fix drawing of a canvas LineSet object

diff --git a/libs/canvas/line_set.cc b/libs/canvas/line_set.cc
index bc2c2c100a61dc313d89a657bf54a0cc6ee0dd0f..dc9f54e10b7adad5aff5949d28cdac95d77789ca 100644 (file)
--- a/libs/canvas/line_set.cc
+++ b/libs/canvas/line_set.cc
@@ -45,11 +45,9 @@ LineSet::compute_bounding_box () const
 {
        if (_lines.empty ()) {
                _bounding_box = boost::optional<Rect> ();
-               _bounding_box_dirty = false;
-               return;
+       } 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)));
        }
-       
-       _bounding_box = Rect (0, _lines.front().y, COORD_MAX, min (_height, _lines.back().y));
        _bounding_box_dirty = false;
 }
 
@@ -71,23 +69,18 @@ LineSet::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 
        for (list<Line>::const_iterator i = _lines.begin(); i != _lines.end(); ++i) {
 
-               Duple self = item_to_window (Duple (area.x0, i->y));
-
-               if (self.y > area.y1) {
-                       /* line is past the ymax for the render rect, nothing
-                          to draw 
-                       */
-                       break;
-               } else if (self.y > area.y0) {
-                       /* line is between ymin and ymax for the render rect,
-                          draw something.
-                       */
-                       set_source_rgba (context, i->color);
-                       context->set_line_width (i->width);
-                       context->move_to (area.x0, self.y);
-                       context->line_to (area.x1, self.y);
-                       context->stroke ();
+               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);
+                       
+               if (!intersect) {
+                       continue;       
                }
+
+               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));
+               context->stroke ();
        }
 }