
+	 *
+	 * XXX but not yet.
+	 */
+
 	return false;
 }